All posts © Rosa Rubicondior. Contents may be reproduced without permission provided credit is given to the author, it is not altered in any way, the context is made clear and a link is provided to the original.

Income generated from ads will be donated to various charities such as moderate centre-left groups, humanist, humanitarian and wildlife protection and welfare organisations. Hopefully religious and other offensive advertising content has now been blocked from this site. Please let me know if you see any.

Thursday, 31 July 2014

More Evolved Mimicry

This is my last blog for a while on the fascinating topic of mimicry in animals and plants. Previously I wrote about Batesian and Müllerian mimicry in Copycat Evolution and More Mimetic Evolution where a harmless species comes to resemble a harmful one and so gains protection from a predator which has learned to avoid the harmful one (Batesian), or two harmful species come to resemble one another and so gain from the evolutionary 'spade-work' of the other (Müllerian).

Now I'm going to look at another form of mimicry where (usually) a plant deceives another species into thinking its something else, not to repel or avoid it, but to attract it. Almost invariably this improves pollen or spore distribution so it's not hard to understand how any improvement in this system gave the plant an advantage and so natural selection favoured it.

Perhaps the most famous are the orchids which resemble female bees or wasps to attract males of the mimicked species which try to mate with them. In doing so, the bees pick up a packet of pollen (a pollinia) which they deposit on the stigma of the next flower they try to mate with. There is also selection pressure on the orchid to resemble their 'victims' more closely and other species less closely otherwise there would be a good probability of the pollen being carried to the wrong species. So, different species of orchid tend to specialise on one type of bee or wasp.


Mirror Bee Orchid - Ophrys speculum
Bumblebee Orchid - Ophrys bomybliflora
Sombre Bee-orchid - Ophrys fusca

Yellow Bee-orchid - Ophrys lutea
Source: Wikipedia - Ophrys

Although many cases of plant mimicry don't appear to harm the duped victim particularly, and there are several instances where they are actually rewarded with food, in these examples of bee mimicry there is probably a cost to the duped male in that they waste sperm on the flower and waste reproductive effort which may be costly in terms of breeding success. So there is probably selection pressure on these bees to be able to distinguish the flower from the real thing. This in turn produces selection pressure on the orchid to perfect the mimicry, hence the often stunningly detailed result. The system is intimately bound up with the reproduction of both species so natural selection will be especially acute forcing the orchid to become as perfect a mimic as is possible but if it became so good that the bee species's survival became threatened then any further improvement might be counter-productive, so we would expect a dynamic to be produced in which bees are fooled often enough for the flowers to get pollinated but not so often that the bees breeding success is unduly affected.


Monkey-faced orchid - Dracula simia
As I mentioned in Copycat Evolution mimicry needs to be seen from the point of view and with the perception of the intended victim of the deception. It's easy to be fooled into thinking something which resembles something else is some sort of mimicry. This example is known as monkey-faced orchids because, to humans with our pattern recognition which tends to see faces in anything remotely resembling a face, it looks a bit like a monkey face. Monkeys play no part in pollination nor does the face act as some sort of deterrent as with Batesian mimicry, so the orchids derive no discernible benefit from this false mimicry.

I've seen this example held up as proof of intelligent design - how they like to find 'proof' everywhere. If anything, it's an example of pointless, stupid design since it serves no special purpose as the face of a monkey. It is a trick of human perception, like so many 'proofs' of intelligent design. It's also a cultivated variety, bred specially to look more like a monkey face for it's novelty value. Such is the 'proof' of intelligent design.

Above: Dendrobium sinense
Below: Vespa bicolor with pollinia.
Mimicry is not confined to visual mimicry. I pinched this especially devious example from the splendid website Why Evolution Is True. The hornet Vespa bicolor hunts bees which produce an alarm pheromone to warn other bees in a typical evolved act of altruism whereby genes sacrifice a few of themselves to ensure the survival of lots more copies of themselves in the other bees of which they are genetic clones - not that there is any conscious decision in this. The hornet has evolved the ability to detect this pheromone. How the orchid Dendrobium sinense has evolved to exploit this was revealed in a paper published a 2009:

Summary
Approximately one-third of the world's estimated 30,000 orchid species are deceptive and do not reward their pollinators with nectar or pollen. Most of these deceptive orchids imitate the scent of rewarding flowers or potential mates. In this study, we investigated the floral scent involved in pollinator attraction to the rewardless orchid Dendrobium sinense, a species endemic to the Chinese island Hainan that is pollinated by the hornet Vespa bicolor. Via chemical analyses and electrophysiological methods, we demonstrate that the flowers of D. sinense produce (Z)-11-eicosen-1-ol and that the pollinator can smell this compound. This is a major compound in the alarm pheromones of both Asian (Apis cerana) and European (Apis mellifera) honey bees and is also exploited by the European beewolf (Philanthus triangulum) to locate its prey. This is the first time that (Z)-11-eicosen-1-ol has been identified as a floral volatile. In behavioral experiments, we demonstrate that the floral scent of D. sinense and synthetic (Z)-11-eicosen-1-ol are both attractive to hornets. Because hornets frequently capture honey bees to feed to their larvae, we suggest that the flowers of D. sinense mimic the alarm pheromone of honey bees in order to attract prey-hunting hornets for pollination.



Conclusions
Orchids show a remarkable variation of floral forms and a high diversity in pollination systems. Nonrewarding flowers are widespread among Orchidaceae, and deceptive orchid species are well known for their specific pollination systems in which only one or a few animal species are attracted. Orchid species pollinated by social wasps are rare, and most of them offer edible rewards or are assumed to mimic food. The pollination system that we have found in the orchid D. sinense represents another fascinating example of chemical mimicry in deceptive pollination. By emitting volatiles indicating the presence of prey, the flower is capable of attracting its pollinator, the foraging social wasp V. bicolor.


On the subject of scent mimicry, a common form is to imitate the smell of dung or rotting flesh to attract dung beetles and flies. The rotting flesh smell of the flowers of the Stapelia are so realistic that blowflies actually lay eggs on them.

A flower which uses this deception is the arum lily (Arum maculatum) also known in the UK as the cuckoopint or Jack-in-the-pulpit and very common in woods and hedges. Using the highly specialised purple structure, the spadix, A. maculatum increases its metabolism to generate enough heat to vaporize a volatile odour substance which smells of rotting flesh. Flies which land on the slippery spathe slip down into the flower chamber at the base of the spathe and through a ring of downward pointing hairs which prevent their escape. They are kept alive with nectar from the female flowers and during the night the male flowers in a ring towards the top of the chamber, produce pollen which the insects transfer onto the female flowers as the try to escape.

Stinkhorn - Phallus impudicus
The timing of this whole sequence is coordinated by the male flowers which release a substance which initiates the production and vaporization of the special odour 6-8 hours before they mature. Once the female flowers have been pollinated the hairs trapping the flies shrink and shrivel up, releasing the flies unharmed.

Stinkhorn mushroom of the genus Phallus attract carrion-feeding flies which feed on the gelatinous covering of the cap which contains spores. These pass through the flies digestive system unharmed and so get dispersed widely.

My last example is one which I find amazing. It is that of the group of mosses of the genus Splanchnum which not only emit the smell of rotting flesh but also have structures resembling the flowers of flowering plants.

Yellow moose-dung moss - Splanchnum luteum
Given that flowering plants (Angiosperms) are assumed to have evolved out of the 'lower' plants such as mosses, liverworts and ferns, leading to the co-evolution of pollinating insects, it is intriguing to think that mosses have short-circuited that whole evolutionary process and now mimic flowers from Angiosperms in order to attract those insects that co-evolved to pollinate them.

Although having evolved as a group far earlier than the flowering plants did, this mimicry can only have evolved after both flowering plants and pollinating insects had evolved. And of course the group has diversified to produce several different flower-like structures to correspond with the preferences of different insects.

This is a beautiful example of an environmental opportunity being exploited by mindless, trial and error evolution and of the information carried by genes only having any meaning when interpreted by their environment. There could have been no possible adaptive advantage for mosses to evolve flower-like structures if there had not been both flowers and pollinating insects in their environment, just as there would be no advantage to orchids to resemble female bees in the absence of male bees, or stinkhorns, Stapelia flowers and cuckoopints mimicking rotting flesh in the absence of flesh to rot and flies to feed and lay eggs on it, or to smell of animal dung in the absence of animals and dung beetles.

There are of course other forms of mimicry which I haven't touched on in this series - maybe a future blog - such as camouflage where a predator is hidden by cryptic colouring or a potential prey resembles a leaf or dead twig, or even a bird dropping, or where the animal is almost invisible against a given background and can even change to resemble it, such as octopuses and chameleons.

All of this can be easily and readily understood as the product of 'selfish' evolution over time, evolutionary arms races, competition for resource and between predator and prey. There is no morality, no direction, no purpose and no sentimentality involved and yet beneficial alliance can and do evolve when it produces more descendants than conflict and competition.

None of this can be explained rationally using an intelligent design model involving an omnibenevolent, omnipotent and omniscient designer. The last thing biology is evidence for is intelligent design, and to dismiss it all as magic simply so you can claim to understand it from a position of ignorance and just so you can feel a nice warm glow of self-importance in the thought that somehow it's all there for you, is to fail to see the real wonder in life on Earth and to experience the real humility of finding out how you fit in with it all.


submit to reddit

Tuesday, 29 July 2014

Murmuring Starlings Do It Naturally.

Decisions ripple through flocks of birds like a wave - physics-math - 27 July 2014 - New Scientist

One of the most spectacular sites in nature in Britain is a winter 'murmuration' of starlings, and I'm fortunate enough to live just a short drive from the open stretch of moorland north of Oxford known as the Otmoor, now a wonderful RSPB-owned nature reserve and important inland wetland site, where this spectacle can be seen most winter evenings at sunset in suitable weather.

Watch these videos first, then I'll discuss them. The first was filmed over Otmoor, the second at Gretna in Scotland.

The most noticeable thing is how the flock seems to move and flow like a single organism, almost as though the birds are obeying a single consciousness with decisions to change direction being almost instantly transmitted to each individual. This has led people to speculate about some sort of telepathy between the members of the flock.

One can almost hear Deepak Chopra declaring to his credulous followers that 'Quantum Cosmic Consciousness' or some such meaningless gibberish explains how everything from flocks of starlings to shoals of fish and even herds of wildebeest and reindeer are all coordinated.

That is, of course, a delusion and simply illustrates how people look for simplistic answers without being too concerned about whether it's the right one. It seems more important to some people to settle for any answer than to have the uncertainty of not knowing and having to admit that to others, or even to themselves. It's the same psychological process which allows people to settle for a 'God did it!' answer to any scientific mystery, and even to things which are actually not scientific mysteries but the science is hard to understand or doesn't give the required confirmation of pre-existing bias.

But what we are witnessing in these spectacular displays is actually something quite basic and fundamental in science. We are seeing how a few simple, natural rules can give rise to apparent order from chaos. It had been assumed that each starling in the flock tries to maintain a discrete space around itself and reacts almost instantly to the position of the five starlings closest to it, so a change in one part of the flock is quickly transmitted across the flock.

Now a new study by a team from Rome, which is noted for its murmurations of starlings, has shown that this is only part of the story. Decisions to change direction appear to be made by a small group of birds flying close to one another as though merely being close triggers a change of direction. This is not always the same birds as there is no formal leader, but can be initiated by any small group that finds itself flying closely together. It's as though the entire dynamics of the group are finely balanced and can flip with a small change, like any system in true chaos or a system subject to quantum fluctuation. In effect we are seeing the result of a law of mass action.

Abstract
Collective decision-making in biological systems requires all individuals in the group to go through a behavioural change of state. During this transition fast and robust transfer of information is essential to prevent cohesion loss. The mechanism by which natural groups achieve such robustness, however, is not clear. Here we present an experimental study of starling flocks performing collective turns. We find that information about direction changes propagates across the flock with a linear dispersion law and negligible attenuation, hence minimizing group decoherence. These results contrast starkly with present models of collective motion, which predict diffusive transport of information. Building on spontaneous symmetry breaking and conservation-law arguments, we formulate a theory that correctly reproduces linear and undamped propagation. Essential to this framework is the inclusion of the birds’ behavioural inertia. The theory not only explains the data, but also predicts that information transfer must be faster the stronger the group’s orientational order, a prediction accurately verified by the data. Our results suggest that swift decision-making may be the adaptive drive for the strong behavioural polarization observed in many living groups.


It's not magic, just basic physics and gives a clue to how information flows through any such dynamic system. The speed of information transfer depends on the degree of orientational order, or, in layman's terms, how parallel they are flying to one another. Those flying parallel to the turning group will turn fastest; this flying at an angle to them will react less strongly, and so on. A wave of change thus propagates through the flock spreading out from the original center. Meanwhile, other small groups will be initiating another change all of their own and the closer the flock becomes concentrated the more ordered will be their orientation so the more quickly they will change. A diffuse part of the group will change less quickly.

As Dylan Winter says in his commentary to the Otmoor video, this flock behaviour has probably evolved for two reasons - to warm up the birds before settling down to roost and as a flight display by which the fittest males establish their supremacy in the flock and so their entitlement to the best perches. And a single bird in a mass of wheeling and changing identical birds is much less likely to be the subject of an attack from a predator such as a peregrine falcon, which will find it difficult to home in on any particular individual. If you look carefully at the Gretna video you can see a peregrine falcon make repeated unsuccessful dives into the flock. The same bird could probably take a single, isolated starling in flight with consummate ease.

The lesson here are three-fold:

  • There is never any need to invoke magic or exotic hypotheses to explain natural phenomena. If the answer is currently not yet known this does not mean it is unknowable. A gap in our understanding does not indicate a gap in the natural order of things; it simply means we haven't worked it out yet.
  • Order can emerge from chaos by the operation of a few simple rules. There is no consciousness or intent required. Order emerges perfectly naturally and inevitably, and quite contrary to one of the favourite lies of creation pseudo-scientists that order cannot come from chaos.
  • The order itself has no real significance. Simply because we recognise a 'design' or a pattern - which we are especially prone to doing - does not mean there was any intent to produce that 'design'. Whatever emerges from chaos will look like a design. In the case of murmurating starlings, we see organic shapes moving and responding like living, flowing organisms do, or at least how we can imagine they do if they were large enough, and so it's easy to assume there must be a consciousness controlling it and an intent to make those shapes in the sky.
The answer is much more interesting than magic, even if it is more difficult to understand. Simple explanations are for simple people who aren't bothered about the truth, and for frauds to sell to simple people so they don't need to think for themselves.

Just like religion in fact. And I've probably given Deepak Chopra an idea for his next million-dollar book.

'via Blog this'

submit to reddit

Monday, 28 July 2014

More Mimetic Evolution

Having blogged a couple of days ago about the role of mimicry in evolution I decided to look more closely at the subject, especially the widespread mimicry found in butterflies. The results are fascinating.

But before I get on to that I just deal quickly with another aspect to evolution - speciation - following on from something I mentioned in the same blog. I pointed out how mimicry involved a two species both of which are prey to the same predator and where at least one of them is toxic or harmful to the predator. I mentioned that the selection pressure for one species to become more and more like the harmful one depends on the presence of the predator in the local environment but the species range may well include areas with different predators, different comimics or indeed the absence of one or both. In this case, and in that part of the range there may be no selection pressure and no particular advantage in adopting the colour pattern of the toxic or harmful species, and there may even be a disadvantage because a different predator my not have any aversion to the mimicked colour.

So, let's take a hypothetical example of a widespread species coexisting in part of its range (we'll call it Area A) with both a toxic comimic and a predator with an aversion to the comimic. In a different part of the range (which we'll call Area B) there may be a different predator and the comimic may be absent. Yet there is nothing to prevent the genes for mimicry flowing from Area A into Area B where they might well act as advertisements rather than deterrents. After all, what's the point of protective mimicry if it isn't conspicuous?

In Area B then, these genes could be being removed from the gene-pool by Natural Selection and there would be a distinct advantage in any mutations which prevented the population in Area B from acquiring genes for mimicry. For example, individuals which selected against potential mates with the mimicry pattern would tend to produce more descendants with that selection preference than those which didn't discriminate, so sex selection and mating displays would come to feature in Area B. These genes would in turn be detrimental as they flowed back to Area A because their carriers would now have genes preventing their offspring acquiring the protective mimicry in Area A.

The environment, together with Natural Selection, would have created the conditions in which it is to both colour varieties' advantage to prevent interbreeding and to evolve barriers to it. In this situation we would expect the two gene-pools to quickly become effectively isolated from one another, or, to put it in taxonomic terms, two new species would have diverged from one original species.

This of course is a simplistic scenario. In reality, and especially with a widespread population, the situation may be far more complex with more than one comimic presenting different levels of risk to predators, more than one predator, overlapping predator ranges, etc, etc., so the result might be a whole range of intermediates, distinct colour forms predominating in different parts of the range and yet not enough environmental pressure for barriers to gene flow to arise.

Creationists tell us that it is impossible for a new species to arise by evolution because they have been fed the lie by creationist pseud-scientists that there is a fundamental difference in the mechanism by which a species changes over time due to changes in its genome, and the mechanism by which gene-pools become effectively isolated with barriers to interbreeding. I would like a creationists therefore to explain to me how the mechanism I have described above by which genes for mimicry are acquired in one part of the range and barriers to the spread of those genes into a different part of the range is fundamentally different and why one is perfectly possible and the other is impossible. During what stage does the mechanism change as the species evolves from allowing full interbreeding to full gene-pool isolation and how does that mechanism then become impossible retrospectively when previously it was perfectly possible? Surely there is a creationist site where this is fully explained, isn't there?

Anyway, on the subject of mimicry in butterflies, scientists have recently discovered that, at least in the Asian swallowtail butterfly, Papilio polytes, wing shape, colouration and pattern are all controlled by a single 'supergene', i.e., a group of genes all physically grouped together on a chromosome making cross linking less likely and so tending to all be inherited together as a single package. Moreover, they have discovered that this supergene is a modified form of another supergene called the doublesex gene which controls sexual dimorphism in butterflies. At some point in their evolutionary history, probably close to the point of divergence of butterflies from the silk moths this gene became doubled so one copy was free to mutate and evolve without being detrimental to the doublesex gene's function.

Abstract
One of the most striking examples of sexual dimorphism is sex-limited mimicry in butterflies, a phenomenon in which one sex—usually the female—mimics a toxic model species, whereas the other sex displays a different wing pattern. Sex-limited mimicry is phylogenetically widespread in the swallowtail butterfly genus Papilio, in which it is often associated with female mimetic polymorphism. In multiple polymorphic species, the entire wing pattern phenotype is controlled by a single Mendelian 'supergene'. Although theoretical work has explored the evolutionary dynamics of supergene mimicry there are almost no empirical data that address the critical issue of what a mimicry supergene actually is at a functional level. Using an integrative approach combining genetic and association mapping, transcriptome and genome sequencing, and gene expression analyses, we show that a single gene, doublesex, controls supergene mimicry in Papilio polytes. This is in contrast to the long-held view that supergenes are likely to be controlled by a tightly linked cluster of loci. Analysis of gene expression and DNA sequence variation indicates that isoform expression differences contribute to the functional differences between dsx mimicry alleles, and protein sequence evolution may also have a role. Our results combine elements from different hypotheses for the identity of supergenes, showing that a single gene can switch the entire wing pattern among mimicry phenotypes but may require multiple, tightly linked mutations to do so.

K. Kunte, W. Zhang, A. Tenger-Trolander, D. H. Palmer, A. Martin, R. D. Reed, S. P. Mullen and M. R. Kronforst;
doublesex is a mimicry supergene;
Nature 507, 229–232 (13 March 2014) doi:10.1038/nature13112

So, at least in this swallowtail butterfly, a single supergene controls the form of mimicry the carrier will have and, because this is tied in with the gene controlling gender expression, mimicry is limited to females.

Papilio Polytes MorphComimic Species
Morph cyrus. Either male or female.
No comimic species. Sexes are alike.
Morph stichius. Female.
Common rose Pachliopta aristolochiae
Morph romulus. Female.
Crimson rose Pachliopta hector

Distribution of the different morphs of Papilio Polytes females corresponds closely with that of the comimic species of Pachliopta.

PLATE XV
CENTRAL AND SOUTH AMERICAN BUTTERFLIES
From Mimicry in Butterflies by Reginald Crundall Punnett

  1. Heliconius mirus
  2. Heliconius telchinia
  3. Heliconius eucrate
  4. Heliconius pardalinus
  5. Heliconius splendens
  6. Mechanitis elisa
  7. Mechanitis saturata
  8. Mechanitis lysimnia
  9. Mechanitis egaensis
  10. Mechanitis methona

In this group from South America, each species of Heliconius has a corresponding comimic in the Mechanitis genus.

PLATE VII
TROPICAL AFRICAN BUTTERFLIES
From Mimicry in Butterflies by Reginald Crundall Punnett

  1. Planema macarista (male)
  2. Planema macarista (female)
  3. Planema tellus
  4. Planema paragea
  5. Planema epaea
  6. Pseudacraea eurytus (male)
  7. Pseudacraea eurytus (female)
  8. Pseudacraea eurytus
  9. Elymnias phegea (female)
  10. Papilio cynorta (female)

Note that each of the top three morphs of Pseudacraea eurytus has a mimic, even mimicking the sexual dimorphism seen in the top two. This linkage of sexual dimorphism and mimicry type reflects the fact that the supergenes for both are closely related and controlled in the same way. A female will also inherit the female mimicry supergene and the male will inherit the male one. These supergenes, although in different species have remained relatively stable in the way they are arranged and in how they express since early in the evolutionary history of butterflies. This can also mean that there is not a whole array of genes which need to evolve as mimicry develops but the entire change can be due to a small number of changes or even a single 'switch'.

Mimicry is by no means confined for insects or course. The following shows Müllerian mimicry in poisonous South American frogs. The top row are all members of the same species (Dendrobates imitator) which have evolved in different areas to resemble other poisonous species.

Above: regional morphs of Pseudacraea eurytus
Dendrobates variabilisDendrobates fantasticusDendrobates ventrimaculatus

With Mülarian mimicry, two harmful species come to resemble one another as a kind of spread bet. The display is conspicuous and each benefits from a predator's aversion to the other.

Coralsnake and a scarlet kingsnake.
Source: http://www.knewance.com/comparisons/coral-snake-v-milk-snake-v-scarlet-kingsnake.html
My last example of mimicry, this time Batesian mimicry where a harmless species gains protection from resembling a dangerous one is the coralsnake and scarlet kingsnake. Remember here that not all of the potential predators on the harmless coralsnake will have colour vision and neither snake will always be seen in perfect lighting or for more than a fraction of a second, so any resemblance, no matter how approximate, will give the coralsnake some protection.

There is of course absolutely no way evolved mimicry can be fitted into an intelligent design model because it is entirely dependent on wasteful competition, predation and avoidance. There is no intelligent reason to design a predator to prey on one species (even if we forget the supposed benevolence) and then design the prey to deter the predator from eating it, and without this need for deterrence there is no reason for the prey to be toxic in the first place so no benefit would accrue from mimicking it.

The only rational explanation for mimicry in living things is as the result of a mindless, purposeless, evolution over time directed only by an unemotional natural selection which results in the genes of those which leave the most descendants coming to predominate in the species local gene-pool. In their advocacy of intelligent design, creationists pseudo-scientists betray one of two things: an ignorance of the subject on which they expound with feigned expertise or a disregard for truth, honesty and integrity. As even devout Old Earth Creationist, Francis Collins pointed out in an otherwise thoroughly dishonest book, The Language of God, Young Earth Creationism (i.e, those who advocate ID and try to have it inserted into school science curricula in pursuit of an extremist political agenda) have reached a point of moral and intellectual bankruptcy, both in it's science and in it's theology.


submit to reddit

Sunday, 27 July 2014

Recent Evolution - That Old Chestnut

Horse chestnut leaves infested with Cameraria ohridella lavae.
If you live in Southern England, for an example of very recent evolution you probably only need walk to your nearest horse chestnut tree. I took this photograph near Sunningwell, Oxfordshire earlier on Saturday when we went out for a last distant look at Didcot Power Station, which is probably England's best-loved 'eyesore' but which is due to disappear in a cloud of dust in a few hours time. The chances are that by now your nearest horse chestnut tree will be becoming infested with the leaf-miner caterpillars of a moth which was unknown before 1985 when the first outbreak was recorded in Macedonia, Greece.

Since then, Cameraria ohridella has spread at an average of 60 Km per year across western Europe reaching England in 2002, where it is now widespread, causing the leaves of horse chestnut trees (Aesculus hippocastanum) to turn brown, wither and fall off by late summer. Devastating though this attack appears, the general health of the trees seems not to be unduly affected since they come back into leaf and grown normally the following spring.

Although this moth was a newly-discovered species in 1985, specimens of it were accidentally collected and pressed in botanical specimens as early as 1879 only to be rediscovered when a team of researchers carried out a systematic search of specimens stored in herbaria.

Abstract
Determining the native geographic range or origin of alien invasive species is crucial to developing invasive species management strategies. However, the necessary historical dimension is often lacking. The origin of the highly invasive horse-chestnut leaf-mining moth Cameraria ohridella has been controversial since the insect was first described in 1986 in Europe. Here, we reveal that herbarium collections across Europe indicate a Balkan origin for C ohridella. We successfully amplified nuclear DNA and mitochondrial DNA barcode fragments from larvae pressed within leaves of herbarium samples collected as early as 1879. These archival sequences confirm an identity of C ohridella and set back its history in Europe by more than a century. The herbarium samples uncovered previously unknown mitochondrial haplotypes and locally undocumented alleles, showing local outbreaks of C ohridella back to at least 1961 and dynamic frequency changes that may be associated with road development. This case history demonstrates that herbaria are greatly underutilized in studies of insect–plant interactions, herbivore biodiversity, and invasive species' origins.

David C Lees, H Walter Lack, Rodolphe Rougerie, Antonio Hernandez-Lopez, Thomas Raus, Nikolaos D Avtzis, Sylvie Augustin, and Carlos Lopez-Vaamonde 2011.
Tracking origins of invasive herbivores through herbaria and archival DNA: the case of the horse-chestnut leaf miner.
Frontiers in Ecology and the Environment 9: 322–328. http://dx.doi.org/10.1890/100098

Spread of C ohridella from the Balkans.
Examination of the DNA from these preserved specimens shows that there have been two or three significant changes which have almost certainly caused the sudden explosion of this moth from its probable homeland in the Balkans, one of them genetic and two environmental. The interesting thing about the genetic change is that it seems to have been in the mitochondrial DNA.

Of the thirty known mitochondrial haplotypes occurring in the Balkans, only three, known as A, B and C are known to have moved into the rest of Europe of which haplotype A is the dominant form. This probably represents a new haplotype which somehow has enabled C ohridella to colonise new environments, something which may have been aided by a succession of years of above average temperature and below average rainfall across Europe. However, hot dry weather as such does not seem to suit the moth judging by its failure so far to invade the Iberian Peninsula.

The second environmental change which may have facilitated the initial expansion out of the Balkans was increased road building - the moths are known to be transported accidentally by road goods vehicles.

So we have an example of a genetic change, in the presence of fortuitous environmental change, leading to a massive increase in population and range of a species but seemingly restricted to just three of the thirty mitochondrial haplotypes and predominantly just one of them. This illustrates the founder effect, in which a small, and therefore genetically unrepresentative, founder population moves out of its normal range into new territory and then moves quickly out into the new territory by a process which increases the proportion of the alleles which facilitated the expansion in the first place, so, for example, the genetic profile of C ohridella in, say, southern England, may be very different to that in the Balkans.

And so we have an example of evolution in progress as the allele frequency in different parts of the range changes and adapts to environmental change and opportunity, and Britain now faces late summers with an important amenity tree becoming disfigured and unsightly and losing most of its leaves by late August.

However, the explosion of C ohridella into western Europe is also an environmental change which other species can exploit. It is now becoming a major food source for blue tits (Parus caeruleus), great tits (Parus major) and marsh tits (Parus palustris) which are learning to extract them from the leaves and are now believed to account for 2 to 4 percent of lavae.

It has also created a potential new resource for parasitic wasps to exploit. The prediction is that a generalised parasitic wasp will 'discover' this new resource and will become a major predator so bringing about a degree of population control of a species which currently appears to be limited only by the availability of horse chestnut trees.


submit to reddit

Friday, 25 July 2014

Copycat Evolution

Which ones would you pick up?
A friend asked me the other day to explain how mimicry can play a role in evolution. This is my attempt to do so.

There are in fact two main types of mimicry recognised by biologists, although the distinction is quite technical and is blurred anyway. For all practical purposes, they can both be regarded as forms of the same thing. They are known to biology as:

  • Batesian mimicry. Named after the English naturalist Henry Walter Bates. This is where a harmless species evolves to resemble a harmful species if it and the harmful species share a common predator.
  • Müllerian mimicry. Named after the German biologist Fritz Müller. This is where two harmful species evolve to resemble one another if they both share a common predator.

The distinction is further complicated by the fact that the mimicry is seen from the point of view of the predator and need not be too readily apparent to a human eye. It is also quite possible for the same species to be a Batesian mimic in respect of one predator and a Müllerian mimic in respect of another. Seeing the mimicry from the predator's point of view is obviously key to understanding how mimicry works. Bear in mind also that a predator might not have colour vision so whatever works in shades of grey will suffice. Some predators may even see in ultraviolet or infrared, so mimicry can be operating outside our own perception altogether.

Key to understanding how it evolves is understanding the fundamental basis of evolution - natural selection incidentally 'favouring' those small variations which produce more descendants so the genes for those small variations increase throughout the population's gene-pool over time and no matter how unlikely the original mutation was, it will become increasingly common in the gene-pool.

You also need to understand the basic economics of the trade off between the risk of being bitten by a poisonous snake, getting badly stung by a wasp or bee, being poisoned by eating a poisonous meal or even being eaten by another predator, and getting a meal. In almost every case the 'cost' to the predator of being killed, injured or made sick is far greater than the cost of missing a meal so the tendency will be for the predator to be highly risk-averse. Where the predator has alternative food, the evolutionary pressure on it to improve its ability to tell the mimic from the comimic might not be that strong so the mimic gets away with only a passing resemblance. This difference is reflected in the different intensity of selection pressure on predator and prey.

Although once thought to be an example of Batesian mimicry, it has recently been discovered that the viceroy butterfly (top) is actually more unpalatable than the monarch butterfly (bottom), making this a case of Müllerian mimicry.
Imagine a situation in which a harmless fly is preyed on by a bird which is also a potential predator on a stinging wasp. The bird will quickly learn to avoid anything that resembles a wasp. Indeed, over time, it may even have evolved a natural reflex avoidance so it doesn't even need to learn by experience.

Imagine now a few flies in the population occasionally having a mutation which, for example, gives them a yellow tip to their abdomen or a yellow stripe across the centre of it, or maybe a yellow thorax - anything which a bird in some situations might mistake for a wasp. This will give the mutant form a slight edge over the normal forms so it will leave more descendants on average than the normal form and the mutation will, over time, become the norm in the population. It's easy to see how even something that works in poor lighting or only on those birds at the lower end of the range of visual acuity for the population - maybe the oldest or the youngest - and the environment will slightly favour the mutant flies.

It's now in the interests of the bird's genes for it to learn to tell this mutation from real wasps, otherwise its former food supply will not be available to it, so natural selection will favour bird genes which enable the bird to tell the difference. Meanwhile, there will now be renewed selection pressure on the fly to overcome this recognition ability by even more closely resembling a wasp. And so we have a classic arms race developing which is driving the fly ever more closely to resemble the wasp and the bird to become ever better at telling the difference. However, the bird may well also have alternative prey species so there is far less selection pressure on it than there is on the fly. The bird only misses a mean and has an alternative; the fly loses its life and fails to pass its genes on.

For another example of this, see Seeing Eye To Eye With A Butterfly, an earlier blog of mine on how the peacock butterfly came to have what look like mammalian eyes on its wings.

Mimicry need not be confined to visual mimicry either. Some bats find the taste of tiger moths distasteful and tiger moths have evolved to produce a sound audible to bats when they hear the bat's echolocatory signals so the bats avoid them. Some other insects have now evolved to mimic these tiger moth sounds. There may be a whole world of auditory mimicry of which we are hardly aware, including in the sea and rivers where dolphins use echolocation extensively.

What we have here of course is the classical situation of a change in the environment of one species being caused by a change in another. In the absence of a predatory bird, yellow stripes on a fly could not have meant, "Avoid me I might be a wasp". In the absence of wasps, they might have meant, "Look! Here I am!", to a predator with no reason to distrust yellowish things, and so would have been quickly removed from the gene-pool. The same mutation with the same information can have entirely different meanings in different environments and the meaning is constantly changing in a dynamic environment.

The same mutation can either be advantageous, detrimental or neutral entirely dependent on environmental context. This could even hold true for the same species with a continuous gene-pool over a wide geographical range, so evolutionary pressures favouring one mutation in one part of the range could be countered by different pressures favouring the normal gene in a different part of the range, so a gradient or 'cline' can develop giving geographical variation in the same species. And of course it's always possible that a species now has a pattern evolved millions of years ago in the presence of a long-extinct predator or a long-extinct comimic. Since colours don't fossilise well we may never know what benefit the species got from a particular pattern when it first evolved it, so it may not be recognised even as evolved mimicry.

It's probably too easy a target to point out how none of this makes any sense as the design of an intelligent designer, since each side of an arms race only makes sense when seen from the narrow perspective of one side or the other, never both, so I'll just challenge creationists to explain how mimicry can be explained in terms of intelligent design by a benevolent designer and how the change in meaning of information by environmental change fits in with the creationist dogma that no new information can arise by mutation.


submit to reddit

Thursday, 24 July 2014

Evolution Arms Race - Moose Spit Detox

Ungulate saliva inhibits a grass–endophyte mutualism

A fascinating example of both evolutionary cooperation and an evolutionary arms race was published in Royal Society Biology Letters yesterday.

Abstract*

Fungal endophytes modify plant–herbivore interactions by producing toxic alkaloids that deter herbivory. However, studies have neglected the direct effects herbivores may have on endophytes. Antifungal properties and signalling effectors in herbivore saliva suggest that evolutionary pressures may select for animals that mitigate the effects of endophyte-produced alkaloids. Here, we tested whether saliva of moose (Alces alces) and European reindeer (Rangifer tarandus) reduced hyphal elongation and production of ergot alkaloids by the foliar endophyte Epichloë festucae associated with the globally distributed red fescue Festuca rubra. Both moose and reindeer saliva reduced the growth of isolated endophyte hyphae when compared with a treatment of distilled water. Induction of the highly toxic alkaloid ergovaline was also inhibited in plants from the core of F. rubra's distribution when treated with moose saliva following simulated grazing. In genotypes from the southern limit of the species' distribution, ergovaline was constitutively expressed, as predicted where growth is environmentally limited. Our results now present the first evidence, to our knowledge, that ungulate saliva can combat plant defences produced by a grass–endophyte mutualism.

Andrew J. Tanentzap, Mark Vicari, and Dawn R. Bazely; Ungulate saliva inhibits a grass–endophyte mutualism
Biol. Lett. July, 2014 10 7 20140460; doi:10.1098/rsbl.2014.0460 1744-957X

The team from the Department of Plant Sciences, University of Cambridge, UK and the Department of Biology, York University, Toronto, Canada were specifically looking for evidence that Moose and Reindeer could counteract the defence mechanism which some grasses have evolved in cooperation with a fungus. The fungus is known to produce the highly toxic alkaloid ergovaline which can cause, amongst other things, hooved animals to lose their hooves.

If these animals continually graze the same plants, then it would be quite beneficial. We are still uncovering novel roles for saliva"

Gary Felton, Penn State University, Pennsylvania, USA
They found evidence that moose saliva not only significantly reduced the concentration of ergovaline by between 41% and 70% but it also inhibited a signalling system whereby grazing the grass stimulates growth of the fungus and so the production of the toxin. This is one of the few example discovered so far of a vertebrate being able to do what some insects are known to do - chemically influence the metabolism of a plant. It has also been shown that sheep saliva can stimulate growth in at least one grass, Leymus chinensis.

The fascinating things here are the example of mutualism, whereby a fungus has formed a mutually beneficial association with a grass to defend the grass against being eaten, and the example of an arms race where the species this defence evolved against has evolved a counter-measure.

First the cooperative, or symbiotic alliance:

Epichloë species and their close relatives, the Neotyphodium species, are systemic and constitutive symbionts of cool-season grasses (Poaceae subfamily Pooideae), and belong to the fungal family Clavicipitaceae. Among the Clavicipitaceae, many species are specialized to form and maintain systemic, constitutive (long-term) symbioses with plants, often with limited or no disease incurred on the host.[1] The best-studied of these symbionts are associated with the grasses and sedges, in which they infect the leaves and other aerial tissues by growing between the plant cells (endophytic growth) or on the surface above or beneath the cuticle (epiphytic growth). An individual infected plant will generally bear only a single genetic individual clavicipitaceous symbiont, so the plant-fungus system constitutes a genetic unit called a symbiotum (pl. symbiota).


The evolution of symbiosis probably goes through a stage of parasitism. In this case a fungal infection of grass. However, if something produced by the parasite benefits the host more than the parasite harms it, the host genes which help ensure the parasite is not attacked will do better than those which attack it, so the host will evolve tolerance rather than resistance. Meanwhile, the parasite genes which increase the benefit and/or reduce the harm will also prosper at the expense of those which do the opposite. Hence, the parasite will also tend to evolve towards cooperation with the host and parasitism will move towards symbiosis.

This is all readily understandable in terms of what benefits the genes of both parties. Cooperation serves the 'selfish' needs of both sets of genes.

Red fescue
The other aspect is the arms race between this mutually evolved defence mechanism which clearly benefits the grass by deterring herbivores from grazing it and both the moose and the reindeer which needs to eat a large volume of vegetation, especially the males which depend on a large size and large antlers to defend their females against other males and which feature in female sex selection, so needing a good supply of nutrients including calcium.

As the authors of this paper point out, the endophytic fungus probably originated some 30-40 million years ago and accompanied the grass as they became the dominant plant type about 10 million years later. This was followed by the evolution of large herbivores which diversified into the new niches provided by grasslands. This in turn would have provided a selective pressure on the fungus to maximise the persistence of their hosts.

Meanwhile, some larger herbivores would have been diversifying yet again to occupy niches found in forests, so leaving the grass-eating herbivores with no alternatives and high selection pressure to evolve counter-measures. The classic conditions for an evolutionary arms race and again fully understandable in terms of 'selfish' genes and a natural selection process which ensures those best able to survive and reproduce are the ones who leave the most descendants.

What is not at all understandable is how either this evolution of mutualism or the evolutionary arms race can be explained in terms of the work of an intelligent designer. Why would an intelligent designer design parasites in the first place, so creating the initial conditions for mutualism to evolve in which the parasite needs to defend its host because if its host get eaten, it gets eaten too? If an intelligent designer wanted to protect grass from being eaten by herbivores, why did it also create herbivores, and it it didn't want the herbivores to eat grass, why did it give them the mechanism for doing so?

Similar arguments apply to the notion of intelligent design and arms races. Ultimately, arms races are about two mutually hostile systems coexisting and needing to run to stand still because each is creating a hostile environment for the other and so selection pressure to overcome it. Arms races are ultimately to neither side's benefit and yet are entirely predictable. As a piece of design, arms races such as that between the grass-fungus complex and the moose, are manifestly stupid, lacking both foresight and ultimate purpose.

Creationist proponents of the notion of intelligent design need to explain parasitism, mutualism and arms races. Evolutionary biologists, on the other hand, have a perfectly rational, easily understood and well-evidenced explanation for them. They are all entirely predicted from the basic principles of evolution by natural selection.

*Copyright © 2014, The Royal Society

'via Blog this'

submit to reddit

Wednesday, 23 July 2014

Around the Bend with Ken Ham

2 January 2013: Astronomers have determined that the Milky Way may contain as many as 400 billion exoplanets, with almost every star hosting at least one planet.
"We'll find a new earth within 20 years" | Around the World with Ken Ham

Signs that Ken Ham may be beginning to panic at the thought that science could soon find evidence of life on another planet emerged recently with this desperate attempt to harness his fundamentalist audience in a bid to stop NASA looking for it, dismissing it as a waste of money which is bound to fail. His panic can be gaged from the horrible muddle he gets into with his argument where he inadvertently 'proves' that there isn't non-human life on Earth either.

He also showed his traditional propensity for making things up, even about the Bible, and relying on his ignorant audience not checking.

I'm shocked at the countless hundreds of millions of dollars that have been spent over the years in the desperate and fruitless search for extraterrestrial life. Even Bill Nye "the Science Guy," in our recent debate, happily gloated about tax dollars being spent toward this effort. And now, secular scientists are at it again.

Of course, secularists are desperate to find life in outer space, as they believe that would provide evidence that life can evolve in different locations and given the supposed right conditions! The search for extraterrestrial life is really driven by man's rebellion against God in a desperate attempt to supposedly prove evolution!

Judging by Hamster's snide swipe at him, it seems too that he may still be smarting at his recent public humiliation at the hands of Bill Nye "the Science Guy" in a widely publicised TV debate, which even many conservative Christians thought Nye had won.

How does Hamster know the search for evidence of life on the ever-expanding number of exoplanets (i.e planets orbiting other suns) will be fruitless? The Bible says so, of course.

The only problem is, he claims the Bible says things it simply doesn't say, even if what the Bronze-Age authors who believed Earth was flat, has a single landmass and a dome over it (Genesis 1:6-10) thought had any relevance. For example:

And I do believe there can't be other intelligent beings in outer space because of the meaning of the gospel. You see, the Bible makes it clear that Adam's sin affected the whole universe. This means that any aliens would also be affected by Adam's sin, but because they are not Adam’s descendants, they can't have salvation.

Er... actually Ken, the Bible says almost exactly the opposite.

Unto the woman he said, I will greatly multiply thy sorrow and thy conception; in sorrow thou shalt bring forth children; and thy desire shall be to thy husband, and he shall rule over thee.

And unto Adam he said, Because thou hast hearkened unto the voice of thy wife, and hast eaten of the tree, of which I commanded thee, saying, Thou shalt not eat of it: cursed is the ground for thy sake; in sorrow shalt thou eat of it all the days of thy life; Thorns also and thistles shall it bring forth to thee; and thou shalt eat the herb of the field; In the sweat of thy face shalt thou eat bread, till thou return unto the ground; for out of it wast thou taken: for dust thou art, and unto dust shalt thou return.

And Adam called his wife's name Eve; because she was the mother of all living.

Unto Adam also and to his wife did the Lord God make coats of skins, and clothed them. And the Lord God said, Behold, the man is become as one of us, to know good and evil: and now, lest he put forth his hand, and take also of the tree of life, and eat, and live for ever: Therefore the Lord God sent him forth from the garden of Eden, to till the ground from whence he was taken.

Genesis 3:16-23

No mention there that Adam's 'sin' affected the whole Universe or even the whole world. In fact, no awareness that there actually was a Universe. The only other species which seems to have been affected is the 'serpent' which gets a curse. There is only the merest hint even that this 'sin' is to be inherited by Adam's descendents even. It's certainly not spelled out with the certainty that Christian fundamentalists like to imagine.

But even if Ken's private version of his 'Holy Bible' were true, wouldn't this apply equally to non-human life on Earth as he says it does to hypothetical life on other planets? Mind you, even Hamsters carefully cultured ignorance of biology would need to go into overdrive to help him pretend there isn't non-human life on Earth, even if the logic of his own argument says there shouldn't be any.

And who was talking about intelligent life anyway? Is Ken preparing an escape hatch here just incase his prophecy is as phoney as that of Ezekiel when he prophesied the destruction of Egypt (Ezekiel 30:10-11) which history shows never happened? Will we be treated to a future creationist fraud confidently telling his audience that only intelligent life is actually living so the living things on other planets don't count?

Ham hasn't thought this through, has he. He's even forgotten now why he had to pretend the Bible said Adam's 'sin' affected the whole Universe. Now he's explaining why it only affected humans. Here he goes again:

Only descendants of Adam can be saved. God’s Son remains the "Godman" as our Savior. In fact, the Bible makes it clear that we see the Father through the Son (and we see the Son through His Word). To suggest that aliens could respond to the gospel is just totally wrong.

An understanding of the gospel makes it clear that salvation through Christ is only for the Adamic race—human beings who are all descendants of Adam.

So, Jesus isn't the saviour of anything non-human so Ken concludes that it can't exist. Er... Ken! Jesus isn't a "Godelephant" or a "Godbacterium" or even a "Godchimpanzee" either. Should we conclude then that elephants, bacteria and chimpanzees don't exist because Jesus can't save them?

In typical Hamster style, he can't help tell a lie about science and what science's aims are either. Remember, Ham's primary mission is to discredit the science he knows is undermining the very foundations of his wealth faith.

Of course, secularists are desperate to find life in outer space, as they believe that would provide evidence that life can evolve in different locations and given the supposed right conditions!



Many secularists want to discover alien life hoping that aliens can answer the deepest questions of life: "Where did we come from?" and "What is the purpose and meaning of life?"

Secularists = scientists, eh? And how would finding life on another planet answer those questions, anyway? Ken wants his audience to think those questions somehow obsess 'secularists' (scientists) because we don't have his glib platitude to save us the bother of asking.

The Creator has told us where we came from: "In the beginning God created the heavens and the earth" (Genesis 1:1; Nehemiah 9:6). And He told us what life's purpose is: "Fear God and keep His commandments" (Ecclesiastes 12:13).

In fact I know of no branch of biology which concerns itself with 'why' questions. There is no reason to suppose there is any purpose for the Universe, for planets or for life on them. These are the stuff of philosophy, charlatan clerics and creationist pseudo-scientists claiming to be able to answer a non question for an audience not too bothered about truth so long as they get a nice warm glow of smug self-importance.

And we know that life arose on Earth by virtue of the simple observation that there are living things on Earth, just as we know that raindrops form in clouds because we can see them. The only thing we are not yet sure of in both cases is the precise details of how it happened and, quite frankly, if we ever find out it will make not one iota of difference to anything very much, so there is no real reason to devote significant time and resource to it. The discovery of a plausible mechanism for abiogenesis will make even less difference to biology than the discovery of the precise details of how raindrops form in a cloud will make to the science of hydrology.

Ken knows the answers of course, because he has it on the authority of ignorant, pre-wheel Bronze-Age people who believed the highest mountains were about forty-five feet high (Genesis 7:19-20), that the sun and moon were lamps hanging from a dome over the Earth (Genesis 1:16-17), that green plants were made before there was sunlight (Genesis 1:11-19) and Heaven was above the stars directly above the Middle-East and within reach of a manmade tower (Genesis 11:1-9). But then Ken Ham is in the business of selling easy answers to ignorant people who are less concerned with truth than with having simple certainties and an authority figure to give them a gloss of respectability.

At least we can see Ken Ham's real worry here - the thought that if life is found on another planet it will show that, in the right conditions, abiogenesis can occur, and if it can occur on another planet it could have occurred on Earth. And so much of creationism depends on their audience swallowing the lie that this is impossible, so creating an unfillable gap in which to sit their god. Ham's 'faith' looks a little shaky on this point.

But to show that life can arise in the right conditions we don't need to find intelligent life or even multicellular life, though that would be good. We don't even need to discover very complex life. All we need to discover is something capable of replicating and of using energy to maintain a degree of order so overcoming the tendency towards disorder, because at its most fundamental level, this is all that life is.

One thing we can be sure of though is that if a simple replicator has arisen on another planet, and has been replicating for a few billion years, as it has on Earth, it will have evolved and diversified and adapted as its home planet changed because this is the inevitable result of a selective environment inevitably selecting in favour of those minor variations in replicators best able to produce the most descendants.

Ken Ham knows this, hence his rather too transparently desperate attempt to stop us finding it out, even needing to invent 'evidence' from the Bible that simply isn't there.

And people still give him money.

'via Blog this'

submit to reddit

Monday, 21 July 2014

The Sacred Conclusion

Most theists will deny that they do it but it's usually easy to demonstrate that religious beliefs are not based an objective assessment of the evidence but on a received conclusion which is then protected and reinforced by highly selective cherry-picking of the evidence which is often heavily weighted whilst contradictory evidence is minimised, ignored or dismissed on spurious grounds.

'Evidence' can even include assumed evidence such as that 'list of eyewitnesses of the life of Jesus', 'all those fulfilled prophecies in the Bible which have been independently verified', or, in the case in point, 'all the historical names, places and events' mentioned in the Bible. Nothing wrong with these as examples of evidence, of course, apart from just one thing - they are all false. There are no authenticated eyewitness of the life of Jesus; there are no fulfilled prophecies in the Bible which can be independently verified and there are no historical names, places or events in the Bible which give it an authenticity as a holy book.

Quite the contrary, in fact. There are a couple of potential eyewitnesses to the life and acts of Jesus yet none of them mention him. None of the claimed list of authors actually do in ways which have any relevance as a historical source; there are very many demonstrably unfulfilled prophecies in the Bible, and many specific historical events and places mentioned are demonstrably wrong or are simple facts which would have been known to anyone such as the names of major cities and countries, the names of Kings or Roman governors and emperors that anyone writing a story claiming it to be true would have used. Does the name of London and Paris and the historical fact of the French Revolution render the novel A Tale of Two Cities by Charles Dickens a historical source document or the mention of Athens, Sparta, Troy and Macedonia turn Greek myths and gods into historical facts?

www.skepticalraptor.com
This is all, of course, an example of what Peter Boghossian calls 'doxastically closed'. The conclusion comes first and the 'evidence' is filled in later from wherever it can be gleaned without too much attention being paid to its authenticity. It fits the conclusion so it must be right because the conclusion is right. Above all, even the possibility of the conclusion being wrong must not be considered. The conclusion is immune to reason.

This can be easily tested and demonstrated by observing what happens when you show the claimed supporting evidence is false. Just as with a science when the previously accepted evidence for a theory is shown to be false, the intellectually honest - Peter Boghossian's 'doxastically open' - response should be to change the conclusion. In other words, when the evidence changes the honest thing to do is to change one's mind. Is this what we see in religious people?

Take a look at this exchange from Facebook. My original post to the 'Why Atheism?' group was:

Theists! If it's rational to believe the claims in your favourite holy book made by people you've never met, why is it not rational to believe the claims in other holy books made by people you've never met?

The following exchange ensued:

NM: At face value you could be addressing Hindus, asking why Hindus don't believe claims in the Bible... Actually they do. They claim Jesus as their own.

RR: I WAS addressing Hindus. Hindus are theists too. How about you give an honest answer the question instead of avoiding it?

NM: the claims in my "favorite holy book" made by people I've never met contain actual historical names, places and events. The claims in other holy books made by people I've never met do not contain actual historical names, places and events.

Okay, so the Quran does... But it's a plagiarization of my favorite holy book anyway.

RR: Where may we see the verified extra-biblical historical evidence which validates the Bible in ways no other holy book can be validated, please? Hint: the Bible is not evidence of it's own validity.

NM: Name me something historical that's also in the Bible and I'll do a search for you.

RR: Nope. YOU made the claim; YOU prove it. Did you not bother to check first? Do you remember who lied to you?

RR: So you believe the Bible because of all the verified historical facts in it - except you can't think of any and explain how they were verified, by whom and where we can see the evidence, eh?

Now you know the basis for your belief is false, will you be changing your belief or just thinking of some more arguments for it?
MN: I'll ask one last time before I give it up. Name me something historical that's also in the Bible and I'll do a search for you.

RR: Nope. If you can't prove your claim it fails by default. How about answering my question about what you do now your claimed basis for your belief in the Bible has been shown to be baseless? Do you do the intellectually honest thing and change your belief or do you try to think of another reason for it like someone too afraid to change their mind would?

RR: Aaaaand.... no answer.


A confident claim, made on the assumption that it must be true, presumably because he's been told it's true, as evidence that the Bible is unique amongst holy books and the only one to have such roof of authenticity, and yet he can't think of an example nor how it was authenticated. He doesn't actually know what he believes proves his faith; he only thought he knew it. His 'proof' had never even been tested!

And all he has is the desperate demand that I help him with his search or even go look for the evidence for him. The usual excuse to break off the debate quickly follows.

So, does our Christian fundamentalist change his mind, having been forced to confront the fact that his declared 'proof' is false? Of course not. He makes an excuse, assigns blame, guilt and responsibility to me and flounces off. He'll be on another Facebook group soon, offering the same proof and using the same tactic when called on it. It's no different to the insistent claims that there is no evidence for evolution; there is masses of evidence for the existence of God/Allah or that Atheists are rapists and murderers. There is no connection between the belief and reality and given the choice, between belief and reality, reality will be dismissed. It's all a test of faith!

The conclusion is sacred so facts must be ignored.


submit to reddit

Thursday, 17 July 2014

No Bread of Heaven for Creationism

Fiendish wheat genome reveals grain's history : Nature News & Comment

It's been another bad week for the Intelligent Design industry. No wonder their secretive five year 'Wedge Strategy' is now well into it's sixteenth year, during which the number of non-believers in the USA has gone up from about 4% to about 20%, conservative Christianity has become the preserve of the white right fringe and court after court has thrown out their attempts to subvert the Constitution and smuggle fundamentalist Christian extremism into the US public school system disguised as science.

As I explained in a recent blog about the genome of the Norwegian spruce (Christmas tree), one of their lines of attack on Darwinian Evolution is that it always moves from the simple to the more complex - something they imagine they can prove to be impossible with a misrepresentation of the Laws of Thermodynamics. They also habitually misrepresent evolution theory as a theory about the origin of humans. This parody puts humans at the top of some notional 'ladder of evolution' with lesser species arranged on the rungs below and making it look like the TOE says one species (represented by a single animal) spontaneously mutated into another in a single act of speciation (curiously, whilst leaving obligatory fossilised examples of 'transitional forms' as it did so).

So, taking these two together, creationist pseudo-scientists are in effect arguing the the TOE claims that humans are the most complex of all species being the most highly evolved. Evolution theory says nothing of the sort, of course. It's simply that creationists have constructed a ludicrous straw man to attack rather than deal with the real Theory of Evolution. More to the point, the idea that in increasingly complex genome means an increasingly complex organism is nonsensical.

Now, following on from the revelation that the Norwegian spruce has a genome seven times larger than that of humans and a functional (i.e. protein-coding) genome almost twice the size of our 17,000 functional genes, we have news that bread wheat (Triticum aestivum) has a genome more than five times as large as the human one.

Wheat got its large genome by a different route to that of the Christmas tree where the cause was a normally-corrected mistake in the DNA copying mechanism common to most species but in which the error-correction mechanism is broken too. So, over about 120 million years the Christmas tree has been accumulating an ever-expanding genome all to no discernible purpose. Not only would a hypothetical designer have made a fundamental error in the DNA copying mechanism but it would also have designed a broken mechanism for correcting its earlier error.

In the case of wheat, the genome came about by a doubling of the number of chromosomes to give a tetraploid form (i.e., one with four copies of each chromosome instead of the normal two) when two related normal diploid species hybridized to give a new species. This form then hybridized in another rare example of spontaneous speciation by hybridization when the tetraploid form again hybridized with another related diploid form to give a hexaploid genome containing six copies of each of seven chromosomes, giving 42 chromosomes in all divided into six sub-genomes. This is believed to have happened somewhere in the Tigris-Euphrates valley and was the environmental change which probably enabled wheat-based agriculture and urbanization to occur. Bread wheat now feeds 30% of the worlds people and provides 20% of our calories. I've already blogged about this rare example of evolution by hybridization so I'll resist the temptation to upset creationists with is again.

I'll simply point out how the example of bread wheat with its hugely complex genome not only represents all the problems for creationism that I outlined with the Christmas tree example but also gives the lie to another of their lines of attack - the idiotic claim that mutations are always harmful and so Natural Selection will never have an advantageous mutation to 'favour'. Given that bread wheat has six copies of every gene without even considering any gene duplication within each sub-genome, all these spare copies are free to mutate without having any detrimental effect whatsoever. If, however, one of these mutations gives a significant advantage, Natural Selection will ensure it spreads throughout the genepool.

Yes, it's been another bad week for creationism. They must pray for the day when scientists stop producing all this evidence against their daft notion.

'via Blog this'

submit to reddit

ShareThis

Related Posts Plugin for WordPress, Blogger...
Web Analytics