Thursday, 29 May 2014

Closing The Gaps - Early Bird Shows Evolution

The fossil bird with its revealing stomach contents (insert)
Credit: © Senckenberg
Eocene fossil is earliest evidence of flower-visiting by birds

We have an interesting discovery reported this week in Biology Letter of a fossil bird which seems to be the earliest known avian nectar-feeder. It shows how evolution is driven by environmental opportunity as diversifying species move into and exploit the opportunities offered by new and evolving niches as the ecosystem they are part of develops, and how cooperation is at least as likely an outcome as are arms races and competition as 'selfish' genes are selected naturally because they produce more descendants.

Two researches, Gerald Mayr of the Ornithological Section and Volker Wilde of the Palaeobotanical Section, of Senckenberg Research Institute and Natural History Museum Frankfurt, Germany have cooperated in examining a fossil bird (Pumiliornis tessellatus) from the middle Eocene of Messel found at Messel, Germany and have shown it to almost certainly be the first known example of a nectivorous bird.

It has long been recognised that flowering plants or angiosperms, and nectar-feeding insects co-evolved as symbiotic relationships - the insects get nectar and the plants get their pollen spread to other flowers of the same species. This process minimises the waste of untargeted wind-blown pollen dispersal and the environmental restrictions of using motile male gamete found in lower plants such as mosses, ferns and liverworts, all of which require a damp environment so the motile gametes have something to swim in.

It's easy to understand how this system could have evolved from crawling insects and ground-hugging plants to flying insects and the wide rage and form of flowering plants now free to move into drier habitats. All this took place prior to the 160 million years ago from when we have the first definite fossil record of flowering plants which are believe to have diverged from the gymnosperms 240-202 million years ago. The major period of rapid diversification seems to have been around 120 million years ago.

Pollen grains in the stomach.
See original paper for explanation.
Meanwhile, the first true birds were diverging from the theropod dinosaurs about 150 million years ago, so they grew up with flowering plants, so so speak, and these provided them with the same ecological niche some insects had moved into, most notably and probably initially a wasp from which the bees have evolved. It's not surprising therefore that some birds such as the humming birds moved into this niche becoming smaller and more bee-like in the process (as incidentally, some other insects such as moths and butterflies, have).

Abstract
Birds are important pollinators, but the evolutionary history of ornithophily (bird pollination) is poorly known. Here, we report a skeleton of the avian taxon Pumiliornis from the middle Eocene of Messel in Germany with preserved stomach contents containing numerous pollen grains of an eudicotyledonous angiosperm. The skeletal morphology of Pumiliornis is in agreement with this bird having been a, presumably nectarivorous, flower-visitor. It represents the earliest and first direct fossil evidence of flower-visiting by birds and indicates a minimum age of 47 million years for the origin of bird–flower interactions. As Pumiliornis does not belong to any of the modern groups of flower-visiting birds, the origin of ornithophily in some angiosperm lineages may have predated that of their extant avian pollinators.

Mayr. G. & Wilde. V.; Eocene fossil is earliest evidence of flower-visiting by birds; Biol. Lett. May 2014 vol. 10 no. 5 20140223; doi: 10.1098/rsbl.2014.0223

As the authors point out, this fossil only provides a minimum estimate for the evolution of ornithophilous (literally, bird-loving) plants but no pre-Eocene plants show any of the characteristics of ornithophilous plants and no earlier avian fossils show adaptation to a nectivorous diet. There is also an interesting reference to the remains of small insects amongst the pollen grains in the bird's stomach, possibly ingested accidentally, as occurs with present-day nectar feeders. However, this could give a clue about the evolution of nectar-feeding in this particular bird having possibly evolved from foraging for insects especially those exploiting the supply of nectar.

I wonder if creationists are able to explain why every single fossil meshes so neatly into our understanding of how evolution works, what it produces and the time-scale over which it operates, and never ever supports their special creation by magic a few thousand years ago notion. Every single discovery seems to be closing the gaps in which they try to fit their ever-shrinking little gods. That should be enough to convince any normal person that their daft notion is wrong, or at least to sow a few seeds of doubt about the wisdom and knowledge of the technologically backward and scientifically illiterate Bronze-Age hunter-gatherers who believed in magic and who came up with it in the first place.

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3 comments :

  1. Do you ever get any responses from creationists?

    Well, here's my explanation: Cthulhu did it! Prove me wrong.

    Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn! Ia! Ia!" :D

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  2. But, Rosa, you must understand that creationists aren't - in your own words - "normal person[s]". ;o)

    They are almost - yes, I dare say ALWAYS - (next to) impossible to convince. Believe me. I've tried. Too. Like you. And never succeeded. Always in vain.

    I often link to your blog, Rosa, when discussing and debating with woos here in Sweden. But I've understood that most woos can be characterized by having serious difficulties reading and understanding written articles in the English language (yes, Swedish woos unfortunately often have the same problems understanding the Swedish language, their mother tongue).

    Maybe their brain's problem with processing verbal information contributes to their lack of understanding knowledge based on logic and facts? Maybe that's why woos are so immune to logic, logical reasoning, hard facts and so on? Do you agree, Rosa?

    The other day I read an article, which seems to explain why it is so: http://mindhacks.com/2014/05/26/the-best-way-to-win-an-argument/ . And here's another one: http://www.yale.edu/cogdevlab/aarticles/IOED%20proofs.pdf%201.pdf .

    The bottom line in both articles seems to be that woos believe they understand the mechanisms of evolution in detail, but of course they don't. Instead they indulge themselves in oversimplified deductive reasoning, built on emotions and wishful thinking. A sort of shortcut thinking (by professor Daniel Kahneman called emotional system #1-thinking or fast thinking).

    So a good tactic for a skeptic discussing with woos would then be to ask the woos to explain their own reasoning, step by step, using a causal thought model. Then - hopefully - the woo will gain the insight that his/her thought and belief paradigm is built upon the sand of faith instead of knowledge/facts. And, possibly, start to listen to the skeptics.

    I end this comment by citing a great quote you yourself used in another blog article quite recently, Rosa:

    If one had sufficient evidence to warrant belief in a particular claim, then one wouldn’t believe the claim on the basis of faith . “Faith” is the word one uses when one does not have enough evidence to justify holding a belief, but when one just goes ahead and believes anyway. - Boghossian, Peter in A Manual for Creating Atheists (Kindle Locations 309-311). Pitchstone Publishing. Kindle Edition.




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    Replies
    1. As Peter Boghossian says in 'A Manual for Creating Atheists' fundamentalists have started from their conclusion and then looked for supporting evidence. They've become convinced that they are right and that faith is a better way to determine truth than looking at the evidence. He calls it 'doxastic closure'. The key to getting through to them is to get them to question their faith in faith.

      See Starting From The Conclusion

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