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| Indigobird, Vidua chalybeata |
A couple of papers recently illustrate just how far a malevolent designer must have gone to create the conditions for parasites to thrive in, if we are to believe intelligent [sic] design advocates.
The first is by scientists from the Zoology Department, Cambridge University, UK and the FitzPatrick Institute of African Ornithology, University of Cape Town concerning mimicry in bird brood parasites.
The 19 African finches of the Vidua genus, also known as indigobirds or wydahs, are all brood parasites on species of grassfinch. Unlike many brood parasites they do not destroy the hosts eggs and sometimes lay more than one egg in their nest. Each species of Vidua parasitises a single species of grassfinch.
Grassfinch chicks are notable for their characteristic markings and colours, including markings on the inside of their mouth and throat. Each is unique to the particular species of grassfinch. These induce the parents to feed them. They also use begging postures and characteristic calls to supplement the markings.
What the researchers found, using pattern-recognition computer software which 'sees' the markings in the same way that a bird sees them, is that there is a remarkable degree of mimicry of these markings in the parasite chicks and small differences exaggerate the grassfinch chick patterns so producing a stronger feeding reflex in the host foster parents, giving the Vidua chicks an advantage. Their research was published open access in Evolution last July.
In addition, the Vidua chicks become imprinted on the host species so males imitate their host species' mating calls and female Vidua favour these males in their sex selection. This produces a powerful driver for greater mimicry in the species and acts as a barrier to hybridization, so reinforcing speciation and increasing the tendency for specialised parasitism on a particular species of grassfinch.Abstract
Brood parasites use the parental care of others to raise their young and sometimes employ mimicry to dupe their hosts. The brood‐parasitic finches of the genus Vidua are a textbook example of the role of imprinting in sympatric speciation. Sympatric speciation is thought to occur in Vidua because their mating traits and host preferences are strongly influenced by their early host environment. However, this alone may not be sufficient to isolate parasite lineages, and divergent ecological adaptations may also be required to prevent hybridization collapsing incipient species. Using pattern recognition software and classification models, we provide quantitative evidence that Vidua exhibit specialist mimicry of their grassfinch hosts, matching the patterns, colors and sounds of their respective host's nestlings. We also provide qualitative evidence of mimicry in postural components of Vidua begging. Quantitative comparisons reveal small discrepancies between parasite and host phenotypes, with parasites sometimes exaggerating their host's traits. Our results support the hypothesis that behavioral imprinting on hosts has not only enabled the origin of new Vidua species, but also set the stage for the evolution of host‐specific, ecological adaptations.Jamie, G.A., Van Belleghem, S.M., Hogan, B.G., Hamama, S., Moya, C., Troscianko, J., Stoddard, M.C., Kilner, R.M. and Spottiswoode, C.N. (2020),
Multimodal mimicry of hosts in a radiation of parasitic finches.
Evolution. doi:10.1111/evo.14057
Copyright: © 2020 The authors. Published by Wiley Online
Reprinted with kind permission under license #4924861479046.
The ID interpretation of this is, of course, that the same intelligent [sic] entity that designed the grassfinches, also designed the mimicry in the Vidua species so they are better able to parasitise the grassfinches, in an act of inexplicably malevolent mendacity. Creationists consider this to be a better explanation of the observable evidence, including as it does, magic and the supernatural, than the perfectly rational, natural explanation offered by amoral, undirected, evolution by natural selection.
The second paper concerns our old favourite, the malaria-causing parasite, Plasmodium falciparum.
Duke Researchers Discover How Malaria Parasites Withstand a Fever’s Heat | Duke Today.
In this paper, scientists from the Department of Molecular Genetics and Microbiology, School of Medicine, Duke University, Durham, USA and the Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, USA, showed how P. falciparum has been 'designed' to make it able to withstand the frequent bouts of very high body temperatures that debilitate its victims. During these bouts, which occur every few days, the parasites continue to eat and destroy red blood cells with impunity.
Like many other protozoans, when P. falciparum ingests food (in this case the red blood cells of its victims) particles are taken into vacuoles within the cell where they are digested by enzymes, rather like a miniature gut. To prevent these enzymes attacking the cell itself, they are surrounded by a membrane which isolates them. The problem for P. falciparum is that at the high temperatures reached during the bouts of fever - 105 degrees Celsius or higher, these vacuole walls would begin to degrade and become leaky, so releasing the digestive enzymes into the cell, where they would begin to destroy it.
What the researchers found was the P. falciparum responds to these high temperatures by producing a special protein, phosphatidylinositol 3-phosphate, or PI(3)P. This protein attracts another protein, Hsp70, the heat-shock protein, to stick to it and together they reinforce and stabilise the vacuole membrane. Their findings were published open access in eLife last September.
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| Malaria parasites at normal body temperature (left) and fever-like temperatures (right). A new study finds that the malaria parasite puts body armour around its ‘gut’ to withstand its human host’s raging fevers. Credit: Kuan-Yi Lu, Duke University |
Abstract
Phosphatidylinositol 3-phosphate (PI(3)P) levels in Plasmodium falciparum correlate with tolerance to cellular stresses caused by artemisinin and environmental factors. However, PI(3)P function during the Plasmodium stress response was unknown. Here, we used PI3K inhibitors and antimalarial agents to examine the importance of PI(3)P under thermal conditions recapitulating malarial fever. Live cell microscopy using chemical and genetic reporters revealed that PI(3)P stabilizes the digestive vacuole (DV) under heat stress. We demonstrate that heat-induced DV destabilization in PI(3)P-deficient P. falciparum precedes cell death and is reversible after withdrawal of the stress condition and the PI3K inhibitor. A chemoproteomic approach identified PfHsp70-1 as a PI(3)P-binding protein. An Hsp70 inhibitor and knockdown of PfHsp70-1 phenocopy PI(3)P-deficient parasites under heat shock. Furthermore, PfHsp70-1 downregulation hypersensitizes parasites to heat shock and PI3K inhibitors. Our findings underscore a mechanistic link between PI(3)P and PfHsp70-1 and present a novel PI(3)P function in DV stabilization during heat stress.
Lu, Kuan-Yi;Pasaje, Charisse Flerida A;Srivastava, Tamanna;Loiselle, David R;Niles, Jacquin C;Derbyshire, Emily
Phosphatidylinositol 3-phosphate and Hsp70 protect Plasmodium falciparum from heat-induced cell death
eLife 2020;9:e56773 DOI: 10.7554/eLife.56773
Open access
Reprinted under a Creative Commons Attribution 4.0 International License (CC BY 4.0)
As with the parasitic finch example, the ID view of this is that P. falciparum must have been designed that way to help it overcome the body's attempt to defend itself and so make it better at making people sick. Since his is the clear result of this modification, it must have been the intent of any intelligent entity that designed it, otherwise it could not be considered either intelligent or a designer.
The unresolved dilemma intelligent [sic] design advocates face with these sorts of examples is in explainign why the only explanation that doesn't leave their putative designer looking like a malevolent, genocidal sadist who deliberately make people and other animals sick and die, is the Theory of Evolution by Natural Selection that they so despise and which they tell their dupes is impossible.
These, and many more examples of the sheer, unavoidable malevolence of any intelligent designer who designed all of nature are in my forthcoming richly illustrated book, The Malevolent Designer: Why Nature's God is not Good", now in it's final stages. This will be a companion book to my popular book, The Malevolent Designer: Refuting the Intelligent Design Hoax, available through Amazon and all good online booksellers and bookshops.
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