Evolution by Loss of Genetic Information Sends Creationists Batty

The common vampire bat, Desmodus rotundus, feeds exclusively on the blood of other animals. Adaptations to this unique diet are due in part to the loss of genes.

Photo: Brock Fenton

Vampires with genetic defects: MPI-CBG

Sometimes, refuting Creationism is too tempting to resist. The basic problem is that Creationism relies on creationists being fooled into believing things that are, frankly, counter-factual and easily demonstrated to be so.

Take, for example, the latest attempt to make it look like science is wrong about evolution and the facts comply with a literal interpretation of the Bible - Michael J Behe's 'Devolution' nonsense, that basically argues that every mutation is a retreat from the initial perfection of creation, (with the implication that this is due to 'sin' following 'The Fall' - a popular Judeo-Christian myth from the Bronze Age). Following his failure to make any progress in the courts with his and the Deception Institute's 'Intelligent [sic] Design' ploy, he has tried to come up with an alternative that makes Bible-literalist creationism look like real science. Sadly though, the facts are once again against him.

For example, this recent open access publication in Science Advances, by scientists from the LOEWE Centre for Translational Biodiversity Genomics in Frankfurt and the Max Planck Institute for Molecular Cell Biology and Genetics in Dresden, which shows that the common vampire bat's ability to live exclusively on a diet of mammalian blood, was made possible by a loss of thirteen genes - mutations which gave them significant advantages so were selected for by natural evolution. It takes some wonderful mental gymnastics to believe that mutations which give an advantage are somehow 'devolutionary' - a meaningless term which implies a 'correct' direction for evolutionary change, so appeals to the childish, teleological thinking of creationists.

Commonn vampire bat, Desmodus rotundus

Credit: Catherine Webber-Hounslow
The Malevolent Designer, p. 108.

Vampire bats consume something like 800 times the amount of iron that humans consume, so they face the problem of how to excrete this vast excess. Other mammals have a gene which inhibits the storage of iron in the epithelial cells lining the gut as these cells are short-lived so there would be a constant loss of iron into the intestinal lumen to be excreted in faeces. Bats have lost this gene, so excrete excess iron in their faeces. Incidentally, intelligent [sic] design advocates might like to consider the intelligence behind absorbing the iron in the normal digestive process, then excreting it this way, so it ends up back where it would have been if not absorbed in the first place, but perhaps it's a little unkind to pile bad news on bad news.

Incidentally, there is a section dedicated to the vampire bats in my popular, illustrated book, The Malevolent Designer: Why Nature's God is not Good, which shows how any designer of them could not be regarded as anything other than malevolent since they are parasitic and superficially look designed to spread rabies.

The details of these new findings are provided by a news release from the Max Planck Institute for Molecular Cell Biology and Genetics:

Vampire bats live up to their name: they feed exclusively on the blood of other vertebrates, which they hunt in the dark. But how do they cope with this unbalanced diet? Blood contains a lot of protein, but sugar and fat are largely absent. A detailed analysis of the genome of the common vampire bat now provides new insights into the evolution of dietary adaptations and other abilities of these unique animals.

[…]

According to the study, gene loss played a role in adaptations of these "living Draculas" to a diet that consists exclusively of blood. Two of the defective genes are responsible for the secretion of the blood sugar-regulating hormone insulin in other animals. Vampire bats, on the other hand, produce very little insulin and have apparently lost these two genes because their blood diet contains little sugar.

[…]

The scientists further assume that the loss of another gene could have had an influence on the evolution of certain cognitive abilities of vampire bats. These bats have also lost a gene that normally breaks down a metabolite in the brain that can have a positive effect on cognitive performance and social behaviour. A higher concentration of this metabolite can promote memory, learning and social behaviour, as several studies on other mammals suggest. Vampire bats have exceptional memory and social behaviour compared to other bat species. For example, they share blood with other starving roost mates, mainly with those who have helped them in the past – a behaviour that requires a good long-term social memory.

Important foundations of this comparative study were a new, high-quality genome of the common vampire bat, which was created using the latest sequencing technologies. Furthermore, a newly developed computational method was used that can detect losses of genes with high accuracy.

"But adaptations to this unique diet are not only due to the loss of genes," says Michael Hiller, Professor of Comparative Genomics at the LOEWE Centre for Translational Biodiversity Genomics who supervised the study. Moreover, there are two other vampire bat species besides the common vampire bat, whose genomes Hiller's team is currently sequencing. "Our goal is to get a complete picture of the genomic changes in all three vampire bat species. And there is still a lot to learn!" says Hiller.

The abstract to the paper in Science Advances gives more detail:

Abstract

Vampire bats are the only mammals that feed exclusively on blood. To uncover genomic changes associated with this dietary adaptation, we generated a haplotype-resolved genome of the common vampire bat and screened 27 bat species for genes that were specifically lost in the vampire bat lineage. We found previously unknown gene losses that relate to reduced insulin secretion (FFAR1 and SLC30A8), limited glycogen stores (PPP1R3E), and a unique gastric physiology (CTSE). Other gene losses likely reflect the biased nutrient composition (ERN2 and CTRL) and distinct pathogen diversity of blood (RNASE7) and predict the complete lack of cone-based vision in these strictly nocturnal bats (PDE6H and PDE6C). Notably, REP15 loss likely helped vampire bats adapt to high dietary iron levels by enhancing iron excretion, and the loss of CYP39A1 could have contributed to their exceptional cognitive abilities. These findings enhance our understanding of vampire bat biology and the genomic underpinnings of adaptations to blood feeding.

Blumer, M., Brown, T., Bontempo Freitas, M., Destro, A.L., Oliveira, J.A., Morales, A.E., Schell, T., Greve, C., Pippel, M., Jebb, D., Hecker, N., Ahmed, A.-W., Kirilenko, B.M., Foote, M., Janke, A., Lim, B.K., Hiller, M.
Gene losses in the common vampire bat illuminate molecular adaptations to blood feeding.
Science Advances 2022, Vol. 8 No. 12; DOI:10.1126/sciadv.abm6494

Copyright: © 2022 The authors. Published by American Association for the Advancement of Science.
Open access
Reprinted under a Creative Commons Attribution-NonCommercial 4.0 International licence (CC BY-NC 4.0).

A very clear example of multiple losses of genetic information resulting in greater fitness to survive and reproduce in the environmental niche occupied by vampire bats, and yet another example of the casual refutation of creationism by simply revealing the facts which refute it - an aim that was probably furthest from the minds of the biologists who produced it. It takes a dedicated fanatic, or a self-interested fraud, to maintain a position like creationism in the face of the raging torrent of information that refutes it.

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