2019/10/04

Highly predictable toxin resistance debunks evolutionary randomness

Predictable genetic changes point to Design, not evolution

https://www.nytimes.com/2019/10/02/science/monarch-butterflies-milkweed.html?utm_source=Nature+Briefing&utm_campaign=1356cd3b8d-briefing-dy-20191003&utm_medium=email&utm_term=0_c9dfd39373-1356cd3b8d-44274365

Excerpt: "The caterpillar of the monarch butterfly eats only milkweed, a poisonous plant that should kill it. The caterpillars thrive on the plant, even storing its toxins in their bodies as a defense against hungry birds.

For decades, scientists have marveled at this adaptation. On Thursday, a team of researchers announced they had pinpointed the key evolutionary steps that led to it.

Only three genetic mutations were necessary to turn the butterflies from vulnerable to resistant, the researchers reported in the journal Nature. They were able to introduce these mutations into fruit flies, and suddenly they were able to eat milkweed, too.
 
Biologists hailed it as a tour-de-force that harnessed gene-editing technology to unscramble a series of mutations evolving in some species and then test them in yet another."

Similar genetic alterations in 47 taxa


https://www.theguardian.com/science/grrlscientist/2015/sep/16/predictable-evolution-bad-news-for-toads-good-news-for-their-predators

Excerpt: "When Dr Ujvari and Dr Casewell’s team widened their investigation to include all 47 taxa that are resistant to cardiac glycosides (whether it was from a plant or an animal source), they found that resistance was due to two amino acid substitutions at just four positions: 111, 119, 120, or 122. Further, the team found that, of the 11 amino acids within this portion of the sodium-potassium exchange pump subunit, one specific amino acid site (111) must always change for resistance to evolve, whereas the second resistance-conferring change then occurs in one of three other amino acid sites (119, 120, or 122), which vary across species."
 
Other papers confirming these highly predictable changes:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3420205/
https://www.researchgate.net/publication/257753708_Amino_acid_substitutions_of_NaK-ATPase_conferring_decreased_sensitivity_to_cardenolides_in_insects_compared_to_mammals
https://onlinelibrary.wiley.com/doi/full/10.1111/eea.12340

My comment: By using keywords 'cardiac glycosides substitutions at positions 111 and 122' we will soon realize that these predictable changes happen in different types of organisms. Nothing to do with random mutations and selection. Nothing to do with evolution. Organisms are able to tweak their genomes by so called natural genetic engineering. There are several epigenetic mechanisms that make it possible for an organism to modify its own genome. They are typically controlled by the immune system, such as AID mediated deamination. This is ecological adaptation, not evolution. This is Design, not random mutations. Don't get lost.
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