“It’s by far the most exciting time to be a biologist, ever, in my opinion — maybe with the exception of going right back to Darwin,” said Sean Stankowski (opens a new tab), an evolutionary geneticist at University College London. “Even when we understood that organisms were programmed by genetic code, we could really never access that. Now, we’re looking at every single [nucleotide molecule] — A, T, G, and C [adenine, thymine, guanine, and cytosine] — in the genome.”
An analysis of genomic ecotypes (opens a new tab) by Johannesson, Stankowski, and other researchers explains how some species can maintain the DNA sequences for multiple adaptations, allowing evolutionary processes to effectively select among ecotypes as environmental conditions change — sometimes within only a few generations. The data also suggests that some canonically diverse groups of species, including Darwin’s finches, may not be separate species at all, but rather different ecotypes of the same species.
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An inversion happens when a portion of DNA from the chromosome breaks off, rotates 180 degrees, and plugs back into the chromosome in the reverse orientation. After inversion, a block of genes sits in one orientation on one chromosome, and in the opposite orientation on the other. This effectively prevents recombination from happening again in that region, and locks that group of genes together in a block. If those genes are somehow related, this can create a supergene, or multiple genes that act as a single unit. The snail traits for thick shells and evasive behavior to hide from crabs, for instance, become linked so that they will be inherited together in subsequent generations.
“It’s like if you had a deck of cards,” said Patrik Nosil (opens a new tab), an evolutionary geneticist at the French National Center for Scientific Research who studies speciation and ecotypes of stick insects. “With normal genetics, you shuffle that deck completely — all 52 cards. Whereas with these chromosomal inversions, you have a part of the deck that refuses to shuffle, so you can never change the order of the cards in there. That’s the part that controls the traits that make the ecotypes different.”
an Explanation in the jargon of board game terms for board game nerds.
For a long time Evolutionary Biologists thought the evolution of species was like a Deckbuilder where trashing cards to thin out useless/lower value cards was the dominant strategy, but now Scientists are beginning to reconsider whether or not the evolution of species is more like a Deckbuilder where trashing certainly does occur to evolve the Deck but the Deck is also expanded over time to balance more and more potentials with certain deck archetypes compressed into card powers through various mechanism that can be selectively emphasized to push the Deck composition into different optimizations. One specific example being cards with the power that they are never placed into the discard pile to be shuffled but rather always placed on the top of the draw deck along with other cards with this power after shuffling. Thus the potential to re-express an effective Deck composition in the future with careful card play is achieved without the synergy being lost from trashing cards to address a more current problem or the Deck becoming too cumbersome to adapt to current conditions.
