{"id":114158,"date":"2024-10-14T20:52:58","date_gmt":"2024-10-14T13:52:58","guid":{"rendered":"https:\/\/hotvideos24.online\/?p=114158"},"modified":"2024-10-14T20:52:58","modified_gmt":"2024-10-14T13:52:58","slug":"nature-keeps-evolving-crabs-and-the-internet-is-obsessed-whats-going-on-here","status":"publish","type":"post","link":"https:\/\/hotvideos24.online\/?p=114158","title":{"rendered":"Nature keeps evolving crabs and the internet is obsessed. What\u2019s going on here?"},"content":{"rendered":"<p> <script async src=\"https:\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js?client=ca-pub-3711241968723425\"\r\n     crossorigin=\"anonymous\"><\/script>\r\n<ins class=\"adsbygoogle\"\r\n     style=\"display:block\"\r\n     data-ad-format=\"fluid\"\r\n     data-ad-layout-key=\"-fb+5w+4e-db+86\"\r\n     data-ad-client=\"ca-pub-3711241968723425\"\r\n     data-ad-slot=\"7910942971\"><\/ins>\r\n<script>\r\n     (adsbygoogle = window.adsbygoogle || []).push({});\r\n<\/script><br \/>\n<\/p>\n<div id=\"\">\n\t\t\t\t\t\t\t\t<input type=\"hidden\" id=\"article_url\" value=\"2024\/10\/14\/is-everything-becoming-crabs\/\"\/><\/p>\n<p>As XEC, <a href=\"https:\/\/www.salon.com\/2024\/10\/09\/all-eyes-on-xec-why-sleuths-are-paying-attention-to-this-variant\/\" target=\"_blank\" rel=\"noopener\">the latest COVID variant takes hold<\/a>, we are watching viral <a href=\"https:\/\/www.salon.com\/2022\/05\/31\/evolution-appears-to-occur-far-faster-than-we-thought-study-finds\/\" target=\"_blank\" rel=\"noopener\">evolution play out on a time scale short enough<\/a> to follow, with different strains of the SARS-CoV-2 virus <a href=\"https:\/\/pubmed.ncbi.nlm.nih.gov\/34537136\/\" target=\"_blank\" rel=\"noopener\">independently acquiring similar or functionally similar mutations<\/a> that improve its ability to infect us or to evade existing vaccines.<\/p>\n<p>This is the same process that occurs over tens of thousands, even millions of years in living creatures, from slugs to dogs to you and me, producing the incredible diversity we see in the tree of life along with startling replays of the same idea, known formally as <a href=\"https:\/\/www.salon.com\/2024\/09\/13\/from-dinosaurs-to-dolphins-what-gaze-following-reveals-about-the-evolution-of-empathy\/\" target=\"_blank\" rel=\"noopener\">convergent evolution<\/a>. This is simply when nature finds similar solutions to similar problems in evolutionarily distant groups \u2014 think about how dolphins and bats each evolved echolocation, despite being unrelated.\u00a0<\/p>\n<p>One of the most prominent \u2014 and pinchy \u2014 ways this manifests is known as carcinization, the idea that nature keeps evolving crabs. Indeed, a <a href=\"https:\/\/www.salon.com\/2023\/07\/03\/crabs-are-intelligent-sensitive-animals--and-scientists-wish-we-didnt-boil-them-alive-in-pots\/\" target=\"_blank\" rel=\"noopener\">crab-like body shape<\/a>, or morphology, has evolved numerous times independently throughout evolutionary history. From an outsider\u2019s view, it seems like crabs appear so often because Mother Nature \u201cloves\u201d crabs. In the immortal words of English zoologist Lancelot Alexander Borradaile, who coined the term, <a href=\"https:\/\/research.nhm.org\/pdfs\/31940\/31940.pdf\" target=\"_blank\" rel=\"noopener\">carcinization<\/a> is \u201cone of the many attempts of Nature to evolve a crab.\u201d<\/p>\n<p>The concept is so intriguing and delightful, it has spawned the <a href=\"https:\/\/knowyourmeme.com\/memes\/carcinization\" target=\"_blank\" rel=\"noopener\">crab meme<\/a>, which swept some little nerdy part of the internet a few years ago and with it, a wacky speculation that we are all going to evolve into crabs one day. But all bizarre fantasies aside, what\u2019s really happening here is far more interesting.<\/p>\n<h3><strong>Cancer the crab<\/strong><\/h3>\n<p>It goes without saying, nature is not consciously trying to evolve anything. Even human intelligence arose through the randomness of natural selection. With all due respect to Borradaile and his fans, that\u2019s not how this works. Rather, if the same sort of thing is evolving over and over, it\u2019s probably because that sort of thing is a trait that offers a survival advantage to species existing in similar situations.<\/p>\n<p>Convergent evolution is what we see when we observe that bats and birds have similar development of their arms into gliding wings, which initially allowed them to glide, and then to fly. Or when we notice that the extinct ichthyosaurs, prehistoric fish, have a very similar body outline, down to the bottlenose shape and tiny teeth, as the modern dolphin \u2014 which is not a fish at all, but a mammal. In either case, the hydrodynamic body shape lets them both swim rapidly over long distances.<\/p>\n<div class=\"right_quote\">\n<p>Carcinization is \u201cone of the many attempts of Nature to evolve a crab.&#8221;<\/p>\n<\/div>\n<p>Another example can be seen among the marsupial mammals of Australia, an island where animal evolution diverged from the rest of the world far back in evolutionary time, we see creatures with eerie parallels to mammals from other continents, creatures that occupy the same ecological niche or role and have evolved similar body shapes or abilities to cope.<\/p>\n<p><img decoding=\"async\" alt=\"Yellow crab on the beach\" class=\"inserted_image\" data-image_id=\"15043915\" id=\"featured_image_img\" src=\"https:\/\/mediaproxy.salon.com\/width\/600\/https:\/\/media2.salon.com\/2023\/06\/yellow_crab_on_the_beach_200565417.jpg\"\/><strong class=\"article_img_desc insert_image\">Yellow crab on the beach (Getty Images\/Bob Stefko)<\/strong>We see this as well in the existence of many types of decapods, which is the technical term for crustaceans with a crab-like body shape. This includes crabs, which evolved from the common ancestor of all crabs, and it includes other kinds of crustaceans with completely different ancestors, occupying a different branch of the evolutionary tree \u2014\u00a0yet a total plagiarism of the idea of crab.<\/p>\n<p>Carcinization is \u201creally only applicable to that one animal group that we call decapods,\u201d Sebastian Groh, a paleontologist at Cardiff Metropolitan University, told Salon. \u201cAnd that\u2019s the only group that it\u2019s actually limited to. It doesn\u2019t really occur anywhere outside it. I think that was sort of a misunderstanding.\u201d<\/p>\n<p>Groh\u2019s area of study is the evolution of crocodiles and their relatives from two hundred million years ago to now, looking for example at the convergent evolution of long, narrow snouts in various different branches of their family tree.<\/p>\n<hr\/>\n<p style=\"text-align:center\"><strong><em>Want more health and science stories in your inbox? Subscribe to Salon&#8217;s weekly newsletter <a href=\"https:\/\/www.salon.com\/newsletter\">Lab Notes<\/a>.<\/em><\/strong><\/p>\n<hr\/>\n<p>The idea that anyone (or any random evolutionary group) might evolve into a crab is a misunderstanding, sure, but makes for a striking meme \u2014\u00a0and maybe a fruitful opportunity to explain how evolution actually works.<\/p>\n<h3><strong>Small changes, big impact<\/strong><\/h3>\n<p>The evolution of any particular trait depends on a huge number of tiny changes. You don\u2019t just have a gene for \u201clooking like a crab.\u201d Rather, for evolution by natural selection to produce crab-like appearance and behavior you would need to have creatures living in environments that give a survival advantage to having these crab-like traits. And you\u2019d need to acquire all genes that code for the many proteins that produce such traits. To understand this, we need to look way closer.<\/p>\n<p>The development of a claw or a flipper requires many particular different genes. And once again, no, the human genome is not a few mutations away from carcinization.<\/p>\n<p>\u201cYou\u2019re not going to find a mammal becoming a crab because maybe [the ancestors of crab-like organisms have] got a lot of other genes that would predispose them to that morphology and to that sort of behavior. They\u2019ve got the set up. They\u2019ve got the background,\u201d James McInerney, who holds the chair in Evolutionary Biology at the University of Liverpool, told Salon in a video interview.<\/p>\n<div class=\"left_quote\">\n<p>There are deterministic relationships in which certain genes go well or badly with other particular genes, and so similar patterns of genes reoccur.<\/p>\n<\/div>\n<p>Then again, we have to wonder whether that set up of genes evolved through natural selection \u2014\u00a0Nature \u201cattempting\u201d to evolve a crab \u2014\u00a0or just random luck. As the <a href=\"https:\/\/www.nature.com\/articles\/ncomms12758\" target=\"_blank\" rel=\"noopener\">authors of one 2016 paper<\/a> on convergence at both the molecular and the more observable, morphological level put it, \u201cconvergence is caused by either repeated adaptations of different evolutionary lineages to similar environmental challenges or chance.\u201d<\/p>\n<p>McInerney was lead author on a <a href=\"https:\/\/www.pnas.org\/doi\/10.1073\/pnas.2304934120\" target=\"_blank\" rel=\"noopener\">study on convergent evolution in bacteria<\/a> that helps us understand how this background might work, and to distinguish these two ways convergence may occur. He and his team used machine learning to look at the genomes of a whole bunch of different strains of <em>Escherichia coli<\/em>, a bacteria in which different strains repeatedly evolve in convergent ways, to see whether this occurs by chance or by a process of natural selection.\u00a0<\/p>\n<p>Now, in bacteria \u2014 which are a type of prokaryote, or single-celled organism \u2014 a lot of evolution happens by horizontal gene transfer. This occurs when genetic material is incorporated into an organism\u2019s genome in some way other than through reproduction. Bacteria pick up new genes from various sources, keeping their evolution interesting. This isn\u2019t necessarily good for us, though: <a href=\"https:\/\/www.salon.com\/2024\/03\/09\/why-warzones-are-the-perfect-place-for-antibiotic-resistance-and-what-that-means-for-palestine\/\" target=\"_blank\" rel=\"noopener\">antibiotic resistance has become a massive problem<\/a> in large part due to horizontal transfer of genes from drug-resistant species into bacteria species that were once routinely killed by medications.<\/p>\n<p>In <em>E.coli<\/em>, this means that its pangenome \u2014 the totality of genes that are found across all strains \u2014 has a huge amount of variability. What McInerny\u2019s team found was that despite all this variability, you could actually predict a lot of what genes you\u2019d find in a particular strain if you knew some of the other genes. To simplify a bit, if Bacteria A acquires gene 1 by horizontal transfer and also acquires gene 2, and then we notice that Bacteria B has also acquired gene 1, we might correctly predict that Bacteria B has gene 2 as well \u2014\u00a0because in this scenario, genes 1 and 2 tend to stick together in a genome.<\/p>\n<p>In the authors\u2019 words, \u201cat least part of the pangenome can be understood as a set of genes with relationships that govern their likely cohabitants, analogous to an ecosystem\u2019s set of interacting organisms.\u201d<\/p>\n<p>What this means is that evolution in <em>E. coli<\/em>, despite the serendipity of horizontal gene transfer, isn\u2019t just a matter of chance. Rather, there are deterministic relationships in which certain genes go well or badly with other particular genes, and so similar patterns of genes reoccur, resulting in repeated patterns of evolution. As a result, where you see convergently similar bacteria that evolved from very different ancestors, you actually see the same types of genes in these very distant relatives. Despite their different evolutionary history, they come up with the same or very similar genetic recipes when faced with similar survival challenges.<\/p>\n<p>The details of convergent evolution might of course be more complex in the eukaryotes, multicellular organisms like humans or decapods with large genomes, the total genetic material of an organism. Most traits you can actually observe \u2014\u00a0what\u2019s called the organism\u2019s phenotype \u2014 result from a unique combination of genes and how those genes are expressed.<\/p>\n<p>\u201cI suspect that in eukaryotes, it won\u2019t be just point mutations, either,\u201d McInerney said, referring to <a href=\"https:\/\/www.genome.gov\/genetics-glossary\/Point-Mutation\" target=\"_blank\" rel=\"noopener\">small changes in a genome<\/a>. \u201cIt\u2019ll be changes in expression and genetic changes that influence other genetic changes to make them more likely or less likely. I think that\u2019s a really productive field of research right now.\u201d<\/p>\n<p>Tim Sackton, director of Bioinformatics for the FAS Informatics Group at Harvard University, notes that while we can easily look at a sequenced genome and identify where the genes that code for proteins are, the other parts that control where and when these genes are expressed is something we\u2019re still trying to figure out.<\/p>\n<p>\u201dWe don&#8217;t really know the code for these in the same way for these regulatory regions,\u201d he told Salon. And those regions may be very important in understanding convergence. Take for example the puzzle of the flightless birds. Evidence suggests that the loss of flight evolved independently as many as six times, rather than just once, in the ancestors of different ratites \u2014\u00a0the group of flightless birds including the extinct moa and elephant birds as well as the ostrich, kiwi, cassowary, emu and rhea. In a 2019 study, <a href=\"https:\/\/www.science.org\/doi\/full\/10.1126\/science.aat7244\" target=\"_blank\" rel=\"noopener\">Sackton and colleagues found<\/a> that regulatory elements \u2014\u00a0the ones that determine when a gene is expressed as a protein, like an on-off switch \u2014 were where the action was.<\/p>\n<p>\u201cWe\u2019d see the same elements would get altered in multiple of these independent transitions to these flightless birds and it\u2019s not only the same element,\u201d Sackton explained. Rather, certain genes tend to accumulate in flightless birds, like clusters of modified elements of the genome.<\/p>\n<p>The loss of flight \u2014 which plays out at the phenotype level in changes in the forelimb, for example \u2014\u00a0thus resulted from way more than a single change in the genome. Instead, various genes work together, with regulatory genes playing the more significant role.<\/p>\n<p>\u201cThere\u2019s a lot going on in these ratites, there\u2019s many changes, both in terms of skeletal morphology but also in terms of feather structure and a lot of other things. So it\u2019s a very complicated phenotype, but not every aspect of it is necessarily convergent,\u201d Sackton noted.<\/p>\n<p>There\u2019s still so much to figure out about how convergent evolution works, not just in crabs but in all organisms. And the results can be striking.<\/p>\n<p>\u201cThe crabs are showing that\u2019s a very overt phenotype, right?\u201d McInerney said. He emphasized that the convergences we see \u2014\u00a0so many things that look like crabs, the camera-like <a href=\"https:\/\/www.salon.com\/2023\/04\/16\/mother-nature-cant-stop-evolving-eyes\/\" target=\"_blank\" rel=\"noopener\">eyes that evolved independently<\/a> in both squids and humans, the emergence of opposable thumbs in giant pandas, chameleons and us \u2014\u00a0emerge from similarly astonishing, if less obvious, evolution at the molecular level: in the once-hidden world of genes.<\/p>\n<p>So why do crabs keep coming up, again and again? Not because nature chooses it, but because the crab \u201cdesign\u201d just works so well at keeping certain species alive and passing down those genes. It\u2019s the intricate beauty of evolution in action. As McInerney put it, \u201cGenome evolution favors particular outcomes, and we see it in bacteria. We see it in crabs.\u201d<\/p>\n<\/p><\/div>\n<p><script async src=\"https:\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js?client=ca-pub-3711241968723425\"\r\n     crossorigin=\"anonymous\"><\/script>\r\n<ins class=\"adsbygoogle\"\r\n     style=\"display:block\"\r\n     data-ad-format=\"fluid\"\r\n     data-ad-layout-key=\"-fb+5w+4e-db+86\"\r\n     data-ad-client=\"ca-pub-3711241968723425\"\r\n     data-ad-slot=\"7910942971\"><\/ins>\r\n<script>\r\n     (adsbygoogle = window.adsbygoogle || []).push({});\r\n<\/script><br \/>\n<br \/><div data-type=\"_mgwidget\" data-widget-id=\"1660802\">\r\n<\/div>\r\n<script>(function(w,q){w[q]=w[q]||[];w[q].push([\"_mgc.load\"])})(window,\"_mgq\");\r\n<\/script>\r\n<br \/>\n<br \/><a href=\"https:\/\/www.salon.com\/2024\/10\/14\/is-everything-becoming-crabs\/\">Source link <\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>As XEC, the latest COVID variant takes hold, we are watching viral evolution play out on a time scale short enough to follow, with different strains of the SARS-CoV-2 virus &hellip; <a href=\"https:\/\/hotvideos24.online\/?p=114158\" class=\"more-link\">Read More<\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8628],"tags":[],"class_list":["post-114158","post","type-post","status-publish","format-standard","hentry","category-science","entry"],"_links":{"self":[{"href":"https:\/\/hotvideos24.online\/index.php?rest_route=\/wp\/v2\/posts\/114158","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/hotvideos24.online\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/hotvideos24.online\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/hotvideos24.online\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/hotvideos24.online\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=114158"}],"version-history":[{"count":0,"href":"https:\/\/hotvideos24.online\/index.php?rest_route=\/wp\/v2\/posts\/114158\/revisions"}],"wp:attachment":[{"href":"https:\/\/hotvideos24.online\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=114158"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/hotvideos24.online\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=114158"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/hotvideos24.online\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=114158"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}