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March 5, 2026<\/p>\n
2 min read<\/p>\n
Add Us On Google<\/span>Add SciAm<\/span><\/span><\/p>\n Koalas show how species can bounce back from genetic bottlenecks<\/p>\n Scientists have discovered a potential path out of devastating genetic bottlenecks that could help these Australian animals, as well as many other vulnerable and endangered species<\/p>\n By Meghan Bartels edited by Andrea Thompson<\/span><\/p>\n Without interrupting their busy sleep schedule, Australia\u2019s cute, if cantankerous, koalas have turned a truism of genetics on its head.<\/p>\n In short, the proliferation of certain koala populations shows how bottlenecks\u2014which occur when a species\u2019 numbers suddenly shrink, reducing genetic diversity\u2014don\u2019t necessarily doom an animal to inbreeding and eventually dying out. Previously bottlenecked species can bounce back, recovering a surprising amount of diversity.<\/p>\n \u201cThe assumption that a bottleneck leads to eventual extinction is not set in stone,\u201d says Rachel O\u2019Neill, a genome biologist at the University of Connecticut, who was not involved in the new research.<\/p>\n If you’re enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.<\/p>\n For the study, published on March 5 in Science, researchers dug into the whole genomes of 418 koalas from different populations to understand how the effective population sizes of different groups had changed over time. Whereas a population size tallies the number of animals in a group, an effective population size measures how those animals\u2019 genetic diversity is distributed among individuals by sexual reproduction.<\/p>\n The researchers found a pattern they didn\u2019t expect among koala populations in the Australian state of Victoria, where the animals have high rates of inbreeding and genetic deformity. Their effective population sizes cratered in the late 1800s because of the fur trade, creating an expected bottleneck. But surprisingly, the scientists found that the effective population sizes of koalas in Victoria have been increasing over the past 40 generations, whereas those of Queensland and New South Wales koala populations\u2014which conservationists have typically considered genetically healthier\u2014have shown sharp declines.<\/p>\n \u201cIt still looks like they\u2019re in bad shape, but if you dig further, we\u2019re actually finding that there\u2019s recovery from the bottleneck,\u201d says study co-author Collin Ahrens, an evolutionary biologist at the independent research company Cesar Australia.<\/p>\n That genetic recovery has come thanks to explosive population growth\u2014in Victoria, koalas are now so numerous that their management consists of trying to limit their numbers rather than increasing them, Ahrens notes. What\u2019s happening is that these populations have increased so dramatically that there have been many opportunities for mutations to occur and even for the limited genes retained during the bottleneck to group in different ways.<\/p>\n \u201cRecombination reshuffles the genetic variation,\u201d Ahrens says. \u201cThat\u2019s really important and something that\u2019s been really difficult to measure.\u201d<\/p>\n What happened with the Victorian koalas has an interesting parallel in invasive species. Scientists have long known that invasive organisms can rapidly proliferate after just a few individuals are introduced to a new ecosystem that they find is to their liking. Instead of being haunted by inbreeding, they sometimes thrive genetically, much to the detriment of the species around them.<\/p>\n The implications of the new research could reach far beyond koalas, given the number of species under threat from climate change and other human-driven pressures. \u201cRight now we\u2019re seeing a lot of anthropogenically driven declines, and I think their findings kind of give those populations hope,\u201d says Caitlin Curry, a population geneticist at the San Diego Zoo Wildlife Alliance, who wasn\u2019t involved in the new research. \u201cIf we give them the right resources and tools to have some kind of rapid expansion, maybe it also can restore their evolutionary potential.\u201d<\/p>\n If you enjoyed this article, I\u2019d like to ask for your support. 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I hope you\u2019ll support us in that mission.<\/p>\n","protected":false},"excerpt":{"rendered":" March 5, 2026 2 min read Add Us On GoogleAdd SciAm Koalas show how species can bounce back from genetic bottlenecks Scientists have discovered a potential path out of devastating genetic bottlenecks that could help these Australian animals, as well as many other vulnerable and endangered species By Meghan Bartels edited by Andrea Thompson Without<\/p>\n","protected":false},"author":1,"featured_media":45998,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[58],"tags":[23587,10197,738,119,241,5004],"class_list":{"0":"post-45997","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-science","8":"tag-bottlenecks","9":"tag-bounce","10":"tag-genetics","11":"tag-koala","12":"tag-show","13":"tag-species"},"_links":{"self":[{"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/posts\/45997","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=45997"}],"version-history":[{"count":0,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/posts\/45997\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/media\/45998"}],"wp:attachment":[{"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=45997"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=45997"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=45997"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}On supporting science journalism<\/h2>\n
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