A magnitude 9.2 earthquake becomes an unexpected landlord.<\/p>\n
At 5:36 PM on Good Friday, 27 March 1964, the crust beneath Prince William Sound released and continued for roughly four and a half minutes. The US Geological Survey continues to classify the Great Alaska Earthquake as the most intense ever recorded in the United States, and the second largest recorded globally, surpassed only by Chile in 1960. Around Montague Island, the ocean floor did something unusual beyond shaking. It elevated.<\/p>\n
Geologists studying the island\u2019s submerged lagoons, as part of a USGS analysis of the Patton Bay splay fault system, reported local rises ranging from 3.7 to 4.3 meters, with certain shorelines uplifted by up to 11 meters. Salt water that had been part of the ocean just hours earlier was found above the tideline by the following morning, gradually transitioning to fresh due to rain and snowmelt.<\/p>\n
Some of those puddles contained fish.<\/p>\n
What the ponds ensnared<\/p>\n
They were threespine stickleback: silver, finger-length, and fortified from gills to tail with a series of bony side plates. Marine stickleback wear this protection as the ocean teems with predators eager to consume them. The new ponds had fewer threats, were devoid of salt, and experienced a winter that covered the surface with ice for extended periods.<\/p>\n
Nearly fifty years later, Emily Lescak, then affiliated with the University of Alaska, guided a team to those remote, scarcely accessible islands to investigate the fate of the castaways. Collaborating with William Cresko\u2019s lab in Oregon, the team collected samples from over a thousand specimens and analyzed more than 130,000 individual DNA variations among them. The approach involved comparing identical short sections of the genome, letter by letter, in each specimen. Their findings, published in the Proceedings of the National Academy of Sciences, presented two findings together.<\/p>\n
Firstly, the genetics substantiated the seemingly obvious conclusion: the pond fish genuinely descended from local ocean stickleback stranded within recent memory, and this phenomenon had independently occurred on multiple islands. Secondly, and less apparent, those nascent populations had already diverged almost as extensively from their ocean relatives as freshwater stickleback that originated thousands of years ago, during the retreat of glaciers. Eyes, body shape, color, bone size, armor. All of it evolved.<\/p>\n
Cresko, cited in a University of Oregon announcement, indicated that the evolutionary clock might operate even more swiftly, noting that in some populations \u201cwe found evidence of changes in fewer than even 10 years.\u201d<\/p>\n
How the fish were prepared<\/p>\n
How does a fish undergo reconstruction in fifty generations? Not by idly waiting for fortunate mutations, which would take significantly longer. The beneficial variations were already present in the ocean.<\/p>\n
Most of the differences in armor can be traced to a singular gene known as Ectodysplasin, or Eda, which instructs the developing fish on the number of plates to produce. Natasha O\u2019Brown and her team at Stanford, in findings published in eLife, identified the difference as stemming from a regulatory switch: a minor adjustment to the DNA that indicates to the gene when to activate, rather than a change within the gene itself. Low-plate variants of that switch appear at low frequencies in marine fish around the world. Introduce a few hundred ocean stickleback into a pond, and selection has raw material to work with from the outset.<\/p>\n
Susan Bassham, a senior research associate in Cresko\u2019s lab, highlighted that this represents a true genetic rearrangement rather than a flexible adaptive response like summer skin tanning. The subsequent research she and Julian Catchen published in the journal Genetics discovered that the same extensive segments of the genome were reshuffled in the earthquake ponds as in much older lakes. Up to a quarter of the genome had been rearranged in just a few dozen generations.<\/p>\n
A lake that conducted the same experiment<\/p>\n
In 1982, the Alaska Department of Fish and Game treated Loberg Lake, a small water body north of Anchorage, with poison to accommodate trout and salmon, eradicating its resident stickleback. Sea-run fish managed to enter between 1983 and 1988. The exact method remains uncertain.<\/p>\n
Michael Bell at Stony Brook began sampling them in 1990 and continued the effort. In a publication in Evolution, he and his co-authors documented a population that was predominantly fully plated in 1990. By 2001, the fully armored variant had decreased to 11 percent while the stripped-down form surged to 75 percent. Twelve years, one small lake, armor mostly absent.<\/p>\n
What this does and doesn\u2019t demonstrate<\/p>\n
Three islands alongside one exceptionally adaptable species don’t necessarily equate to a universal natural law. Stickleback possess an enormous reservoir of freshwater-ready variability due to the species continuously migrating between salt and fresh water for millions of years, and many animals lack any comparable potential for adaptation. A coral or a specialized alpine insect subjected to the same shock would likely face significant difficulties.<\/p>\n","protected":false},"excerpt":{"rendered":"
A magnitude 9.2 earthquake becomes an unexpected landlord. At 5:36 PM on Good Friday, 27 March 1964, the crust beneath Prince William Sound released and continued for roughly four and a half minutes. The US Geological Survey continues to classify the Great Alaska Earthquake as the most intense ever recorded in the United States, and […]<\/p>\n","protected":false},"author":1,"featured_media":376286,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"Default","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[179],"class_list":["post-376285","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized","tag-source-scienceblog-com"],"_links":{"self":[{"href":"https:\/\/wolfscientific.com\/index.php?rest_route=\/wp\/v2\/posts\/376285","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/wolfscientific.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/wolfscientific.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/wolfscientific.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/wolfscientific.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=376285"}],"version-history":[{"count":0,"href":"https:\/\/wolfscientific.com\/index.php?rest_route=\/wp\/v2\/posts\/376285\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/wolfscientific.com\/index.php?rest_route=\/wp\/v2\/media\/376286"}],"wp:attachment":[{"href":"https:\/\/wolfscientific.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=376285"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wolfscientific.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=376285"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wolfscientific.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=376285"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}