{"id":280117,"date":"2022-04-04T07:55:35","date_gmt":"2022-04-04T07:55:35","guid":{"rendered":"https:\/\/sciblogs.co.nz\/?p=280117"},"modified":"2022-08-17T21:20:01","modified_gmt":"2022-08-17T21:20:01","slug":"from-the-smallest-of-bones-come-the-biggest-of-secrets","status":"publish","type":"post","link":"https:\/\/blogs.otago.ac.nz\/lost-worlds\/2022\/04\/04\/from-the-smallest-of-bones-come-the-biggest-of-secrets\/","title":{"rendered":"From the smallest of bones come the biggest of secrets"},"content":{"rendered":"

Ask any museum curator if you could destroy the only known bone of a diminutive extinct animal for genetic research, and the answer, once the curator had regained their composure\u2026well, I\u2019ll leave that one to your imagination. <\/strong><\/p>\n

Walk into the behind-the-scenes collection at any museum in Aotearoa New Zealand and you’re immediately drawn to the big things, whether that\u2019s historical taxidermy, like imposing carnivores with their glassy eyes that eerily follow you around the room, or the skeletons of marine leviathans that once explored the ocean’s depths. Yet tucked away, dwarfed by the adjacent shelves upon shelves of carefully curated moa drumsticks, is a single non-descript wax-lined box full of tiny treasures. Hundreds of precious fossil gecko bones from before the arrival of humans, some thousands of years old.<\/p>\n

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A menagerie of the minutiae: Hundreds of gecko bones are now a paleontological tabula rasa. Photo courtesy of Lachie Scarsbrook.<\/em><\/figcaption><\/figure>\n

Scientific attention has always been drawn to the Brobdingnagian giants, which can handle having small chunks of bone cut out for ancient DNA research without erasing any of the tell-tale bumps that help differentiate species; like a heavy-footed moa<\/a> from a giant moa<\/a>. Try the same on one of these tiny Lilliput gecko bones though, which at most are half the size of my pinkie fingernail, and all you\u2019d have left is an empty box. Who said size doesn\u2019t matter?<\/p>\n

But what if you could reconstruct the gecko<\/a>\u2019s genetic whakapapa without destroying the very bone that has kept its secrets for thousands of years? What about the myriads of other small bones hiding on museum shelves for that matter be it skink<\/a>, frog<\/a>, or bird, recovered through years of painstakingly sieving mountains of dirt? Or even taonga t\u016bturu \u2013 a bone comb<\/a>, awl<\/a>, or fish-hook<\/a> for instance, with significant cultural importance.<\/p>\n

Queue my fantastic Masters’ student Lachie Scarsbrook<\/a>, currently at the University of Oxford<\/a>, who developed a specialised technique that allows scientists to non-destructively extract ancient DNA from these precious remains and sequence their genomes \u2013 with not even a micro-CT scanner capable of detecting any change before and after the process. But first, how did we get here?<\/p>\n

We know a lot about the impacts of human arrival in Aotearoa. But that knowledge is mostly restricted to our charismatic megafaunal giants \u2013 the moa<\/a>, pouakai Haast\u2019s eagle<\/a>, and r\u0101poka sea lions<\/a> to name a few. By comparison, we know virtually nothing about some of our smallest inhabitants \u2013 up to three frogs<\/a> and potentially one skink<\/a> have gone extinct. But what about geckos<\/a>; a unique lineage that has adapted to life on the coast up to the sub-zero alpine zone, stretching from the tip of Cape Reinga to Rakiura Stewart Island?<\/p>\n

Gecko bones have been discovered in fossil sites<\/a> across New Zealand, ranging from cave sites to sand dunes and predator deposits (think regurgitation from the extinct laughing owl<\/a> and falcons<\/a> at their roost sites). However, these jumbled, half-digested assemblages have been a little bit of a black box. It had been thought that you couldn\u2019t distinguish gecko bones by their shape<\/a>, so they were coarsely binned into quasi-taxonomic size classes comparable to living geckos \u2013 big fossil gecko bone equals biggest living gecko. The problem is that most of Aotearoa\u2019s geckos show considerable overlap in size…not exactly helpful when you are trying to discriminate between species.<\/p>\n

What we set out to do (well, let\u2019s be honest, Lachie did all the hard work) was use a combination of 3D scanning<\/a> and palaeogenomics<\/a> to crack the gecko DaVinci Code. 3D scanning of living gecko jawbones amazingly showed that we could in fact distinguish different gecko genera using shape alone<\/a> \u2013 turns out size doesn\u2019t matter after all. The upshot was that all previous sized-based identifications were likely wrong<\/a>\u2026 meaning what we know about New Zealand\u2019s geckos at the time of human arrival is now tabula rasa, a palaeontological clean slate.<\/p>\n

Interestingly, when we analysed the CT scans of the \u2018large\u2019 size class<\/a> (think a 10-cent piece) of fossil geckos from mainland New Zealand loosely identified as \u201cDuvaucel\u2019s gecko<\/a>\u201d, they looked very different to living individuals. Were we dealing with an unknown, now-extinct species, or the loss of morphological diversity as Duvaucel\u2019s gecko was exiled to offshore islands after rats arrived on the scene? To answer this, we needed access to the genetic memory<\/a> stored in these unique individuals, but using conventional methods meant destroying these taonga.<\/p>\n

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Invention test: Non-destructive techniques can now allow scientists to sequence ancient genomes from Lilliputian bones and reveal their long-hidden genetic secrets. Figure courtesy of Lachie Scarsbrook.<\/em><\/p>\n

What Lachie developed<\/a> not only unlocked this molecular secret but potentially vast swaths of natural history and archaeological collections globally to similar genetic analysis. Through soaking out ancient DNA (in a lukewarm bone bath complete with a protein-munching enzyme) from these small fossil bones and sequencing their genomes, not only were we able to show that Duvaucel\u2019s gecko underwent a massive loss of morphological diversity during its exile, but we could retrace the biological heritage back five million years to the Miocene-Pliocene boundary.<\/p>\n

This wasn\u2019t the greenhouse world of the early Miocene, made famous by the St Bathans fossil deposit<\/a> that recently produced a large fossil duck<\/a> \u2013 it was a world slowly cooling towards the coming Ice Age and a very different, geologically dynamic New Zealand. The tupuna ancestors of today\u2019s Duvaucel\u2019s gecko crossed the Manawatu Strait, that separated the two main islands of New Zealand, around five million years ago \u2013 the rough and tempestuous Cook Strait didn\u2019t exist until around 500,000 years ago \u2013 and evolved in isolation on the North and South Island for millions of years. So much so we think they are different species\u2026but that will take more work to prove.<\/p>\n

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That’s not a lizard, it’s a baby dinosaur: Lachie spending some quality time with his thesis animal.<\/em><\/figcaption><\/figure>\n

On the South Island, Duvaucel\u2019s gecko would be exposed to the full force of the Ice Age, contracting into and expanding out of northern and southern refugial utopia with the movement of vast ice sheets that developed on the freshly formed Southern Alps. Populations were further isolated on offshore islands in Cook Strait like castaways, as sea levels rose at the end of the Ice Age. In the North Island, it was a tale of two different worlds – deep lineages resided in remote and rugged areas like Waitomo and Northland, and old islands such as Poor Knights and Great Barrier, compared to shallow lineages on other offshore islands that were connected to the North Island by now drowned runways, that until relatively recently were high and dry.<\/p>\n

From our freshly dusted chalkboard, we have teased apart how Duvaucel\u2019s gecko responded to past climatic and human impacts, which is already allowing evidence-based conservation management of these taonga species. But that\u2019s not all. We now are using these techniques to finally reconstruct the long-lost ecological history of Aotearoa\u2019s other geckos and skinks (sized-based identifications have plagued this group too), and frogs and tuatara, in collaboration with DoC and M\u0101ori iwi.<\/p>\n

Far from forgotten on a museum shelf amongst the giants and leviathans that steal people\u2019s hearts and attention, these smallest of bones are starting the reveal the biggest of secrets. Secrets that will no doubt change what we know of Aotearoa\u2019s herpetofauna. I say, bring it on.<\/p>\n","protected":false},"excerpt":{"rendered":"

Ask any museum curator if you could destroy the only known bone of a diminutive extinct animal for genetic research, and the answer, once the curator had regained their composure\u2026well, I\u2019ll leave that one to your imagination. Walk into the behind-the-scenes collection at any museum in Aotearoa New Zealand and you’re immediately drawn to the … Continue reading “From the smallest of bones come the biggest of secrets”<\/span><\/a><\/p>\n","protected":false},"author":40066,"featured_media":280618,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[87395,12254],"tags":[87406,87434,87443,87486,87489,87516,62,87527,87564],"class_list":["post-280117","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-environment-and-ecology","category-science","tag-ancient-dna","tag-ct-scanning","tag-duvaucels-gecko","tag-human-impact","tag-ice-age","tag-morphology","tag-new-zealand","tag-non-destructive-sampling","tag-skinks"],"_links":{"self":[{"href":"https:\/\/blogs.otago.ac.nz\/lost-worlds\/wp-json\/wp\/v2\/posts\/280117","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.otago.ac.nz\/lost-worlds\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.otago.ac.nz\/lost-worlds\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.otago.ac.nz\/lost-worlds\/wp-json\/wp\/v2\/users\/40066"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.otago.ac.nz\/lost-worlds\/wp-json\/wp\/v2\/comments?post=280117"}],"version-history":[{"count":0,"href":"https:\/\/blogs.otago.ac.nz\/lost-worlds\/wp-json\/wp\/v2\/posts\/280117\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blogs.otago.ac.nz\/lost-worlds\/wp-json\/wp\/v2\/media\/280618"}],"wp:attachment":[{"href":"https:\/\/blogs.otago.ac.nz\/lost-worlds\/wp-json\/wp\/v2\/media?parent=280117"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.otago.ac.nz\/lost-worlds\/wp-json\/wp\/v2\/categories?post=280117"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.otago.ac.nz\/lost-worlds\/wp-json\/wp\/v2\/tags?post=280117"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}