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Sunday Spinelessness – Libera fratercula David Winter Mar 11

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If you are a cricket fan you’ll know what sort of weather we’ve had in Dunedin – wet and grey with a chance of denying New Zealand a glorious victory.* The gloomy picture outside the window is made worse for by the fact I’ve spent most of the afternoon sorting through pictures taken for my fieldwork in the Cook Islands. So, between the carefully numbered photographs of the snails that went on to be the basis of my thesis I’m met with scenes from a tropical paradise:

There are also some interesting critters in the “official” photos – like this snail:

That’s Libera fratercula Pease, 1867 and if you believe that subspecies are a meaningful category you can call in Lfratercula rarotongensis Solem, 1976. The genus Libera is part of one of the most important land snails families in the Pacific – the Endodontidae. These tiny snails (most have shells only a few millimeters across) are found on most islands in Pacific and in some cases underwent very large evolutionary radiations. In fact, there were so many species that Alan Solem seemed to have trouble coming up with names for them in his 1976 monograph . Solem introduced the genera Aaadonta and Zyzzyxdonta (so named because he believed them to be morphological opposites, which should appear at opposite ends of his work) and named one species Baa humbugi (the genus named for a part of Fiji and the species name the result of an “irresistible impulse”).

It’s not really possible to write about Pacific land snail faunas in the present tense – it’s quite likely most of the species Solem described are now extinct as the result of habitat destruction and introduced pests. In the Cooks there were two major radiations, the Sinployea and Minidonta of Rarotonga, both now severaly eroded. The Cook’s Libera are less diverse, but also have an interesting evolutionary history. There are forest-dwelling Libera species in many islands in the SW Pacific, and Rarotonga was no different with one species L. cavernula making its living in the vegetation. Libera fratercula (the handsome species photographed above) appears to be the closest relative of L. cavernula (that is, the two species arose within Rarotonga) but at some stage this lineage gave up on forest and started living on the beach. Specifically,  L. fratercula lives in the piles coral rubble that accumulate on Rarotonga’s beaches, having been broken away from the island’s fringing reef. This is a harsh environment, with changes in temperature, saltiness and moisture occuring all the time – but the switch appears to have worked out for L. fratercula, which still has quite large populations around island whereas L. cavernula is now missing presumed extinct.

Rarotonga has plenty of coral rubble, but the other islands in the Southern Cook Islands are basically made of coral rubble. Mitiaro, Mangia, Atiu and Mauke are all small islands that have already gone through the all the steps of the typical life cycle of a pacific island: a fiery birth as a volcano; subsequent erosion into an ever smaller,  flatter island; treading water as an atoll and finally dipping below the surface for ever. The islands of the Southern Cooks got another shot at life when, about 2 million years ago, fresh volcanic activity lifted the crust on which they sit and thrust the fossilsed remains of their coral reefs above the surface. These so-called makatea islands have no shortage of coral rubble and the Rarotongan L. fratercula populations live in just the right place to be swept out to sea. It seems that, among the thousands of snails that must have died having been washed out to sea, at least a few washed ashore on the makatea islands and took advantage of all that coral.  Libera fratercula has made it to each of these smaller islands and they each have (or at least have had) populations of this species.

There’s on more really cool think about about L. fratercula – but I’ll have to wait until I take a few more photos (sadlt no field work required) to talk about that one. Here’s a close up for the mean time:


*Hey, I can dream….

Sunday Spinelessness – Hadda beetle David Winter Feb 06

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Time for another tropical beetle from Vanuatu, and what could be more charming than a ladybird*?

A large orange ladybird beetle, with many black spots

Or its absurdy spikey larvae?

This ladybird is probably a bit larger, a bit rounder and a bit oranger than the ones you are used to seeing in your garden. The more familiar ladybirds are more that just a pretty set of elytra, they’re a force for good. Both the larvae and the adults of most of the familiar red and black ladybirds eat aphids, so having a few around in your garden saves on insecticide:

Coccinella septempunctata

Ladybird larvae ‘controlling’ aphids, thanks to Gilles San Martin for making this image CC 2.0

The big orange ladybird in that first photo is not nearly so helpful. It’s Henosepilachna vigintioctopunctata**, commonly known as the 28 spotted ladybird or the hadda beetle. The hadda beetle is a major agricultural best, because both the adult and larval stages are herbivorous and have a patricular liking plants of the family Solanaceae. That means potatoes, tomatoes, eggplants and (worst of all?) chilies can have their leaves skeletonised by beetles, and a beetle infestation can reduce a year’s crop by up to 25% if not controlled.

You might note that this is the third post I’ve written about invertebrates from Vanuatu, and it’s the third time I’ve written about an introduced pest. That’s not by chance. Islands are hugely interesting for evolutionary biologists, but human introductions have seriously changed island ecosystems.

Take another look at that chewed-over leaf. Now imagine that each of those small white sections to the left of the photograph is a brand new island in a green ocean. In almost no time at all, winds would carry seeds to our little archipelago and life would start to claim the bare rocks. But we don’t know which plants would make it. Dispersal and colonisation are random events, each island would collect its own subset of the seeds drifting past , and so start to develop its own flora. Once those plants have taken hold, the rain of wayward and drifting insects (and even snails) that fall everywhere on earth would have a chance to establish themselves. Again, the isolation of our islands means different species will fall on each one, and different ecological relationships will start to form. Our islands might survive for 20 million years before they’re reclaimed by the sea, and in that time the unique beginnings of each island’s ecosystem will mean a different evolutionary history will play out. In this way islands are evolutionary experiments, and island ecosystems have given risr to some of evolution’s weirdest creations – isolation from the mainland has let iguanas become marine animals, finches become vampires and pigeons give up on flying.

But islands are no longer isolated from the rest of the world. The hadda beetle is probably native to Russia and, without humans moving plants around, would never have had a chance of making it to a Pacific islands. Now it lives in almost all the way across the tropical Pacific (here’s a terrible photo of one I took in Rarotonga, 3000km away from Vanuatu):

In fact, there is an entire “tramp” assemblage including, but hardly limited to, big-headed ants, mynas, land snails, centipedes, paper wasps and mile-a-minute weed that can be found almost everywhere you find people in the tropical Pacific. These Pacific-wide introductions have pushed out native species, and together they have replaced some of evolutions most exuberant expressions with a bland mono-culture. The problem is not quite as bad as it might seem. The tramp species are mainly moved about by commerce, so many of the introduced species are associated with agriculture or at least lowland environments. In most islands, as you climb higher you find a more ‘native’ flora and fauna (for instance, all the partulid species left in the Society Islands are restricted to mountain tops).

By the way, the hadda beetle’s bid for world domination continues: last year it was recorded in New Zealand for the first time. It’s known to have set up shop in Auckland, but if you find hadda beetles somewhere else MAF might want to know about the invasion’s spread.


*That’s “ladybug” in American English, coccinellid or “lady beetle” among scientists and “ngoikura” in Māori

** That name might seem like a mouthful, but the species epithet at least makes sense, viginti-octo-punctatameans “twenty-eight-spotted”. Most ladybird species names follow this rule

The First New Zealanders and their rats David Winter Jul 29

ResearchBlogging.org

Crispin Jago has made a very cool thing, a periodic table of irrational nonsense. Rolling my eyes over the groups, wondering how people can believe some of these things, made me think about New Zealand’s unique ecosystem of kooky ideas. We don’t have to suffer creationists in any organised sense and I don’t think anyone is too into ear candelling, but those TV psychics have found themselves a niche to exploit and most people seem think chiropratric and homeopathy are normal parts of medicine. Then I was reminded about our very own, home grown cranks. There are people who believe that New Zealand was settled by Celts several hundred years before it was discovered by the ancestors of modern Māori. It probably goes without saying that these people are nuts, but the idea of a pre-Māori civilization in New Zealand is one of our culture’s enduring myths. It’s worth talking about why people who are serious about studying our country’s prehistory have discarded it.

People coming to this question for the first time my want a little bit of background. The settlement of the Pacific is one of the most interesting stories in our species’ history. I did the field work for my PhD (on landsnails, and not people) in the Cook Islands and you get a feel for the enormity of that achievement when you travel around that group. To fly from one island to another you walk out across the tarmac and meet your pilot, who is almost invariably sitting on the steps to his 12 seater plane, reading the paper through massive aviator glasses. Once you’re safetly stowed you get your safety briefing (“it’s gonna be pretty fine all the way, should be a good flight”) and you take off. The pilots don’t close the door to the cockpit, so you can see out the windscreen, but all you see is ocean and sky. You can fly for an hour without seeing land in front of you or out your window. Then an island looms. A few minutes later you land, and, even among the Cook Islands, you’re in a new culture. The Polynesian people who discovered and settled these tiny islands separated by such vast distances were master navigators. Without metal tools or written records, let alone maps and compasses, they very deliberately settled islands (taking livestock and crops with them), maintained trading relationships between island groups and almost certainly made it to South America (very likely beating Columbus in the process).

map of Pacific settlement based on language evolution

Schematic of the settlement of the Pacfic (this one is taken from a study of the evolution of Austronesian languages)

The “mainstream” view on the settlement of New Zealand fits nicely into what’s known about the settlement of the Pacific. There is good evidence that the bulk of Polynesia was settled in a stepwise fashion, moving west to east with the prevailing winds. Eastern Polynesia was settled by about 800 AD. The far reaches reaches of Polynesian – Hawai’i, Rapanui and New Zealand would require a different pattern of migration (upwind, or over vast distances) and remained, with Antartica, as the last uninhabited lands on earth for hundreds of years.

The first evidence for humanity in the New Zealand archeological record comes from the Wairau bar, where artifacts similar to those from contemporaneous sites in the Society Islands and the Southern Cooks have been dated to about 1280 AD. At the same time the pollen record shows New Zealand’s first wide scale deforestation, trees being replaced by bracken, scrub and charcoal. A few hundred years later the much sparser record of sub-fossil animals shows its first mega-faunal extinctions. Combined with evidence for “sattelite” settlements in the Kermadec islands (on the edge of the tropical Pacfic) you have exactly the pattern of evidence you’d expect to see with the settlement of islands as remote as Te Wai Pounamu and Te Ika a Māui – settlement as an extension of an ongoing process with clear evidence for human impacts starting from a date that makes sense in that framework

Compare that with the Celtic NZ people. The idea of Celts arriving in New Zealand without leaving any real evidence of their presence anywhere else outside of Europe hardly needs talking about. When we look within New Zealand, almost all the evidence supposed to support a pre-Maori celtic civilization amounts to big rocks that form, if you just imagine they used to be arranged slightly differently, a giant surveying network. Or astronomical observatories. Proponents of the Celtic NZ hypothesis spend very little time trying to find any evidence for the populations that must have lived, died, eaten, built, dug, farmed, and buried their dead in New Zealand to support these mad priests’ plans to move megaliths across the country. And when they do the results are less are less than convincing

By all accounts they treat the historical method with about as much respect as the scientific one, so academics don’t take them very seriously. In fact, you’d think these claims are so kooky that there was really no need to rebut them. Sadly, the Celtic NZ people seem to have convinced at least a few people that they are on to something. I’m sure part of the reason for that is New Zealanders were once taught that the ancestors of modern Māori did meet another people when they came to New Zealand.Up untill about the 1960s school textbooks said the Moriori were a Melanesian people that were driven off the New Zealand mainland by Māori, with a few survivors taking refuge on the Chatham Islands (called Rekohu in their language). That idea had been rejected by every scholar who’s addressed it since the 1920s because it’s clear that the Moriori descended from mainland Māori and the unique aspects of their culture were acquired during their subsequent isolation. Part of the reason the Moriori myth came about in the first place is that it fitted into a Victorian narritive view of history – a chain of never ending progress It was only right that Moriori hunter-gatherers were replaced my the adventurous and noble Māori, just as the advanced British settlers would in turn assimilate the Māori. We might have given up that story, but the Moriori myth is still tied to politics in New Zealand. For people who think the New Zealand government shouldn’t make reparations for its breaches of the Treaty of Waitangi the idea that Maori themselves were once colonisers looks like a get out of jail free card. Russell Brown quoted one example in 2004:

Leaders and academics that hark back to the pre-European days of Maori domination of New Zealand have driven this opportunism. They appear to conveniently forget that Maori violently conquered the Moriori, the original settlers, and their claims of tangata whenua status and demands for compensation for historical grievances appear to many to be ill informed.

Ignoring the gaps in the logic (the Treaty is between Maori and the crown, and is not contingent on Maori being the original inhabitants of New Zealand) such claims also face a pretty big evidence gap. The piece Brown picked up was from then Member of Parliament Muriel Newman. Dr Newman is no longer and MP, but she has set up a think tank (which shows about as much evidence for thought as any group with that name) and it seems she hasn’t given up on her politically motivated brand of crypto-history. Here’s her latest, in which she tries to argue New Zealand has no indigenous people:

Archaeologists agree that humans first settled in New Zealand well over 1,000 years before the main Maori migration, which is estimated to have arrived around 1200 AD. Their evidence is based on the exhaustive forensic examination of historic plant and animal remains. They believe that the settlement of New Zealand was most likely a continuous process, a view that is certainly consistent with early settler journal accounts (from the proceedings of the Royal Society of New Zealand) which indicate that not only did Moriori precede Maori, but that when they arrived in the Chatham Islands, ’they found the country in the possession of aboriginal natives called Hiti’- inhabitants of the ’Flint age’, who used not stone, but ’chips of obsidian as cutting implements.’ There is also strong evidence of an early presence of people of Celtic and Chinese ancestry as well as Greek, French, Portuguese, Spanish and others – in addition to settlers of Polynesian descent.

Breathtaking. But perhaps the most amazing bit of that bizarre paragraph is that somewhere, deep under the layers of crazy, there is just a little science peaking through. We’ve already seen that archeologists don’t agree that New Zealand was settled a thousand years before the Māori arrived. But there has been one little hint among the prehistoric “plant and animal remains” that humans might have got to New Zealand before the people that lived at Wairau Bar. Old Rat bones.

A Pacific Rat (photograph of museum specimen)

A Pacfic rat, image is CC 2.0 thanks to wikipedia user Tolter Alter Man

The Pacific rat (Rattus exulans or the kiore) is native to South East Asia and Melanesia, but it can be found everywhere Polynesian people visited. The kiore isn’t much of a swimmer so the presence of R. exulans bones on an island is unambiguous evidence for human contact. In 1996 Richard Holdaway published the first radiocarbon dates for kiore bones in New Zealand, and they were surprising. Holdaway published dates for 18 bones and all but two of them were older that the first archeological evidence for humans (at 1280 AD) and some of them dated to around 10 AD. Quite how the presence of the Pacific rat in New Zealand in 10 AD gives support to the wild claims of people like Newman or the Celtic NZ crowd I can’t imagine, but those results did fuel a genuine scientific controversy. Why were there rats in New Zealand almost a thousand years before there is any evidence for humans? At the time there were three answers; Holdaway himself argued that the bones were evidence that humans had visited New Zealand but either left immediately or failed to establish themselves, a few archeologists held that the bones were evidence the ancestors of Maori arrived in New Zealand a long time ago but didn’t leave a mark until they adapted to the colder climate, and others said the dates must just be wrong.

Atholl Anderson dedicated a lot of time to testing the reliability of radiocarbon dates from kiore bones. The bones Holdaway had used to establish the antiquity of New Zealand’s rats had come for so called “natural” sites, most notably laughing owl nests and caves, which offer little in the way of corroboratory evidence for the ages estimated from the rat bones. In contrast, Anderson focused on archeological sites (those associated with human habitation) which provide plenty of contemporaneous material to set the dates determined for rat bones in context. Anderson did indeed find the dates determined from rat bones often differed greatly to those determined from the contents of the same midden. They even found bones from well studied archeological sites that were estimated to be thousands of years older than the site! Clearly, there’s something odd about those dates. The real smoking gun for the “old rats” hypothesis came when Anderson looked at the relationship between the age estimated for a bone and the date of the labwork done to determine that age. Almost all the bones measured before 1997 were older than that magic mark at 1280 AD, and every single bone measured at the same facility since 1997 was younger (or at least, the error bars cross that date):

dot plot (with error bars) for dates estimated from rat bones. Dates clearly fall into two group, depending on when they were dated

Dates estimated from rats fall into two distinct groups, depending on when they were analysed. From Wilmshust et al (2008) cited below

There is no reason to think the real age of the kiore bones sampled over time will fall into two such distinct classes (it’s not as if the oldest bones will be the easiest to get to) and it’s easy to bias the date estimated by carbon dating by failing to prepare the bones properly (or by introducing contamination in the lab) so it looks like the surprising results Holdaway reported where actually a lab error which has since been taken care of. It’s (barely) conceivable that originally published dates were right, and that the Anderson’s archeological sites were biased in some particular way, but that hypothesis really doesn’t make sense given what we now know about the settlement of the Pacific. It’s widely accepted that Eastern Polynesian wasn’t settled until about 800 AD, meaning any earlier rats in New Zealand would have had to come from visitors from the Western Pacific. That’s against the main direction of settlement, but, more tellingly, genetic evidence has established that modern kiore in New Zealand come from Eastern Polynesia. Kiore also make their first mark on New Zealand’s faunal record around 1300 AD, when Plactostylus landsnails with gnawed shells show up for the first time. If you want to believe rats were in New Zealand 2000 years ago you also have to believe the first bones to be carbon dated were the oldest, dates estimated from archeological bones are more unreliable than those for bones sourced from “natural” sites and that those old rats left not descendants in modern New Zealand populations and left no mark on the New Zealand faunal record until just after Polyneisian settlement of New Zealand.

You might be wondering why someone hasn’t just gone back an re-analysed the bones that made for Holdaway’s original surprising results. Radiocarbon dating is a destructive process and rat bones are small, so, apparently there isn’t enough bone from the original samples to re-determine their age. Recently, a team from Landcare Research and lead by Janet Wilmshurst did the next best thing, and went back to sites that gave up the apparently old rat bones and re-excavated them. I’m sure you can guess what they found, none of the bones had a pre-1280 AD date. But they didn’t just look at rat bones. The subfossil record of plants is almost always more finely grained than animal records. Every year plants put out millions of seeds and pollen grains, some of which are recorded in pits and lake beds and soil horizons. The Landcare team took advantage of this high resolution record to look for the first appearance of distinctively rat-gnawed seeds, and they found them after 1280 AD, but earlier than the oldest rat bones. Importantly, some of the deposits with relatively old rat-gnawed seeds contain much older seeds, with no evidence of rats. The team plans to go on an use this high-resolution record to establish the dates of settlement for other Pacfic islands.

The sort of people who think the presence of the Pacific rat in New Zealand would be evidence for a pre-Maori Celtic population aren’t likely to let evidence get in the way of their stories. They already think the entire New Zealand acadame is par of a grand conspiracty (they’ve apparently never tried to organise a meeting between three academics let alone pull of a conspiracy among them…). But hopefully the long story of the first New Zealanders and their rats, only summarised above, and the kinds of evidence scientists use to test their ideas will help to make it clear what such “alternative” archeologists lose when they turn their backs on established methods


This post got way longer than I thouhgt it would, and I’m emdebted to a lot of excellent source on the web to get me up to speed on the subject.

Scott Hamilton and Matthew Dentith have written extensively about the Celtic NZ crowd and Te Ara has a nice article on historical ideas on of the orign of Māori (check out the galleries in particular to get an idea of European attitudes at different times)

The orignal paper with the old dates is:

  • Holdaway, R. (1996). Arrival of rats in New Zealand Nature, 384 (6606), 225-226 DOI: 10.1038/

Atholl Anderson’s critque of those is summarised in this paper:

  • Anderson, A (2000). Differential reliability of 14C AMS ages of Rattus exulans bone gelatin in south Pacific prehistory Journal of the Royal Society of New Zealand, 30 (3)

And the recent landcare paper is this one:

  • Wilmshurst, J., Anderson, A., Higham, T., & Worthy, T. (2008). Dating the late prehistoric dispersal of Polynesians to New Zealand using the commensal Pacific rat Proceedings of the National Academy of Sciences, 105 (22), 7676-7680 DOI: 10.1073/pnas.0801507105

Sunday Spinelessness – The end of Drosophila melanogaster? David Winter Apr 25

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It looks like Drosophila melanogaster, the subject of a recent Sunday Spinelessness post, is about to be lost the world. The species itself isn’t under threat of extinction, you can still have them delivered to your door, it’s the name that looks set to go the way of the Brontosaurus.

One of the goals of taxonomy is to give scientists a precise set of terms that refer to a mutually understood group of organisms. The name D. melanogaster is a case in point, geneticists frequently refer to that species as “the fruit fly” but the common name “fruit fly” could equally be applied to the whole genus Drosophila (more than 1400 species), the family Drosophilidae (containing another 50 or so genera) or the related family Tephritidae. Believe it or not, the lack of precision conveyed by the term fruit fly became part of the USA’s 2008 presidential election. Sarah Palin made some snide and ignorant remarks about “fruit fly research” in one of her speeches which were interpreted by scientific types all over the world as a swipe at basic research. People wrote pieces on the importance of D. melanogaster research in understanding human disease and media picked up the story. But Palin wasn’t talking about Drosophila, she was referring to a project on an economically important Tephritid. She was still being ignorant and playing the “aren’t those scientists stupid” card, be she was doing it about a project that stood to help a multi-million dollar industry that employs thousands of people.



Combined phylogenetic tree (“supertree”) stolen from Michael Bok, who redrew it from van der Linde and Houle (2008)

When we say D. melanogaster instead of fruit fly we all know what we’re talking about, and in modern biology a species name can be a key to huge amounts of information. But there’s a problem with Drosophila. The genus as it is currently prescribed is a mess, species currently included in the genus come out in disparate groups in phylogenetic analyses like the one one the left. The solution is obvious, break up the big malformed genus into a set of smaller ones, giving all but one a new name. Such a process is pretty common in taxonomy, and the code used to my animal taxonomists explains how to go about doing it. Each genus has a “type species” which acts as the name bearer and when a genus is split, it’s the group with the type species that keeps the original name. In molecular biology D. melanogaster is very much the name bearing Drosophila (it’s frequently referred to just by that name or even as “the fly”) but the same isn’t true in taxonomy. The type species is D. funebris and no matter how Drosophila is broken up D. funebris and D. melanogaster are going to end up in different genera so melanogaster will lose its forename. But D. melongaster isn’t just any fly – changing that name would render thousands of textbooks, papers and databases out of date.

Kim van der Linde saw the coming of the Drospho-pocalypse, and applied to the International Committee of Zoological Nomenclature (ICZN) to have D. melanogaster installed as the type species, preventing any changes to the taxonomy of the group from changing the species name. A couple of weeks ago the ICZN made their decision: the application was turned down and D. melanogaster will almost certainly have it’s name changed. You can read the decision online – the committee make arguments for their decision with varying degrees of credibility. Perhaps the weakest justification revolves around this mosquito (I couldn’t have two Sunday Spinelessness posts in a row without one photo from me!):

Aedes aegypti  Stegomyia aegypti ?

This photo was taken on Mitiaro in the Cook Islands, and at the time I took I knew for sure that those white striped legs marked it out as Aedes aegypti. If that species of mosquito had bitten me on any other island in the Cooks I wouldn’t have calmly framed a photo, it’s a vector for dengue fever which is, by all accounts, a horrible disease to have (Mitiaro’s population of 200 people isn’t enough to sustain Dengue, and since the main features of the island are two huge brackish lakes fill of mosquito larvae you soon give up on swatting bugs and spraying DEET). But the point of me showing you this photo now is to tell you that mosquito is no longer Aedes aegypti. Some ICZN committee members cited the fact this species has recently been renamed to Stegomyia aegypti as evidence that renaming a widely studied organism isn’t the end of the world, which rather ignores that fact medical workers, ecologists, parasitologists and geneticists have ignored the reassignment entirely and some prominent journals have even issued editorials encouraging researchers to use the “old” name.

Surely in Aedes aegypti we have a model of what will happen when D. melnoagster gets its genus reassignment – taxonomists will refer to it by the new name and the rest of the world will cray on as if nothing had happened. By refusing to make a small change to the existing taxonomy of the group the ICZN runs the risk of driving a gap between the taxonomic community and other scientists. The only good thing to come from the whole ordeal is that “D. melanogaster” will almost certainly become Sophophora melanogaster which tranlates as “dark bodied bearer of knowledge”, a fitting name for such an important fly.


Plenty of other bloggers have been talking about this story, some with quite different takes than mine. You should check out Kim van der Linde who made the the application to the ICZN and has been blogging the aftermarth as well as Micheal at Arthropoda, Chris at Catalogue of Organisms and Dave at Seed.

The tree is from the following paper:


Kim Van der Linde, & David Houle (2008). A supertree analysis and literature review of the genus Drosophila and closely related genera (Diptera, Drosophilidae)Insect Syst. Evol., 39, 241-267

Sunday Spinelessness – Extreme Close-up David Winter Mar 14

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Almost all the photos I’ve used to illustrate these Sunday Spinelessness posts have been taken with my fixed lens digital camera. I think it does a pretty nice job in macro mode but sometimes you just want to get a little closer to your subject. I photographed each of the landsnails I collected for my PhD research so that I could have a record of their pigmentation, which degrades once you preserve a specimen in ethanol. Obviously, the more detail I could get the better so I borrowed some very exciting toys from the department’s photography office:

macro

The camera is a DSLR with a 100mm f2.8 macro lens, an extension tube and a twin flash. The mammal crashing this invertebrate-celebrating series is me.

Of course, I couldn’t have a toy like this to play with and limit myself entirely to photographing snails. In amongst those important snail photos I have jumping spiders, hornets, geckos and really anything else that chanced across the porch I was taking photos on. One of the more striking subjects is this red-eyed fly:

ff2

And the head-on shot…

ff1

It turns out the pretty red-eyed fly is Oxysarcodexia taitensis, one of the Sarcophagidae. That family name gives you a clue to how this fly makes its living, it translates as “flesh eating” (it stems from the same root words as sarcophagus, the Greeks believed limestone ate away at corpses sealed in it). Most of the flesh-flies feed on dead animals but a few have earned a place in vertebrate nightmares, horror movies and even medical practice by depositing their maggots in on open wounds.

Relying on dead animals for food is a chancy business. Corpses are usually patchily distributed and there a plenty of other scavangers out there to compete with. This problem is especially bad for the larval stages of insects, without wings to get them to the next corpse their entire future depends on the continued existence of the flesh they are born on. The sarcophogids have developed a neat trick for making the most of corpse when they find one – they give birth to live maggots. Technically, the flesh flies are ovo-larviparous, meaning the larva develops inside an egg which is retained in the female until the larva hatches. Flesh-fly maggots can start eating as soon as they are born, maximizing their chances of getting through their lifecycle before another scavenger eats the corpse they live in.

It’s easy to get freaked out about a creature that spends it’s life eating decaying flesh but we should remember that flesh-flies play an important role in ecosystems. Sarcophigids and other scavengers turn dead flesh into living flesh. WD Hamilton, one of evolutionary biology’s most insightful and original thinkers, recognised the important role of carrion feeding insects in his burial instructions:

“I will leave a sum in my last will for my body to be carried to Brazil and to these forests. It will be laid out in a manner secure against the possums and the vultures just as we make our chickens secure; and this great Coprophanaeus beetle will bury me. They will enter, will bury, will live on my flesh; and in the shape of their children and mine, I will escape death. No worm for me nor sordid fly, I will buzz in the dusk like a huge bumble bee. I will be many, buzz even as a swarm of motorbikes, be borne, body by flying body out into the Brazilian wilderness beneath the stars, lofted under those beautiful and un-fused elytra which we will all hold over our backs. So finally I too will shine like a violet ground beetle under a stone.”.

Sunday Spinelessness – a snail! David Winter Dec 13

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So far, every single post in the Sunday Spinelessness series has been an arthropod. That’s not surprising in terms of numbers – by any sensible metric arthropods are the most successful animals on earth. They include about 90% of described species and only nematodes could get close to springtails and ticks in terms of numbers of individuals. Still, it’s a shame to use a series of posts aimed at highlighting some of the overlooked creatures around us and just ignore 35 phyla each as different from each other as arthropods are from us chordates. Especially if you study landsnails for a living!

Allow me to introduce you to Orobophana pacifica

Orobophana pacifica

O. pacifica is one of the snails I collected in my field trip to the Cook Islands as a bit of a back up plan – if the species I focused on turned out to be dull then I could fall back on studying these guys. In fact, the species I’ve focussed on have turned out to be, in my own estimation, pretty exciting so I haven’t spent any time trying to understand O. pacfica which is a pity because they’re pretty cool snails. They are tiny (the shell is around 5mm diameter) and live on coral rubble mainly around the coast on each of the Southern islands in the Cook Islands. Even though they live on land they aren’t closely related to the “true” landsnails in the order Stylommatophora. To see the difference you need to look into their eyes. If you click on the image above to get a high resolution version you might just be able to see the eye – it’s a black dot just underneath the tentacles (“feelers”). In true landsnails like the ones you find in you garden the eyes sit on the ommatophores, a second set of tentacles which are retractable. Orobophana sits inside a family of snails called the Helicinidae which represent an invasion of the land by snails distinct from that which gave us the “true” landsnails.

O. pacifica plays an important part in Cook Island’s culture especially in the southern most island Mangaia. The Māori name for the snail is pÅ«pÅ« and locals have traditionally laced the shells together to make necklaces called ‘ei pÅ«pÅ« – you can see some examples in Te Papa’s online collections. In Mangaia at least the tradition is kept up – the process of making ‘ei pÅ«pÅ« is taught at school and you can buy Mangaian necklaces in Rarotonga (though they are often sold alongside much cheaper Chinese manufactured necklaces). Peter Buck recorded six different names for types of pÅ«pÅ« in his Material Culture of the Cook Islands – it’s likely one of those names represents a distinct Helicinid species while the others may represent rare varieties of shell within O. pacifica.

Arachnophilia David Winter Jul 13

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I like spiders. I mean I really like spiders. So, even though my recent field trip to the Cook Islands was all about the landsnails, and I collected hundreds of them, I wasn’t going to miss the opportunity to explore a whole new spider fauna.

It would actually have been impossible to avoid spiders in the cooks, blazing a trail through the bush means you find yourself reflexively expelling air and scrapping an unseen web of you every couple of minutes. The web spinning spiders behind these snares are only the tip of the arachnid iceberg though, so today I’m going share some pictures of a spider that takes a completely different approach to getting fed.

A. whitneei, side on

That’s Athamas whitmeei, a widespread pacific jumping spider. Quite often my search for arboreal snails on the leaves of shrubs on Rarotonga’s mountains would also turn up these guys with their wonderful orange spots (which are worn only by the males). The one in the photo was actually stalking around our motel unit while I was taking photos of snails so I guess they’re quite happy to adapt to different environments.

Look into my eyes…

Unlike their passive, web-spinning cousins jumping spiders need to go out and hunt their food. As a result they have very good vision. The two large, forward-looking eyes can resolve and image onto their retina which appears to be have four different classes of ‘cones’ (one more than our red, green and blue tuned cells) which may allow them to see a much greater range of colours than ourselves.

Even sharp-eyed hunters can fall prey to other hunters. For mammals and birds choosing where to place your eyes is something of a trade off. Forward facing eyes like Athamas’ help you zero in on your target but limit your ability to see around you. Hence sheep with eyes on the side of their head and wolves with forward looking ones. Athamas as no such trade-off to make, having eight eyes in your body plan leaves a couple spare to point backwards!

Look into my eyes…

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