Systematics of South Pacific sap beetles

The species of Carpophilus of particular interest: dorsal habitus above, male parameres below.

Two and a half years ago, I completed my MSc looking at the sap beetles in the genus Carpophilus. In particular, I looked at the C. oculatus species complex from the South Pacific. The species was first described in 1864, before it settled into obscurity. It was only mentioned a few times in the literature until 1993, when Ron Dobson published the results of a study where he looked at a large series of the species. He described three subspecies, two of which were widespread and sympatric, while the third was confined to Vanuatu. Another species, C. maculatus is rather similar in appearance, to the extent that questions were being raised as to the validity of the taxon complex.

My task was to look at this group using molecular methods. In particular, I used three genes to investigate the relationships between these four taxa, and any other species of Carpophilus I could get my grubby hands on. I found that C. maculatus is indeed a distinct species from C. oculatus, and also found sufficient evidence to warrant raising the subspecies from Vanuatu to a full species. The other two subspecies, while being somewhat distinct, did not form entirely separate groups, which suggests that something interesting has happened in the genetic history of these taxa. It was a successful and enjoyable project, and I am proud to say that I completed my MSc with first class honours.

So far, so good. However, the currency of modern academia is peer-reviewed publications. The preparation of manuscripts is an arduous process, and over the past two years the one describing the aforementioned research has been languishing on various people's desks (mine, mainly). In the past month though, it been brought into the light of day and has been published in Molecular Phylogenetics and Evolution. Check it out! If you don't have access to it, feel free to email the author.

References:
Brown SDJ, Armstrong KF, Cruickshank RH. 2012. Molecular phylogenetics of a South Pacific sap beetle species complex (Carpophilus spp., Coleoptera: Nitidulidae). Molecular Phylogenetics and Evolution, 64(3), 428–440

Rapid dispersal of Tahitian biological control agents

The glassy-winged sharpshooter (above) and its parasitoid (below). Pictures courtesy of the Center for Invasive Species Research. License: CC: BY-NC-ND

In 1999, Tahiti was invaded by the glassy-winged sharpshooter (Homalodisca vitripennis, a sap-sucking bug that feeds on a huge variety of plants. In the absence of its natural predators, the bug became extremely numerous. This was of concern for two reasons. The first was that the sharpshooter had the potential to spread bacteria that kill plants. The second was more aesthetic. The sharpshooter feeds on the xlyem fluid of plants, which is high in water and low in nutrients. The result is that the insect needs to drink a lot to get the nutrition it needs. In doing so, it excretes the excess water. When sharpshooter numbers get high, the result can be fairly unpleasant as this video shows. The "rain" in the video is actually water secreted by hundreds of glassy-winged sharpshooters.

Something had to be done, and it was. After pre-release testing, a minute parasitic wasp Gonatocerus ashmeadi (pictured above) was released on the island in 2005. This wasp parasitises the eggs of the sharpshooter. It rapidly became established, and glassy-winged sharpshooter numbers plunged dramatically. When I visited Tahiti in 2008, I found very few sharpshooters despite extensive collecting on the island.

A paper by Petit and co-authors investigated the dispersal of the wasp from two release sites on the island. Sites up to 5 km away were regularly monitored after the wasps were released, to determine how quickly they were moving around. They found that the wasps only took 50 days to be collected 1 km away, and were first collected from the 5 km sites 106 days after the initial release. The team calculated that this insects that is less than 2 mm in length was travelling at around 40 m/day.

This biological control scheme has been especially effective, and will (or should) become a textbook example of successful biological control introductions. Results have been clearly recognised within a short time period, thanks to this parasitoid which has managed to disperse rapidly despite its size.

Reference:
Petit JN, Hoddle MS, Grandgirard J, Roderick GK, Davies N. 2008. Short-distance dispersal behaviour and establishment of the parasitoid Gonatocerus ashmeadi (Hymenoptera: Mymaridae) in Tahiti: Implications for its use as a biological control agent against Homalodisca vitripennis (Hemiptera: Cicadellidae). Biological Control 45: 344-352

Panbiogeography of New Caledonia

Two weeks ago, I reviewed Nattier et al's paper concerning the dispersal of the eneopterine crickets to New Caledonia. This week I discuss the opposing view of Michael Heads, who vociferously promotes the idea that the biota of New Caledonia has its origins in a vicariance framework; i.e. plate tectonic processes have had more of an influence on organism distribution than chance dispersal processes. In particular, Heads is a practicioner of the method known as panbiogeography—a method that emphasises the importance of recurring patterns in the distribution of organisms.

After giving an overview of New Caledonian geology, Heads discusses the various distributional patterns displayed by a variety of taxa in New Caledonian mainland, including the Loyalty Islands. He identifies 10 primary patterns, which can be broadly summarised as restricted to the Loyalty Islands; shared between the Loyalty Islands and Grande Terre; and distributions corresponding to the geology of Grande Terre. Of particular note is his observation that the strange shrub Amborella is restricted to central Grande Terre, on what Heads calls the basement terranes.

I enjoy reading Head's papers. His perspective is an interesting one, his promotion of mapping distributions and having an understanding of geological processes is important and his papers are full of fascinating examples. However, I do see a something of a contradiction in some of his views. He's a proponent of the metapopulation theory, whereby organisms jump between islands that are emerging and disappearing as part of island building processes, resulting in organisms having a longer evolutionary history than the islands that they currently inhabit. I don't have problems with that. However, once land gets accreted, his explanations rely on organisms remaining on those terranes, and not moving far from them at all. The combination of these two views sits somewhat uneasily with me.

Biogeography is a fascinating subject. What I also find amazing is that debates regarding biogeographic processes and methods become incredibly passionate. Panbiogeography is one of those sub-disciplines that is fiercely defended by its proponents and viciously denigrated by its critics. I don't count myself in either camp, preferring to take the useful bits out of any research and always bearing in mind that our perception of the past will always be incomplete, and that discussions regarding the past should be conducting in the light of that fact.

References:
Heads M. 2008. Panbiogeography of New Caledonia, south-west Pacific: basal angiosperms on basement terranes, ultramafic endemics inherited from volcanic island arcs and old taxa endemic to young islands. Journal of Biogeography 35: 2153–2175

Dispersal of crickets to New Caledonia

An eneopterine cricket in the genus Cardiodactylus. Photo courtesy of Guido Bohne

New Caledonia is one of the largest islands in the Pacific, being exceeded only by New Guinea, New Britain, and the main islands of New Zealand. Like New Zealand, the composition of the biota, which includes several relict groups such as the Amborella shrub and the Kagu (Rhynochetus jubatus), has lead many to believe that the island is a fragment of Gondwana, with a long biological history. Also like New Zealand, this story has been questioned in recent years by geological evidence that the island underwent submergence at various points in its history, and that the biota is a result of long-distance dispersal. Cue a classic dispersal-vicariance stoush that is a trademark of biogeographic discussion.

In the dispersal corner is Romain Nattier and coauthors, who present evidence of a "recent" arrival in New Caledonia of the eneopterine crickets. This subfamily of crickets have a wide range throughout several islands of the Pacific, South-East Asia and South America. Their analysis of four genes show that the New Caledonian eneopterine crickets are most closely related to species on other Melanesian islands, and that they've likely been in New Caledonia for "only" 5–16 million years. They then use this evidence to indicate argue against an ancient presence of New Caledonia.

I've got no quarrel with their conclusions regarding this group of crickets. The evidence for a recent arrival of these guys seems pretty clear. However, I do wonder why the authors chose this group of insects to test their hypothesis. The distribution of the non-New Caledonian species suggests that this group is fairly vagile. Their presence in archipelagoes such as Vanuatu, a young island group by most people's standards, hints at their dispersal ability. Much more convincing with regard to their New Caledonia drowning hypothesis would be one of the groups that is less likely to move around as much. Of course, with this criteria, the taxon of choice would be likely to be one of the relict species—which by definition are species poor and with few close relatives—leading to a biased outcome.

I was surprised that none of the Australian representatives were closely related to the New Caledonian crickets. An Australia–New Caledonia link is a fairly common pattern in New Caledonian biogeography, but it hasn't held up in this instance. I was also surprised by the sister-taxon relationship between a genus in Fiji and Samoa, and a couple of genera in Central and South America. Those sorts of relationships seem fairly strange, but not too much stock can be placed on it without knowing more details about the group, and the sampling regime used in the study.

As always, this is not the last word on the subject of the origin of New Caledonia and its biota. It isn't even the definitive on the evolution of this group of crickets. This is one piece of the puzzle that is New Caledonia's biota, and one that will illuminate further research on the natural history of the island, as well as being a valuable addition to the literature of eneopterine crickets.


References:
Nattier R, Robillard T, Desutter-Grandcolas L, Couloux A, Grandcolas P. 2011. Older than New Caledonia emergence? A molecular phylogenetic study of the eneopterine crickets (Orthoptera: Grylloidea). Journal of Biogeography 38: 2195–2209

Phylogeny of Pacific pigeons

Orange dove Ptilinopus victor. Picture courtesy of aviceda on Flickr

In the avifauna of the Pacific, pigeons rule. Considering the region as a whole, pigeons are one of the most widespread and speciose groups of birds in the area. In particular, the imperial pigeons (Genus Ducula) and the fruit doves (Genus Ptilinopus) are especially widespread, being found from South-east Asia to French Polynesia, and with most major islands having at least one endemic species. Despite this diversity however, South Pacific pigeons have tended to not be included in analyses of pigeon evolution as a whole.

To rectify this, Gillian Gibb and David Penny present a phylogeny estimated from a number of mitochondrial genes that includes 9 species of imperial pigeon, and 13 species of fruit dove (including the orange dove Ptilinopus victor shown above), along with representatives of a number of other pigeon genera. Australasia and Oceania have the bulk of the representation in this analysis—of the 25 genera represented, only 10 have no species in the region.

They found that the imperial pigeons are monophyletic (that is, they form a natural grouping) and are rather distinct from the remainder of the pigeons sampled. The fruit doves on the other hand are prevented from forming a natural clade by the presence of the cloven-feathered dove (Drepanoptila holosericea) of New Caledonia, and the blue dove (Alectroenas madagascariensis) of (you guessed it...) Madagascar. When you look at pictures of these two, it's not surprising that they might be fairly close to Ptilinopus. What is surprising though, is that these two species are resolved as being sister taxa, despite being so geographically distant from each other. This puzzle obviously requires rather more investigation.

References:
Gibb GC, Penny D. (2010). Two aspects along the continuum of pigeon evolution: A South-Pacific radiation and the relationships of pigeons within Neoaves. Molecular Phylogenetics and Evolution 56: 698–706

Trigonopterus diversity in New Guinea

The weevil genus Trigonopterus is found in the islands of Indonesia, eastwards to Fiji and Samoa. There are around 90 described species, but thanks to the work of Alexander Riedel, the true diversity of the genus is becoming apparent. One of the latest works of Riedel and coauthors was published earlier this year in PLoS ONE, and describes how a DNA barcoding approach is helping to make sense of the group.

In this study, over 1000 specimens were collected from five broad regions of New Guinea. Initial sorting suggested that there were 270 species represented in this group with each area possessing an average of 41 species. After sorting, these specimens had their COI gene sequenced and analysed using a number of different methods. These analyses slightly increased the total number of species to 279, due to the presence of very similar-looking species being present in the sample.

The authors argue that when facing sorting through groups of greater than 50 species, it becomes inefficient to circumscribe them using traditional means. In these situations, DNA barcoding approaches can make the task more tractable and form a solid base for ongoing taxonomic research. In addition, they recommend that Trigonopterus form a key group for use in biodiversity assessment surveys within Melanesia.

This study shows how much there is to learn about the biota of Melanesia. Unfortunately though, the are resources available for researchers interested are relatively scarce. Additionally, most of the research done is by researchers based in places such as Europe and the States, with involvement by Pacific Islanders generally being limited to providing technical assistance. This paper is a case in point. While a 'man blo niu guinea' is a coauthor, he was not involved in the experimental design or in the writing of the paper; both valuable skills for success in science. Locally based scientists in the Pacific will continue to struggle until more funding becomes available from their governments, and they take opportunity to be involved in all parts of the scientific process from design to publication.

References:
Tanzler R, Sagata K, Surbakti S, Balke M, Riedel A (2012) DNA barcoding for community ecology—How to tackle a hyperdiverse, mostly undescribed Melanesian fauna. PLoS ONE 7(1): e28832.

Amphibious caterpillars in Hawaii

The Hawaiian Islands are renowned for their unique biota that display a number of bizarre adaptations that do not appear elsewhere in the world. Widely known examples of these include the predacious caterpillars in the genus Eupithecia, and the wekiu bug (Nysius wekiuicola) that lives on Mauna Kea eating insects that are blown to them on the wind.

Recent work by Daniel Rubinoff and Patrick Schmitz have added another example to the list: amphibious caterpillars. In a paper published in March in PNAS they describe the ecology of some recently discovered 12 currently undescribed species of the moth genus Hyposmocoma that are able to develop equally well both in and out of water. Intriguingly, a phylogenetic tree hypothesizing the evolution of these insects suggest that this amphibious trait arose independently at least four times, an unexpected result for a specialised trait such as amphibiousness.

The major driving force for the development of this unique lifestyle in Hawaii is believed to be due primarily to a lack of competition. Hawaii lacks the major aquatic insect orders of the stoneflies, mayflies and caddisflies (the latter two represented by introduced species only), leaving Hawaii's freshwater environments unexploited. Hyposmocoma has stepped into the breech.

In addition to the written paper, the authors have provided movies showing the caterpillars moving in and out of the water. They are provided as supplementary information to the paper and available on the PNAS website here and here. Unfortunately, a David Attenborough documentary this isn't. There is no informative commentary spoken with a British accent, but it is an interesting watch nonetheless.

References:
Rubinoff D, Schmitz P. 2010. Multiple aquatic invasions by an endemic, terrestrial Hawaiian moth radiation. Proceedings of the National Academy of Sciences of the United States of America 107(13):5903-5906

Zimmerman EC. 1957. Insects of Hawaii. Volume 6, Ephemeroptera-Neuroptera-Trichoptera and Supplement to Volumes 1 to 5. University of Hawai'i Press.

Featured insect: Ceresium tuberculatum (Coleoptera: Cerambycidae)

One of the unfortunate aspects of South Pacific entomology is the lack of Pacific Islanders that are actually involved in the discovery and naming of their biota. Thankfully, there are signs that this situation is beginning to change. Last August on a trip to Fiji I had the immense privilege of meeting a number of young scientists from Fiji, the Solomon Islands and the Cook Islands. One of these was Hilda Waqa, the senior author of this paper describing two new Fijian longhorn beetles, one of which is the beetle pictured, Ceresium tuberculatum.

The Cerambycidae commonly known as the longhorn beetles tend to be wood borers in the larval stages. These larval stages can last for a long time---several years in some species. The larvae of some of the larger species are eaten occasionally and are considered delicacies in some areas. Unfortunately, very little is known about the biology of Ceresium tuberculatum specifically. It has been collected from the Fijian islands of Gau and Viti Levu, and have been collected from primary, undisturbed forest in the heart of Viti Levu as well as secondary, plantation forests in the vicinity of Suva.

The paper is well illustrated with some very clear photos of various characters that are useful for identification. Unfortunately though, there is little in the way of comparison with other species of Ceresium in Fiji and the South Pacific. This makes the paper less useful than it might have been. It remains a valuable addition to the literature, and it is well worth having a look at for the illustrations alone, whether or not you have any further interest in Cerambycidae.

References:
Waqa H, Lingafelter SW. 2009. New Fijian Callidiopini (Coleoptera: Cerambycidae). In: Fiji Arthropods XV. Edited by Neal L. Evenhuis & Daniel J. Bickel. Bishop Museum Occasional
Papers 106: 3–15 (2009).

South Pacific insects in a Russian Journal

The Russian Entomological Journal is not the usual outlet for taxonomic research on South Pacific insects. That said, it has published a number of papers over the last few years that are freely available to everyone on their website. For some reason, they all deal with the Hemiptera. So, if you ever wanted to know about Microveliines from Fiji, Maana emeljanovi (Lophopidae) from West Papua, or Nerthra kerzhneri (the first species of the Gelastocoridae found from New Caledonia, pictured), now you know where to look.

Featured insect: Aureopterix micans (Lepidoptera: Micropterigidae)

The moth fauna of the Pacific is still fairly unknown, with most of the work that's been done on the region's being rather old and with few recent revisions. An addition to the literature was recently published by George Gibbs in Zootaxa today on the Micropterigidae of Australia, New Zealand and New Caledonia. In it, he describes the species pictured:

Aureopterix micans from New Caledonia. This beautiful species is fairly widespread and common throughout New Caledonia at moderate altitudes.

As suggested by the name of the family, the Micropterigidae are part of the microlepidoptera---an informal name for a bunch of families that are small and tend to escape the notice of the public. They also tend to escape the notice of most specialists, and so their biology is not particularly well known. This is true for Aureopterix micans, however, the larvae for some of the other species described in the paper are known to feed on foliose liverworts. This is likely to be true of A. micans also.

It is believed that the distribution of the Micropterigidae may offer insights into the biogeography of the South Pacific region. The distribution of Auropterix offers a fairly standard interpretation of New Caledonian biogeography. While A. micans is restricted to New Caledonia; the only other species currently known in the genus, A. sterops, is found in northern Queensland, Australia. This East Coast Australia---New Caledonia connection is fairly typical of a lot of the fauna of the island. Other species of Micropterigidae however do not show this pattern, being closer to species in New Zealand than Australia. While Biogeography is full of interesting details such as these, going from hypotheses of pattern to process can be difficult to test, and will require greater research into the fauna of each area and underlying geology and ecology of the species involved.

References:

Gibbs GW. 2010. Micropterigidae (Lepidoptera) of the Southwestern Pacific: a revision with the establishment of five new genera from Australia, New Caledonia and New Zealand. Zootaxa 2520: 1-48.

Conservation Biology papers with a Pacific focus

The most recent (April 2010) issue of Conservation Biology has a number of papers which focus on the fauna, flora and environment of the South Pacific.

The issue starts off with an editorial by David Melick on economic schemes to negate carbon emissions. In particular he deals with the scheme to compensate landowners for NOT cutting down forests on their land (REDD) and the way this has played out thus far in the Papua New Guinea scene. He ends with this very pertinent statement:

... REDD will come to nothing if the system is not supported by the people who own and live in the forests. If the process is not rushed (it may take years, not months) and the PNG government is willing to accept international scrutiny and advice, forest governance and communitybenefits for the rural poor may finally be improved significantly...

Highly relevant for all who work in the South Pacific, particularly those of us with a western, productivity-based mindset. As the Mainland cheese ads say---Good things take time.

William Laurance and others discuss the impact of Oil Palm cultivation and some of the issues and opportunities surrounding it. In particular, they discuss the Roundtable on Sustainable Palm Oil (RSPO) a nonprofit organisation that hopes to promote and market sustainably grown palm oil. Unfortunately, its track record appears to be fairly poor. The seeming blind eye the organisation has taken toward the destruction caused by growing oil palm in peat swamps is singled out as being a major failing of the RSPO. however Laurance et al. refuse to be pessimistic about the situation and make some recommendations, most of which involve fairly major restructuring of the RSPO and developments in its monitoring and enforcement policies. However, the real problem in the situation is the lack of market demand for sustainably grown palm oil, meaning that the RSPO has little clout.

Alison Boyer revisits the very high extinction rate of Pacific Island birds, this time investigating what ecological traits seem to have an influence on extinction rate. She concludes that differences in endemism, body size and diet influence the potential for extinction and gives a list of bird species that may be worthy of a higher threat category than currently given.

Shankar Aswani and Armagan Sabetian look at the impact that urbanisation has had on the parrotfish population around Gizo and Munda, in the Western Province of the Solomon Islands. Not surprisingly, they found that over the period 2004--2005 parrotfish numbers decreased around Gizo. However, they did find that some customary management systems were effectively preserving larger and greater numbers of parrotfish. The most effective systems were those that prevented all fishing in certain areas.

Mayeul Dalleau and team looked at shallow marine habitats around Wallis Island and used digital imagery and habitat maps as surrogates for biodiversity in the proposal of marine protected areas. While they promote this method as being an effective and efficient of surveying large areas, they do recognise that it is very desirable to do some actual field work to complement the habitat data, particularly in regions such as the Red Sea which has a very different environment from the oceanic Pacific islands.

It's a good issue. Well worth a read, certainly if any of the above issues pique your interest.

References:

Aswani S, Sabetian A. 2010. Implications of Urbanization for Artisanal Parrotfish Fisheries in the Western Solomon Islands. Conservation Biology 24(2): 520-530

Boyer AG. 2010. Consistent Ecological Selectivity through Time in Pacific Island Avian Extinctions Conservation Biology 24(2): 511-519

Dalleau M, Andréfouët S, Wabnitz CCC, Payri C, Wantiez L, Pichon M, Friedman K, Vigliola L, Benzoni F. 2010. Use of Habitats as Surrogates of Biodiversity for Efficient Coral Reef Conservation Planning in Pacific Ocean Islands. Conservation Biology 24(2): 541-552

Laurance WF, Koh LP, Butler R, Sodhi NS, Bradshaw CJA, Neidel JD, Consunji H, Vega JM. 2010. Improving the Performance of the Roundtable on Sustainable Palm Oil for Nature Conservation. Conservation Biology 24(2): p 377-381

Melick, D. 2010. Credibility of REDD and Experiences from Papua New Guinea. Conservation Biology 24(2): 359-361

Molecular identification of New Guinea mammal poo

The use of environmental DNA samples for identification and monitoring of animals has been increasingly widely used over the past five years or so. This essentially involves extracting DNA from non-tissue materials and analysing it in such a way as to discover the creatures that produced/lived in/ate/passed by the material. For example, pond water has been analysed to discover what frog species were present in the area and faecal matter has been analysed to figure out both what was eaten and who was the eater.

This last scenario has been played out on the Huon Peninsula in Papua New Guinea. Research has begun on the endangered Matschie's tree kangaroo (Dendrolagus matschiei) looking into its population structure and genetics. This research has applications to help direct the future conservation of the species by giving an indication as to how many individuals there are and how much they move around. However, the capture and collection of tissues from a rare, endangered animal that spends the majority of its time in montane rainforest canopies present both logistic and ethical concerns which are alleviated by the collection of DNA from their faeces. Finding poo is sometimes a lot easier than the beast itself!

Unfortunately, poo from one marsupial often looks the same as poo from another and so faeces were mistakenly collected from an additional two species the New Guinea pademelon (Thylogale browni) and the small dorcopsis (Dorcopsulus vanheurni). A recent paper published in Molecular Ecology Resources by Thomas McGreevy and coauthors give a method for determining which species of marsupial produced the poo of interest. The primer set they've developed amplifies a portion of DNA that is a different length in each species---making it easy to distinguish which came from what and making sure that time is not spent looking at the wrong ones.

References:
McGreevy TJ Jr, Dabek L, Husband TP. (2010). A multiplex PCR assay to distinguish among three sympatric marsupial taxa from Huon Peninsula, Papua New Guinea, using the mitochondrial control region. Molecular Ecology Resources. 10(2): 397-400.

Highly diverse weevils in northern New Guinea

New Guinea is an amazing place. It is one of the final frontiers of exploration, particularly in the biological realm with highly diverse rainforest that cover huge areas and a nearly unbelievable range of habitats from hot, humid mangrove swamp forests to 4,000 m high mountains and glaciers. The diversity of the island astounds everyone who works there and the amount remaining to be discovered absolutely boggles the mind.

A case in point was published late last year, when research on Trigonopterus weevils from the Cyclops Mountains was published. This research was headed up by Alexander Riedel and they looked at the congruence between clades revealed by cytochrome c oxidase 1 (COI) DNA sequences and morphological variation. They found 51 morphospecies which were all congruent with COI data. What is incredible though is the genetic distances within this group. Uncorrected distances between species were incredibly high, the lowest being 16.5% and a mean of 20.5%. Within species variation ranged from 0% (not too surprising), to a whopping 8.8%. To put this in context, a 2% genetic distance is usually bandied about as being the point at which you're thinking that you've got two different species.

This diversity is particuarly impressive when one considers that these results are derived from a single transect in a relatively low area in one mountain range. The authors justifiably expect that more extensive sampling will produce many more species.

Not only are they incredibly diverse, these weevils are also tough. Being cryptorhynchine weevils, their rostrum can fold up into a groove in their thorax when they're disturbed. Unlike most other cryptorhynchines though their elytra are fused together and to the thorax, making them able to withstand extremely high pressure and ensuring that they are very difficult to dissect. This is a problem when dissections are necessary to fully characterise and identify these beetles.

It's a very interesting paper on a really cool group of weevils. Check out the supporting information for habitus photos of the morphospecies and get an idea of the morphological variation in the group.


References:

Riedel A, Daawia D, Balke M. 2010. Deep cox1 divergence and hyperdiversity of Trigonopterus weevils in a New Guinea mountain range (Coleoptera, Curculionidae). Zoologica Scripta 39(1): 63--74.

Fire ant origins and genetics

The fire ant Wasmannia auropunctata is one of the most annoying things in the Solomon Islands. They have a very irritating and itchy bite, are so small as to be invisible, and they have a penchant for living in your underwear draw. Not pleasant. Unfortunately, they are another of the invasive species that have invaded the islands from elsewhere, in this case South America. They are found naturally through a large part of South America, from Argentina to the Caribbean islands. They have been introduced to a number of places, including Hawaii and the United States, Gabon in West Africa, and in the South Pacific both the Solomon Islands and New Caledonia.

To investigate where these ants came from, Alexander Mikheyev and Ulrich Mueller conducted a genetic study on a bunch of both natural and introduced populations of the fire ant. Looking at a little bit of the mitochondrial COI gene, they discovered that the Solomon Island populations have affinities with US and Hawaiian, and Northern South America and Caribbean populations. New Caledonian specimens were quite different, originating from southern natural populations in Argentina and Brazilian populations. Gabon has also been invaded by this group. This suggests that the two Pacific populations sampled were independantly derived, probably through trade or troop movements during WWII.

An assumption that I've usually made with invasive species in the Pacific is that they tend to do a bit of island-hopping, and in this case I would've hypothesised that the New Caledonian and Solomon Island populations would be the same. This is obviously not the case here, and it is a reminder that it's worth keeping in mind that there are many ways for organisms to get from place to place.

References:
Mikheyev AS, Mueller UG. 2007. Genetic relationships between native and introduced populations of the little fire ant Wasmannia auropunctata. Diversity and Distributions 13:573-579.

Melicope: Hawaii's export to the Pacific

Over the years, the general consensus has been that islands of the Pacific, and particularly the incredibly isolated archipelago we fondly know as Hawaii have been the passive collectors of fauna and flora that have just happened to have swum, flown, drifted, or been blown onto their fair shores. It's generally been thought to have been a one-way process, that once something has arrived there, it settles down and makes the most of their tropical paradise. Something that those of us stuck in cold climates can relate to very well -- why would you want to leave a place that is extremely amiable and is yours for the taking?

However, recent systematic research on a number of organisms is starting to shake up this tidy story somewhat. It appears that we may have underestimated the ability of these islands to send their biota elsewhere.

The particular paper sparking this post, written by Danica Harbaugh and coauthors, features the shrub Melicope. It's widely distributed across Asia and the South Pacific, but has undergone an "explosive radiation" in Hawaii, with 47 species found in the group. As usual, the authors hypothesised that all Hawaiian species had originated from a single colonisation and formed a monophyletic group restricted to the islands. Data from a number of genes were analysed, and it was found that although it does seem to be the case that all Hawaiian Melicope were derived from a single colonisation, it hasn't remained stuck in the one place. Surprisingly, their data suggested that Hawaii has exported some of their plants to the Marquesas Islands, where they have subsequently speciated.

This data adds to the body of work that suggests that Pacific biogeography is a lot more dynamic and complicated than initially suspected. It is also another example of the very intriguing connection that exists between Hawaii and the Marquesas.

References:
Harbaugh DT, Wagner EI, Allan GJ, Zimmer EA. 2009. The Hawaiian Archipleago is a stepping stone for dispersal in the Pacific: an example from the plant genus Melicope (Rutaceae). Journal of Biogeography 36: 230-241.

Tokelau Ant Communities

Tokelau is a small place, far away from anywhere. Unfortunately, like all Pacific Islands, it has been overrun by invasive ants, which have massive impacts on the ecosystem of the islands. Phil Lester and his crew from Victoria University in Wellington, New Zealand made the most of a bad thing and took the opportunity to investigate community structure and assembly processes on these islands. What they did which few others have done was investigate the effect of abundance on community assembly, as opposed to just recording which species are found in the same places as each other. As expected, they found that as the abundance of ants went up, the number of species present decreased.

The ant that was dominant, was the yellow crazy ant, Anoplolepis gracilipes. And boy, was it dominant! Maximum abundances were 100 times that of the most abundant species. Rather unsurprisingly, the authors comment that

"in high abundance, A. gracilipes was associated with reductions in the number of co-occurring species and their abundance."

In this research, the authors only looked at the effect on other ant, which are also introduced to Tokelau. However, the effect of the ants can be devestating. One of the most publicised crazy ant invasions is their effect on the ecosystem of Christmas Island, Indian Ocean, home to the charismatic red land crab. A couple of reports about the invasion in the popular press are this one from the ABC and a report from the Australian Government

Reference:
PJ Lester, KL Abbott M Sarty and KC Burns. 2009. Competitive assembly of South Pacific invasive ant communities. BMC Ecology 9:3

Fruit bats going the wrong way

A couple of years back, Jeremy Pulvers and Don Colgan published an interesting paper on the intriguing fruit bat genus Melonycteris, that is restricted to the Solomon Islands and the Bismarck Archipelago. The fascinating thing about this bat is that it is believed to be placed right at the base of the Megachiroptera (flying foxes and their ilk). Why it is that this supposedly old lineage is restricted to these isolated island groups is still unknown, but it is not alone in this pattern. In the birds, a number of the more ancient groups are found in and around New Guinea and the Australasian region.

This however, is not the thrust of the Pulvers and Colgan paper. What they did is look at the genetic systematics and variation within the genus, particularly the Solomon Island species. To summarise, they found that the Solomon species are a group separate from the single Bismarck species. What was more interesting was the pattern of relationships within the Solomon Islands population. They found that the species on Makira (San Cristobal) was sister to the rest, followed by the Malaitan species, then the species found in the New Georgia group. Choiseul, Isabel and Guadalcanal populations composed a single group and were the most derived.

What is interesting about this pattern is that it is the opposite of what would be expected from a simple dispersal model originating in the Bismarcks. If that was the case, you would expect the sequence to be essentially the opposite---New Georgia; Choiseul, Isabel and Guadalcanal; Malaita, then Makira.

There has been increasing evidence from birds that the "Dispersal from New Guinea" model of the makeup of the Solomon Island fauna is not the only story, but as far as I'm aware, this is the first publication of evidence in vertebrates other than birds.

Reference:
Pulvers JN, Colgan DJ. 2007. Molecular phylogeography of the fruit bat genus Melonycteris in northern Melanesia. Journal of Biogeography 34:713-723.

The bizarre family of the Silktail

The silktail (Lamprolia victoriae) is a small bush bird, restricted to the Fijian islands of Vanua Levu and Taveuni. From its first description in 1874 its systematic position has been debated with suggested closest relatives ranging from the australian robins (Petroicidae), and the monarch flycatchers (Monarchidae), to the birds of paradise (Paradisaeidae). The late, great Ernst Mayr famously called the silktail "One of the most puzzling birds of the world". Last year, a group of european, american and south african scientists headed up by Martin Irestedt brought DNA evidence to the party to shed further light on the subject. Their results were published here.

What they discovered was totally unexpected. Their data suggests that the closest living relative to the silktail is the Papuan mountain drongo (PMD, Chaetorhynchus papuensis), a little-known bird of the New Guinea highlands. The PMD has traditionally been grouped with the drongos (Dicruridae), but in the Irestedt study, both the silktail and PMD are sister to the fantail family (Rhipiduridae).

The authors discuss at length the biogeographic implications of their finding, suggesting either long distance dispersal or a vicariant metapopulation origin, but are unable to come to a conclusion either way. Unfortunately, they don't suggest ways of testing these hypotheses. I suggets it may be a little premature to speculate too seriously about this single result, interesting though it is. Future work on the geology of the region and further systematic research on the silktail and the remainder of the avifauna of Melanesia may reveal other potential explanations.

References:
Irestedt M., Ruchs J., Jonsson K., Ohlson J. I., Pasquet E., Ericson P. G. P. (2008) The systematic affinity of the enigmatic Lamprolia victoriae (Aves: Passeriformes) - An example of avian dispersal between New Guinea and Fiji over Miocene intermittent land bridges? Molecular Phylogenetics and Evolution 48: 1218-1222

Picture courtesy of Birdlife International

Reef fish phylogeny and connectivity

A paper on the intraspecific phylogeny of the damsel fish Pomacentrus moluccensis was published the other day by Joshua Drew and Paul Barber as a short communication in Molecular Phylogenetics and Evolution. This paper is well worth reading as it demonstrates that specimens from Fiji form a monophyletic sister group to those from further west. Vanuatu species are also monophyletic, while those from the Solomons to Sumatra form a third, most derived clade.

What makes this interesting is that this runs counter to the traditionally accepted mode of dispersal in the Pacific, where the area around New Guinea and Indonesia act as a source area for the remainder of the Pacific.

As the authors point out, this story is based only on mitochondrial DNA sequences, and as such only tell a partial story of P. moluccensis' history. More data may change the story somewhat, but the results published here are intruiging and will hopefully stimulate further investigation.

References:

Drew, J., and Barber P. H. (2009) Sequential cladogenesis of the reef fish Pomacentrus moluccensis (Pomacentridae) supports the peripheral origin of marine biodiversity in the Indo-Australian archipelago. Molecular Phylogenetics and Evolution. 53(1): 335-339.

Picture stolen from the Encyclopedia of Life (http://eol.org/pages/212092)

Homona mermerodes eats a lot.

With the advent of cheap and effective DNA amplification and sequencing methods, there has been an increased appreciation of biological diversity. In particular, a field that has particularly benefited from the techniques has been the detection of cryptic species. These are groups of organisms that appear the same, but a look into the DNA of the creatures reveal that they are complexes of genetically different populations. Frequently, these cryptic species are found to be host specific to certain food types, while the former "superspecies" was thought to have a range of hosts.

There has been a lot of work done recently on the northern coast of Papua New Guinea by the Binatang Research Centre. Their research has a focus on rainforest invertebrate dynamics and ecology, and they have done a sterling job in encouraging science in the country. They've trained several PNG citizens as parataxonomists, and a look at their publication list is rather impressive. As part of this research, they have investigated the population structure of the leafroller moth Homona mermerodes (Lepidoptera: Tortricidae). They used the fabled cytochrome oxidase gene (commonly abbreviated to cox1 or COI) to investigate whether the species is a widespread polyphagous species, or whether it is made up of a lot of cryptic species that are specific to certain plants. The COI gene is found in the mitochondrial DNA, and is famous as the gene of choice for what has become known as barcoding. This is an ambitious scheme to sequence the COI gene region for every organism on the planet to allow it to be quickly and easily identified.

Hulcr et al published the results of the work on Homona in Molecular Ecology Notes in July this year. Their analysis shows that the use of COI made some very nice distinct groups (clades), with big differences between the different clades. The interspecific genetic distances are larger than the intraspecific distances, forming a bimodal (twin-peaked) distribution with very marginal overlap. There were certainly no genetic differences between H. mermerodes reared on different plants, nor were there major differences between PNG and Australian (Queensland) populations.

One of the things that impressed me by this paper was the incorporation of pictures of the moth including both adult, larvae, and genitalia. It has been a concern of mine that much of the rhetoric surrounding barcoding seems to neglect other taxonomic evidence, whether it's morphological or other genes. I believe this is from the enthusiasm surrounding the power of the techniques as opposed to deliberately believing that barcoding is the ONLY way. Single-character taxonomy will always provide misleading results, whether it's in a morphological sense, or if it's only single gene region being looked at. I have experienced this myself when trying to identify things and getting involved with single things rather than looking at the organism as a whole. Good taxonomy takes a lot of information into account in order to try and infer species limits.

It is also good to have an example where a wide ranging, generalist and morphologically variable species has a well-defined genetic structure. Frequently it seems that the genetics of creatures that display these traits suggests that there are a number of cryptic species. It is gratifying (to me at least) to know that these cryptic species groups aren't a given. Further research that attempts to deduce the factors that influence the formation of cryptic species groups will be highly interesting.

Hulcr J, Miller SE, Setliff GP, Darrow KA, Mueller ND, Hebert PDN, Weiblen GD. 2007
DNA Barcoding confirms polyphagy in a generalist moth, Homona mermerodes (Lepidoptera: Tortricidae).
Molecular Ecology Notes 7: 549-557