Archive for November, 2007

Nov

28

2007
 
 

Forty two degrees C



Extreme climate events take flying-foxes to the brink

If you can't take the heat you shouldn't hang aroundJanuary 13 and 14, 2002 must have been bleak days for Justin Welbergen and colleagues, as they collected the corpses of thousands of Australian fruit bats whose deaths they had documented the day before. The bats, mainly grey-headed Pteropus poliocephalus and black flying-foxes P. alecto had succumbed to an extreme heat wave, with the temperature at Dallis Park, New South Wales, topping 42.9°C – that’s 107.6°F. Writing in Proc. Royal Soc. B this week, Cambridge University’s Welbergen presents an analysis of the tragic die-off – one of at least nineteen to have taken place since 1994. In mixed colonies, P. alecto fared worse than P. poliocephalus: juveniles and adult females were far less tolerant of the searing heat than males. Extreme climatic events are expected to become more common, so monitoring roosts when the mercury is set to soar above the critical mark sounds like a good idea. That way, falling off the perch might not mean the end. Source: Welbergen JA, Klose SM, Markus N & Eby P (2007) Climate change and the effects of temperature extremes on Australian flying-foxes. Proceedings of the Royal Society of London B DOI: 10.1098/rspb.2007.1385

Image © Jan Rihak

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Nov

26

2007
 
 

There and back again



Hybridization destroys and creates species: it depends on the environment

While he coyote, he not wolf. Right?Young species often occur together, separated by a barrier to gene flow that, according to a study published recently in Molecular Ecology, is all too easily broken down. The result? Hybridization — a frequent driver in the formation of new species — can act to meld them together into one. The study, led by University of Bern ecologists Ole Seehausen and Gaku Takimoto, presents a string of real world examples — the genetic tussle between coyotes Canis latrans and grey wolves C. lupus being a particularly striking one. Next, a computer model shows how hybridiziation interacts with environmental variation to generate, or erode, biodiversity. Collapsing species groups into hybrid swarms doesn’t necessarily mean a loss of genetic diversity but it plays havoc with conservation action plans. Once species have been doing their own thing for a while, though, they become resistant to such rapid demise. The first two to five million years are the worst, apparently. Source: Seehausen O, Takimoto G, Roy D & Jokela J (2007) Speciation reversal and biodiversity dynamics with hybridization in changing environments. Molecular Ecology DOI: 10.1111/j.1365-294X.2007.035293.x

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Nov

23

2007
 
 

Tooth and paw



Genetic analysis reveals the real culprit behind Scandinavian sheep kills

bad to the boneBiologists at Uppsala University, Sweden, have successfully extracted DNA from saliva around bite wounds in two savaged sheep. Carles Vilà and colleagues swabbed the grisly remains, used some clever machines to get the DNA out, and compared their findings against known genetic sequences. Wolves Canis lupis perusing the online pages of Conservation Genetics will no doubt delight in discovering that the predator responsible was in fact a single very naughty dog — the two faithful farm mutts have also been ruled out of the investigation. The technological advance should ensure that wolves aren’t made into scapegoats, so to speak, and blamed unfairly for crimes they did not commit. You see how science can make us all more happy? Except sheep, of course. Source: Sundqvist A-K, Ellegren H & Vilà C (2007) Wolf or dog? Genetic identification of predators from saliva collected around bite wounds on prey. Conservation Genetics DOI: 10.1007/s10592-007-9454-4

Related stories in Conservation magazine: The Last Gladiators | The Look of Success

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Nov

22

2007
 
 

Biodiversity on a budget



Scientists figure out how to describe the world in the most efficient way

making pieces of eight go furtherMeasuring biodiversity falls into the really-important-but-incredibly-difficult-to-do category of chores, so when someone comes up with a scheme to make it more cost-effective (i.e. easier) they deserve to be heard. A lengthy list of international conservation biologists, fronted by the University of East Anglia’s Toby Gardner, has done just that, and just they’ve published their findings in Ecology Letters. After sampling a wide range of taxa at sites across 500 000 hectares of Brazilian Amazonia, birds and dung beetles shook out as being particularly good – and cheap – indicators of general biodiversity. However, focusing on these groups is a double-edged sword: on the one hand the money goes further, but on the other we remain ignorant of those poorly understood, expensive to study species. Source: Gardner TA, Barlow J, Araujo IS, Ávila-Pires TC, Bonaldo AB, Costa JE, Esposito MC, Ferreira LV, Hawes J, Hernandez MIM, Hoogmoed MS, Leite RN, Lo-Man-Hung NF, Malcolm JR, Martins MB, Mestre LAM, Miranda-Santos R, Overal WL, Parry L, Peters SL, Ribeiro-Junior MA, da Silva MNF, da Silva Motta & Peres CA (2007) The cost-effectiveness of biodiversity surveys in tropical forests. Ecology Letters DOI: 10.1111/j.1461-0248.2007.01133x

Related stories in Conservation magazine: Democratizing Taxonomy

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Nov

21

2007
 
 

What’s up? DOC



Falling acid rain turns rivers brown, but in a good way

a browner shade of waterReductions in sulfur emissions have turned our rivers and lakes brown, say the authors of a paper in Nature this week. An international group of scientists, headed by Don Monteith, an aquatic ecologist at University College, London, analyzed data collected from remote areas of North America and northern Europe during 1990–2004. The water’s brownness — the color comes from increased levels of dissolved organic carbon (DOC) — stems from reductions in acid rain and sea salt deposition (the latter due to unusual meteorological conditions in the early 1990s). However, the scientists suggest the effect is simply a return to pre-industrial levels of DOC as soil acidification is reversed. Climate change factors, such as increasing air temperatures and elevated carbon dioxide, have been implicated in destabilizing terrestrial carbon stocks, but for once it seems their role has been overstated. Source: Monteith DT, Stoddard JL, Evans CD, de Wit HA, Forsius M, Høgåsen T, Wilander A, Skjelkvåle BL, Jeffries DS, Vuorenmaa J, Keller B, Kopácek J & Vesely J (2007) Dissolved organic carbon trends resulting from changes in atmospheric deposition chemistry. Nature DOI: 10.1038/nature06316

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Nov

21

2007
 
 

Bear hugs on thin ice



Scientists predict that polar bears might have trouble finding love

Ladies' night is not so much fun in the ArcticCanadian male polar bears Ursus maritimus spend much of their time tracking potential mates across the rapidly disappearing sea ice, but a study published this week warns that climate change is not the only threat to their survival. Writing in the Proceedings of the Royal Society, University of Alberta biologist Péter Molnár and colleagues subject polar bear mating behavior to computer modeling (nothing is sacred in biology) and find that the heavily male-biased “harvest” — resulting from a combination of bear behavior and hunting management practice — could leave the remaining animals subject to many a long, lonely polar night. Although the population is currently secure, a reduction of numbers by, say a third, would likely step over a “tipping point”, leaving the population vulnerable to collapse. Source: Molnár PK, Derocher AE, Lewis MA & Taylor MK (2007) Modelling the mating system of polar bears: a mechanistic approach to the Allee effect. Proc. Roy. Soc. Lond B DOI: 10.1098/rspb.2007.1307

Related story in Conservation Magazine: Saint Ursus Maritimus

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Nov

15

2007
 
 

Katrina’s final blow



Hurricane-destroyed forests have a lasting impact on regional carbon balance

Dead trees in Katrina's wakeTwo years after Hurricane Katrina slammed into the Gulf Coast a less obvious cost has come to light, according to a paper published today in Science. Tulane University ecologist Jeff Chambers and colleagues put some alarming figures to the effect the destruction of an estimated 320 million large trees is still having. The total biomass loss of around 105 Teragrams (megatonnes) of carbon is equivalent to somewhere between 50 and 140 percent of the total amount locked up each year by US forests. Given that up to a third of all US carbon emissions are currently soaked up by trees, that’s a big hit to take. Chambers’ report also warns of a gloomy future if, as many scientists predict, climate change brings more hurricanes. The widespread loss of trees releases a huge pulse of carbon, at the same time removing one of the most potent ways of locking it back up. Source: Chambers JQ, Fisher JI, Zeng H, Chapman EL, Baker DB & Hurtt GC (2007) Hurricane Katrina’s carbon footprint on U.S. Gulf Coast forests. Science DOI: 10.1126/science.1148913

Related stories in Conservation magazine: That Sinking Feeling

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Nov

14

2007
 
 

One in five fish is missing



Global species inventories are incomplete in the worst places, fish study finds

I'm just a number, meIf “difficultizing” ever becomes a word (and a certain current world leader might just make it so) it will surely apply to taxonomic databases. A study published today in the Proceedings of the Royal Society of London complains that the blackest holes in our knowledge of marine fish are where we least need them. Camilo Mora and colleagues at Dalhousie University analyzed the largest publicly available dataset of marine fish — the 2.1 million datum-strong Ocean Biogeographical Information System — and found it wanting. At a global scale, the scientists estimate that only 79% of species have been formally described, with the biggest gaps occurring in known biodiversity hotspots. Given that fish are one of the most intensively studied marine taxonomic groups, things don’t bode well for the remaining oceanic biota. And if we don’t know what we’ve got, how can we save it? Source: Mora C, Tittensor DP & Myers RA (2007) The completeness of taxonomic inventories for describing the global diversity and distribution of marine fishes. Proc. Roy. Soc. Lond. B DOI: 10.1098/rspb.2007.1315

Image © Tammy Peluso

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Nov

12

2007
 
 

Data in the drink



Global species database gives a misleading view of the world, study shows

Twenty thousand leeks under the seaA “mission to make the world’s biodiversity data freely and universally available via the Internet” is not one to take lightly, and a study published recently in PLoS ONE shows why users of the Global Biodiversity Information Facility (GBIF) need to exercise caution. The vast, sprawling database is also rather patchy, say a group of biologists led by the University of Reading’s Alastair Culham. Closer inspection of the data, focusing on legumes — there are some 20,000 known species of these flowering plants – has revealed an alarming number of errors, amounting to 16% of the sampled data. The claimed geographic location of a specimen often places a strictly terrestrial plant somewhere in the sea; in other cases latitude and longitude have been inadvertently swapped, had their signs reversed, or are absent altogether. Most worrying, however, is the uneven coverage: many biodiversity hotspots, such as the winter-rainfall hotspot of the Cape floristic region, are poorly represented within the database. It’s early days though, and knowing about problems is part way to solving them. Source: Yesson C, Brewer PW, Sutton T, Caithness N, Pahwa JS, Burgess M, Gray WA, White RJ, Jones AC, Bisby FA & Culham A (2007) How global is the Global Biodiversity Information Facility? PLoS ONE DOI: 10.1371/journal.pone.0001124

Related stories in Conservation magazine: GIS-Based Conservation Planning: A Powerful Tool to be Used with Caution…

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Nov

8

2007
 
 

Stuffed rabbits



Climate change and captive coyness are pushing endangered species to the brink

What can you see? Will it still be there in 2050?Wild populations of the riverine rabbit, found only in South Africa’s Karoo region, are plummeting, and a study published this week in Biological Conservation paints a bleak future for the species. Strangely — for a rabbit — the critically endangered Bunolagus monticularis is reluctant to breed in captivity. Couple that with predicted climate change-driven shifts in the distributions of food and cover plant species, and things don’t look good. Gregory Hughes, a biologist at the South African National Biodiversity Institute, and co-workers used a computer model to show that – even under a conservative climate change scenario – almost all potentially suitable habitat is likely to disappear by 2050. There is some good news though: the model revealed large tracts of unexplored habitat that could be hiding isolated populations. The discovery of more rabbits now would be welcome, if only as a source of genetic material to freeze for resurrection if we ever manage to avert environmental meltdown. Source: Hughes GO, Thuiller W, Midgley GF & Collins K (2007) Environmental change hastens the demise of critically endangered riverine rabbit (Bunolagus monticularis). Biological Conservation DOI: 10.1016/j.biocon.2007.08.004

Related stories in Conservation magazine: The Last Gladiators

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