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Archive for May, 2007
May
31
2007
One of the most successfully implemented conservation tools, the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) could in fact be damaging the prospects of the species it aims to protect, according to a commentary published this week in Nature. Philippe Rivalan and colleagues at the University Paris-Sud and the Durrell Institute of Conservation and Ecology, show how the lag between a proposal to uplist a species and the changes actually coming into effect allows a window of opportunity for an increase in trade. The delay, typically lasting between 240 and 420 days – during which the merits of the proposal are considered in detail – corresponds to a significant spike in recorded legal trade as dealers rush to move stocks before restrictions come into force. Better management of those species not yet threatened with extinction, such as permitting limited trophy-hunting quotas, could help CITES to respond more flexibly to changing situations and/or improved data. Source: Rivalan P, Delmas V, Angulo E, Bull LS, Hall RJ, Courchamp F, Rosser AM & Leader-Williams N (2007) Can bans stimulate wildlife trade? Nature DOI: 10.1038/447529a
Related story in Conservation magazine: Healing Powers
Image © Nico Smit
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May
30
2007
If following a large carnivore around until it “answers the call of nature” is your thing, read on. Working in the Serengeti National Park, Tanzania, biologists from the Zoological Society of London, led by Dada Gottelli, did just that to collect 171 dung samples from cheetahs Acinonyx jubatus that were traceable to their owners. DNA analysis of said stools, published this week in the Proceedings of the Royal Society of London, revealed a hitherto unknown facet of cheetah reproductive biology: females often mate with more than one male. Forty-three percent of litters containing more than one cub were sired by more than one male. That’s good news for cheetah conservation prospects because it suggests that a much higher number of males contribute to the gene pool, so helping to keep levels of genetic diversity from being eroded. The findings should inform management plans for the survival of this most flighty, promiscuous of cats. Source: Gottelli D, Wang J, Bashir S & Durant SM (2007) Genetic analysis reveals promiscuity among female cheetahs. Proceedings of the Royal Society of London B DOI: 10.1098/rspb.2007.0502
Related story in Conservation magazine: More than Meets the Eye: Behavior and Conservation
Image © Susann Evans
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May
28
2007
Rapid climate change will affect species in different ways, but those locked in a closed system such as a lake will face the most dramatic challenges. Case in point a study published this week in PNAS, which shows how rainbow trout Oncorhynchus mykiss adjust their feeding patterns to counter the negative impact of warmer water on their metabolism and hence growth rate. Lead author Peter Biro, at the University of Technology, Sydney, carried out a two-year experiment to study the effects of water temperature on juvenile trout growth and survival. The fish compensate for higher temperature – which slows growth – by foraging for longer. Unfortunately, this behavioral shift increases their exposure to Predator Number One, adult trout. Biro and co-authors conclude that the effect is so strong it could lead to the extirpation of fish populations from entire water bodies. Advice to anglers: catch ’em while you can! Source: Biro PA, Post JR & Booth DJ (2007) Mechanisms for climate-induced mortality of fish populations in whole-lake experiments. Proceedings of the National Academy of Sciences USA DOI: 10.1073/pnas.0701638104
Related story in Conservation magazine: Evolutionary Tinkering | When Worlds Collide
Image © Oktay Ortakcioglu
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May
24
2007
Conservation efforts often lean towards the need of specialist taxa, but a study published this week in PLoS ONE shows how we shouldn’t ignore the generalists. Cardiff University evolutionary biologists Yoshan Moodley and Mike Bruford carried out a genetic analysis of bushbuck Tragelaphus scriptus – Africa’s most widespread ungulate, which has adapted to a rich variety of habitats – to identify 28 key sub-Saharan biogeographic regions. Linking the bushbuck’s diverse lineage to major climatic shifts sheds light on which regions might harbor the most unique set of genes. A similar approach will help establish conservation priorities across species ranges and different ecoregions. Amazing what you can do with a PCR-machine-thingy. Source: Moodley Y & Bruford MW (2007) Molecular biogeography: towards an integrated framework for conserving pan-African biodiversity. PloS ONE DOI: 10.1371/journal.pone.0000454
Related story in Conservation magazine: Designing Marine Reserve Networks
Image © Dmitry Pichugin
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May
23
2007
With the finding reported this week in Biology Letters that hammerhead sharks can reproduce asexually, we mammals are left as the only jawed vertebrate lineage that can’t. (No doubt certain individuals spring to mind that confirm our oddness as a good thing). Genetic analyses carried out by marine scientists Paulo Prodöhl, Demian Chapman -- now at the Pew Institute for Ocean Science -- and colleagues have unequivocally confirmed that a female bonnethead shark Sphyrna tiburo pup -- born at a Florida aquarium -- was indeed a clone of her virgin mother. We now need to know how frequently sharks reproduce asexually, and what the effects might be on the population genetics of endangered species. There’s a problem to sink one’s teeth into... Source: Chapman DD, Shivji MS, Louis E, Sommer J, Fletcher H & Prodöhl PA (2007) Virgin birth in a hammerhead shark. Biology Letters DOI: 10.1098/rsbl.2007.0189
Image © John Stublar
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May
22
2007
Fathead minnows Pimephales promelas -- described in their role of ecological health indicator as the freshwater equivalent of the miner’s canary -- are important prey for many fish species, such as lake trout Salvelinus namaycush, walleye Sander vitreus and northern pike Esox lucius. But according to a study published this week in PNAS they could be at risk from exposure to waste water effluents laced with traces of estrogen, mostly derived from contraceptive pills. Although the potential impacts of estrogen on fish -- it causes males to develop female traits -- have been known for some time, the long term effects on wild populations have been a mystery. So University of New Brunswick fish biologist Karen Kidd and colleagues spiked an entire lake in Ontario, Canada, with a level of estrogen within the range typically observed in municipal wastewaters. Over a seven year period the fathead minnow population crashed to near extinction, failing to recover after the three-year treatment had ended. And the trouble is, we’ve been “treating” the water since the carefree Swinging Sixties... Source: Kidd KA, Blanchfield PJ, Mills KH, Palace VP, Evans RE, Lazorchak JM & Flick RW (2007) Collapse of a fish population after exposure to a synthetic estrogen. Proceedings of the National Academy of Sciences USA DOI: 10.1073/pnas.0609568104
Image © Duane Raver | US Fish & Wildlife Service
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May
21
2007
What could be safer than life on an organic farm? If you’re a ground-nesting bird, such as the common but declining European lapwing Vanellus vanellus, the answer is plenty. Drawn by the lack of pesticides and herbicides, the lapwing’s chicks suffer the consequences of chemical-free farming. Steven Kragten and Geert De Snoo, environmental scientists at Leiden University, Netherlands, carried out a pairwise survey of lapwing nest success on organic and conventional farms. Writing in Ibis, they note that despite the greater density of nests on organic farms, nest success per 100 hectares – the bottom line as far as a bird’s survival goes – was roughly the same as on conventional farms. Shunning herbicides, organic farmers resort to mechanical methods of weed removal: the ensuing mêlée of whirring blades and crushing rollers means all to many nests meet a sticky end. Other ground-nesting species including skylark Alauda arvensis, yellow wagtail Motacilla flava and stone curlew Burhinus oedicnemus could also be vulnerable. The green life ain’t the simple life. Source: Kragten S & De Snoo GR (2007) Nest success of lapwings Vanellus vanellus on organic and conventional arable farms in the Netherlands. Ibis DOI: 10.1111/j,1474-919x.2007.00702.x
Image © Kurt Hahn
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May
17
2007
Relying on the world’s oceans to take carbon out of our overloaded atmosphere isn’t a good idea, according to a study published today in Science. A global collaboration of earth scientists, led by the University of East Anglia’s Corinne Le Quéré, discovered that increased winds over the Southern Ocean -- brought about through ozone depletion and increases in greenhouse gases – are reducing the Ocean’s ability to act as a carbon sink. The strengthened winds trigger a release of stored CO2 back into the atmosphere and prevent further absorption by the sea water. The group predicts these effects will intensify for years, decades, to come. Like we said before; if only mopping up carbon were simple! Source: Le Quéré C, Rödenbeck C, Buitenhuis ET, Conway TJ, Langenfelds R, Gomez A, Labuschagne C, Ramonet M, Nakazawa T, Metzl N, Gillett N & Heimann M (2007) Saturation of the Southern Ocean CO2 sink due to recent climate change. Science DOI: 10.1126/science.1136188
Related story in Conservation magazine: That Sinking Feeling
Image © Alexander Hafemann
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May
16
2007
West Nile virus has hit some US bird species much harder than others, according to a study published today in Nature. A group of biologists led by Shannon LaDeau at the Smithsonian Migratory Bird Center, Washington DC, compared census data for twenty species -- collected by the Breeding Bird Survey -- with lab-based assessments of how susceptible each species is to the disease. Some, such as the American crow Corvus brachyrhynchos, have been hammered: others, such as the gray catbird Dumetella carolinensis have pretty much shrugged the malaise off. But in addition to the way individual species have responded, the overall impact on the broader community is important, with knock-on effects echoing throughout the entire ecosystem. Declines in American robin Turdus migratorius populations, for example, are thought to have intensified human West Nile virus epidemics. Well, a mossie’s gotta drink... Source: LaDeau SL, Kilpatrick AM & Marra PP (2007) West Nile virus emergence and large-scale declines of North American bird populations. Nature DOI: 10.1038/nature05829
Image © Douglas Allen
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May
16
2007
An interdisciplinary group of McGill University scientists has discovered a somewhat unsettling link between economic inequality and biodiversity loss. Writing in PLoS ONE, Gregory Mikkelson and colleagues describe how the level of economic inequality -- how wealth is distributed -- is a robust predictor of the proportion of bird species in decline: the greater the divide between rich and poor, the higher the number of threatened species. The effect was found at both national and state levels (45 countries and 45 US states were tested). As the study’s authors point out, by learning to share the cash more fairly with our fellow humans we might also learn to share the planet more fairly with our fellow species. Source: Mikkelson GM, Gonzalez A & Peterson GD (2007) Economic inequality predicts biodiversity loss. PLoS ONE DOI: 10.1371/journal.pone.0000444
Related story in Conservation magazine: Sitting Out the Big Game
Image © Daniel Hassard
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