Archive for February, 2007

Feb

28

2007
 
 

Hot in the city



leafcutter antLeafcutter ants will cope with global warming, urban study shows

Leafcutter ants Atta sexdens living in the city of São Paulo, Brazil, can tolerate higher temperatures than their rural counterparts, according to a study published this week. The urban jungle can be as much as 12 degrees C hotter than the countryside, making it a great testing ground for understanding how life might cope with future climate change, say the study’s authors, an international team led by Indiana State University’s Michael Angilletta Jr. It’s not clear whether the ant’s increased ability to stand the heat is genetically based or down to “heat hardening”, but the result is the same: some day, ants will indeed take over the world :) .

Source: Angilletta MJ Jr, Wilson RS, Niehaus AC, Sears MW, Navas CA & Ribeiro PL (2007) Urban physiology: city ants possess high heat tolerance. PLoS ONE DOI: 10.1371/journal.pone.0000258

Image © Andre Nantel

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Feb

27

2007
 
 

Thai surprise



A reed warbler like this, perhaps?Missing bird shows up again after 139 year absence

The large-billed reed warbler Acrocephalus orinus, known only from a single bird caught in India in 1867, has finally reappeared, this time in Thailand. According to the recently published findings of a team of surprised ornithologists, led by Philip Round at Mahidol University, Bangkok, the bird was trapped during field work at the Laem Phak Bia Environmental Research and Development Project, a whopping 3100 km from where it was last recorded. DNA analysis on a “donated” tail feather confirmed the bird’s identity and allowed the scientists to take a stab at estimating the global population size. There could be between 26 and 40 breeding birds left in the wild, although some big assumptions had to be made to arrive at those figures. Not believing the old adage, Pound’s team released their captive, hoping that there are indeed more out there in the bush.

Source: Round PD, Hansson B, Pearson DJ, Kennerley PR & Bensch S (2007) Lost and found: the enigmatic large-billed reed warbler Acrocephalus orinus rediscovered after 139 years. Journal of Avian Biology DOI: 10.1111/j.2007.0908-8857.04064.x

Image © Iurii Konoval (NB: It’s not Acrocephalus orinus!)

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Feb

26

2007
 
 

Dung map exposes poachers



Illegally poached ivoryGenetic technique reveals heartland of elephant carnage

A genetic “map” of Africa’s elephants Loxodonta africana, based on samples of dung, is proving to be a powerful tool in the fight against illegal ivory poaching, according to a report published this week. An international team, led by Sam Wasser at the Center for Conservation Biology, University of Washington, Seattle, compared DNA samples from confiscated tusks to the map to locate the epicenter of the elephant trade. On the basis of a 6.5-ton haul of contraband ivory, intercepted en route to Singapore, it’s Zambia. Despite the official claim that only 135 Zambian elephants were illegally culled in the last ten years, Wasser’s study suggests that between 3000 and 6500 died in the region just to supply that single shipment. The soaring price of ivory has driven poaching to pre-1989 CITES trade ban levels. The ability to pinpoint poaching hotspots provides a vital way to focus policing efforts.

Source: Wasser SK, Mailand C, Booth R, Mutayoba B, Kisamo E, Clark B & Stephens M (2007) Using DNA to track the origin of the largest ivory seizure since the 1989 trade ban. Proceedings of the National Academy of Sciences USA DOI: 10.1073/pnas.0609714104

Related story: click here

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Feb

22

2007
 
 

You ain’t seen me



gecko pretending not to be seenGeckos re-emerge after rat eradication from island

Islands need a breather after rats or other invasive species have been eradicated, warns a study published this week. Rather than starting an immediate program of translocations to boost beleaguered indigenous species, a period of months should be allowed to pass first, according to a team of Victoria University of Wellington scientists, led by Jo Hoare. What unfolds can tell an interesting story. Just six months after Pacific rats Rattus exulans were wiped from the island of Ōhīnau, off the coast of New Zealand, Hoare’s group recorded a four-fold increase in adult Duvaucel’s geckos Hoplodactylus duvauceli. The unexpected finding – the geckos take seven years just to reach sexual maturity – has a surprisingly simple explanation; they were there all along. Although Pacific rats prey on young Duvaucel’s geckos, they also eat many of the same things. The geckos responded to the rodent invasion by changing their behavior, most likely by avoiding habitat preferred by the rats. But when the rats were removed, the geckos heaved a collective sigh of relief and returned once more to their [relatively] carefree ways.

Source: Hoare JM, Pledger S, Nelson NJ & Daugherty CH (2007) Avoiding aliens: behavioural plasticity in habitat use enables large, nocturnal geckos to survive Pacific rat invasions. Biological Conservation DOI: 10.1016/j.biocon.2006.12.022

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Feb

21

2007
 
 

Pinning down the truth



Fruitfly -- just like any other endangered mammalFruitfly experiment undermines conservation biologists’ dogma

Many endangered, fragmented populations can’t be saved from extinction by the local addition of individuals, according to a study published this week. Sutirth Dey and Amitabh Joshi at the Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India, carried out a laboratory experiment on Drosophila fruitflies and made the discovery that although an influx of flies from elsewhere – akin to long-distance immigration – helped a local population avoid dying out, their presence was barely felt across the whole fragmented network. That’s not good news for workers planning to bolster threatened populations through such localized reintroductions – a technique called “pinning”. But then knowledge is power, isn’t it?

Source: Dey S & Joshi A (2007) Local perturbations do not affect stability of laboratory fruitfly metapopulations. PLoS ONE DOI: 10.1371/journal.pone.0000233

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Feb

19

2007
 
 

Birds, bats and barcodes



Mountain chickadee, who are you?DNA taxonomy reveals unknown North American birds, South American bats

Fifteen possible new bird species and eight new bat species have been uncovered in two large-scale DNA barcoding studies. A survey of 93% of North American bird species, led by Kevin Kerr at the University of Guelph, Ontario, found the new species tucked away among the rank and file of birds – such as the mountain chickadee Parus gambeli – that have been studied by ornithologists for centuries. The authors of the bat study, led by another of Paul Hebert’s Guelph charges, Elizabeth Clare, found that six of Guyana’s 87 described lineages contained more than one distinct species. Together, the studies lend weight to the value of DNA barcoding, a genetic technique that relies on a single stretch of mitochondrial DNA. No doubt the often-heated debate on the usefulness of the method will continue, however: DNA taxonomy is anything but black and white!

Source: Kerr KCR, Stoeckle MY, Dove CJ, Weigt LA, Francis CM & Hebert PDN (2007) Comprehensive DNA barcode coverage of North American birds. Molecular Ecology Notes DOI: 10.1111/j.1471-8286.2006.01670.x

Source: Clare EL, Lim BK, Engstrom MD, Eger JL & Hebert PDN (2007) DNA barcoding of Neotropical bats: species identification and discovery within Guyana. Molecular Ecology Notes DOI: 10.1111/j.1471-8286.2006.01657.x

Image © Rob Pavey

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Feb

16

2007
 
 

Shell shock



Giant tortoises do it for funMolecular monitoring of Galápagos tortoises reveals unexpected interloper

The near forty-year plan to restock the Galápagos island of Española with its missing giant tortoises recently suffered a heart-in-the-mouth moment, according to a report published this week. A group of scientists, led by the University of Brussels’ Michael Milinkovitch, studied the DNA of free-ranging captive-bred tortoises to find out how inbred they are (and they are, badly). But the real surprise was the discovery of an individual — tortoise E1465 — whose molecular fingerprint suggests its origins lay outside the controlled breeding program. The hunt is now on to track down the interloper and any of its relatives before they “contaminate” the island’s indigenous gene pool. Milinkovitch and colleagues suggest that E1465’s father, or even its grandfather, were brought over by whalers from the nearby island of Pinzón in the 17th — 19th centuries.

Source: Milinkovitch MC, Monteyne D, Russello M, Gibbs JP, Snell HL, Tapia W, Marquez C, Caccone A & Powell JR (2007) Giant Galápagos tortoises: molecular genetic analyses identify a trans-island hybrid in a repatriation program of an endangered taxon. BMC Ecology DOI: 10.1186/1472-6785-7-2

Image © Gary Unwin

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Feb

14

2007
 
 

Vive la Différence!



King_proteaSpecies richness is not the same as phylogenetic diversity, but you knew that, right?

Conservation strategies should focus on the relatedness of species rather than their sheer number, according to a study published this week. A team of scientists headed by Kew Gardens’ Félix Forest and Richard Grenyer proved their point by comparing species richness with phylogenetic diversity – the evolutionary links between species – at the Cape of South Africa, one of the world’s most spectacular botanical biodiversity hotspots. Although they found more species in the west, these tended to be closely related, recently evolved groups. The east had fewer but more diverse species, and thus a higher “evolutionary potential”. Saving the most feature-rich areas is the best bet-hedging strategy for conservation planners, say the study’s authors, although there are other factors to take into account. One is the effect of political boundaries: the best conservation plan for a country is not necessarily the best for the region as a whole. If only life were simple…

Source: Forest, F, Grenyer, R, Rouget, M, Davies, TJ, Cowling, RM, Faith, DP, Balmford, A, Manning, JC, Procheş, van der Bank, M, Reeves, G, Hedderson, TAJ & Savolainen, V (2007) Preserving the evolutionary potential of floras in biodiversity hotspots. Nature DOI: 10.1038/nature05587

Image © Félix Forest

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Feb

14

2007
 
 

A burning issue



Acacia trees in the Egyptian desertPoor recruitment of saplings can’t compensate loss of desert trees

Demand for charcoal is killing off the Eastern Desert in Egypt, scientists report this week. At least, it probably is. Gidske Anderson and Knut Krzywinski, both at the University of Bergen, Norway, put data from the CORONA US spy satellite to good use, by comparing high-resolution images from 1965 with modern data on Acacia and Balanites trees as they stand today. The decline in mature trees couldn’t be explained by factors such as climate, altitude or location. Although the nomadic human inhabitants of the Eastern Desert don’t exactly keep detailed records of how many trees they burn, Anderson and Krzywinski found telltale evidence of charcoal production from living trees. The harsh conditions — heat, drought and livestock grazing — make life for seeds and saplings extremely tough, so the Egyptian desert looks set to become even sandier than it is. And it’s already very sandy indeed.

Source: Anderson, GL & Krzywinski, K (2007) Mortality, recruitment and change of desert tree populations in a hyper-arid environment. PLoS ONE DOI: 10.1371/journal.pone.0000208

Image © Dejan Sarman

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Feb

13

2007
 
 

Wormafrost



It's a can of worms, alrightPredatory flatworms invade subantarctic island — 10 metres each year

The southernmost tip of Australia is being invaded by killer flatworms, according to a recently published study led by Penelope Greenslade at the Australian National University. Two species of the predatory planarians, Kontikia andersoni and Arthurdendyus vegrandis, have been on the march – er, slither – across Macquarie Island for roughly 100 years since their probable introduction from New Zealand. The legless aliens like nothing better than a tasty Annelid or two, bad news for the island’s earthworms. Worse still is the prospect of the flatworms hitching a lift back to Tasmania or even mainland Australia. Once there, their predatory habits could wreak agricultural havoc by decimating the earthworms on which farmers depend.

Source: Greenslade, P, Stevens, MI & Edwards, R (2007) Invasion of two exotic terrestrial flatworms to subantarctic Macquarie Island. Polar Biology DOI: 10.1007/s00300-007-0254-6

Image © Maartje van Caspe

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