Archive for April, 2007

Apr

30

2007
 
 

High hopes for George



Is the loneliest animal on the planet ready for a relationship?

good lookin' fellaPerhaps Lonesome George isn’t the end of the line for Galápagos giant tortoises Geochelone abingdoni after all. Writing in Current Biology this week, a group of scientists including UBC’s Michael Russello and Yale’s Gisella Caccone describe how a hybrid tortoise has turned up on Isabela, a neighboring island to George’s homeland of Pinta. This first generation cross, revealed only through modern genetic techniques, raises hopes that a full-blown member of George’s clan might be found among the one or two thousand animals in the Isabela population. And if she is, could we ever hear the pitter-patter of tiny tortoise feet? No pressure George, of course… Source: Russello MA, Beheregaray LB, Gibbs JP, Fritts T, Havill N, Powell JR & Caccone A (2007) Lonesome George is not alone among Galápagos tortoises. Current Biology DOI: tba

Image © Alison Llerena/CDRS

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Apr

27

2007
 
 

Rodent swapsies



Success in eradicating rats from Buck Island has allowed mice to gain a pawhold

nobody loves me, everybody hates me...A report published this week in Wildlife Research describes the eradication of roof rats Rattus rattus from Buck Island, a tiny jewel in the Caribbean Sea. The systematic eradication program used diphacinone-based anticoagulent bait in specially designed traps. This allowed the team of scientists, led by Gary Witmer at the USDA National Wildlife Research Center, to target just the rats whilst ensuring that the island’s endemic species – such as pearly-eyed thrashers Margarops fuscatus – suffered minimal danger. With the rats gone, the island’s hawksbill turtle Eretmochelys imbricata population is recovering and there are plans to reintroduce the endangered St Croix ground lizard Ameiva polops. The only cloud on the horizon is the unexpected resurgence of the mouse Mus musculus population, which has boomed in the absence of their larger rodent cousins. And given what mice can do to seabirds, who says they won’t have a go at turtles too? Source: Witmer GW, Boyd F & Hillis-Starr Z (2007) The successful eradication of introduced roof rats (Rattus rattus) from Buck Island using diphacinone, followed by an irruption of house mice (Mus musculus). Wildlife Research DOI: 10.1071/WR06006

Related story in Conservation magazine: The Conundrum of Biological Control: Weighing Urgency Against Uncertainty

Image © Aleksandr Lukin

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Apr

26

2007
 
 

What goes down could come up



Study uncovers huge variation in amount of sinking carbon making it to the ocean floor

only a diatom, but loaded with CPathetically little is known about the oceanic “twilight zone”, the murky region extending from the last sunlit water down to about 1000 metres, but a paper published this week in Science provides evidence that it has a major impact on the amount of organic carbon that safely reaches the ocean floor. A large multidisciplinary group of scientists, led by Ken Buesseler at the Woods Hole Oceanographic Institution, used some cool collection tubes – “neutrally buoyant sediment traps” – to sample the amount of particulate carbon matter (that’s mainly plankton poo) snowing down at a series of predetermined depths. Only a small amount made it through the twilight zone (the rest is recycled by bacteria and thence up the food chain), but that amount varied between 20 and 50 percent. On a global scale that variation would stack up to a margin of uncertainty exceeding 3 Petagrams a year, around half of the current anthropogenic output. To understand oceanic sinks, and paraphrasing Chief Brody, we’re going to need a bigger model. Source: Buesseler KO, Lamborg CH, Boyd PW, Lam PJ, Trull TW, Bidigare RR, Bishop JKB, Casciotti KL, Dehairs F, Elskens M, Honda M, Karl DM, Siegel DA, Silver MW, Steinberg DK, Valdes J, Van Mooy B & Wilson S (2007) Revisiting carbon flux through the ocean’s twilight zone. Science DOI: 10.1126/science.1137959

Related story in Conservation magazine: Sequencing the Ocean

Image © Mary Wilcox Silver

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Apr

25

2007
 
 

Umbrellas, icons and keystones



Different research approaches must work together for conservation to succeed

Panda pretending to be a leadbeater's possumConcentrating conservation effort on understanding a single species doesn’t guarantee a successful outcome, but neither does more general, ecosystem-level research. Instead, say the authors of a paper published in Oikos, a combined, complementary approach is needed. The group of scientists, spearheaded by David Lindenmeyer at the Australian National University, describe several attempts to save species – such as Leadbeater’s possum Gymnobelideus leadbeateri – where research focused on both the target species and its encompassing habitat worked side by side to good effect. It sounds obvious maybe, but this approach could be the best way to target those species that can actually be saved from extinction, rather than those that cannot. Source: Lindenmeyer DB, Fischer J, Felton A, Montague-Drake R, Manning AD, Simberloff D, Youngentob K, Saunders D, Wilson D, Felton AM, Blackmore C, Lowe A, Bond S, Munro N & Elliott CP (2007) The complementarity of single-species and ecosystem-oriented research in conservation research. Oikos DOI: 10.1111/j.2007.0030-1299.15683.x

Related stories in Conservation magazine: The Biodiversity Knowledge Commons | Designing Marine Reserve Networks | Evidence-Based Conservation

Image © Paul Erickson

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Apr

24

2007
 
 

Passage to freedom



Long distance bird migrants could be just the ticket for invading plants to hitch a ride

Swallow, transport and fertilize!Barn swallows Hirundo rustica are helping spread the invasive rooikrans Acacia cyclops throughout the Fynbos Biome, South Africa, a recent study reports. Writing in Ibis, Cape Town University scientists Les Underhill and Jan Hofmeyr describe how the birds – typically associated with aerial insect predation – were seen consuming the native Australian plant’s conspicuous and abundant seeds. Because of the large distances covered by swallows, the seeds – once expelled in their own little blob of “fertilizer” – could spread the advance of the unwanted alien plant at an unprecedented rate. Underhill and Hofmeyr emphasize the urgent need to eradicate rooikrans from the Fynbos, even though the data they present are over eighteen years old! Source: Underhill LG & Hofmeyr (2007) Barn swallows Hirundo rustica disperse seeds of Rooikrans Acacia Cyclops, an invasive alien plant in the Fynbos Biome. Ibis DOI: 10.1111/j.1474-919x.2006.00598.x

Related story in Conservation magazine: Aliens Among Us

Image © Arpad Benedek

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Apr

23

2007
 
 

Yay-boo for fish



Different effects of climate change on shallow and deep water fish

Deep sea fish: all washed up?Increasing sea surface temperatures are helping Australian shallow-water fish species grow faster, according to findings published this week in PNAS. A group of scientists led by Ron Thresher at CSIRO Marine and Atmospheric Research used fish otoliths, which have growth rings like those found in trees, to calculate how the growth patterns of eight fish species have changed in recent years. The three shallow-dwelling species, which included the jackass morwong Nemadactylus macropterus, now make it through their juvenile years faster than they did a few decades ago – good news for the fish and those dependent on catching them. However, deep water temperatures are currently on a downward trend. That’s bad news for species such as the warty oreo Allocyttus verrusosus – which the Australian Government recommends serving with a nice sauvignon blanc, semillon or chardonnay – as they now grow more slowly, making them vulnerable to over-exploitation and possibly extinction. It’s never just good news, is it? Source: Thresher RE, Koslow JA, Marison AK & Smith DC (2007) Depth-mediated reversal of the effects of climate change on long-term growth rates of exploited marine fish. Proceedings of the National Academy of Sciences USA DOI: 10.1073/pnas.0610546104

Related stories in Conservation magazine: Point of No Return

Image © Gremlin

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Apr

19

2007
 
 

Monkey dies, tree dies



Bushmeat trade takes out more than animals, it takes the plants that depend on them

Red howlers, great for the gardenBushmeat hunting is a major threat to medium and large primates, but it’s also associated with a particularly nasty negative feedback, according to a specially themed section in the current issue of Biotropica. In one study, authored by Gabriela Nuñez-Iturri and Henry Howe, both at the University of Chicago at Illinois, the species compositions of tree saplings within two protected sites at Manu National Park, Peru were compared with that of an unprotected site outside the park, from which large primates had been exterminated and medium-sized species were rapidly following suit. Killing off primates is bad news for those trees that depend on them for seed dispersal: other plant species that rely on bats, birds and smaller monkeys jump at the chance to fill vacant real estate. This downward spiral could make forest restoration difficult, because without their favored fruits the big guys will likely head elsewhere for food. Source: Nuñez-Iturri G & Howe HF (2007) Bushmeat and the fate of trees with seeds dispersed by large primates in a lowland rainforest in Western Amazonia. Biotropica DOI: 10.1111/j.1744-7429.2007.00276.x

Related stories in Conservation magazine: Tastes Like Chicken | Rules of Engagement for Conservation

Image © Ra\’id Khalil

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Apr

18

2007
 
 

At loggerheads with the Navy



show me the way to go home...Unexpected migratory patterns could land sea turtles in trouble

Not all loggerhead turtles Caretta caretta wander across the oceans in the same direction, according to a study published recently in Diversity and Distributions. A team of scientists – led by University of Exeter, Cornwall marine biologist Brendan Godley – studied detailed satellite tracking data collected from twelve tagged turtles over a three-year period. The results show that while some turtles leaving nesting grounds in North Carolina head north, others swim south to warmer climes. For both, life is a delicate balancing act on the edge of the Gulf Stream, a question of trading life in warm water (cold water and ectothermy don’t mix well) against the energy-sapping currents. But the unexpected migratory patterns sound a warning against the US Navy proposal to create an underwater training battleground off south-eastern North Carolina: in the light of the new information, measures outlined to leave the turtles in peace might not go far enough.

Source: Hawkes LA, Broderick AC, Coyne MS, Godfrey MH & Godley BJ (2007) Only some like it hot – quantifying the environmental niche of the loggerhead sea turtle. Diversity and Distributions DOI: 10.1111/j.1472-4642.2007.00354.x

Image © Lucy Hawkes

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Apr

17

2007
 
 

A little more K, a bit less r



sometimes you're on top, others you aren'tInvading fruit flies don’t always follow the rules, but no one told them

Fruit flies know a thing or two about invasion, and now they’re teaching biologists how it’s done. East of Madagascar, the island of La Réunion has recently played host to successive waves of incoming species; Ceratitis capitata, C. rosa and Bactrocera zonata. Writing in Diversity and Distributions, island biologist Pierre-François Duyck and colleagues describe how each new invader out-competed the existing incumbents to the extent that C. catoirii – the formerly widespread endemic species – is facing its final mango. The findings undermine current dogma that invasive species are “r-selected” (having traits that boost the number of offspring) rather than “K-selected” (producing fewer, more competitive offspring). Whether the results apply to other invaded ecosystems remains to be seen, but the fruit flies of La Réunion have told an enlightening tale.

Source: Duyck P-F, David P & Quilici S (2007) Can more K-selected species be better invaders? A case study of fruit flies in La Réunion. Diversity and Distributions DOI: 10.1111/j.1472-4642.2007.00360.x

Image © Scott Bauer

Related stories in Conservation magazine:

Nitrogen-Fixing Tree Paves the Way for Other Invaders

Exotic Herbivores Promote Plant Invasions

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Apr

16

2007
 
 

Litter critters hit



A frog called russelAmphibians and reptiles decline by 75% in Costa Rica, study shows

It’s not just the frogs and salamanders having a hard time in Costa Rica, a study reports today in PNAS: the snakes and lizards are in trouble too. A collaborating group of scientists led by Florida International University’s Steven Whitfield analyzed records dating back over three decades collected at the La Selva Biological Research Station. Populations of leaf litter-dwelling amphibians have plummeted in the old-growth primary rainforest, although in neighboring abandoned cacao plantations numbers have risen. This, coupled with the fact that snakes and lizards have suffered a similar fate, rules out the two usual suspects behind amphibian declines – global climate change and chytrid fungus. Instead, the authors contend, it’s likely the local effect of increasingly warm and wet conditions: trees hold onto their leaves better, meaning there’s less leaf litter for the little critters to rummage around in.

Source: Whitfield SM, Bell KE, Philippi T, Sasa M, Bolaños F, Chaves G, Savage JM & Donnelly MA (2007) Amphibian and reptile declines over 35 years at La Selva, Costa Rica. Proceedings of the National Academy of Sciences USA DOI: 10.1073/pnas.0611256104

Image © Nalukai

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