Archive for September, 2007

Sep

27

2007
 
 

Snap nav



Fearsome predators display exceptional navigational skills, tracking study shows

No place like homeSaltwater crocodiles Crocodylus porosus have a remarkable ability to find their way home across great distances, according to a study making use of the latest satellite tracking technology. A group of scientists – led by Craig Franklin at the University of Queensland – describe in PLoS ONE how they caught and tagged three large male salties, then transported them 56, 99 and 411 km along the Australian coastline. After a short period of hanging around their new gaffs, all three males set off back home with unnerving accuracy. The findings represent the longest known homeward travel by a crocodilian, and should make public health officials think twice before translocating potentially dangerous crocs away from human settlements: it looks like they’ll just swim straight back! Source: Read MA, Grigg GC, Irwin SR, Shanahan D & Franklin CE (2007) Satellite tracking reveals long distance coastal travel and homing by translocated estuarine crocodiles, Crocodylus porosus. PLoS ONE DOI: 10.1371/journal.pone.0000949

Related stories in Conservation magazine: Tour de Turtle | Taking the Bite out of Wildlife Damage

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Sep

24

2007
 
 

Kelp in hot water



Scientists discover previously unknown biodiversity hotspots

Kelp, kelp, kelp. Is there nothing else to eat?Forests of kelp Eisenia galapagensis have been discovered growing off the Galápagos islands, thanks to the predictions of a computer model. Michael Graham at the Moss Landing Marine Laboratories, California — together with marine biologist coworkers — report their findings in PNAS. Combining oceanic data with information on the growing requirements of kelp, they predicted where kelp forests might be found between the tropics of Cancer and Capricorn. Kelp forests are incredibly productive centers of biodiversity, but because of their need for plenty of light and nutrients are generally considered to occur only in shallow, cool water regions. However, clearer tropical waters allow light to penetrate to greater depths, and Graham’s study uncovered a remarkable 23,500 square kilometers of potentially suitable habitat. Donning SCUBA gear aboard a suitably-sized boat, the intrepid scientists then found what they were looking for in the field — and the alga’s IUCN “Vulnerable” classification might now be due some revision. Source: Graham MH, Kinlan BP, Druehl LD, Garske LE & Banks S (2007) Deep-water kelp refugia as potential hotspots of tropical marine diversity and productivity. Proceedings of the National Academy of Sciences USA DOI: 10.1073/pnas.0704778104

Image © Sean Connell

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Sep

21

2007
 
 

Google bugs



Giant search engine helps scientists find where the tiny creatures live

bugs from spaceSatellite imagery is helping researchers to pinpoint the whereabouts of rare insects, according to evidence published recently in the Journal of Insect Conservation. Using freely available, high resolution satellite images from Google Earth and Microsoft Terraserver, Smithsonian Institute entomologist Jonathan Mawdsley located nineteen potential oases for tiger beetles at the US Fish and Wildlife Service’s Patuxent Research Refuge, Maryland. Tiger beetles are staggeringly picky when it comes to preferred habitat, a characteristic that makes finding small, sparsely distributed suitable patches a nightmare in the field. However, that same trait was used to advantage by Mawdsley, because the favored patches of bare earth were relatively conspicuous among the otherwise verdant satellite images. Tiger beetles were found at fifteen of the newly discovered sites, increasing the reserve’s species count from three to eight. Amazing what you can find on the internet these days. Source: Mawdsley R (2007) Use of simple remote sensing tools to expedite surveys for rare tiger beetles (Insecta: Coleoptera: Cicindelidae). Journal of Insect Conservation DOI: 10.1007/s10841-007-9113-6

Image © Jim Jurica

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Sep

18

2007
 
 

Dietary flippers



Carnivorous young turtles swim the oceans before settling down as vegetarians

OK, OK. What's next?The image of newly hatched turtles scrabbling ungainly paths down the beach to the surf is a familiar one, but what happens next has puzzled scientists for decades. No one knew where young green turtles Chelonia mydas spend their early years, or what they eat, but Kimberley Reich and colleagues at the Archie Carr Center for Sea Turtle Research have used a high tech approach to partly solve the mystery. Writing in Biology Letters, they describe how the secret is chemically locked within the layers of scute – hard tissue covering the turtle’s bony shell – that grow continuously throughout the animal’s life. By analyzing the chemical signatures of tiny samples of scute, the young turtle’s whereabouts and dietary preferences were revealed. Traces of certain stable nitrogen and carbon isotopes showed that the youngsters couldn’t be more different from their older shallow-water dwelling, vegetarian counterparts. Instead they have a taste for life on the open ocean, not to mention an eye for a tasty jellyfish or two. Nevertheless, after three to five years, the rebels settle down and end up just like their parents. That’s teenagers the world over. Source: Reich KJ, Bjorndal KA & Bolten AB (2007) The “lost years” of green turtles: using stable isotopes to study cryptic life stages. Biology Letters DOI: 10.1098/rsbl.2007.0394

Image © Alan Tobey

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Sep

17

2007
 
 

Army of one



Biological invasions can be launched from the smallest possible population

one's enoughA single, mated solitary ground-nesting bee Lasioglossum leucozonium successfully invaded North America, claim a group of York University, Toronto biologists. Writing in PLoS ONE, Amro Zayed and colleagues describe how North American populations have extraordinarily low levels of genetic variation compared with their European counterparts. Such low diversity usually means that the population is descended from a small number of ancestors, and this particular genetic bottleneck – which took place between 50 and 150 years ago – bears all the hallmarks of being about as severe as it could. The arrival of just one mated female, probably in soil used as ships’ ballast, marked the start of a continent-wide expansion. The findings undermine current theories of biological invasion, notably that success is positively linked to the size of the founder population. So conservationists, be vigilant; keep an eye out for those single aliens. Source: Zayed A, Constantin SA & Packer L (2007) Successful biological invasion despite a severe genetic load. PLoS ONE DOI: 10.1371/journal.pone.0000868

Related stories in Conservation magazine: When Worlds Collide | The Conundrum of Biological Control

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Sep

13

2007
 
 

Eggs is eggs



Trout offspring from salmon parents — a conservation dream turned reality

OUCH!Extinction need no longer be the end of the line – at least if you’re a salmonid fish – according to findings published recently in Science. A group of biologists at Toyku University of Marine Science and Technology, led by Goro Yoshizaki, has found a way to make one species of fish – in this case the salmon Oncorhynchus masou – create the sperm and eggs of another. They demonstrated the method, which involves microinjecting reproductive germ cells into surrogate fish larvae, by successfully producing apparently normal rainbow trout O. mykiss. With many salmonid species on the brink, the technique opens the door for countless conservation possibilities. Does it make you wonder if they’ll do the same for pandas one day? Source: Okutsu T, Shikina S, Kanno M, Takeuchi Y & Yoshizaki G (2007) Production of trout offspring from triploid salmon parents. Science DOI: 10.1126/science.1145626

Related story in Conservation magazine: Some Fins Wrong

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Sep

12

2007
 
 

The sailing snail’s trail



Did prehistoric snail farms provide modern refugia for embattled molluscs?

these ones are all dead...Genetic data have helped clear up a problem that’s been puzzling scientists for over a century: how the endangered Tahitian tree snail Partula hyalina is absent from neighbouring islands, yet [relatively] thriving populations occur on islands more than a thousand kilometres away. Writing in the Proceedings of the Royal Society, University of Michigan biologist Diarmaid Ó Foighil and colleagues show that founder populations radiated from Tahiti to islands in the Cook and Austral archipelagos, probably within the last thirty thousand years. The timing of the snails’ spread coincides with a period of human exploration, settlement and trade among the remote Oceania athols. The species’ unusual white shell — valued in traditional jewelry making — could explain why P. hyalina reached its far-flung shores, whereas its altogether-less-striking sister species P. clara never made it off the island. And with Tahiti’s tree-snail population being decimated by the carnivorous alien Euglandina rosea, those distant outposts could make all the difference. Source: Lee T, Burch JB, Coote T, Fontaine B, Gargominy O, Pearce-Kelly P & Ó Foighil D (2007) Prehistoric inter-archipelago trading of Polynesian tree snails leaves a conservation legacy. Proceedings of the Royal Society of London B DOI: 10.1098/rspb.2007.1009

Related story in Conservation magazine: Extinction at a Snail’s Pace

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Sep

10

2007
 
 

Whale falls down



Eastern gray whales haven’t recovered yet, genetic data suggest

bonesPacific gray whale Eschrichtius robustus populations are only a quarter to a half of their size before whaling began in earnest, according to a study based on detailed genetic analysis. Writing in PNAS, Stanford University’s Elizabeth Alter and colleagues say their estimate of the historical head count, centered on an average of 96400 animals, dwarfs the current population census-based figure of 18000-29000 eastern gray whales (the tiny western population remains critically endangered; the Atlantic population is long extinct). The findings, which reach back in time through the DNA variation seen today, undermine claims that the eastern population has fully recovered. Although there might never be so many gray whales again – climate change is reducing the amount of habitat available – they have a long way to go before they start getting crowded. Best leave the harpoon at home for now. Source: Alter SE, Rynes E & Palumbi SR (2007) DNA evidence for historic population size and past ecosystem impacts of gray whales. Proceedings of the National Academy of Sciences USA DOI: 10.1073/pnas.0706056104

Image © Martyn Unsworth

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Sep

5

2007
 
 

Dog gone



Conservation managers are right to ban dog walkers from sensitive areas

Nature's worst enemyWaggy tails, slobbery jowls and boundless enthusiasm for life might endear dogs to their human owners, but Australia’s native wildlife isn’t so keen. University of New South Wales biologists Peter Banks and Jessica Bryant carried out the first systematic study of the impact of dog walking on woodland birds, publishing their findings in Biology Letters. A series of carefully controlled walkies along a range of woodland trails measured the effect Rover, Fido and Lassie have: dog-walked areas have 41% fewer birds and 35% fewer bird species – a figure rising to 50% of ground dwelling species – than uninterrupted control areas. Man’s best friend is, after all, just a predator on a string. Source: Banks PB & Bryant JV (2007) Four-legged friend or foe? Dog walking displaces native birds from natural areas. Biology Letters DOI: 10.1098/rsbl.2007.0374

Image © Abby Wilcox

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Sep

3

2007
 
 

Some fins wrong



Two decades of intensive effort to save the wrong species, DNA shocker

We got the wrong fish!Genetic tools are invaluable in the quest to unravel evolution’s pathway, but they’re also uncovering conservation bloopers, as a study published in Molecular Ecology shows. Efforts to save the endangered greenback cutthroat trout Oncorhynchhus clarkii stomias – through the reintroduction of captive bred fish to cleared and restored habitats – were recently hailed a success, and the subspecies’ federal protection could soon be lifted. Not so fast, say a group of scientists led by the University of Colorado’s Jessica Metcalf. Their DNA analysis sprang a nasty surprise: many of the donor populations for the breeding program were actually the closely related Colorado cutthroat trout O. c. pleuriticus. Within it’s native range, the greenback cutthroat trout is currently at a greater risk of extinction than ever before. At least we know now… Source: Metcalf JL, Pritchard VL, Silvestri SM, Jenkins JB, Wood JS, Cowley DE, Evans RP, Shiozawa DK & Martin AP (2007) Across the great divide: genetic forensics reveals misidentification of endangered cutthroat trout populations. Molecular Ecology DOI: 10.1111/j.1365-294X.2007.03472.x

Related story in Conservation magazine: Do No Harm

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