Coping With Climate Change: Can We Predict Which Species Will Be Able to Move Far or Fast Enough to Adapt?

ScienceDaily (May 11, 2011) — As global temperatures rise, suitable sites for many plants and animals are shifting to cooler and higher ground. Can we predict which species will be able to move far or fast enough to keep up? A new study says the secrets to success in the face of a warming world are still elusive.

Rather than sticking around and sweating it out, some groups of plants and animals are responding to rising temperatures by migrating northward and upward to higher latitudes and elevations, studies show.

But when researchers working at the National Evolutionary Synthesis Center and the National Center for Ecological Analysis and Synthesis took a closer look at recent range shifts, they noticed a peculiar pattern: some species are migrating much farther and faster than others.

"Some species are moving well ahead of the curve, while others seem to be stuck behind," said lead author Amy Angert, a biologist at Colorado State University.

Pinpointing what sets the fastest-shifting species apart from the stragglers could help scientists and policymakers predict which species are likely to be left behind in a warming world, the researchers said.

"The species that aren't able to expand their range are the ones we need to spend more resources protecting," said co-author Sarah Gilman of Claremont McKenna College in California.

The researchers wondered if general traits such as body size, diet and lifespan might help scientists predict which species are likely to keep pace as weather warms.

To find out, they looked at data gathered from more than 400 species of birds, plants, insects and mammals known to have shifted their ranges to different degrees in the last century in response to warming.

The data set included North American birds such as house finches and bald eagles, dragonflies and damselflies in Europe, grasses and other plants in the Swiss Alps, and small mammals such as shrews, mice and chipmunks in the Sierra Nevada of California.

The species quickest to expand their range should be those that reproduce the fastest, disperse the farthest, and are the least picky about food, shelter, or mates, models predict.

To find out if predictions hold true, the researchers compiled data on how far each species had shifted, and compared it to various intrinsic features of the species themselves, such as their mode of dispersal, breeding rate, and dietary preferences.

The result? Global warming's winners and losers may be hard to predict based on broad traits related to dispersal ability or reproduction, the researchers explained.

"For each group we found one or more traits that do explain some variation in recent range shifts, but none with clear influence across all groups," wrote Angert, who studies the effects of climate change on range shifts in monkeyflowers.

One possibility is that the traits that really matter for a species' ability to move to more suitable sites -- such as temperature tolerance -- are difficult to measure or find a proxy for, the authors argue.

Another possibility is that external factors, such as habitat fragmentation and availability, may be just as important as the species themselves. Plants and animals on mountain peaks or near the poles may simply have nowhere cooler to go, the researchers explained.

The findings were published in Ecology Letters.

Other authors on the paper include Lisa Crozier of the Northwest Fisheries Science Center in Seattle, Leslie Rissler of the University of Alabama, Josh Tewksbury of the University of Washington, and Amanda Chunco of the University of North Carolina at Chapel Hill.

Source: Sciencedaily.com

Wildlife in Trouble from Oil Palm Plantations, Researchers Say

ScienceDaily — Forest fragmentation driven by demand for palm oil is having a catastrophic effect on multiple levels of biodiversity, scientists from Queen Mary, University of London have discovered.

The researchers are worried that unless steps are taken to safeguard and manage the remaining forest, then certain species will struggle to survive.

The study, which focused on bats as an indicator of environmental change, was published in the journal Ecology Letters.

The team conducted bat surveys in pristine forest and also in forest patches of varying size in central Peninsular Malaysia. They recorded the numbers of different species present and also assessed the level of genetic diversity within populations of some species.

Lead author Matthew Struebig, jointly based at Queen Mary University of London and the University of Kent, said: "We found that smaller forest areas support fewer species, and that those species that remain face an eventual decline, potentially leading to local extinction in the long-term."

When the team compared the number of species present to genetic diversity within populations they found that fragmentation appeared to have an even greater impact on genetic loss, which might also be important for long-term population viability.

"We found that in order to retain the numbers of bat species seen in pristine forest, forest patches had to be larger than 650 hectares, however to retain comparable levels of genetic diversity, areas needed to be greater than 10,000 hectares," he said.

Co-author Stephen Rossiter, also at Queen Mary, emphasised that the findings could have important implications for forest management in the face of the ever-growing demand for oil palm plantations.

He said: "We found that while more species existed in larger forest patches, even small fragments contributed to overall diversity. Therefore, conservation managers should aim to protect existing small fragments, while seeking to join up small forest areas to maximise diversity."

Source: Sciencedaily.com

Tarantulas Shoot Silk from Their Feet

ScienceDaily (May 17, 2011) — Climbing is possibly one of the riskiest things an adult tarantula can do. Weighing in at anything up to 50g, the dry attachment systems that keep daintier spiders firmly anchored are on the verge of failure in these colossal arachnids.

"The animals are very delicate. They wouldn't survive a fall from any height," explains Claire Rind from the University of Newcastle, UK.

In 2006, Stanislav Gorb and his colleagues published a paper in Nature suggesting that tarantulas may save themselves from falling by releasing silk threads from their feet. However, this was quickly refuted by another group that could find no evidence of the silk. Fascinated by spiders and intrigued by the scientific controversy, Rind decided this was too good a challenge to pass up and discovered that tarantulas shoot silk from their feet when they lose their footing. She publishes her results in The Journal of Experimental Biology.

Teaming up with undergraduate Luke Birkett, Rind tested how well three ground-dwelling Chilean rose tarantulas kept their footing on a vertical surface. Gently placing one of the animals in a very clean aquarium with microscope slides on the floor, the duo cautiously upended the aquarium to see if the tarantula could hang on. "Given that people said tarantulas couldn't stay on a vertical surface, we didn't want to find that they were right," remembers Rind. But the spider didn't fall, so the duo gave the aquarium a gentle shake. The tarantula slipped slightly, but soon regained its footing. So the spider had held on against the odds, but would Rind find silk on the microscope slides?

Looking at the glass by eye, Rind couldn't see anything, but when she and Birkett looked closely under a microscope, they found minute threads of silk attached to the microscope slide where the spider had stood before slipping.

Next, Rind had to prove that the silk had come from the spiders' feet and not their web-spinning spinnerets. Filming the Chilean rose tarantulas as they were rotated vertically, Rind, Benjamin-James Duncan and Alexander Ranken disregarded any tests where other parts of the spiders' bodies contacted the glass and confirmed that the feet were the source of the silk. Also, the arachnids only produced their safety threads when they slipped.

But where on the spiders' feet was the silk coming from? Having collected all of the moulted exoskeletons from her Mexican flame knee tarantula, Fluffy, when she was young, Rind looked at them with a microscope and could see minute threads of silk protruding from microscopic hairs on Fluffy's feet. Next, the team took a closer look at moults from Fluffy, the Chilean rose tarantulas and Indian ornamental tarantulas with scanning electron microscopy and saw minute reinforced silk-producing spigots, which extended beyond the microscopic attachment hairs on the spiders' feet, widely distributed across the foot's surface. Rind also looked at the tarantula family tree, and found that all three species were only distantly related, so probably all tarantula feet produce the life-saving silk threads.

Finally, having noticed the distribution of the spigots, Rind realised that tarantulas could be the missing link between the first silk-producing spiders and modern web spinners. She explains that the spread of spigots on the tarantula's foot resembled the distribution of the silk spigots on the abdomen of the first silk spinner, the extinct Attercopus spider from 386 million years ago. The modern tarantula's spigots also looked more similar to mechanosensory hairs that are distributed over the spider's entire body, possibly making them an evolutionary intermediate in the development of silk spinning. So, not only has Fluffy settled a heated scientific debate but she also may be a link to the silk spinners of the past.

Source: Sciencedaily.com

There's No Magic Number for Saving Endangered Species

ScienceDaily (May 17, 2011) — A new study offers hope for species such as the Siberian Tiger that might be considered 'too rare to save', so long as conservation efforts can target key threats.

The findings have important implications for conserving some of the world's most charismatic endangered species, which often exist in populations far smaller than the many thousands of individuals that earlier studies had argued were necessary for viability.

Charismatic examples include the mountain gorilla, which likely now number 1,000 or less, the approximately 450 remaining Amur or Siberian tigers, the 180-500 remaining mature Philippine eagles, and the 70 wild Puerto Rican parrots.

The findings of a UK-US research team, the largest critical review of the use of minimum viable population (MVP) (*1) numbers in conservation, dispute the use of a universal MVP as a yardstick for conservation policies. According to the researchers there is no single population size that can be used as a catch-all guideline to save endangered species.

Co-author of the report, Dr. Philip Stephens, School of Biological and Biomedical Sciences, Durham University, said: "Populations usually show rapid declines as a result of human activities such as hunting and habitat conversion. The results of the study are encouraging and show that if we can remove the negative effects of human activities, even relatively small populations could be viable in the long term."

Dr. Greg Hayward, the U.S. Forest Service's (USFS) regional ecologist for Alaska said: "This is good news for biologists working to save species like the tiger. There's a lot of work to do to arrest the effects of poaching, prey loss and habitat destruction. However, if that work is successful, the tiger might yet be able to recover, despite the relatively small size of most tiger populations."

The study, published in the journal, Trends in Ecology and Evolution, shows that population sizes required for long-term viability vary, both within and among species, and depend on the specific circumstances in which the population is found. Estimates of viable population sizes were typically reduced to hundreds rather than thousands of individuals for populations that were relatively stable.

Previous studies have suggested that the allocation of conservation effort should be related to the number of individuals in threatened populations. For species which would require intense effort to raise numbers to 5,000 individuals, it might be too late to act and better to concentrate limited conservation resources elsewhere, the previous studies have suggested.

Researchers on the US-UK team argue that conservationists should not give up on saving an endangered species if its population is below an MVP figure, and they advise policy-makers to be cautious about setting guidelines for 'safe' population sizes.

The researchers also warn against potential complacency and stress the need to look in detail at the specific threats that a species faces. They argue that no population size is likely to be safe from extinction when conservation activities fail to reduce the impact of the factors causing the population to decline.

Dr. Curt Flather, a research ecologist with the USFS Rocky Mountain Research Station in Colorado said: "The enormous variability in estimates shows that many populations also need to be highly abundant to be viable. The extinction of the passenger pigeon, which numbered 3 to 5 billion individuals in North America during the 1800s, is a reminder that population size alone is no guarantee against extinction."

Read more at http://www.sciencedaily.com/releases/2011/05/110516201101.htm

Source: Sciencedaily.com