Showing posts with label climate change. Show all posts
Showing posts with label climate change. Show all posts

Saturday, March 31, 2012

The Side-Blotched Lizard & A Warming Climate

A side-blotched lizard, Pima Co., AZ, JCM
Side-blotched lizards of the genus Uta are perhaps the most abundant and most frequently seen lizards in western North American deserts. Males are usually larger than females and have brightly colored throats that are used to signal other lizards. They mature rapidly and reproduce at young age. Many fall prey to a variety of birds, mammals, and other reptile, thus in some populations few live longer than a year. Mature females regularly lay two clutches (and in some years possibly three), yearlings frequently lay only one clutch unless environmental conditions are especially favorable.

Clark & Zani (2012) used the side-blotched lizard to examine the impact of climate change, hypothsizing that temperate ectotherms, especially those at higher latitudes, would benefit from climate warming. Most previous studies on the effects of climate change use a model of uniform annual change, which assumes that temperature increases are symmetric on diurnal or seasonal time scales. In this study, Clark & Zani simulated observed trends in the asymmetric alteration of diurnal temperature range by increasing night-time temperatures experienced by female lizards during their ovarian cycle as well as by the resulting eggs during their incubation. They found that higher night-time temperatures during the ovarian cycle increased the probability of reproductive success and decreased the duration of the reproductive cycle, but did not affect embryo stage or size at oviposition, clutch size, egg mass or relative clutch mass. However, higher incubation temperatures increased hatchling size and decreased incubation period but had no effect on incubation success. Subsequent hatchlings were more likely to survive winter if they hatched earlier, but the sample size of hatchlings was relatively small. Their results suggest higher night-time temperatures affect the rates of processes and that certain aspects of life history are less directly temperature dependent. Thus climate warming is likely to increase the rate of development as well as advance reproductive phenology, and the authors predict that warmer nights during the breeding season will increase reproductive output as well as subsequent survival in many temperate ectotherms, both of which should have positive fitness effects.

Clarke DN, and Zani PA. 2012. Effects of night-time warming on temperate ectotherm reproduction: potential fitness benefits of climate change for side-blotched lizards, Journal of Experimental Biology 215:1117-1127. doi:10.1242/jeb065359

Thursday, January 26, 2012

Multiple Paternity, Green Turtles, & Climate Change

A hatching Green Turtle. Photo credit:
 Kimberly Stokes, University of Exetar.
The mating habits of marine turtle may help protect them against the effects of climate change, according to new research led by the University.

Published yesterday (25 January 2012) in the Proceedings of the Royal Society B, the study shows how mating patterns of a population of endangered green turtles may be helping them deal with the fact that global warming is leading to a disproportionate number of females being born.

The gender of baby turtles is determined by the temperature of the eggs during incubation, with warmer temperatures leading to more females being born. Higher average global temperatures mean that offspring from some populations are predominantly female. This is threatening the future of some populations and there are concerns that inbreeding within groups due to a lack of males will lead to health problems.

The study focused on a population of the green turtle, Chelonia mydas, nesting in Northern Cyprus, where, due to the high summer temperatures, 95 per cent of babies are female. The study involved a team from the University of Exeter (UK), University of Lefke (Turkey) and North Cyprus Society for Protection of Turtles. Through DNA testing, they were able to ascertain the paternity of baby turtles and, contrary to what they had expected, they found a large number of mating males.

The researchers found that 28 males sired offspring with 20 nesting females: an average of 1.4 males for every female. This means that each female’s offspring were sired by one or more fathers. The researchers were surprised to find no evidence that any males fathered offspring born in that season with more than one female.

The Cornwall Campus-based research team had thought that one single male might be breeding with multiple females. However, their results suggest that a large number of males are mating with different females at different times. This means that there is less chance of inbreeding.

The team also carried out satellite tracking to discover that males cover thousands of miles of ocean within one breeding season. This suggests they could have also been mating with females at other sites in Turkey or North Africa.

Lead researcher University of Exeter Biosciences PhD student Lucy Wright said: “It is fantastic to know that there are so many males fathering offspring in this population of green turtles. There is great concern that a lack of males could lead to inbreeding in small populations of marine turtles, potentially causing a population crash. However our research suggests that there are more males out there than expected considering the female-biased hatchling sex ratios and that their mating patterns will buffer the population against any potential feminising effects of climate change.”

Corresponding author Dr Annette Broderick added: “Climate change remains a great threat to marine turtles, but our ongoing research will help us focus on where the priority areas are for management that may help them cope with future change.”

The work was funded by a NERC studentship with additional support from NERC Biomolecular Analysis Facility, Sheffield.

L. I. Wright, K. L. Stokes, W. J. Fuller, B. J. Godley, A. McGowan, R. Snape, T. Tregenza, & A. C. Broderick. Turtle mating patterns buffer against disruptive effects of climate change. Proceedings of the Royal Society B: Biological Sciences, 2012; DOI: 10.1098/rspb.2011.2285

Thursday, December 8, 2011

Climate Modeling With Rattlesnakes

The following is a press release from Indiana University. The link to the entire article on-line can be found at the bottom. There are some very nice videos that show predictions in changing geographic distributions for a number of rattlesnake species that can be downloaded from the article.

Species, like this Crotalus basiliscus will be greatly impacted by climate change over the next few hundred years. JCM

BLOOMINGTON, Ind. -- The ranges of species will have to change dramatically as a result of climate change between now and 2100 because the climate will change more than 100 times faster than the rate at which species can adapt, according to a newly published study by Indiana University researchers.

The study, which focuses on North American rattlesnakes, finds that the rate of future change in suitable habitat will be two to three orders of magnitude greater than the average change over the past 300 millennia, a time that included three major glacial cycles and significant variation in climate and temperature.

"We find that, over the next 90 years, at best these species' ranges will change more than 100 times faster than they have during the past 320,000 years," said Michelle Lawing, lead author of the paper and a doctoral candidate in geological sciences and biology at IU Bloomington. "This rate of change is unlike anything these species have experienced, probably since their formation."

The timber rattlesnake could be displaced from much of its range in the eastern U.S. by climate change projected to take place by 2100.

The study, "Pleistocene Climate, Phylogeny, and Climate Envelope Models: An Integrative Approach to Better Understand Species' Response to Climate Change," was published by the online science journal PLoS One. Co-author is P. David Polly, associate professor in the Department of Geological Sciences in the IU Bloomington College of Arts and Sciences.

The researchers make use of the fact that species have been responding to climate change throughout their history and their past responses can inform what to expect in the future. They synthesize information from climate cycle models, indicators of climate from the geological record, evolution of rattlesnake species and other data to develop what they call "paleophylogeographic models" for rattlesnake ranges. This enables them to map the expansion and contraction at 4,000-year intervals of the ranges of 11 North American species of the rattlesnake genus Crotalus.

Projecting the models into the future, the researchers calculate the expected changes in range at the lower and upper extremes of warming predicted by the Intergovernmental Panel on Climate Change -- between 1.1 degree and 6.4 degrees Celsius. They calculate that rattlesnake ranges have moved an average of only 2.3 meters a year over the past 320,000 years and that their tolerances to climate have evolved about 100 to 1000 times slower, indicating that range shifts are the only way that rattlesnakes have coped with climate change in the recent past. With projected climate change in the next 90 years, the ranges would be displaced by a remarkable 430 meters to 2,400 meters a year.

Increasing temperature does not necessarily mean expanded suitable habitats for rattlesnakes. For example, Crotalus horridus, the timber rattlesnake, is now found throughout the Eastern United States. The study finds that, with a temperature increase of 1.1 degree Celsius over the next 90 years, its range would expand slightly into New York, New England and Texas. But with an increase of 6.4 degrees, its range would shrink to a small area on the Tennessee-North Carolina border. C. adamanteus, the eastern diamondback rattlesnake, would be displaced entirely from its current range in the southeastern U.S. with a temperature increase of 6.4 degrees.

The findings suggest snakes wouldn't be able to move fast enough to keep up with the change in suitable habitat. The authors suggest the creation of habitat corridors and managed relocation may be needed to preserve some species.

Rattlesnakes are good indicators of climate change because they are ectotherms, which depend on the environment to regulate their body temperatures. But Lawing and Polly note that many organisms will be affected by climate change, and their study provides a model for examining what may happen with other species. Their future research could address the past and future effects of climate change on other types of snakes and on the biological communities of snakes.

Friday, August 19, 2011

Further, faster, higher: wildlife responds increasingly rapidly to climate change

New research by scientists in the Department of Biology at the University of York shows that species have responded to climate change up to three times faster than previously appreciated. These results are published in the latest issue of the leading scientific journal Science.

Faster distribution changes. Species have moved towards the poles (further north in the northern hemisphere, to locations where conditions are cooler) at three times the rate previously accepted in the scientific literature, and they have moved to cooler, higher altitudes at twice the rate previously realised.

These changes are equivalent to animals and plants shifting away from the Equator at around 20 cm per hour, for every hour of the day, for every day of the year

Analysing data for over 2000 responses by animal and plant species, the research team estimated that, on average, species have moved to higher elevations at 12.2 metres per decade and, more dramatically, to higher latitudes at 17.6 kilometres per decade.

Project leader Chris Thomas, Professor of Conservation Biology at York, said: “These changes are equivalent to animals and plants shifting away from the Equator at around 20 cm per hour, for every hour of the day, for every day of the year. This has been going on for the last 40 years and is set to continue for at least the rest of this century. ”

The link to climate change. This study for the first time showed that species have moved furthest in regions where the climate has warmed the most, unambiguously linking the changes in where species survive to climate warming over the last 40 years.

First author Dr I-Ching Chen, previously a PhD student at York and now a researcher at the Academia Sinica in Taiwan, said: “This research shows that it is global warming that is causing species to move towards the poles and to higher elevations. We have for the first time shown that the amount by which the distributions of species have changed is correlated with the amount the climate has changed in that region.”

Co-author Dr Ralf Ohlem├╝ller, from Durham University, said: “We were able to calculate how far species might have been expected to move so that the temperatures they experience today are the same as the ones they used to experience, before global warming kicked in. Remarkably, species have on average moved towards the poles as rapidly as expected.”

A diversity of changes. These conclusions hold for the average responses of species, but individual species showed much greater variation. Some species have moved much more slowly than expected, others have not moved, and some have even retreated where they are expected to expand. In contrast, other species have raced ahead, perhaps because they are sensitive to a particular component of climate change (rather than to average warming), or because other changes to the environment have also been driving their responses.

Co-author Dr David Roy, from the Centre for Ecology & Hydrology, illustrates this variation among species: “In Britain, the high brown fritillary butterfly might have been expected to expand northwards into Scotland if climate warming was the only thing affecting it, but it has in fact declined because its habitats have been lost. Meanwhile, the comma butterfly has moved 220 kilometres northwards from central England to Edinburgh, in only two decades.”

Similar variation has taken place in other animal groups. Cetti’s warbler, a small brown bird with a loud voice, moved northwards in Britain by 150 kilometres during the same period when the Cirl bunting retreated southward by 120 kilometres, the latter experiencing a major decline associated with the intensification of agriculture.

How they did the research. The researchers brought together all of the known studies of how species have changed their distributions, and analysed them together in a “meta-analysis”. The changes that were studied include species retreating where conditions are getting too hot (at low altitudes and latitudes), species expanding where conditions are no longer too cold (at high altitude and latitudes), and species staying where they are but with numbers declining in hotter parts and increasing in cooler parts of the range.

They considered studies of latitudinal and elevational range shifts from throughout the world, but most of the available data were from Europe and North America.

Birds, mammals, reptiles, insects, spiders, other invertebrates, and plants featured in the evidence. For example, I-Ching Chen and her colleagues discovered that moths had on average moved 67 metres uphill on Mount Kinabalu in Borneo.

Co-author Jane Hill, Professor of Ecology at York, said: “We have taken the published literature and analysed it to detect what the overall pattern of change is, something that is not possible from an individual study. It’s a summary of the state of world knowledge about how the ranges of species are responding to climate change. Our analysis shows that rates of response to climate change are two or three times faster than previously realised.”

Implications. The current research does not explicitly consider the risks posed to species from climate change, but previous studies suggest that climate change represents a serious extinction risk to at least 10 per cent of the world’s species. Professor Thomas says: “Realisation of how fast species are moving because of climate change indicates that many species may indeed be heading rapidly towards extinction, where climatic conditions are deteriorating. On the other hand, other species are moving to new areas where the climate has become suitable; so there will be some winners as well as many losers.”

Original Article:
I.-C. Chen, J. K. Hill, R. Ohlemuller, D. B. Roy, C. D. Thomas. Rapid Range Shifts of Species Associated with High Levels of Climate Warming. Science, 2011; 333 (6045): 1024 DOI: 10.1126/science.1206432

Tuesday, July 12, 2011

Decline in species shows climate change warnings not exaggerated

Forest frogs are temperature sensitive.
One in 10 species could face extinction by the year 2100 if current climate change impacts continue. This is the result of University of Exeter research, examining studies on the effects of recent climate change on plant and animal species and comparing this with predictions of future declines.

Published in leading journal Proceedings of the National Academy of Sciences (PNAS), the study uses the well-established IUCN Red List for linking population declines to extinction risk. The research examines nearly 200 predictions of the future effects of climate change from studies conducted around the world, as well as 130 reports of changes which have already occurred.

The research shows that on average the declines that have already happened match predictions in terms of the relative risk to different species across the world.

Many studies have predicted that future climate change will threaten a range of plants and animals with extinction. Some of these studies have been treated with caution because of uncertainty about how species will respond to climate change. But widely published research showing how animals and plants are already responding to climate change gave the Exeter team the opportunity to check whether the predictions were wide of the mark. By producing the largest review ever of such studies, they show that predictions have, on average, been accurate, or even slightly too cautious.

Lead author Dr Ilya Maclean of the University of Exeter said: "Our study is a wake-up call for action. The many species that are already declining could become extinct if things continue as they are. It is time to stop using the uncertainties as an excuse for not acting. Our research shows that the harmful effects of climate change are already happening and, if anything, exceed predictions."

The study covered a wide range of species in all types of habitat across the globe. The findings confirm that human-induced climate change is now a threat to global biodiversity.

Co-author Dr Robert Wilson, also of the University of Exeter, said: "By looking at such a range of studies from around the world, we found that the impacts of climate change can be felt everywhere, and among all groups of animals and plants. From birds to worms to marine mammals, from high mountain ranges to jungles and to the oceans, scientists seem to have been right that climate change is a real threat to species.

"We need to act now to prevent threatened species from becoming extinct. This means cutting carbon emissions and protecting species from the other threats they face, such as habitat loss and pollution."

Examples of existing responses to climate change:

Decreased ice cover in the Bering Sea reduced the abundance of bivalve molluscs from about 12 to three per square metre over a very short period of time (1999-2001). These shells are the main food source for species higher up the food chain, such as Spectacled Eider.

Climatic warming and droughts are causing severe declines in once-common amphibian species native to Yellowstone National Park in the United States of America. Between 1992-1993 and 2006- 2008, the number of blotched tiger salamander populations fell by nearly half, the number of spotted frog populations by 68 per cent, and the number of chorus frog populations by 75 per cent.

In Antarctica, few animals exist on land, but one of the most abundant, a nematode worm living in the soil in dry, cold valleys experienced a 65 per cent decline between 1993 and 2005 as a result of climate change.

Examples of predicted responses to climate change:

On Tenerife, an endemic plant, the Ca┼ładas rockrose has a 74 to 83 per cent chance of going extinct in the next 100 years as a result of climate change related droughts.

In Madagascar, climate warming is predicted to cause endemic reptiles and amphibians, often found in mountain ranges, to retreat towards the summit of the mounts. With a warming of just two degrees Celsius, well within current projections, three species are predicted to lose all of their habitat.

Birds living in northern Boreal Forests in Europe are expected to decline as a result of global warming. Species such as Dotterel are predicted to decline by 97 per cent by 2100 and species such as Two-barred Crossbill and Pine Grosbeak could lose their entire range within Fenno-Scandia.

Ilya M. D. Maclean and Robert J. Wilson. 2011. Recent ecological responses to climate change support predictions of high extinction risk. PNAS 10.1073/pnas.101735

Thursday, December 9, 2010

Reptile Extinction in the Agean

This is an almost unedited press release from

A sample group of Aegean wall lizards 
was captured during field work on one 
of the Greek study islands. 
Credit: Johannes Foufopoulos
A wave of reptile extinctions on the Greek islands over the past 15,000 years may offer a preview of the way plants and animals will respond as the world rapidly warms due to human-caused climate change, according to a University of Michigan ecologist and his colleagues.
The Greek island extinctions also highlight the critical importance of preserving habitat corridors that will enable plants and animals to migrate in response to climate change, thereby maximizing their chances of survival.

As the climate warmed at the tail end of the last ice age, sea levels rose and formed scores of Aegean islands that had formerly been part of the Greek mainland. At the same time, cool and moist forested areas dwindled as aridity spread through the region.

In response to the combined effects of a shifting climate, vegetation changes and ever-decreasing island size, many reptile populations perished.

To gain a clearer understanding of the past consequences of climate change, Johannes Foufopoulos and his colleagues calculated the population extinction rates of 35 reptile species---assorted lizards, snakes and turtles---from 87 Greek islands in the northeast Mediterranean Sea. The calculated extinction rates were based on the modern-day presence or absence of each species on islands that were connected to the mainland during the last ice age.

Foufopoulos and his colleagues found a striking pattern to the island extinctions. In most cases, reptile populations disappeared on the smallest islands first---the places where the habitat choices were most limited.
Especially hard hit were "habitat specialist" reptiles that required a narrow range of environmental conditions to survive. In addition, northern-dwelling species that required cool, moist conditions showed some of the highest extinction rates. 

The study results appear in the January edition of American Naturalist.

The researchers conclude that a similar pattern of extinctions will emerge at various spots across the globe as the climate warms in the coming decades and centuries. In addition to adapting to a changing climate, plants and animals will be forced to traverse an increasingly fragmented natural landscape. 

Foufopoulos, J., A. Marm Kilpatrick, and A. R. Ives. 2011. Climate Change and Elevated Extinction Rates of Reptiles from Mediterranean Islands. The American Naturalist 177:19-129.