Birds build nests to keep eggs and nestlings warm in cold weather, but also make adjustments to nest insulation so the little ones can stay cool in very hot conditions. Mammals such as rabbits or marmots sleep or hibernate in underground burrows that offer stable, moderate temperatures and avoid above-ground conditions that are often much more extreme outside the burrow.
Michael Dillon, an associate professor in the Department of Zoology and Physiology at the University of Wyoming, was part of a research group studying the ability of animals to respond to climate change, which likely depends on how well they alter their habitats such as nests and caves.
So how are these animals doing? Do they succeed, do they fight, or are their efforts a mixed mix to adapt their habitats to climate change?
“One of the main reasons we wrote this paper is that we don’t know the answer to this very important question!” Says Dillon. “We hope the paper will encourage scientists to answer this question.”
Dillon is co-author of an article entitled “Extended Phenotypes: Buffers or Amplifiers of Climate Change?” has been published Trends in ecology and evolution. The journal publishes commissioned, peer-reviewed articles in all areas of ecology and evolutionary science.
The lead author of the paper is Arthur Woods, Professor of Life Sciences at the University of Montana. Other contributors to the paper were from Tours University in Tours, France; and Stellenbosch University in Stellenbosch, South Africa.
The study looked at expanded phenotypes, which are changes that organisms – birds, insects, and mammals – make to their habitats.
“An expanded phenotype can range from a simple hole in the ground occupied by an animal, to leaves being rolled into cavities by insects, to nests of all shapes and sizes built by birds and mammals Termite mounds and colonies of bees are enough, ”says Dillon.
Extended phenotypes are important because they filter the climate into local conditions around the organism. This is what biologists call the microclimate.
Because extended phenotypes are constructed structures, they are often modified in response to local climate variability and possibly in response to climate change. This process is known as the plasticity of the expanded phenotype.
“An example could be a bird’s nest that is well insulated to protect eggs or young birds from the cold. If the climate does not adapt to the warm climate, the young can overheat if the bird does not adapt the insulation in the nest, ”explains Dillon.
In another prime example, termites build mounds that capture wind and solar energy to propel airflow through the colony, which stabilizes the colony’s temperature, relative humidity, and oxygen levels.
However, the idea of microclimates is broader than constructed habitats. Microclimates typically differ significantly from nearby climates, which means that the climate in an area may provide little information about what animals experience in their microhabitats.
As an analogy, a weather station could tell the public that the temperature in Laramie is 90 degrees Fahrenheit, simply by moving from the south to the north side of a building, one can experience microclimates that are strikingly different, and often not from the weather data, says Dillon.
The same goes for animals of many different sizes. For example, a moose can move from an open sagebrush landscape into a shady river corridor to cool off; a snake can move from its underground hole to a sunny rock to warm up; and a tiny insect shuttling back and forth between the top and bottom of a leaf can experience temperature differences of more than 20 degrees Fahrenheit.
“Animals take advantage of microclimates, both by moving around and building structures like nests, caves, hills and mines,” says Dillon.
Globally, rising levels of carbon dioxide in the earth’s atmosphere lead to a rise in temperatures and a shift in precipitation patterns. A key problem for biologists is understanding the current impacts of climate change on species and predicting future impacts, including how the range of species may shift and the relative risks of extinction for different animal species groups.
The research team advocates renewed efforts to understand how expanded phenotypes mediate how organisms experience climate change.
“We need a much better understanding of the basic biophysical principles by which extended phenotypes change local conditions,” says Sylvain Pincebourde, an ecologist at the Institute of Insect Biology at Tours University and one of the co-authors of the article.
Another important challenge is understanding how much plasticity there is in expanded phenotypes and how much and how quickly they can develop.
“At this point, we have next to no idea,” says Dillon. “Can structures that buffer temperature fluctuations keep up with the pace of climate change?”
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