Evolution Not Fast Enough For Climate Change
July 10, 2013

Many Species Can’t Evolve Fast Enough For Climate Change

Brett Smith for redOrbit.com - Your Universe Online

New research from two biologists at the University of Arizona and Yale suggests that evolution is not an option for species looking to cope with rising global temperatures.

According to a study, terrestrial vertebrate species could not adapt to the 4 degree Celsius rise in average global temperatures, and many of these species could be driven to extinction.

"Every species has a climatic niche, which is the set of temperature and precipitation conditions in the area where it lives and where it can survive," explained co-author John J. Wiens, a professor of ecology and evolutionary biology at the University of Arizona. "For example, some species are found only in tropical areas, some only in cooler temperate areas, some live high in the mountains, and some live in the deserts."

To reach their findings, the pair of scientists looked at the genetic data of 17 different evolutionary trees of terrestrial vertebrates, including frogs, snakes, crocodilians, birds and mammals. The evolutionary data was then compared to the climatic niche of each species to determine how quickly these niches can change or evolve among species.

"Basically, we figured out how much species changed in their climatic niche on a given branch, and if we know how old a species is, we can estimate how quickly the climatic niche changes over time," Wiens explained. "For most sister species, we found that they evolved to live in habitats with an average temperature difference of only about 1 or 2 degrees Celsius over the course of one to a few million years."

"We then compared the rates of change over time in the past to projections for what climatic conditions are going to be like in 2100 and looked at how different these rates are," he added. "If the rates were similar, it would suggest there is a potential for species to evolve quickly enough to be able to survive, but in most cases, we found those rates to be different by about 10,000-fold or more."

In addition to evolving for a particular climate niche, species are also capable of moving to a more hospitable region, such as higher latitudes or elevations to escape rising temperatures. Species could also survive the coming changes if they have disparate enough populations across various ecosystems.

However, Wiens stated that picking up and moving might not be a viable solution for many species.

"Some studies suggest many species won't be able to move fast enough," he said. "Also, moving may require unimpeded access to habitats that have not been heavily disturbed by humans. Or consider a species living on the top of a mountain. If it gets too warm or dry up there, they can't go anywhere."

He added that climate change could put species in a situation they are not acclimated for or built to succeed in, including dealing with species-species interactions and shifting resources.

"What seemed to be a big driver in many species declines was reduced food availability," Wiens said. "For example, bighorn sheep: If it gets drier and drier, the grass gets sparse and they starve to death."

Their study appears in the latest edition of the journal Ecology Letters.