Brown tawny owl in a tree.

Just one example of adaptation: brown tawny owls are becoming more common than grey ones in Finland as snow cover declines. 
Photo: Andreas Trepte, www.photo-natur.de \ CC BY-SA 2.5

Environmental “tipping points” can provide researchers with valuable clues to detect when species are facing population collapse or extinction.

Research published Monday in the Proceedings of the National Academy of Sciences by an international team from the Netherlands, Norway and the United States found the type of dramatic evolution required by a species is less critical to their survival than how those changes alter their physiology within their overall existence.

It’s not as abstract as it sounds. Carlos Botero, lead author of the report and a postdoctoral fellow with the Initiative on Biological Complexity at North Carolina State University, told A\J his study examined how species evolve their “genotypic expression” to suit changing environments. This includes physical changes like coat thickness, behavioural changes like a species’ desire to huddle with others of the same species or physiological changes like how much they sweat. He also measured for variables such as temperature and precipitation.

Botero’s research found the vast majority of species will be able to undergo even dramatic adaptations in response to changing environments projected as a result of climate change so long as the shift keeps a species within their comfort zone. One example of this is simple genetic changes that don’t affect major body functions or organs. While genetic shifts may seem extreme, Botero said, “as long as it’s within their [natural] range, it’s going to be easy for evolution” to handle.   

The threat of population collapse or extinction comes when the adaptation a species undertakes in order to stay alive shifts them to the margins of their comfort zone. The loss of complex organs or a considerable readjustment of their basic physiology makes the threat of extinction more likely.

Things are really great up to one point and then you cross a boundary and things go to hell.

If they’re already existing at the margins, “no matter how tiny or minuscule the change is … it may lead to dramatic population collapse and extinction,” Botero said. “That’s what we’ve called the ‘tipping point’ because things are really great up to one point and then you cross a boundary and things go to hell.”

This can lead to population collapse and, occasionally, extinctions, Botero said.

The study came about when similar modelling he and fellow researcher Jonathan Wright from the Norwegian University of Science and Technology were doing didn’t match up. They sat down to discuss the differences, but eventually, Botero said, they decided it was best to let evolution show them the right answer.

The combined approach worked better than he thought it would. The result is this paper, which provides tools to better understand the extent to which different species may adapt to environmental variabilities.

If conservation managers trying to stem the tide of extinctions know what indicators to search for, they may be better positioned to move quickly in helping species on the verge of collapse. Botero is in talks with biologists and other field researchers about how they can use his model to determine where in the comfort zone a particular species is and where they predict it’s headed.

Evolution will carry the day in the majority of cases.

But determining when a particular species is dangerously close to the margins of their comfort zone isn’t easy, and the line between thriving and collapse is razor thin.  

“There are several species that may be undergoing dramatic changes … but there’s no risk of extinction,” Botero said. “Yet tomorrow when they cross that tiny boundary they could potentially go extinct,” succumbing to what he calls “cryptic threats.” Often how a species appears to be doing on the surface provides little indication of how precarious their existence is due to environmental variables we may not know of.

But it’s not all doom and gloom. Species at risk of moving toward extinction are the minority, according to the study. And after running the scenarios through the model, scientists now have a greater ability to predict how species will evolve in reaction to individual environmental stressors over the next 1,000 years.

“Evolution is actually remarkably flexible,” Botero said. “It allows a lot of species to adapt to changes that may seem really dramatic. We’re actually saying evolution will carry the day in the majority of cases, but it’s also giving us some tools to understand when it won’t.”

Andrew Reeves is an environmental writer completing a book about Asian carp in North America. He is a contributing editor at Alternatives Journal and This Magazine’s environmental columnist. His work has also appeared in the Globe & MailSpacing and Corporate Knights.

Follow him on Twitter.

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