Hurricanes as a source of episodic natural selection
Storm study shows adaptive selection in southeast lizards
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A new study led by the University of Rhode Island's Jason Kolbe examines adaptive selection in Anolis lizards in the southeastern U.S.
view moreCredit: Jason Kolbe
How do intermittent events like hurricanes impact natural selection? How do animals adapt to challenging weather? A University of Rhode Island professor has set out to track natural selection in the Anolis lizard over time to see how the species has weathered hurricanes in the southeastern United States.
A new paper by Jason Kolbe and colleagues published in the Proceedings of the National Academy of Sciences finds hurricane-induced selection and responses to hurricanes in Anolis lizards. Chair of URI’s Department of Biological Sciences, Kolbe studies how human-mediated global change phenomena drive evolutionary change in the natural world.
High winds associated with hurricanes can result in natural selection on traits related to clinging performance in anole lizards.
If species’ mortality depends on specific traits, then hurricanes — extreme and intermittent in nature — provide a source of episodic natural selection on affected populations. The predicted increase in hurricane activity and strength in the North Atlantic has the potential to alter patterns of selection and evolution for populations, especially in coastal areas and islands.
The paper’s focus brought Kolbe back to the start of his professional research career. He has studied lizards for 25 years and used genetic markers to reconstruct the invasion histories of Anolis lizards introduced to Florida from the Caribbean for his dissertation.
As part of his Ph.D. research, Kolbe studied the ecology and evolution of anole populations on islands in the Bahamas. When Hurricane Sandy hit their study site there in 2012, he decided to use the devastating storm’s impact to compare lizards before and after impact.
The invasion of Anolis sagrei in the southeastern U.S. provided a rare opportunity to put a timestamp on the start of adaptive evolution for populations in this region, Kolbe says. Over 100 hurricanes have hit Florida since the start of the A. sagrei invasion.
Their results affirmed that hurricanes are a source of episodic selection with lasting evolutionary effects on lizard traits connected to weathering storms. Kolbe’s team’s preliminary analysis found lizards with longer limbs survived better during the hurricane and that lizards with longer limbs possessed greater clinging ability, supporting hurricanes as a source of natural selection for lizard populations.
“Our studies of the brown anole in Florida provided an excellent opportunity to test whether hurricane-induced selection could shape the morphology of lizards over the course of their invasion, around 100 years,” he says. “Because we have a good estimate of the time each brown anole population in our study was established and hurricane records go back to 1851, we were able to estimate the number of hurricanes impacting each population and test for an association with traits that increase clinging performance.”
Introduced lizard
The Anolis sagrei was introduced in Florida and Georgia beginning in 1887 in the Florida Keys. It showed up on the peninsula a half-century later. Kolbe’s team reconstructed a chronology of the A. sagrei invasion in Florida and Georgia using dates from published observations and museum specimen records.
Brown anoles were introduced to the U.S. from at least eight geographically and genetically distinct source populations in their native range, mostly from Cuba. These introductions likely occurred accidentally via shipping or intentional introductions (release of pets into the wild).
Kolbe and his colleagues found that brown anole populations experiencing more hurricanes had longer limbs and larger toepads, traits that help them hold on — both in the immediate sense of a single storm and in the long-term as well, in terms of natural selection. Their results confirm hurricanes as a major force shaping variation in Anolis lizards and highlight how the evolutionary trajectories of animal populations will be altered as climate change modifies historical patterns of natural selection, he says.
An evolutionary ecologist, Kolbe studies the evolutionary response of species adapting to rapid environmental shifts and says that biological invasions are useful scenarios to study rapid evolution.
Although there aren’t many good studies on the ecological impacts of this species, its high densities, rapid spread and generalist nature suggest potential impacts on other species, Kolbe says, noting that other species could be studied, as well.
“Lizards are surely not the only species potentially experiencing selection during hurricanes,” says Kolbe. “Our understanding of episodic selection may be enhanced by studies on the evolutionary effects of hurricanes on other species, not only lizards.”
This work was made possible by funding from the National Science Foundation.
Journal
Proceedings of the National Academy of Sciences
Method of Research
Case study
Subject of Research
Animals
Article Title
Morphological and genomic responses to hurricanes arise and persist during a biological invasion
High winds associated with hurricanes can result in natural selection on traits related to clinging performance in anole lizards.
Credit
Jason Kolbe
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