Tag: Rapid Evolution

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Overfishing of Atlantic Cod Likely Did Not Cause Genetic Changes: Pinsky et al. paper out in PNAS

This article was adapted from Todd Bates’ press release.

Atlantic cod
Bottom-dwelling fish such as Atlantic cod are often found near structures such as
shipwrecks. Photo: NOAA

Overfishing likely did not cause the Atlantic cod, an iconic species, to evolve genetically and mature earlier, according to a study led by Drs. Malin Pinsky and Bastiaan Star.

“Evolution has been used in part as an excuse for why cod and other species have not recovered from overfishing,” said Malin. “Our findings suggest instead that more attention to reducing fishing and addressing other environmental changes, including climate change, will be important for allowing recovery. We can’t use evolution as a scapegoat for avoiding the hard work that would allow cod to recover.”

The study, which focuses on Atlantic cod (Gadus morhua) off Newfoundland in Canada and off Norway, appears in the journal Proceedings of the National Academy of Sciences.

Atlantic cod range
Atlantic cod habitat includes both sides of the north Atlantic Ocean and beyond. Image: NOAA

Many debates over the last few decades have centered on whether cod have evolved in response to fisheries, a phenomenon known as fisheries-induced evolution. Cod now mature at a much earlier age, for example. The concern has been that if the fish have evolved, they may not be able to recover even if fishing is reduced, according to Pinsky.

Cod populations with late-maturing individuals can produce more offspring and more effectively avoid predators, he said. They are also better protected against climate variability.

Both theory and experiments suggest that fishing can lead to an earlier maturation age. But prior to the new study, no one had tried to sequence whole genomes from before intensive fishing to determine whether evolution had occurred. So, this team sequenced cod earbones and scales from 1907 in Norway, 1940 in Canada and modern cod from the same populations. The northern Canadian population of cod collapsed from overfishing in the early 1990s, while the northeast Arctic population near Norway faced high fishing rates but smaller declines.

The team found no major losses in genetic diversity and no major changes that suggested intensive fishing induced evolution, suggesting that we focus on managing for more direct threats (e.g., overfishing, environmental change) than for evolution.

This study prompts future investigations to see if other species, especially those with shorter lifespans (in contrast to cod), do or don’t show signs of evolution.

Scientists at the University of Oslo, Fisheries and Oceans Canada, Institute of Marine Research (Norway), University of Basel and University of Zurich contributed to the study.

Read additional coverage by Science Magazine here!

Read the original press release here!

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Deadly White-Nose Syndrome Changed Genes in Surviving Bats: Gignoux-Wolfsohn et al. paper out in Molecular Ecology

A little brown bat that survived white-nose syndrome. Photo: Sarah Gignoux-Wolfsohn

This post is adapted from Todd Bates‘ article in Rutgers Today.

Former Pinsky Lab Post-doc, Dr. Sarah Gignoux-Wolfsohn led a study in Molecular Ecology which uncovered the genetic differences between bats killed by white-nose syndrome and bats that survived. She was supported by a team of co-authors from Rutgers (Dr. Malin Pinsky, Dr. Kathleen Kerwin, and Dr. Brooke Maslo), the NY Department of Environmental Conservation, the NJ Department of Enviornmental Protection, the Vermont Fish and Wildlife Department, and the University of Tennessee. Their results suggest that survivors pass on traits for resistance to the fungal disease causing rapid evolution in exposed bat populations.

White-nose syndrome has killed millions of bats in North America since 2006, following its introduction from Europe. The syndrome, caused by the fungal pathogen Pseudogymnoascus destructans, is arguably the most catastrophic wildlife disease in history. It has led to unprecedented declines in many North American bat species, including the little brown bat (Myotis lucifugus).

“Our finding that little brown bat populations have evolved, which could be why they survived, has large implications for management of bat populations going forward,” said lead author Sarah Gignoux-Wolfsohn, a former postdoctoral associate at Rutgers University–New Brunswick now at the Smithsonian Environmental Research Center in Maryland. “Management decisions, such as whether to treat for white-nose syndrome or protect populations from other detrimental factors, can be informed by knowing which bats are genetically resistant to the disease.”

“The deployment of vaccines or treatments for the fungus may be most needed in populations with few disease-resistant individuals,” said Gignoux-Wolfsohn, who led the study – published in the journal Molecular Ecology – while at Rutgers. “Our study also has implications for other diseases that cause mass mortality. While rapid evolution in response to these diseases is often difficult to detect, our study suggests it may be more common than previously thought.”

The team sequenced bat genomes from three hibernating colonies in abandoned mines in New York, New Jersey and Vermont to determine whether little brown bats evolved as a result of the disease. They compared the genomes of bats killed by white-nose syndrome to survivors in recovering populations to identify genetic differences that may be responsible for survival.

The bats’ evolution appears to have particularly affected genes associated with weight gain before hibernation and behavior during hibernation. Rapid evolution may have allowed the remaining bats to keep hibernating and survive infection that killed off millions of other bats.

“Evolution is often thought of as a process that happened long ago,” Gignoux-Wolfsohn said. “We have found that it has also been happening right in our backyards and barns over the last decade.”

This group is now conducting a similar study in Indiana bats (Myotis sodalis). While also affected by white-nose syndrome, this species has experienced lesser declines than little brown bats.

Read the article in Molecular Ecology.

Read additional news coverage in Rutgers Today and Yahoo! News.