Chromosomal Inversions Help Aquatic Species Adapt to Changing Environments

New research finds that chromosomal inversions allow mobile aquatic species to maintain genetic differences across diverse habitats.

Published on Mar. 7, 2026

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A new study from Cornell University and the University of Connecticut has found that chromosomal inversions - where a chunk of a chromosome containing many genes flips and reattaches - help mobile aquatic species like Atlantic silversides maintain genetic differences adapted to various regions, even when the fish interbreed across habitats. The inversions act as "genetic switches" that preserve beneficial gene combinations for survival in either cold or warm water, preventing the breakup of these adaptations in hybrid offspring.

Why it matters

Understanding how species like Atlantic silversides can rapidly adapt to changing environments, such as warming oceans, is crucial as the climate continues to shift. The research suggests that certain genetic mechanisms like chromosomal inversions may play a key role in how quickly and predictably populations can respond to environmental changes.

The details

The researchers cross-bred Atlantic silversides from Georgia and New York, raised their offspring under different temperatures, and studied the fish's genetics and important traits like growth rate and swimming performance. They found that chromosomal inversions containing genes for critical adaptive traits like growth, metabolism, and vertebral number were essential for maintaining local adaptation, even when the fish from different regions interbred.

  • The study was published on March 5, 2026 in the journal Science.
  • The research was conducted over several years, with the fish being cross-bred and their offspring raised and studied.

The players

Nina Overgaard Therkildsen

Associate professor of natural resources and the environment in the Cornell CALS Ashley School of Global Development and the Environment, and co-senior author of the study.

Maria Akopyan

Ph.D. '23, a former doctoral student in Therkildsen's lab and now a postdoctoral researcher at University of California, Riverside.

Hannes Baumann

Associate professor at the University of Connecticut and collaborator on the study.

David Conover

Emeritus professor at the University of Oregon and collaborator on the study.

Atlantic silversides

A small fish species that lives along the Atlantic coastline of the United States and has long been a model for studying natural selection and adaptation in the ocean.

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What they’re saying

“Each chromosomal inversion locks together a large set of genes, effectively forming a genetic switch with two states, flipped or not flipped. What's surprising here is that multiple 'switches' can combine to generate smooth, continuous variation, not just on-or-off differences.”

— Nina Overgaard Therkildsen, Associate professor (Science)

“The work is stunning in its complexity and comprehensiveness. Silversides, like many species, have several massive inversions on multiple chromosomes. The novelty of our study is that we show that these inversions contain vital genetic information for genes that determine growth, metabolism, vertebral number and lipid content.”

— Hannes Baumann, Associate professor (Science)

What’s next

The researchers plan to further investigate how the chromosomal inversions in Atlantic silversides and other mobile aquatic species allow them to rapidly adapt to changing environmental conditions, such as warming oceans.

The takeaway

This research provides important insights into the genetic mechanisms that enable certain species to quickly adapt to diverse habitats and environmental changes. The findings suggest that chromosomal inversions may play a critical role in maintaining local adaptation, which could shape how predictably populations respond as the climate continues to shift.