Analysis of Stickleback Genome Sequence Catches Evolution in Action

In HHMI, David Kingsley and his team at Stanford School of Medicine have recently published their investigations on the genome sequence of stickleback fish and how both genome sequence as well as gene expression change over time as the species adapts to environmental changes.

Marine sticklebacks are normally found in salt water, but as glaciers melted during the last ice age 10,000 to 20,000 years ago, many sticklebacks found themselves in fresh water.  Such dramatic environmental changes became settings for evolutionary changes, and fresh-water sticklebacks were naturally selected to survive to their new conditions in ways that make sense physiologically.  For instance, their natural armor became softer to help escape predators and their osmoregulation adapted to the fresh-water environment.

As scientists sequence the genome of both fresh-water and marine-water sticklebacks, they have found that 147 'reused' regions of the fish's genome are responsible for the variations found.  Intriguingly, these genes not only account for phenotypic variations [such as softer armor] but also subtle genetic changes in cell metabolics, developmental signaling, and behavioral interactions between animals.  These changes, such as the ones found in the WNT family that helps stickleback's osmoregulation in fresh water, must work in concert in order to produce functional changes that increase survival.

The study of evolutionary changes through genome sequencing also have allowed scientists to make determinations on what changes are genomic mutations and what changes are gene regulation and how the two are related.

[caption id="attachment_4269" align="aligncenter" width="353" caption="The Stickleback."][/caption]