Contemporary patterns of genetic variation

Anadromous herrings

The spatial distribution of neutral genetic variation for most species reflects a complex mosaic of historical demographic factors associated with climatic change, microevolutionary process, and anthropogenic influences–the relative effects of which are often difficult to discern.


American shad, alewife and blueback herring are anadromous fishes with broad native distributions along the Atlantic coast of North America; spawning in rivers from Florida to Quebec. These species exhibit philopatry, leading to reproductive isolation among spawning runs, and the establishment of genetically distinguishable groups. Anadromous herrings are of increasing conservation concern, and knowledge of the spatial scale of population structure is a prerequisite to designating conservation units. My colleagues and I have resolved the spatial scale of genetic architecture for these species, and have explored the relative roles of historical demography, microevolutionary processes, anthropogenic factors, and intraspecific life history variation on the partitioning of neutral genetic variation.