Comparing genome scans among species of the stickleback order reveals
three different patterns of genetic diversity
Abstract
Comparing genome scans among species is a powerful approach for
investigating the patterns left by evolutionary processes. In
particular, this offers a way to detect candidate genes that drive
convergent evolution. We compared genome scan results to investigate if
patterns of genetic diversity and divergence are shared among divergent
species within the stickleback order (Gasterosteiformes): the threespine
stickleback (Gasterosteus aculeatus), ninespine stickleback (Pungitius
pungitus) and tubesnout (Aulorhynchus flavidus). Populations were
sampled from the southern and northern edges of each species’ range, to
identify patterns associated with latitudinal changes in genetic
diversity. Weak correlations in genetic diversity (FST
and expected heterozygosity) and three different patterns in the genomic
landscape were found among these species. Additionally, no candidate
genes for convergent evolution were detected. This is a counterexample
to the growing number of studies that have shown overlapping genetic
patterns, demonstrating that genome scan comparisons can be noisy due to
the effects of several interacting evolutionary forces.