Tidepool Copepod

Genetic basis of Hybrid Breakdown

In Tigriopus, like in many other organisms, hybridization between populations typically results in hybrid vigor in the first generation (F1), and hybrid breakdown in the second generation (F2)(e.g. Edmands 1999).

We are using quantitative genetic methods to look at the genetic architecture underlying these fitness effects. We are also using marker-based methods to hone in on gene regions contributing to hybrid breakdown. Segregation ratios for mapped loci in interpopulation hybrids are being used to infer gene interactions. Non-recombinant crosses are used to test the effects of whole chromosomes (Harrison & Edmands 2006), while recombinant crosses are used to test for interactions within chromosomes (Edmands et al., in prep). Work to date shows many chromosomes contributing to hybrid breakdown, with surprising concordance between different interpopulation crosses.

Understanding the genetic basis of hybrid breakdown is important both for basic knowledge of the speciation process, and for conservation issues involving accidental and intentional mixing between divergent populations.