Hybrid Incompatibility

Hybrid incompatibility is the reduced viability or fertility of offspring from between-species crosses. Incompatibility is caused by genetic fixations in diverging lineages. How can these genes that cause reduced offspring fitness evolve?

Using genetic trait mapping, we study the genetic basis of hybrid male and female sterility between species to:

• identify genes that cause hybrid inviability and sterility (and other ecologically important traits),

• understand the evolutionary forces that act on these genes.

Comparative genomics of hybrid incompatability

We are mapping hybrid male and female sterility in crosses among species in the plant group Lycopersicon. Comparing QTL between multiple, closely-related species pairs allows us to identify general patterns in the evolution of reproductive barriers.

• Are the same genetic changes, classes of genes, or regions of the genome, repeatedly involved in hybrid incompatibility?

• How do sterility loci accumulate over increasing evolutionary divergence?

Epistasis between sterility factors

Interactions among different incompatability loci can affect how rapidly new species evolve. We are using 'double introgression lines' to test whether individual sterility loci act additively, synergistically, or antagonistically when combined together in a common genetic background.

Identifying and cloning sterility loci

Using fine-scale genetic mapping in our current populations, we aim to identify and isolate individual genes responsible for hybrid sterility (so-called ‘speciation genes’). In complementary research, we are also taking a candidate gene approach to examine the molecular population genetics of loci involved in early embryonic and seed development.

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