In our new paper (published in PLoS genetics) I use patterns within and among founding haplotypes to learn about the the selfing plant, Capsella rubella.
Selfing plants reproduces predominantly by fertilizing their eggs with their own pollen. The ecological and evolutionary impacts of this mode of reproduction (including the impact of selfing on establishment, and invasions, the ”purging” of the genetic load, and the relaxation of intragenomic conflicts in a homozygous genome) are among the ideas that first got me super excited about science.
Because patterns of variation across the genome contain information about species’ history, population genomic data offers promise towards helping us understand these questions. Because selfing increases homozygosity and ultimately decreases the effective recombination rate, genomes of selfing plants consist of long chunks of ancestry (‘haplotypes’), only rarely broken up by ancestral recombination events. By finding contiguous regions of the genome where individuals are identical at sites polymorphic in the population ancestral to C. rubella, we identified long haplotypes representing long stretches of ancestry descended form a chromosome that founded this species. We used patterns of variation within and among these founding haplotypes to (1) learn how many individuals founded the species, (2) document an ‘out-of-Greece’ population bottleneck, (3) observe a relaxation in purifying selection since the origin of selfing and and (4) find a remarkably stable population size in Greece over the last ~ 10k years.
for more read our paper