My current postdoctoral work, with Stephen Wright and Marc Johnson at the University of Toronto, examines the evolutionary consequences of the repeated evolution of functional asexuality in the plant genus Oenothera. The ancestral state of this genus is sexual reproduction (outcrossing), however, ~30% of species have evolved a form of functional asexuality called Permanent Translocation Heterozygosity (PTH; see figure).
I have been working with a large RNAseq dataset from 30 Oenothera species, including within-species sampling, that encompasses 10 transitions between sexual reproduction and PTH (functional asexuality). I am exploring Oenothera genomic diversity utilizing both phylogenomic (macro-evolutionary) and population genomic (micro-evolutionary) approaches. Current and future research plans include the following questions:
1. Does asexual reproduction reduce the efficacy of purifying selection on non-synonymous (amino-acid changing) mutations? (The answer is yes!)
2. How do the timescales over which PTH has evolved compare with speciation times among sexual/PTH pairs? Was speciation concurrent with the evolution of PTH? Did PTH evolve by inter-specific hybridization, or within-species fixation of structural heterozygosity?
3. How do reciprocal translocations evolve within Oenothera populations? What are the population and molecular genetic factors underlying the high rate of translocations in this genus? How do the genes controlling crossing over and chromosome segregation differ among Oenothera species, and among genera in the Onagraceae?