32 Oral - Platform Session #3 Speciation, Hybridization, and Introgression
Thursday June 09, 10:35 AM - 10:50 AM

Authors:
Paul Blischak; Mathews Sajan; Michael Barker; Ryan Gutenkunst

Affiliation: University of Arizona, Tucson, AZ

Keywords:
Theory & Method Development

Polyploidy is an important generator of evolutionary novelty, occurring within a single lineage (autopolyploidy) or by hybridization between different lineages (allopolyploidy). Historically, these scenarios have been treated as completely separate cases based on chromosome pairing, with autopolyploids pairing among all homologous chromosomes and allopolyploids pairing only among chromosomes from the same parent lineage. But if they are similar enough, chromosomes from distinct lineages may pair and thus alleles may be exchanged between subgenomes. Quantitatively inferring demographic history and rates of subgenomic exchange within polyploids may shed light on the evolutionary history of key species, including many crops. We thus developed diffusion models for genetic variation in polyploids with variable inheritance patterns and implemented them in the dadi software. We used SLiM simulations to validate our models and test their inference properties, focusing on the case in which reads from two subgenomes cannot by distinguished bioinformatically. We then applied these models to infer demographic history and subgenome exchange for shepherd's purse (Capsella bursa-pastoris), a recently formed allotetraploid, to investigate the timing and impact of hybridization and genome duplication.