Abstract Detail

Population Genetics/Genomics

Sutherland, Brittany [1], Galloway, Laura [1].

Interploid reproductive isolation differs with cytotype in mixed-ploidy contact zones.

Whole genome duplication often confers reproductive isolation between polyploids and their diploid progenitors. However, evidence suggests that reproductive isolation may be weaker among higher-order cytotypes than between diploids and tetraploids. If the magnitude of reproductive isolation varies with parental ploidy, related cytotypes may show different patterns of interploid reproduction and gene flow when occurring in sympatry. We assessed interploid reproductive isolation and gene flow in four mixed-ploidy contact zones throughout the distribution of the Campanula rotundifolia polyploid complex. We sampled leaf tissue from 30-125 individuals in each of two diploid-tetraploid contact zones, and two tetraploid-hexaploid contact zones. Each individual sampled was cytotyped via flow cytometry, and genotyped using microsatellite markers. In the diploid-tetraploid contact zones, only diploid and tetraploid individuals were recovered. However, in the tetraploid-hexaploid contact zones, pentaploid plants accounted for 35-42% percent of all sampled individuals, indicating that interploid reproduction was common between tetraploid and hexaploid populations. Furthermore, substantial genome size variation occurred between pentaploids and hexaploids, suggesting that backcrossing may be occurring between pentaploid hybrids and hexaploid parents. Microsatellite data confirmed little to no gene flow between diploid and tetraploid cytotypes, but suggested significant introgression between tetraploids and hexaploids. The marked difference in both cytotypic distribution and population structure in these two classes of interploid contact zones suggest that reproductive isolation is reduced in higher-order polyploids and may be permitting more gene flow among polyploids than between diploids and polyploids. The presence of disparate patterns of gene flow within a polyploid complex suggests that divergence may be ploidy-specific, with greater divergence over time between diploids and polyploids than among polyploids.

1 - University of Virginia, Biology, 229 Gilmer Hall, 485 McCormick Road, P.O. Box 400328, Charlottesville, VA, 22903, USA

Keywords:
Polyploidy
Polyploid Complex
Contact Zone
gene flow
Reproductive isolation.

Presentation Type: Oral Paper
Session: 40, Population Genetics/Genomics
Location: Sundance 5/Omni Hotel
Date: Wednesday, June 28th, 2017
Time: 2:45 PM
Number: 40006
Abstract ID:341
Candidate for Awards:Margaret Menzel Award