Abstract Detail

Hybrids and Hybridization

Ostevik, Kate [1], Rifkin, Joanna [2], Liao, Irene [3], Rausher, Mark [4].

Diverse mechanisms contribute to reproductive isolation between selfing and outcrossing morning glory species.

Highly selfing plants have repeatedly originated and diverged from outcrossing relatives. Reproductive isolation can arise between these pairs through diverse mechanisms, some of which are directly associated with their differences in mating systems. Here, we dissected two primary reproductive barriers – cross incompatibility and hybrid sterility – that occur between the highly selfing morning glory, Ipomoea lacunosa, and its mixed-mating sister species, I. cordatotriloba. We found that cross incompatibility is complex, with contributions acting before and after fertilization and exhibiting extensive asymmetry. Fertilization failure varied with the direction of the cross and was affected by pollen size and style length. In addition, fertilized ovules from interspecific crosses failed to mature, and cross direction affected hybrid seed provisioning. Genetic mapping of this crossing barrier revealed multiple factors with variable strengths that contribute to incompatibility between the species. Parental sex asymmetries were common, and imprinting of hybrid seed provisioning is likely critical. In contrast, hybrid pollen sterility was less complex and largely caused by two epistatically interacting loci. Our study highlights the role of multiple reproductive isolating mechanisms between outcrossing and selfing species, each of which may have independent evolutionary histories.

1 - UC Riverside, Department of Evolution, Ecology, and Organismal Biology, 3401 Watkins Dr, Riverside, CA, 92507, USA
2 - 25 Willlcocks St, Toronto, ON, M5S3B2, Canada
3 - UCLA, MCDB, 610 Charles E Young Dr East, 4018 TLSB Terasaki Life Sciences Building, Los Angeles, CA, 90095, United States
4 - Duke University, Department Of Biology, 137 BioSciences, Durham, NC, 27705, USA

Keywords:
speciation
Morning glory
Cross incompatibility
Hybrid sterility
QTL mapping.

Presentation Type: Oral Paper
Number: HH2003
Abstract ID:340
Candidate for Awards:None