Abstract Detail

Hybrids and Hybridization

Bog, Manuela [1], Heine, Gabriel [1], Bässler, Claus [2], Oberprieler, Christoph [3].

Farewell to diversity: population genomic analyses along elevational transects through a hybrid zone of Senecio hercynicus and S. ovatus (Compositae, Senecioneae) indicate the irreversible merging of the two speci.

Senecio hercynicus and S. ovatus are two central European representatives of the S. nemorensis group showing vertical vicariance, with S. hercynicus growing in montane to subalpine regions and S. ovatus growing in colline to montane environments. Although the species show differences in their flowering time, natural hybridisation is a common phenomenon and leads to introgressive hybrid swarms. We have used a population genomic approach to (a) infer the intensity of hybridisation in a hybrid zone along elevational transects in the Bavarian Forest National Park and (b) to determine whether there are hints for the acting of a reinforcement process that may lead to the completion of the speciation process through the selection against maladaptive hybrid genotypes. Using AFLP fingerprinting, 689 individuals from 38 populations of the two species along four elevational transects (ca. 650-1350 m) in the Bavarian Forest National Park were genotyped for 618 anonymous loci. Based on Bayesian cluster algorithms implemented in Structure (Falush et al. 2007) and NewHybrids (Anderson & Thompson 2002), all populations were identified as being hybrid swarms with different admixture proportions of both parental genotypes, indicating the intense introgressive hybridisation realised in this hybrid zone. To check for a reinforcement process in action, we searched for loci under selection by using either FST-based (BayeScan v2.1, Foll 2012) or logistic regression model-based techniques (MatSAM v1, Joost et al. 2007). As results, we identified four AFLP markers under selection, which showed a significant correlation with some environmental variables along the transects. Furthermore, two of these loci under selection turned out to be species-specific. The low number of species-specific markers under selection compared to the high number of neutrally evolving ones makes it quite questionable that a reinforcement mechanism is acting, which is strong enough for an enforcement of prezygotic barriers (e.g., flowering-time differences) that would allow the two species to escape their eventual merging.

Broader Impacts:

1 - University of Regensburg, Institute of Botany, Universitätsstr. 31, Regensburg, D-93040, Germany
2 - Bavarian Forest National Park, Freyunger Str. 2, Grafenau, D-94481, Germany
3 - Institute Of Botany, University Of Regensburg, Universitätsstr. 31, Regensburg, N/A, D-93040, Germany

Keywords:
hybridization
conservation
Genetics
ecology
reinforcement.

Presentation Type: Poster:Posters for Topics
Session: P
Location: Grand Salon A - D/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 5:30 PM
Number: PHB001
Abstract ID:365
Candidate for Awards:Genetics Section Poster Award