Abstract Detail



Hybrids and Hybridization

Feliner, Gonzalo N. [1], Alvarez, Ines [1], Heuertz, Myriam [2], Villa-Machío, Irene [1].

Asymmetric introgressive hybridization in a peripheral population of Armeria pungens (Plumbaginaceae).

Introgressive hybridization and related issues, such as the drivers of evolution of introgressed blocks, remain poorly understood in most angiosperms despite good evidence from a few organisms that introgressive hybridization can facilitate adaptation and even trigger speciation. Armeria (Plumbaginaceae) is a primarily Mediterranean genus with low pre- and postzygotic reproductive isolation, in which a number of taxa have been proposed to be of hybrid origin. The southernmost population of a coastal sand-dune Iberian-Corsica-Sardinian species (A. pungens) was identified to be introgressed by a sympatric congener (A. macrophylla) based on nrDNA ITS and plastid DNA Sanger sequences, morphometric data, genome size variation and ecological niche.    To determine the genetic structure of this introgressed population, infer its origin and examine how such a recent or ongoing hybridization event fits the overall hybridization patterns across the genus, we have undertaken a genomic study based on genotyping-by-sequencing (GBS) data. Preliminary results indicate that introgression is asymmetric and thus confirm that A. pungens is extensively introgressed in contrast to A. macrophylla. Also, introgressed samples span a large space in a PCA of the GBS data, suggesting a wide variability for introgressed genotypes probably including late generation hybrids and introgressants. The most likely interpretation is that extensive introgression of A. macrophylla into A. pungens originated with a few immigrants of the latter species that predominantly hybridized with local congeners of A. macrophylla instead of conspecifics, facilitated by their strict incompatibility system. This situation probably led to plastid capture and extensive asymmetric nuclear introgression. Such a scenario fits simulation studies by Currat et al. (2008) who predicted predominant introgression of invaders by local endemics. These results are compatible with the largely geographic pattern of variation detected in the genus years ago for ITS sequences, but adds an additional cause for such a pattern ―population dynamics in peripheral populations, characterized by reduced densities― to the molecular-based cause initially proposed ―biased homogenization of sequences from these multicopy regions.   


1 - Real Jardin Botanico, Biodiversity and Conservation, Plaza de Murillo 2, Madrid, 28014, Spain
2 - INRA UMR1202 Biogeco, Cestas (Bordeaux), France

Keywords:
introgressive hybridization
GBS
genomics
plastid capture
Armeria (Plumbaginaceae)
Iberian Peninsula.

Presentation Type: Oral Paper
Number: 0005
Abstract ID:725
Candidate for Awards:Margaret Menzel Award


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