Abstract Detail

Hybrids and Hybridization

Villa-Machío, Irene [1], Heuertz, Myriam [2], Álvarez, Inés [1], Nieto Feliner, Gonzalo [1].

Demography-driven vs. adaptive introgression in hybridizing species of the Armeria syngameon.

Syngameons represent networks of otherwise distinct species interconnected by limited gene exchange. Although most studies have focused on how species maintain their identities despite gene flow in these networks, there are additional relevant questions regarding the evolutionary dynamics of syngameons and their drivers, as well as the success of their members and the whole network. Using a ddRADseq approach, we analyzed the genetic structure, genomic clines and demographic history of a coastal hybrid zone involving two species of the Armeria (Plumbaginaceae) syngameon in Southern Spain. We inferred that one peripheral population of the sand dune-adapted A. pungens experienced genetic drift after a founder event and was subsequently introgressed by a local more abundant pinewood congener, A. macrophylla. This led to A. pungens capturing A. macrophylla plastid in the whole hybrid zone. Despite this, genomic cline analysis identified bidirectional introgression, but more outliers with an excess ancestry of A. pungens than of A. macrophylla, which suggests A. pungens alleles are being selected for in the hybrid zone. This is consistent with the findings that phenotype was associated to habitat so that the A. pungens-phenotype is selected for open habitats. This scenario implies that bidirectional introgression may be useful for the two hybridizing species. On the one hand, it is driven by demographic forces towards the range-edge bottlenecked population of A. pungens, which reduces its risk of stochastic extinction and increases its evolutionary potential as a novel hybrid lineage. On the other hand, introgression towards A. macrophylla is driven by selection of alleles with A. pungens ancestry, which enable individuals to grow in open highly-irradiated habitats.

1 - Real Jardín Botánico, CSIC, Claudio Moyano, 1, Madrid, M, 28014, Spain
2 - Biogeco, Inrae, Univ. Bordeaux, Inrae UMR BIOGECO 1202, 69 route d'Arcachon, CS 80227, Cestas, 33612, France

Keywords:
syngameon
hybrid zone
bidirectional introgression
adaptive introgression
Demographic history
Armeria (Plumbaginaceae).

Presentation Type: Oral Paper
Number: HH1005
Abstract ID:1027
Candidate for Awards:Margaret Menzel Award