Natural selection influences AFLP intraspecific genetic variability and introgression patterns in Atlantic eels

Area of Science:

• Evolutionary Biology
• Population Genetics
• Conservation Genetics

Background:

• Hybridizing species offer insights into natural selection's effects on genetic variation and gene flow.
• Atlantic eels (Anguilla rostrata and A. anguilla) inhabit diverse environments, potentially influencing their genetic makeup.
• Viable hybrids of these eel species are exclusively found in Iceland, prompting investigation into selection's role.

Purpose of the Study:

• To assess the influence of natural selection on genetic variation within and between Atlantic eel species.
• To investigate how selection may shape the distribution of hybrids in Iceland.
• To analyze population genomics and admixture data for evidence of non-neutral evolutionary mechanisms.

Main Methods:

• Revisiting amplified fragment length polymorphism (AFLP) data.
• Employing population genomics and admixture analyses.
• Testing for non-neutral mechanisms influencing genetic variation at intra- and interspecific levels.

Main Results:

• Identified candidate loci under directional selection within both Anguilla rostrata and A. anguilla.
• Observed spatial patterns of allele frequencies potentially linked to environmental gradients and life-history traits.
• Detected outlier loci indicating non-neutral introgression between species in Iceland.
• Found evidence of accelerated introgression at specific loci into A. anguilla, increasing with eel developmental stage.

Conclusions:

• Natural selection significantly influences genetic variation within Atlantic eel species and their hybridization dynamics.
• Differential survival of admixed genotypes contributes to the observed spatio-temporal patterns of hybrids in Iceland.
• These findings enhance understanding of evolutionary processes in hybrid zones and inform conservation strategies for migratory fish.