title: Evaluating the adaptive potential of the European eel: is the immunogenetic status recovering?
abstract: The recent increased integration of evolutionary theory into conservation programs has greatly improved our ability to protect endangered species. A common application of such theory links population dynamics and indices of genetic diversity, usually estimated from neutrally evolving markers. However, some studies have suggested that highly polymorphic adaptive genes, such as the immune genes of the Major Histocompatibility Complex (MHC), might be more sensitive to fluctuations in population dynamics. As such, the combination of neutrally- and adaptively-evolving genes may be informative in populations where reductions in abundance have been documented. The European eel (Anguilla anguilla) underwent a drastic and well-reported decline in abundance in the late 20th century and still displays low recruitment. Here we compared genetic diversity indices estimated from neutral (mitochondrial DNA and microsatellites) and adaptive markers (MHC) between two distinct generations of European eels. Our results revealed a clear discrepancy between signatures obtained for each class of markers. Although mtDNA and microsatellites showed no changes in diversity between the older and the younger generations, MHC diversity revealed a contemporary drop followed by a recent increase. Our results suggest ongoing gain of MHC genetic diversity resulting from the interplay between drift and selection and ultimately increasing the adaptive potential of the species.
authors.affiliation: Evolutionary Ecology of Marine Fishes, GEOMAR Helmholtz Centre for Ocean Research Kiel , Kiel , Germany.
authors.forename: Miguel
authors.initials: M
authors.lastname: Baltazar-Soares
authors.affiliation: Evolutionary Ecology of Marine Fishes, GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany; Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany.
authors.forename: Seraina E
authors.initials: SE
authors.lastname: Bracamonte
authors.affiliation: Evolutionary Ecology of Marine Fishes, GEOMAR Helmholtz Centre for Ocean Research Kiel , Kiel , Germany.
authors.forename: Till
authors.initials: T
authors.lastname: Bayer
authors.affiliation: Department of Biology, McGill University , Montréal Québec , Canada.
authors.forename: Frédéric J J
authors.initials: FJ
authors.lastname: Chain
authors.affiliation: Thünen-Institute of Fisheries Ecology , Hamburg , Germany.
authors.forename: Reinhold
authors.initials: R
authors.lastname: Hanel
authors.affiliation: Universidad de Antofagasta, Instituto de Ciencias Naturales Alexander von Humboldt , Antofagasta , Chile.
authors.forename: Chris
authors.initials: C
authors.lastname: Harrod
authors.affiliation: School of Biological and Chemical Sciences, Queen Mary University of London , London , United Kingdom.
authors.forename: Christophe
authors.initials: C
authors.lastname: Eizaguirre
keywords: Adaptive potential; European eel; Major Histocompatibility Complex; Population dynamics; Temporal analyses