title: Genetic differentiation and selection against migrants in evolutionarily replicated extreme environments.
abstract: We investigated mechanisms of reproductive isolation in livebearing fishes (genus Poecilia) inhabiting sulfidic and nonsulfidic habitats in three replicate river drainages. Although sulfide spring fish convergently evolved divergent phenotypes, it was unclear if mechanisms of reproductive isolation also evolved convergently. Using microsatellites, we found strongly reduced gene flow between adjacent populations from different habitat types, suggesting that local adaptation to sulfidic habitats repeatedly caused the emergence of reproductive isolation. Reciprocal translocation experiments indicate strong selection against immigrants into sulfidic waters, but also variation among drainages in the strength of selection against immigrants into nonsulfidic waters. Mate choice experiments revealed the evolution of assortative mating preferences in females from nonsulfidic but not from sulfidic habitats. The inferred strength of sexual selection against immigrants (RI(s)) was negatively correlated with the strength of natural selection (RI(m)), a pattern that could be attributed to reinforcement, whereby natural selection strengthens behavioral isolation due to reduced hybrid fitness. Overall, reproductive isolation and genetic differentiation appear to be replicated and direct consequences of local adaptation to sulfide spring environments, but the relative contributions of different mechanisms of reproductive isolation vary across these evolutionarily independent replicates, highlighting both convergent and nonconvergent evolutionary trajectories of populations in each drainage.
authors.affiliation: J. W. Goethe-University Frankfurt/M., Evolutionary Ecology Group, Max-von-Laue Str. 13, 60438, Frankfurt, a. M., Germany. mplath@bio.uni-frankfurt.de.
authors.forename: Martin
authors.initials: M
authors.lastname: Plath
authors.forename: Markus
authors.initials: M
authors.lastname: Pfenninger
authors.forename: Hannes
authors.initials: H
authors.lastname: Lerp
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Riesch
authors.forename: Christoph
authors.initials: C
authors.lastname: Eschenbrenner
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Slattery
authors.forename: David
authors.initials: D
authors.lastname: Bierbach
authors.forename: Nina
authors.initials: N
authors.lastname: Herrmann
authors.forename: Matthias
authors.initials: M
authors.lastname: Schulte
authors.forename: Lenin
authors.initials: L
authors.lastname: Arias-Rodriguez
authors.forename: Jeane
authors.initials: J
authors.lastname: Rimber Indy
authors.forename: Courtney
authors.initials: C
authors.lastname: Passow
authors.forename: Michael
authors.initials: M
authors.lastname: Tobler
mesh_terms: D000222:Adaptation, Physiological; D025041:Animal Migration; D000818:Animals; D017753:Ecosystem; D004777:Environment; D019143:Evolution, Molecular; D005260:Female; D056084:Genetic Fitness; D008297:Male; D052586:Mating Preference, Animal; D018895:Microsatellite Repeats / Q000235:genetics; D060985:Natural Springs / Q000737:chemistry; D011036:Poecilia / Q000235:genetics; D060047:Reproductive Isolation; D045483:Rivers; D012641:Selection, Genetic; D013440:Sulfides
chemical_list: D013440:Sulfides
keywords: Ecological speciation; Poecilia mexicana; isolation-by-adaptation; local adaptation; reinforcement; sexual isolation