title: The contribution of post-copulatory mechanisms to incipient ecological speciation in sticklebacks.
abstract: Ecology can play a major role in species diversification. As individuals are adapting to contrasting habitats, reproductive barriers may evolve at multiple levels. While pre-mating barriers have been extensively studied, the evolution of post-mating reproductive isolation during early stages of ecological speciation remains poorly understood. In diverging three-spined stickleback ecotypes from two lakes and two rivers, we observed differences in sperm traits between lake and river males. Interestingly, these differences did not translate into ecotype-specific gamete precedence for sympatric males in competitive in vitro fertilization experiments, potentially owing to antagonistic compensatory effects. However, we observed indirect evidence for impeded development of inter-ecotype zygotes, possibly suggesting an early stage of genetic incompatibility between ecotypes. Our results show that pre-zygotic post-copulatory mechanisms play a minor role during this first stage of ecotype divergence, but suggest that genetic incompatibilities may arise at early stages of ecological speciation.
authors.affiliation: Department of Evolutionary Ecology, Max Planck Institute for Evolutionary Biology, Plön, Germany kaufmann@evolbio.mpg.de.
authors.forename: Joshka
authors.identifier: http://orcid.org/0000-0002-7850-3500
authors.initials: J
authors.lastname: Kaufmann
authors.affiliation: GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany School of Biological and Chemical Sciences, Queen Mary University of London, London, UK.
authors.forename: Christophe
authors.initials: C
authors.lastname: Eizaguirre
authors.affiliation: Department of Evolutionary Ecology, Max Planck Institute for Evolutionary Biology, Plön, Germany.
authors.forename: Manfred
authors.initials: M
authors.lastname: Milinski
authors.affiliation: Department of Evolutionary Ecology, Max Planck Institute for Evolutionary Biology, Plön, Germany.
authors.forename: Tobias L
authors.initials: TL
authors.lastname: Lenz
mesh_terms: D000818:Animals; D017753:Ecosystem; D060146:Ecotype; D005260:Female; D049810:Genetic Speciation; D005858:Germany; D008297:Male; D060047:Reproductive Isolation; D023701:Smegmamorpha / Q000235:genetics*; D013094:Spermatozoa / Q000502:physiology
keywords: Gasterosteus aculeatus; ecological speciation; ecotype; fertilization success; gamete precedence