title: Experimental Evidence for the Negative Effects of Self-Fertilization on the Adaptive Potential of Populations.
abstract: Self-fertilization is widely believed to be an "evolutionary dead end" [1, 2], increasing the risk of extinction [3] and the accumulation of deleterious mutations in genomes [4]. Strikingly, while the failure to adapt has always been central to the dead-end hypothesis [1, 2], there are no quantitative genetic selection experiments comparing the response to positive selection in selfing versus outcrossing populations. Here we studied the response to selection on a morphological trait in laboratory populations of a hermaphroditic, self-fertile snail under either selfing or outcrossing. We applied both treatments to two types of populations: some having undergone frequent selfing and purged a substantial fraction of their mutation load in their recent history [5], and others continuously maintained under outcrossing. Populations with a history of outcrossing respond faster to selection than those that have experienced selfing. In addition, when self-fertilization occurs during selection, the response is initially fast but then rapidly slows, while outcrossing populations maintain their response throughout the experiment. This occurs irrespective of past selfing history, suggesting that high levels of inbreeding depression, contrary to expectation [6], do not set strong limits to the response to selection under inbreeding, at least at the timescale of a few generations. More surprisingly, phenotypic variance is consistently higher under selfing, although it quickly becomes less responsive to selection. This implies an increase in non-heritable variance, hence a breakdown of developmental canalization [7] under selfing. Our findings provide the first empirical support of the short-term positive and long-term negative effects of selfing on adaptive potential.
authors.affiliation: Centre d'Ecologie Fonctionnelle et Evolutive (CEFE), UMR 5175, CNRS - Université de Montpellier - Université Paul Valéry Montpellier - EPHE, 1919 Route de Mende, 34293 Montpellier Cedex 5, France. Electronic address: elsacnoel@gmail.com.
authors.forename: Elsa
authors.initials: E
authors.lastname: Noël
authors.affiliation: Centre d'Ecologie Fonctionnelle et Evolutive (CEFE), UMR 5175, CNRS - Université de Montpellier - Université Paul Valéry Montpellier - EPHE, 1919 Route de Mende, 34293 Montpellier Cedex 5, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Jarne
authors.affiliation: Institut des Sciences de l'Evolution (ISEM - UMR 5554 Université de Montpellier - CNRS-IRD-EPHE), CC64, Place Eugène Bataillon, 34095 Montpellier Cedex, France; Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, 75236 Uppsala, Sweden.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Glémin
authors.affiliation: Centre d'Ecologie Fonctionnelle et Evolutive (CEFE), UMR 5175, CNRS - Université de Montpellier - Université Paul Valéry Montpellier - EPHE, 1919 Route de Mende, 34293 Montpellier Cedex 5, France.
authors.forename: Alicia
authors.initials: A
authors.lastname: MacKenzie
authors.affiliation: Centre d'Ecologie Fonctionnelle et Evolutive (CEFE), UMR 5175, CNRS - Université de Montpellier - Université Paul Valéry Montpellier - EPHE, 1919 Route de Mende, 34293 Montpellier Cedex 5, France.
authors.forename: Adeline
authors.initials: A
authors.lastname: Segard
authors.affiliation: Centre d'Ecologie Fonctionnelle et Evolutive (CEFE), UMR 5175, CNRS - Université de Montpellier - Université Paul Valéry Montpellier - EPHE, 1919 Route de Mende, 34293 Montpellier Cedex 5, France.
authors.forename: Violette
authors.initials: V
authors.lastname: Sarda
authors.affiliation: Centre d'Ecologie Fonctionnelle et Evolutive (CEFE), UMR 5175, CNRS - Université de Montpellier - Université Paul Valéry Montpellier - EPHE, 1919 Route de Mende, 34293 Montpellier Cedex 5, France.
authors.forename: Patrice
authors.initials: P
authors.lastname: David
mesh_terms: D000818:Animals; D005075:Biological Evolution; D005828:Genetics, Population; D000071422:Inbreeding Depression; D009154:Mutation; D012641:Selection, Genetic; D057945:Self-Fertilization; D012908:Snails / Q000235:genetics / Q000502:physiology*
keywords: Physa acuta; adaptation; adaptive potential; experimental evolution; inbreeding depression; purging; self-fertilization