title: High gene flow between alternative morphs and the evolutionary persistence of facultative paedomorphosis.
abstract: Paedomorphosis and metamorphosis are two major developmental processes that characterize the evolution of complex life cycles in many lineages. Whereas these processes were fixed in some taxa, they remained facultative in others, with alternative phenotypes expressed in the same populations. From a genetic perspective, it is still unknown whether such phenotypes form a single population or whether they show some patterns of isolation in syntopy. This has deep implications for understanding the evolution of the phenotypes, i.e. towards their persistence or their fixation and speciation. Newts and salamanders are excellent models to test this hypothesis because they exhibit both developmental processes in their populations: the aquatic paedomorphs retain gills, whereas the metamorphs are able to colonize land. Using microsatellite data of coexisting paedomorphic and metamorphic palmate newts (Lissotriton helveticus), we found that they formed a panmictic population, which evidences sexual compatibility between the two phenotypes. The high gene flow could be understood as an adaptation to unstable habitats in which phenotypic plasticity is favored over the fixation of developmental alternatives. This makes then possible the persistence of a polyphenism: only metamorphosis could be maintained in case of occasional drying whereas paedomorphosis could offer specific advantages in organisms remaining in water.
authors.affiliation: Laboratory of Fish and Amphibian Ethology, Behavioural Biology Unit, Freshwater and Oceanic Science Unit of Research (FOCUS), University of Liège, 22 Quai van Beneden, 4020 Liège, Belgium.
authors.forename: Neus
authors.initials: N
authors.lastname: Oromi
authors.affiliation: Conservation Genetics, University of Liège, Institute of Botany (Bat. 22), 2 Chemin de la Vallée, 4000 Liège, Belgium.
authors.forename: Johan
authors.initials: J
authors.lastname: Michaux
authors.affiliation: Laboratory of Fish and Amphibian Ethology, Behavioural Biology Unit, Freshwater and Oceanic Science Unit of Research (FOCUS), University of Liège, 22 Quai van Beneden, 4020 Liège, Belgium.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Denoël
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D005075:Biological Evolution; D004247:DNA / Q000032:analysis / Q000378:metabolism; D017753:Ecosystem; D051456:Gene Flow / Q000502:physiology*; D014644:Genetic Variation; D005838:Genotype; D008675:Metamorphosis, Biological; D018895:Microsatellite Repeats / Q000235:genetics; D010641:Phenotype; D016133:Polymerase Chain Reaction; D012455:Salamandridae / Q000235:genetics*; D014562:Caudata / Q000235:genetics*
chemical_list: D004247:DNA