title: Extreme Environments Facilitate Hybrid Superiority - The Story of a Successful Daphnia galeata × longispina Hybrid Clone.
abstract: Hybridization within the animal kingdom has long been underestimated. Hybrids have often been considered less fit than their parental species. In the present study, we observed that the Daphnia community of a small lake was dominated by a single D. galeata × D. longispina hybrid clone, during two consecutive years. Notably, in artificial community set-ups consisting of several clones representing parental species and other hybrids, this hybrid clone took over within about ten generations. Neither the fitness assay conducted under different temperatures, or under crowded and non-crowded environments, nor the carrying capacity test revealed any outstanding life history parameters of this hybrid clone. However, under simulated winter conditions (i.e. low temperature, food and light), the hybrid clone eventually showed a higher survival probability and higher fecundity compared to parental species. Hybrid superiority in cold-adapted traits leading to an advantage of overwintering as parthenogenetic lineages might consequently explain the establishment of successful hybrids in natural communities of the D. longispina complex. In extreme cases, like the one reported here, a superior hybrid genotype might be the only clone alive after cold winters. Overall, superiority traits, such as enhanced overwintering here, might explain hybrid dominance in nature, especially in extreme and rapidly changing environments. Although any favoured gene complex in cyclic parthenogens could be frozen in successful clones independent of hybridization, we did not find similarly successful clones among parental species. We conclude that the emergence of the observed trait is linked to the production of novel recombined hybrid genotypes.
authors.affiliation: Department of Ecosystem Research, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany; Department of Biology II, Ludwig-Maximilian-University Munich, Planegg-Martinsried, Germany.
authors.forename: Johanna
authors.initials: J
authors.lastname: Griebel
authors.affiliation: Department of Biology II, Ludwig-Maximilian-University Munich, Planegg-Martinsried, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Gießler
authors.affiliation: Department of Biology II, Ludwig-Maximilian-University Munich, Planegg-Martinsried, Germany.
authors.forename: Monika
authors.initials: M
authors.lastname: Poxleitner
authors.affiliation: Department of Biology II, Ludwig-Maximilian-University Munich, Planegg-Martinsried, Germany.
authors.forename: Amanda
authors.initials: A
authors.lastname: Navas Faria
authors.affiliation: MOE Key Laboratory for Biodiversity Science and Ecological Engineering, School of Life Science, Fudan University, Shanghai, China.
authors.forename: Mingbo
authors.initials: M
authors.lastname: Yin
authors.affiliation: Department of Ecosystem Research, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany; Department of Biology, Chemistry, Pharmacy, Institute of Biology, Freie Universität Berlin, Berlin, Germany.
authors.forename: Justyna
authors.initials: J
authors.lastname: Wolinska
mesh_terms: D000818:Animals; D003080:Cold Temperature; D003441:Crowding; D003621:Daphnia / Q000502:physiology*; D005260:Female; D005298:Fertility; D006824:Hybridization, Genetic; D008297:Male; D012621:Seasons