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Environmentally independent selection for hybrids between divergent freshwater stickleback lineages in semi-natural ponds |
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| Authors: | Cameron Marshall Hudson Maria Cuenca Cambronero Marvin Moosmann Anita Narwani Piet Spaak Ole Seehausen Blake Matthews |
| Institution: | 1. Department of Fish Ecology and Evolution, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Center of Ecology, Evolution and Biochemistry, Lucerne, Switzerland;2. Department of Fish Ecology and Evolution, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Center of Ecology, Evolution and Biochemistry, Lucerne, Switzerland
Aquatic Ecology Group, University of Vic, Central University of Catalonia, Vic, Spain Contribution: Conceptualization (equal), Methodology (equal), Resources (equal), Validation (equal), Writing - review & editing (equal);3. Department of Fish Ecology and Evolution, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Center of Ecology, Evolution and Biochemistry, Lucerne, Switzerland Division of Aquatic Ecology and Evolution, Institute of Ecology and Evolution, University of Bern, Bern, Switzerland Contribution: Conceptualization (equal), Methodology (equal), Resources (equal), Visualization (equal), Writing - review & editing (equal);4. Department of Aquatic Ecology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Zürich, Switzerland Contribution: Conceptualization (equal), Methodology (equal), Resources (equal), Writing - review & editing (equal);5. Department of Aquatic Ecology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Zürich, Switzerland Contribution: Conceptualization (equal), Funding acquisition (equal), Project administration (equal), Resources (equal), Writing - review & editing (equal);6. Department of Fish Ecology and Evolution, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Center of Ecology, Evolution and Biochemistry, Lucerne, Switzerland Division of Aquatic Ecology and Evolution, Institute of Ecology and Evolution, University of Bern, Bern, Switzerland Contribution: Conceptualization (equal), Funding acquisition (equal), Project administration (equal), Supervision (equal), Writing - review & editing (equal);7. Department of Fish Ecology and Evolution, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Center of Ecology, Evolution and Biochemistry, Lucerne, Switzerland Contribution: Conceptualization (equal), Funding acquisition (equal), Methodology (equal), Project administration (equal), Supervision (equal), Validation (equal), Visualization (equal), Writing - original draft (equal), Writing - review & editing (equal) |
| Abstract: | Hybridization following secondary contact of genetically divergent populations can influence the range expansion of invasive species, though specific outcomes depend on the environmental dependence of hybrid fitness. Here, using two genetically and ecologically divergent threespine stickleback lineages that differ in their history of freshwater colonization, we estimate fitness variation of parental lineages and hybrids in semi-natural freshwater ponds with contrasting histories of nutrient loading. In our experiment, we found that fish from the older freshwater lineage (Lake Geneva) and hybrids outperformed fish from the younger freshwater lineage (Lake Constance) in terms of both growth and survival, regardless of the environmental context of our ponds. Across all ponds, hybrids exhibited the highest survival. Although wild-caught adult populations differed in their functional and defence morphology, it is unclear which of these traits underlie the fitness differences observed among juveniles in our experiment. Overall, our work suggests that when hybrid fitness is insensitive to environmental conditions, as observed here, introgression may promote population expansion into unoccupied habitats and accelerate invasion success. |
| Keywords: | adaptation hybridization invasive species threespine stickleback |