Affiliation:
1. Department of Ecology and Evolutionary Biology, Tulane University, 6823 St Charles Avenue, New Orleans, LA 70118, USA
Abstract
Spatially and temporally varying selection can maintain genetic variation within and between populations, but it is less well known how these forces influence divergence between closely related species. We identify the interaction of temporal and spatial variation in selection and their role in either reinforcing or eroding divergence between two closely related
Mimulus
species. Using repeated reciprocal transplant experiments with advanced generation hybrids, we compare the strength of selection on quantitative traits involved in adaptation and reproductive isolation in
Mimulus guttatus
and
Mimulus laciniatus
between two years with dramatically different water availability
.
We found strong divergent habitat-mediated selection on traits in the direction of species differences during a drought in 2013, suggesting that spatially varying selection maintains species divergence. However, a relaxation in divergent selection on most traits in an unusually wet year (2019), including flowering time, which is involved in pre-zygotic isolation, suggests that temporal variation in selection may weaken species differences. Therefore, we find evidence that temporally and spatially varying selection may have opposing roles in mediating species boundaries. Given our changing climate, future growing seasons are expected to be more similar to the dry year, suggesting that in this system climate change may actually increase species divergence.
Funder
National Institute of General Medicinal Sciences of the National Institute of Health under Award
Tulane University Department of Ecology and Evolutionary Biology
Subject
General Agricultural and Biological Sciences,General Environmental Science,General Immunology and Microbiology,General Biochemistry, Genetics and Molecular Biology,General Medicine
Cited by
4 articles.
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