Reproductive isolation is necessary for population divergence to lead to the formation of separate species. This can occur due to physical isolation of populations, which drives allopatric speciation, or other methods of isolation, such as sympatric speciation where the diverging species are physically in the same range, but structural genomic changes or mutations cause the population to diverge into two different species. Parapatric speciation occurs when populations that are geographically adjacent to each other diverge, which can be driven by adaptations to environmental differences, even with ongoing gene flow. Two desert- adapted brittlebush species, Encelia farinosa and Encelia californica, diverged less than 1 million years ago (Singhal et al., 2020) and have a parapatric distribution, residing in different environments in the Mojave and Sonoran deserts. Encelia farinosa (Brittlebush) has unique silvery leaves that are covered in tiny hairs (leaf pubescence) to better control leaf temperature in the hot and arid conditions of the Sonoran Desert. Encelia californica (California Brittlebush) does not display leaf pubescence and is found in a smaller region of the Mediterranean-like environment of the west coast of North America. Encelia californica is exposed to more precipitation than most other Encelia species. Even with their different morphologies, thesemore »
Landscape Genomics Provides Evidence of Ecotypic Adaptation and a Barrier to Gene Flow at Treeline for the Arctic Foundation Species Eriophorum vaginatum
Global climate change has resulted in geographic range shifts of flora and fauna at a global scale. Extreme environments, like the Arctic, are seeing some of the most pronounced changes. This region covers 14% of the Earth’s land area, and while many arctic species are widespread, understanding ecotypic variation at the genomic level will be important for elucidating how range shifts will affect ecological processes. Tussock cottongrass ( Eriophorum vaginatum L.) is a foundation species of the moist acidic tundra, whose potential decline due to competition from shrubs may affect ecosystem stability in the Arctic. We used double-digest Restriction Site-Associated DNA sequencing to identify genomic variation in 273 individuals of E. vaginatum from 17 sites along a latitudinal gradient in north central Alaska. These sites have been part of 30 + years of ecological research and are inclusive of a region that was part of the Beringian refugium. The data analyses included genomic population structure, demographic models, and genotype by environment association. Genome-wide SNP investigation revealed environmentally associated variation and population structure across the sampled range of E. vaginatum , including a genetic break between populations north and south of treeline. This structure is likely the result of subrefugial isolation, more »
- Award ID(s):
- 2220863
- Publication Date:
- NSF-PAR ID:
- 10400870
- Journal Name:
- Frontiers in Plant Science
- Volume:
- 13
- ISSN:
- 1664-462X
- Sponsoring Org:
- National Science Foundation
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Range shifts in a foundation sedge potentially induce large Arctic ecosystem carbon losses and gains
Abstract Foundation species have disproportionately large impacts on ecosystem structure and function. As a result, future changes to their distribution may be important determinants of ecosystem carbon (C) cycling in a warmer world. We assessed the role of a foundation tussock sedge (
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Identifying the evolutionary and ecological mechanisms that drive lineage diversification in the species-rich tropics is of broad interest to evolutionary biologists. Here, we use phylogeographic and demographic analyses of genomic scale RADseq data to assess the impact of a large geographic feature, the Amazon River, on lineage formation in a venomous pitviper, Bothrops atrox. We compared genetic differentiation in samples from four sites near Santarem, Brazil that spanned the Amazon and represented major habitat types. A species delimitation analysis identified each population as a distinct evolutionary lineage while a species tree analysis with populations as taxa revealed a phylogenetic tree consistent with dispersal across the Amazon from north to south. Phylogenetic analyses of mtDNA variation confirmed this pattern and suggest that all lineages originated during the mid- to late-Pleistocene. Historical demographic analyses support a population model of lineage formation through isolation between lineages with low ongoing migration between large populations and reject a model of differentiation through isolation by distance alone. Our results provide a rare example of a phylogeographic pattern demonstrating dispersal over evolutionary time scales across a large tropical river and suggest a role for the Amazon River as a driver of in-situ divergence by both impeding (butmore »
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Accepted Manuscript1.0
- Publisher's Version of Record
- https://doi.org/10.3389/fpls.2022.860439
