Dataset Information

Positive selection at sites of chemosensory genes is associated with the recent divergence and local ecological adaptation in cactophilic Drosophila.

ABSTRACT: BACKGROUND:Adaptation to new hosts in phytophagous insects often involves mechanisms of host recognition by genes of sensory pathways. Most often the molecular evolution of sensory genes has been explained in the context of the birth-and-death model. The role of positive selection is less understood, especially associated with host adaptation and specialization. Here we aim to contribute evidence for this latter hypothesis by considering the case of Drosophila mojavensis, a species with an evolutionary history shaped by multiple host shifts in a relatively short time scale, and its generalist sister species, D. arizonae. RESULTS:We used a phylogenetic and population genetic analysis framework to test for positive selection in a subset of four chemoreceptor genes, one gustatory receptor (Gr) and three odorant receptors (Or), for which their expression has been previously associated with host shifts. We found strong evidence of positive selection at several amino acid sites in all genes investigated, most of which exhibited changes predicted to cause functional effects in these transmembrane proteins. A significant portion of the sites identified as evolving positively were largely found in the cytoplasmic region, although a few were also present in the extracellular domains. CONCLUSIONS:The pattern of substitution observed suggests that some of these changes likely had an effect on signal transduction as well as odorant recognition and protein-protein interactions. These findings support the role of positive selection in shaping the pattern of variation at chemosensory receptors, both during the specialization onto one or a few related hosts, but as well as during the evolution and adaptation of generalist species into utilizing several hosts.

SUBMITTER: Diaz F

PROVIDER: S-EPMC6148956 | biostudies-literature | 2018 Sep

REPOSITORIES: biostudies-literature

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Positive selection at sites of chemosensory genes is associated with the recent divergence and local ecological adaptation in cactophilic Drosophila.

Diaz Fernando F Allan Carson W CW Matzkin Luciano M LM

BMC evolutionary biology 20180920 1

<h4>Background</h4>Adaptation to new hosts in phytophagous insects often involves mechanisms of host recognition by genes of sensory pathways. Most often the molecular evolution of sensory genes has been explained in the context of the birth-and-death model. The role of positive selection is less understood, especially associated with host adaptation and specialization. Here we aim to contribute evidence for this latter hypothesis by considering the case of Drosophila mojavensis, a species with ...[more]

PMID: 30236055

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Project description:Documenting effects of climate change is an important step towards designing mitigation and adaptation responses. Impacts of climate change on terrestrial biodiversity and ecosystems have been well-documented in the Northern Hemisphere, but long-term data to detect change in the Southern Hemisphere are limited, and some types of change are generally difficult to measure. Here we present a novel approach using local ecological knowledge to facilitate a continent-scale view of climate change impacts on terrestrial biodiversity and ecosystems that people have perceived in Australia. We sought local knowledge using a national web-based survey, targeting respondents with close links to the environment (e.g. farmers, ecologists), and using a custom-built mapping tool to ask respondents to describe and attribute recent changes they had observed within an area they knew well. Results drawn from 326 respondents showed that people are already perceiving simple and complex climate change impacts on hundreds of species and ecosystems across Australia, significantly extending the detail previously reported for the continent. While most perceived trends and attributions remain unsubstantiated, >35 reported anecdotes concurred with examples in the literature, and >20 were reported more than once. More generally, anecdotes were compatible with expectations from global climate change impact frameworks, including examples across the spectrum from organisms (e.g. increased mortality in >75 species), populations (e.g. changes in recruitment or abundance in >100 species, phenological change in >50 species), and species (e.g. >80 species newly arriving or disappearing), to communities and landscapes (e.g. >50 examples of altered ecological interactions). The overarching pattern indicated by the anecdotes suggests that people are more often noticing climate change losers (typically native species) than winners in their local areas, but with observations of potential 'adaptation in action' via compositional and phenological change and through arrivals and range shifts (particularly for native birds and exotic plants). A high proportion of climate change-related anecdotes also involved cumulative or interactive effects of land use. We conclude that targeted elicitation of local ecological knowledge about climate change impacts can provide a valuable complement to data-derived knowledge, substantially extending the volume of explicit examples and offering a foundation for further investigation.

Dataset Information

Positive selection at sites of chemosensory genes is associated with the recent divergence and local ecological adaptation in cactophilic Drosophila.

Publications

Positive selection at sites of chemosensory genes is associated with the recent divergence and local ecological adaptation in cactophilic Drosophila.

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