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ABSTRACT Human disturbance can have profound effects on biodiversity, including increasing hybridization between reproductively isolated species. One approach for understanding how human activity affects hybridization dynamics is to evaluate correlations between disturbance (e.g., urbanisation, temperature change) and hybridization. Because variation in hybridization can also arise from historical factors unrelated to recent human disturbance, it is essential to account for population structure to avoid spurious correlations. Here, we combine environmental and high‐coverage whole‐genome resequencing data to investigate how human disturbance and population structure affect hybridization dynamics between a pair of pine sawflies adapted to different pines,Neodiprion leconteiandNeodiprion pinetum. We find thatN. leconteiandN. pinetumexhibit strikingly different patterns of population structure, which we hypothesise stem from differences in host use. We also find that recent admixture is both asymmetric and geographically variable. Linear regression analyses reveal that admixture proportion is predicted by indirect human disturbance (i.e., climate change) and not direct human disturbance (e.g., urbanisation) in bothN. leconteiandN. pinetum. Lastly, inN. pinetum, we find evidence of a spurious association between admixture and direct human disturbance that disappears when regression models account for population structure via inclusion of genetic principal component scores as covariates. Together, our data suggest that indirect human disturbance and population structure both contribute to geographic variation in admixture betweenN. leconteiandN. pinetum. Our study also highlights the importance of adequately controlling for population structure when attempting to identify environmental predictors (human disturbance‐related or not) of hybridization.
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Evolution of Plasticity in Response to Ethanol Between Recently Separated Populations of D. melanogaster With Different Ecological Histories
ABSTRACT While there is abundant theoretical work on the evolution of phenotype plasticity, empirical support has lagged. One model for the evolution of phenotype plasticity is by genetic accommodation. Under this model of evolution, when a population encounters a new environment there are widely variable responses among different genotypes, which are then pruned by selection into a single adaptive response. Because of the requirement to replicate genotypes, testing this prediction requires inbred lines as well as populations that are both adapted and not adapted to a resource. We previously demonstrated thatD. melanogasteradapted to ethanol through genetic accommodation usingD. simulansas an ancestral proxy lineage. However, we wondered how generalizable these results were. Here, we used a new population ofD. melanogasterfrom France and an ancestral range population from Zambia and measured behavioral tolerance to ethanol exposure in multiple genotypes from each population, as well as genome‐wide gene expression and alternative splicing in response to ethanol using RNA sequencing. We found that the ZambianD. melanogasterhave lower tolerance to ethanol than the FrenchD. melanogaster, with the Zambian flies becoming sedated while the French flies remain active under the same exposure. At the transcriptional level, Zambian genotypes showed extensive genotype‐specific changes in gene expression and splicing in response to ethanol exposure, while the French genotypes showed relatively modest and fewer genotype‐specific changes, consistent with having a more uniform, population response. We also found that gene expression and splicing appear to evolve independently of one another and that the splicing response to ethanol is largely distinct between populations. Thus, we have independently replicated evidence for evolution by genetic accommodation inD. melanogaster, suggesting that the evolution of plasticity may be an important contributor to the ability to exploit novel resources.
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- Award ID(s):
- 2032756
- PAR ID:
- 10663861
- Publisher / Repository:
- Ecology and Evolution
- Date Published:
- Journal Name:
- Ecology and Evolution
- Volume:
- 16
- Issue:
- 1
- ISSN:
- 2045-7758
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1002/ece3.72874
