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1. Rural selection drives the evolution of an urban–rural cline in coat color in gray squirrels

   https://doi.org/10.1002/ece3.10544  

   Cosentino, Bradley J. ; Vanek, John P. ; Gibbs, James P. ( October 2023 , Ecology and Evolution)

   Phenotypic differences between urban and rural populations are well‐documented, but the evolutionary processes driving trait variation along urbanization gradients are often unclear. We combined spatial data on abundance, trait variation, and measurements of fitness to understand cline structure and test for natural selection on heritable coat color morphs (melanic, gray) of eastern gray squirrels (Sciurus carolinensis) along an urbanization gradient. Population surveys using remote cameras and visual counts at 76 sites along the urbanization gradient revealed a significant cline in melanism, decreasing from 48% in the city center to <5% in rural woodlands. Among 76 squirrels translocated to test for phenotypic selection, survival was lower for the melanic than gray morph in rural woodlands, whereas there was no difference in survival between color morphs in the city. These results suggest the urban–rural cline in melanism is explained by natural selection favoring the gray morph in rural woodlands combined with relaxed selection in the city. Our study illustrates how trait variation between urban and rural populations can emerge from selection primarily in rural populations rather than adaptation to novel features of the urban environment.

    

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2. Postzygotic Isolation Evolves before Prezygotic Isolation between Fresh and Saltwater Populations of the Rainwater Killifish, Lucania parva

   https://doi.org/10.1155/2012/523967  

   Kozak, Genevieve M. ; Rudolph, Arthur B. ; Colon, Beatrice L. ; Fuller, Rebecca C. ( January 2012 , International Journal of Evolutionary Biology)

   Divergent natural selection has the potential to drive the evolution of reproductive isolation. The euryhaline killifish Lucania parva has stable populations in both fresh water and salt water. Lucania parva and its sister species, the freshwater L. goodei , are isolated by both prezygotic and postzygotic barriers. To further test whether adaptation to salinity has led to the evolution of these isolating barriers, we tested for incipient reproductive isolation within L. parva by crossing freshwater and saltwater populations. We found no evidence for prezygotic isolation, but reduced hybrid survival indicated that postzygotic isolation existed between L. parva populations. Therefore, postzygotic isolation evolved before prezygotic isolation in these ecologically divergent populations. Previous work on these species raised eggs with methylene blue, which acts as a fungicide. We found this fungicide distorts the pattern of postzygotic isolation by increasing fresh water survival in L. parva , masking species/population differences, and underestimating hybrid inviability. 

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3. Modifying Scientific Research into Introductory Science Course Lessons Using a 5E Lesson Format: An Active Learning Approach

   Idsardi, R. ( May 2019 , Journal of college science teaching)

   Science faculty are being asked to create active learning experiences that engage students in core concepts and science practices. This article describes an approach to developing active learning lessons from authentic science research projects using the 5E lesson format. Included is a description of the 5Es and a template for creating a 5E lesson. A description of the authors’ scientific research and the resulting 5E lesson for an introductory biology course are provided as an example of this approach. In the lesson described, students collected, analyzed, and interpreted data to construct explanations about the potential for evolution to occur in response to climate change. This approach supported students in learning core concepts and science practices and allowed the instructors to implement an active learning environment based on national science reforms. The results of this exploratory study and the rich descriptions of the lesson design should be used to raise awareness of one active-learning approach. Scientists can consider using this approach in their own teaching, and science education researchers can consider this approach in future comparative studies across various activelearning approaches. 

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4. Strong evidence for positive and negative correlational selection revealed by recreating ancestral variation

   https://doi.org/10.1093/evolut/qpac001  

   Waterman, Robin ; Sahli, Heather ; Koelling, Vanessa A. ; Karoly, Keith ; Conner, Jeffrey K. ( December 2022 , Evolution)

   The study of adaptation helps explain biodiversity and predict future evolution. Yet the process of adaptation can be difficult to observe due to limited phenotypic variation in contemporary populations. Furthermore, the scarcity of male fitness estimates has made it difficult to both understand adaptation and evaluate sexual conflict hypotheses. We addressed both issues in our study of two anther position traits in wild radish (Raphanus raphanistrum): anther exsertion (long filament − corolla tube lengths) and anther separation (long − short filament lengths). These traits affect pollination efficiency and are particularly interesting due to the unusually high correlations among their component traits. We measured selection through male and female fitness on wild radish plants from populations artificially selected to recreate ancestral variation in each anther trait. We found little evidence for conflicts between male and female function. We found strong evidence for stabilizing selection on anther exsertion and disruptive selection on anther separation, indicating positive and negative correlational selection on the component traits. Intermediate levels of exsertion are likely an adaptation to best contact small bees. The function of anther separation is less clear, but future studies might investigate pollen placement on pollinators and compare species possessing multiple stamen types.

    

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5. Demographic history and genomic signatures of selection in a widespread vertebrate ectotherm

   https://doi.org/10.1111/mec.17269  

   Judson, Jessica M. ; Hoekstra, Luke A. ; Janzen, Fredric J. ( January 2024 , Molecular Ecology)

   Environmental conditions vary greatly across large geographic ranges, and yet certain species inhabit entire continents. In such species, genomic sequencing can inform our understanding of colonization history and the impact of selection on the genome as populations experience diverse local environments. As ectothermic vertebrates are among the most vulnerable to environmental change, it is critical to understand the contributions of local adaptation to population survival. Widespread ectotherms offer an opportunity to explore how species can successfully inhabit such differing environments and how future climatic shifts will impact species' survival. In this study, we investigated the widespread painted turtle (Chrysemys picta) to assess population genomic structure, demographic history, and genomic signatures of selection in the western extent of the range. We found support for a substantial role of serial founder effects in shaping population genomic structure: demographic analysis and runs of homozygosity were consistent with bottlenecks of increasing severity from eastern to western populations during and following the Last Glacial Maximum, and edge populations were more strongly diverged and had less genetic diversity than those from the centre of the range. We also detected outlier loci, but allelic patterns in many loci could be explained by either genetic surfing or selection. While range expansion complicates the identification of loci under selection, we provide candidates for future study of local adaptation in a long‐lived, widespread ectotherm that faces an uncertain future as the global climate continues to rapidly change.

    

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