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1. Sex-biased infections scale to population impacts for an emerging wildlife disease

   https://doi.org/10.1098/rspb.2023.0040  

   Kailing, Macy J.; Hoyt, Joseph R.; White, J. Paul; Kaarakka, Heather M.; Redell, Jennifer A.; Leon, Ariel E.; Rocke, Tonie E.; DePue, John E.; Scullon, William H.; Parise, Katy L.; et al (March 2023, Proceedings of the Royal Society B: Biological Sciences)

   Demographic factors are fundamental in shaping infectious disease dynamics. Aspects of populations that create structure, like age and sex, can affect patterns of transmission, infection intensity and population outcomes. However, studies rarely link these processes from individual to population-scale effects. Moreover, the mechanisms underlying demographic differences in disease are frequently unclear. Here, we explore sex-biased infections for a multi-host fungal disease of bats, white-nose syndrome, and link disease-associated mortality between sexes, the distortion of sex ratios and the potential mechanisms underlying sex differences in infection. We collected data on host traits, infection intensity and survival of five bat species at 42 sites across seven years. We found females were more infected than males for all five species. Females also had lower apparent survival over winter and accounted for a smaller proportion of populations over time. Notably, female-biased infections were evident by early hibernation and likely driven by sex-based differences in autumn mating behaviour. Male bats were more active during autumn which likely reduced replication of the cool-growing fungus. Higher disease impacts in female bats may have cascading effects on bat populations beyond the hibernation season by limiting recruitment and increasing the risk of Allee effects. 

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2. Surviving the Squeeze: Genomic Analysis of a Successful Invasion by European Common Wall Lizards (Podarcis muralis) in North America (Ohio, USA )

   https://doi.org/10.1111/mec.70288  

   Bode, Emily R; Mason, Andrew J; Bolton, Peri E; Petren, Ken; Gangloff, Eric J; Gibbs, H Lisle (March 2026, Molecular Ecology)

   ABSTRACT Invasive species that undergo a founder event may experience a decline in genetic diversity yet still establish successful populations. A possible example is a population of the common wall lizard (Podarcis muralis) in Cincinnati, Ohio, USA, which was founded following an introduction in the 1950s of a small number of individuals from Europe. We used whole genome sequences of individuals from source and introduced populations to assess the origin, demographic history, population structure, and possible signatures of adaptation in this successful lizard introduction. We first confirmed that the introduced lizards in Ohio arePodarcis muralisusing phylogenetic analysis. Patterns of genetic diversity indicate introduced lizards in Cincinnati went through a short‐term bottleneck with increased inbreeding but then rapidly increased in population size, thus minimising losses in genetic diversity. Comparisons of genomic variation between source and introduced populations demonstrate that populations in Cincinnati represent a subset of source genetic variation and show minimal losses of overall genetic diversity. Comparisons of mutation load between source and introduced populations reveal only small increases in load in introduced populations. Finally, tests for selection on the basis of outlier analyses detect targets for potential positive selection in multiple regions of the genome of introduced individuals, suggesting possible adaptation to a novel environment. Overall, we suggest that rapid population growth and possible adaptation have allowed the founding population of introduced lizards to evade the potential negative genetic impacts of small population size and successfully colonise a novel environment. 

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3. Local Adaptation Is Highest in Populations With Stable Long‐Term Growth

   https://doi.org/10.1111/ele.70071  

   Carley, Lauren N; Geber, Monica A; Morris, William F; Eckhart, Vincent M; Moeller, David A (February 2025, Ecology Letters)

   ABSTRACT Theory suggests that the drivers of demographic variation and local adaptation are shared and may feedback on one other. Despite some evidence for these links in controlled settings, the relationship between local adaptation and demography remains largely unexplored in natural conditions. Using 10 years of demographic data and two reciprocal transplant experiments, we tested predictions about the relationship between the magnitude of local adaptation and demographic variation (population growth rates and their elasticities to vital rates) across 10 populations of a well‐studied annual plant. In both years, we found a strong unimodal relationship between mean home‐away local adaptation and stochastic population growth rates. Other predicted links were either weakly or not supported by our data. Our results suggest that declining and rapidly growing populations exhibit reduced local adaptation, potentially due to maladaptation and relaxed selection, respectively. 

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4. Demography and linked selection interact to shape the genomic landscape of codistributed woodpeckers during the Ice Age

   https://doi.org/10.1111/mec.16841  

   Moreira, Lucas Rocha; Klicka, John; Smith, Brian Tilston (January 2023, Molecular ecology)

   The influence of genetic drift on population dynamics during Pleistocene glacial cycles is well understood, but the role of selection in shaping patterns of genomic variation during these events is less explored. We resequenced whole genomes to investigate how demography and natural selection interact to generate the genomic landscapes of Downy and Hairy Woodpecker, species codistributed in previously glaciated North America. First, we explored the spatial and temporal patterns of genomic diversity produced by neutral evolution. Next, we tested (i) whether levels of nucleotide diversity along the genome are correlated with intrinsic genomic properties, such as recombination rate and gene density, and (ii) whether different demographic trajectories impacted the efficacy of selection. Our results revealed cycles of bottleneck and expansion, and genetic structure associated with glacial refugia. Nucleotide diversity varied widely along the genome, but this variation was highly correlated between the species, suggesting the presence of conserved genomic features. In both taxa, nucleotide diversity was positively correlated with recombination rate and negatively correlated with gene density, suggesting that linked selection played a role in reducing diversity. Despite strong fluctuations in effective population size, the maintenance of relatively large populations during glaciations may have facilitated selection. Under these conditions, we found evidence that the individual demographic trajectory of populations modulated linked selection, with purifying selection being more efficient in removing deleterious alleles in large populations. These results highlight that while genome-wide variation reflects the expected signature of demographic change during climatic perturbations, the interaction of multiple processes produces a predictable and highly heterogeneous genomic landscape. 

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5. Evolution of Physiological Tolerance and Performance During Freshwater Invasions

   https://doi.org/10.1093/icb/43.3.439  

   Lee, Carol Eunmi (July 2003, Integrative and Comparative Biology)

   Invasive species that penetrate habitat boundaries are likely to experience strong selection and rapid evolution. This study documents evolutionary shifts in tolerance and performance following the invasion of fresh water by the predominantly estuarine and salt marsh copepod Eurytemora affinis. Common-garden experiments were performed on freshwater-invading (Lake Michigan) and ancestral saline (St. Lawrence marsh) populations to measure shifts in adult survival (at 0, 5, and 25 PSU), and survival during development and development time (both using full-sib clutches split across 0, 5, 15, and 25 PSU). Results showed clear evidence of heritable shifts in tolerance and performance associated with freshwater invasions. The freshwater population exhibited a gain in low-salinity tolerance and a reduction in high-salinity tolerance relative to the saline population, suggesting tradeoffs. These tradeoffs were supported by negative genetic correlations between survival at fresh (0 PSU) versus higher salinities. Mortality in response to salinity occurred primarily before metamorphosis, suggesting that selection in response to salinity had acted primarily on the early life-history stages. The freshwater population exhibited curious patterns of life-history evolution across salinities, relative to the saline population, of retarded development to metamorphosis but accelerated development from metamorphosis to adulthood. This pattern might reflect tradeoffs between development rate and survival in fresh water at the early life-history stages, but some other selective force acting on later life-history stages. Significant effects of clutch (genotype) and clutch-by-salinity interaction (G × E) on survival and development time in both populations indicated ample genetic variation as substrate for natural selection. Variation for high-salinity tolerance was present in the freshwater population despite negative genetic correlations between high- and low-salinity tolerance. Results implicate the importance of natural selection and document the evolution of reaction norms during freshwater invasions. 

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