Mini-symposium "Integrating Genomic, Ecological, and Evolutionary Perspectives on Biodiversity"

Do chromosomal inversions contribute to local adaptation in sticklebacks?

Katie Peichel Evolutionary Ecology, Institute of Ecology and Evolution, University of Bern, Switzerland

Since their discovery 100 years ago, chromosome inversions have captured the attention of evolutionary biologists, who have long postulated that they might play a special role in adaptation and speciation. This fascination with inversions comes from the fact that there is virtually no crossing-over within the inversion in heterozygous individuals. Thus, these regions of the genome can harbor genetic differences that can contribute to local adaptation, even if the rest of the genome experiences gene flow. Indeed, whole genome sequencing studies are revealing that inversion polymorphisms are common between closely related species or populations adapted to divergent habitats. Despite a rich body of theory and these recent empirical findings, many fundamental questions about the evolution of inversions remain. To address some of these questions, we are using the threespine stickleback (Gasterosteus aculeatus) system, in which there are three chromosomal inversions that are highly differentiated between stickleback populations adapted to marine versus freshwater habitats across both the Pacific and Atlantic basins. In particular, we are taking multiple approaches to identify the phenotypic traits associated with these inversions, determine the strength and type of selection acting on inversions, and identify the loci that are targets of selection within the inversions. Our preliminary results suggest that inversions in sticklebacks are indeed under selection and harbor loci associated with multiple adaptive phenotypes, as predicted by theory. We are currently using CRISPR-Cas9 genome editing to “flip” the inversions in order to identify the loci that contribute to these adaptive phenotypes.

Evolutionary Conservation Genomics of Freshwater Fish Biodiversity

Philine Feulner Fish genomics group, Department Fish Ecology and Evolution, EAWAG, University of Bern, Switzerland

Genomic diversity reflects the adaptive potential of populations and impacts the extinction risk of species. Empirical data on genomic diversity of populations before environmental perturbations are rare hence our understanding on the impact of perturbation on diversity remains limited. In this talk I will present two studies utilising whole-genome resequencing data to inform biodiversity conservation. In the first example, genomic data of Alpine whitefish covers a period of strong but transient anthropogenic environmental change and permits to track changes in genomic diversity over time. The observed decline of genome wide genetic variation and differentiation that evolved in the process of adaptation to alternative ecologies between species demonstrates the sensitivity of biodiversity in evolutionary young adaptive radiations towards environmental disturbance. The second study assessed the intraspecific diversity of European grayling in Switzerland, an area with known population collapses and past stocking efforts. Results revealed clear divergence between and within river catchments and of several hatchery fish from their wild counterparts. Together with evidence of local adaptation this suggests that translocations and stocking are no suitable management options. Estimates of effective population size however confirm concerns regarding Swiss grayling populations and may warrant future genetic biodiversity monitoring.

Sexual conflict in though times: condition dependence and population persistence

Miguel Gómez Llanos Department of Environmental and Life Sciences, Karlstad University, Sweden

Sexual conflict, a by-product of sexual selection, can profoundly influence population dynamics by reducing female fitness and constraining population growth. Because reproductive behaviours associated with male harm are energetically demanding, individuals in better condition, often locally adapted, tend to invest more in such traits. This condition-dependence sexual conflict means that the costs associated with male harm can be mediated by the ecological and evolutionary context. In this talk, I will explore how condition-dependent sexual conflict shapes species persistence through its effects on evolutionary rescue and biological invasions. The results I will show reveal that condition-dependent sexual conflict can both hinder and facilitate population persistance. Together, the results highlight a dynamic and often counterintuitive role of sexual conflict in mediating population persistence.

Ecology of Gene Expression

Sean Rogers Bamfield Marine Sciences Centre, Department of Biological Sciences, University of Calgary, Canada

Gene expression—the process by which DNA is transcribed into RNA and ultimately translated into function—is fundamental to life. Yet only recently have molecular ecologists begun to explore the ecological and evolutionary roles of gene expression in depth. In this talk I will highlight a recent special issue in Molecular Ecology that brought together 43 contributions investigating how gene expression functions as a molecular phenotype, including responses to environmental stressors, mediating biotic interactions, and linking organismal traits to fitness. Recent methodological advances— including long-read RNA sequencing and rapid environmental RNA approaches— are dramatically expanding our capacity to probe gene‐expression in non-model organisms. Beyond empirical insights, our novel approach to equity, diversity and inclusion also highlighted the importance of increasing diversity of authorship to strengthen molecular ecology’s reach and relevance. Recommendations to integrate functional transcriptomics into ecological experimental designs, adopt gene network and pathway‐level thinking, embrace larger sample sizes and annotation‐poor systems, while promoting equity in authorship and research leadership will be discussed.