Evolution and plasticity of "arrive and survive" phenotypes driving parallel range shifts in the wild.

Many species are undergoing contemporary range shifts to higher latitudes and elevations, representing one of the most dramatic and consequential biotic responses to climate change. Historically, researchers assumed that range shifts simply involved ecological processes of dispersal to track suitable climates. However, we now know that range shifts in fact also involve rapid evolutionary change, reflecting: niche shifts and niche expansion, increases in dispersal, and altered patterns of neutral genetic variation. However, the mechanisms and salience of each of these evolutionary shifts are poorly understood, limiting our ability to predict range shifts and estimate their potential impact on high latitude or high elevation communities.

Recent work suggests that shifts in endogenous, epigenetic modifications to DNA may play a central role in enabling range shifts and associated adaptations. This is because such epigenetic modifications represent a way to achieve improved flexibility in trait expression, enabling individuals to better respond to novel environments at the expanding range edge. In fact, epigenetic variation is often a better predictor than genetic variation in predicting species' niche limits. However, the role genetic vs. epigenetic variation in enabling poleward range expansions has never been formally compared, for either explanatory power or predictive ability.

In this proposal we aim to conduct a landscape scale study to discover the genetic variants and epigenetic patterns that reliably predict and reflect range shifting adaptations and rates. For this work we propose to use an established model study system for range shifting evolutionary dynamics, the blue-tailed damselfly Ischnura elegans. This iconic species is strongly limited by temperature, and is currently undergoing rapid range expansion into higher latitudes in response to climate change, associated with previously-described evolutionary shifts in niche breadth, competitive ability, and dispersal phenotypes. Being geographically widespread, with well-developed genomic resources, high-quality citizen science data, and documented ecological impacts on invaded habitats, I. elegans provides the ideal system to study range shift evolutionary processes in parallel in the wild.

To evaluate the relative importance of genetic and epigenetic processes for range shifting, we will establish four, independent, parallel range shift transects at the northern margin of I. elegans' range. We will combine field sampling with laboratory experiments, to establish drivers of variation, and eco-evolutionary modelling, to uncover key processes and predictions. The proposed work will provide a first, robust test of how genetic and epigenetic processes facilitate range shifts into higher latitudes, via their effects on dispersal and thermal adaptations (what we coin 'arrive and survive' phenotypes). Our validated forecasting models will further establish the relative importance of different genetic and epigenetic processes, and provide a platform for predicting rates of range shifting and adaptation in the Anthropocene.