The evolutionary consequences of environmental uncertainty

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Natural environments are continually changing, which is known to cause sometimes extreme variation in evolutionary fitness. Existing species are the few representatives of survivors of all environments to the present time. The ultimate goal of this NSERC-supported research program is to contribute to an understanding of how organisms evolve in the face of continual change. It addresses fundamental questions, but has broad applicability. For example, evolution of infectious disease-causing microbes is a story of adaptation to changing host environments. There are three main ways in which organisms respond to change: 1) by adaptively "tracking" changing environments, 2) through "plastic" adjustments within a lifetime, and 3) by evolving "bet-hedging" traits that reduce risk of complete failure. Little is known about the relative importance of these three forms of response, how they interact to influence success, or the time scales over which they evolve. The research supported by this NSERC Discovery Grant takes theoretical, observational and experimental approaches conducted both in the lab and the field to advance understanding of organismal response to changing environments.    The first study uses computation and experiments to ask how the evolution of so-called bet hedging is even possible. By definition, bet-hedging traits are advantageous over long time periods, but are detrimental during "normal" times. One PhD student aims to discover the genetic basis of not "un-evolving" the detrimental bet-hedging trait during normal times; another will build a computational model to ask about the evolution of such constraints over longer time periods.    A second set of projects uses the herbaceous plant, Lobelia inflata, to ask questions about the mechanisms responsible for expression of traits underlying fitness. For example, how did the self-fertilizing mating system in L. inflata evolve from outcrossing? This question will be addressed by comparing this species with closely related outcrossing species, and through citizen science (iNaturalist) photographic evidence of geographical differences in mating systems of L. inflata across eastern N.A.    The third set of projects focuses on the tiny floating aquatic plant, Spirodela polyrhiza, unique in producing hardy seed-like "turions" that sink to the sediment, allowing survival despite the unpredictable onset of winter. The timing of reactivation from the sediment in the spring is influenced by a diversified risk-spreading strategy, and this strategy differs genetically among populations. This plant offers the opportunity to ask fundamental questions about the importance of diversification for survival, and also about "eco-evolutionary dynamics": the effect of genetic differences in diversification on the outcome of competitive interactions among species. This research will contribute to fundamental knowledge of organismal response to environmental variance, including extinction resistance.