Evolutionary response to environmental uncertainty

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Natural environments are constantly changing; changes can be of any magnitude and occur over all time scales. Over 99% of species that have inhabited this planet are now extinct, and the remaining species are representatives of evolving lineages that have survived all change. Study of adaptation to change has broad applicability; for example, evolution of infectious disease-causing microbes is a story of rapid adaptation to new (host) environments. Despite its importance, much remains to be learned about how organisms evolve to cope with change. We do know that adaptation takes three main forms: 1) evolutionary “tracking” of the environment as it changes, 2) the evolution of the ability to make plastic adjustments to suit the circumstances within an organism’s lifetime, and 3) the evolution of safe or “bet-hedging” characteristics to avert risk during hard times (analogous to purchasing insurance). Little is known about the relative importance of these three forms of adaptation, or how they interact to influence survival through future change. The research supported by this NSERC Discovery Grant will lead to progress in the understanding of organismal response to environmental variation by using novel experimental laboratory and field approaches. In an experimental evolution study, we will subject the fungus Neurospora crassa to variable environments to observe evolution directly. We aim to discover how important the past pattern of changing environments is to the evolution of traits that allow it to survive into the future. We will then use DNA sequencing techniques to identify the genes that are involved in this adaptation to change. Using duckweed, the smallest flowering plants in the world, we will ask what mechanisms allow survival through harsh times. The aquatic species we study survives winter by producing “turions” that sink to the bottom of ponds. To better understand adaptation to unpredictable season length, we will study the relative importance of innate and environmental differences in determining the phenology of turion production. In another set of studies, we will use “DNA fingerprinting” techniques to directly study the effect of variable environments on the fate of genotypes of herbaceous plants in the field. Finally, we use information contained in tree rings to inform us about how variable particular environments have been, and then ask whether adaptations in herbaceous plants in the same environments are as would be predicted, and what the nature of these adaptations are. Thus, we use a wide array of experimental systems that enable us to address problems all unified by the central question of how organisms evolve in response to environmental variation. This fundamental research provides knowledge that has potential applications important to Canada ranging from response to climate change to medicine.