Genes, environment, and plasticity in C. elegans behaviour

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Environments change, and in order to survive organisms must have mechanisms to adapt to these changes. Because environmental conditions are variable on different time scales, adaptive plasticity mechanisms must also vary in the time scales on which they operate. For example, physiological changes can help adjust to temperature fluctuations that occur over the 24-hour day/night cycle, while seasonal fluctuations in temperature might be associated with growing or losing fur, or dramatic metabolic changes like hibernation. As species expand or change their range or the overal climate shifts, evolution drives adaptive changes in populations. This research program focuses on foraging behaviour in the nematode Caenorhabditis elegans. We study C. elegans because of its advantages as a model system, particularly the expansive set of tools for analyzing the genetic and neural basis of behaviour. Foraging behaviours are especially attractive in ethology and behavioural neuroscience because there are well-developed conceptual models that help make predictions about how an optimal forager should behave given a particular environment or set of experiences. The goal of this program is to understand how variation and plasticity in foraging strategies operates across various time scales. Short-term regulation of foraging based on feeding state and food availability has eben extensively studied in C. elegans. Our interests are in longer-term forms of plasticity: the time scales of an entire life (days, for a nematode) mediated by adaptive developmental plasticity, over the course of weeks via transgenerational epigenetic inheritance, and variation between wild populations that have adapted to different local conditions. Aim 1. The genetic basis of foraging plasticity. Our recent work identified the genetic basis of domestication-associated changes in foraging behaviour, which differs from the standing variation among wild isolates. We will using a panel of sequenced strains to identify genetic and behavioural variation that produces different foraging strategies in wild isolates. Aim 2. Seasonal adaptation and transgenerational plasticity. Multiple groups have identified transgenerational effects on behaviour and physiology that are mediated by small RNA inheritance, all of which last on the order of 5-7 generations. We will test the hypothesis that this is a mechanism tuned to environmental changes associated with seasonal progression in temperate climates. Aim 3. Exploration, dispersal, and fitness in naturalistic environments. On the longest time scale, evolution drives adapative genetic changes in populations. Here, we will use large, designed environments to test predictions about dispersal and foraging with respect to fitness in long-term experimental evolution experiments.