====== Review on genetic vs. plastic adaptation to climate change ====== * [[Snippets]] * [[Topics and papers to include]] ===== Possible structure (potentially as list of questions) ===== ==Introduction== * **What can theory contribute to the study of adaptation to climate change?** * Identify important parameters * Make rough predictions about quantitative change * Suggest measures and scalings * **What theory cannot do** * Predict the ratio of genetic vs. plastic responses * Make exact quantitative predictions * **Scope of this paper** * Phenotypic evolution of quantitative change * Simple selective scenarios * Focus on rates == Methods == * **How should evolutionary change be measured?** * Darwins, haldanes, haldane numerators * mean- vs. variance standardization (Herford et al. 2004) * extrapolation to per-generation rates (Gingerich) * **How to model phenotypic evolution?** * Quantitative genetics (adaptation from standing genetic variation) * population genetics (adaptation by single large mutations) * adaptive walks (new mutations only) * optimality, game theory (not needed for simple scenarios considered here; relevant for evolution of plasticity) * adaptive dynamics (for evolution of plasticity, eco-evolutionary feedbacks) * **Which scenarios of environmental change have been considered?** * sudden change, * moving optimum, * stochastic fluctuations * increased variability * range shifts???? == What is the genetic basis of adaptation? == * Standing variation vs. new mutations * Small or large mutation * How does the genetic basis affect adaptation? (Difficult to discuss details here; maybe just use as announcement, or combine with modeling approaches) == Basic models == * Sudden change, quantitative genetic * Sudden change, major locus * linearly moving optimum, quantitative genetic * linearly moving optimum, major locus == Univariate models == * **Rate of adaptation** * From new mutations: fixation probability (Haldane, Kimura, Gomulkiewicz and Kirkpatrick, Orr and Uncless, Uecker and Hermisson) * From standing variation (quantitative genetic models): Lande's equation * Additive genetic variance (under mutation-selection balance and during evolution); when will additive variance be exhausted? * Selection gradients * **Evolutionary rescue** * from standing variation or new mutations * in models with sudden change * in models with moving optimum * critical rates of environmental change * phenotype vs. fitness == Multivariate models == * **How to model multivariate evolution?** * Multivariate Lande's/breeders' equation * Fisher's geometric model * Pleiotropic side effects * **How many traits? (Organismal complexity)** * **What are the effects of multivariate mutation and selection?** * G-matrix, M-matrix * Evolution of G-matrix * Genetic line of least resistance * multivariate constraints * evolution of mean fitness * **Evolvability** === Plasticity === * How to model plasticity? * How plastic are organisms? * How does plasticity interact with genetic evolution? * Does plasticity evolve during adaptation? * How does plasticity contribute to evolutionary rescue? == Open questions == * Evolutionary change in a community context * Effects of plasticity (trait-mediated indirect effects etc.) * Eco-evolutionary dynamics * Ecological constraints on adaptation (niche conservatism) ===== List of questions ===== == Introduction == * What can theory contribute to the study of adaptation to climate change? * How to measure (rates of) adaptation? * What is evolutionary rescue? * Which modeling approaches have been used? == Genetic adaptation: univariate case == * Basic scenarios: sudden change and moving optimum, adaptation from quantitative variation or a single major mutation * How fast can genetic adaptation be? * What is the genetic basis of adaptation, and how does genetic variation evolve? * Adaptation in time and space == Genetic adaptation: multivariate case == * What are the effects of multivariate selection and genetic correlations? * How does the G-matrix evolve? * What determines evolvability? == Plasticity == * How can plasticity be modeled? * How and when does plasticity evolve? * Does plasticity facilitate genetic adaptation? == Responses at the community level == * ===== Questions for empiricists ===== In all cases, the answer may be quantitative, or may contain a list of factors that influence the result. * Overall questions: * How fast can adaptation happen? * Plastic or genetic adaptation? * Evolutionary rescue? * How much due to plasticity? (no general answers) * Adaptation from standing variation or new mutations? * Small or large mutations? * How much standing genetic variation? * What happens to genetic variance during adaptation? * What constrains adaptation? * What determined evolvability? * Maximal rate of genetic adaptation? * Evolutionary rescue due to genetic adaptation? * How much plasticity? * Will plasticity evolve? * Can plasticity enhance genetic adaptation? * Evolutionary rescue with plasticity? * What happens at the community level? ===== Questions in Barrett and Hendry (2012) ===== == How important is genetic (as opposed to plastic) change? == * We might ask: What is possible with genetic change only? == Will plasticity evolve? == * Most likely yes:-) * Approaches: Lande 2009, earlier models from 1990s, Draghi and Whitlock * Baldwin effect etc. == Is evolution fast enough == * How fast without plasticity? * Factors determining speed: * Genetic variance (large literature here) * Selection gradient * Multivariate constraints * Evolvability, complexity etc. * Evolutionary rescue * critical rates: explain * Explain Lynch and Lande (1993) * Key factors: selection gradient vs. mean fitness * Strong selection is a good thing with a moving optimum * additional factors: demographic and environmental stochasticity == Standing variation vs. new mutations? == * Different theoretical approaches/traditions * Quantitative genetics vs. adaptive walks * Some results from quantitative genetics (Hill...) * Open questions == How many genes and what effect == * Lots of recent interest in models of adaptive walks (from new mutations only) * Kopp and Hermisson 2009b: at least in univariate case, adaptive walk predictions are good approximations to quantitative genetic model == Constraints: limited genetic variation == * models on maintenance of genetic variation == Constraints: Trait correlations == * multivariate constraints * Fisher's model etc. == Constraints: Ultimate constraints == * trade-offs? ===== What can one say abouts phenotypic rates of adaptation from sgv? ===== === Univariate case === * Starting point: Lande's equation: selection gradient and additive variance * Lot's of literature on additive variance * Selection gradient vs. mean fitness: depends on fitness function * double exponential fitness function: selection gradient constant * Problem: How to deal with phenotypic variance and sampling error? For an observed change to be significant, the difference in haldanes must be (\bar x - \bar y)/\sigma_p > 1.96\sqrt(2/n); for n = 100, this is 0.087. * check out Lande 1976, Hendry and Kinnison 1999, Gingerich 2009 for this * essentially dividing the Lande equation by sigma_p leads to standardized selection gradients, discussed and critized in Herford et al. 2004 === Multivariate case === * Multivariate Lande's equation * critized by Morrisey et al. 2010 * Multivariate constraints: Walsh and Blows 2009 ===== Narrative ===== **What happens when a populations experiences environmental change, and which theoretical problems do we encounter along the way?** * Before the change: maintenance of genetic variation (mutation-selection balance, fluctuating selection ...) * Different kinds of environmental change * Adaptation from standing genetic variation * Adaptation from new mutations (unlikely) * Evolutionary rescue? * Plasticity * Which factors favor adaptation: genetic variation, plasticity, evolvability, modularity, lack of complexity