Data from: Can extreme climatic events induce shifts in adaptive potential? A conceptual framework and empirical test with Anolis lizards

Multivariate adaptation to climatic shifts may be limited by trait
integration that causes genetic variation to be low in the direction of
selection. However, strong episodes of selection induced by extreme
climatic pressures may facilitate future population-wide responses if
selection reduces trait integration and increases adaptive potential
(i.e., evolvability). We explain this counter-intuitive framework for
extreme climatic events in which directional selection leads to increased
evolvability and exemplify its use in a case study. We tested this
hypothesis in two populations of the lizard Anolis scriptus that
experienced hurricane-induced selection on limb traits. We surveyed
populations immediately before and after the hurricane as well as the
offspring of post-hurricane survivors, allowing us to estimate both
selection and response to selection on key functional traits: forelimb
length, hindlimb length, and toepad area. Direct selection was parallel in
both islands and strong in several limb traits. Even though overall limb
integration did not change after the hurricane, both populations showed a
non-significant tendency toward increased evolvability after the hurricane
despite the direction of selection not being aligned with the axis of most
variance (i.e., body size). The population with comparably lower
between-limb integration showed a less constrained response to selection.
Hurricane-induced selection, not aligned with the pattern of high trait
correlations, likely conflicts with selection occurring during normal
ecological conditions that favor functional coordination between limb
traits, and would likely need to be very strong and more persistent to
elicit a greater change in trait integration and evolvability. Future
tests of this hypothesis should use G-matrices in a variety of wild
organisms experiencing selection due to extreme climatic events.

生物对气候变迁的多变量适应性，可能受性状整合（trait integration）的限制：这类整合会使得遗传变异在选择作用的方向上处于较低水平。不过，若极端气候压力诱导的强选择事件能够降低性状整合程度、提升进化潜能（evolvability），则可促进后续种群整体的适应性响应。我们针对极端气候事件阐释了这一反直觉的理论框架：在该框架中，定向选择可提升进化潜能，并通过一则案例研究展示了该框架的应用方式。我们以两种经历过飓风诱导的四肢性状选择压力的脚本安乐蜥（Anolis scriptus）种群为对象，对该假说进行了验证。我们在飓风发生前后即刻对种群进行了调查，同时也统计了飓风后存活个体的后代，借此得以估算关键功能性状——前肢长度、后肢长度与趾垫面积——所受的选择强度以及选择响应。两座岛屿的直接选择模式高度一致，且多个四肢性状均受到了较强选择压力。尽管飓风过后整体四肢性状整合程度未发生改变，但两个种群均表现出进化潜能提升的非显著趋势，尽管选择方向并未与多数变异的主轴线（即体型）对齐。四肢间整合程度相对更低的种群，其对选择的响应所受的约束程度也更低。飓风诱导的选择与性状间高相关性的模式并不匹配，这大概率与常态生态条件下的选择相冲突：常态选择倾向于维持四肢性状间的功能协调性，且此类选择通常需要极强且更持久的作用，方能促使性状整合与进化潜能发生更为显著的改变。未来对该假说的检验，应在多种经历极端气候事件引发选择压力的野生生物类群中运用G矩阵（G-matrices）开展。