Nicotra Fan Selection Software 33 |BEST|
Nicotra Fan Selection Software 33
The focus of this review is on how selection might act on phenotypic plasticity in response to changes in temperature, which represents the one of the most widespread forms of plasticity. We also include consideration of other measures of plasticity, such as plasticity of flowering time and of growth rates, and report estimates of selection, when these have been available. Our review considered studies from the wild, but excludes data on industrial or agricultural populations, as these populations may be subject to different selection regimes from natural populations, and so are likely to have different responses to the same selection regimes. We place the question of adaptive or non-adaptive plasticity in the context of climate change, however we emphasize that our review focuses on the implications of plasticity for natural populations, and not on biotechnological breeding of crops for desired traits. Given the disparate methods employed in the studies reviewed, we conclude with a number of considerations for future research. We show how a quantitative method, which can be applied to most forms of plasticity, can be used to estimate selection on plasticity.
The term “plasticity” is used in many contexts and is applied differently in different studies. In this review, we use the term “plasticity” to refer to phenotypic change in response to an environmental change, within an organism’s genotype, such that the expression of a phenotype varies across environments. When used with the prefix “non-”, “non-plasticity” refers to phenotypic differences not caused by environmental change, such as differences between castes or generations. When used with the prefix “adaptive”, “adaptive plasticity” refers to plasticity that improves fitness across environments. We define “non-adaptive plasticity” as plasticity that does not improve fitness. This categorization is not the only possible one, and it is possible that non-adaptive plasticity could be adaptive, and vice versa, but we do not consider these issues here. With the caveat that plasticity may always be an adaptive trait of evolutionary significance when the context of plasticity and selection is understood, we take it that “non-adaptive” denotes lack of fitness advantage in one environment and “adaptive” denotes fitness advantage in at least one environment, and that both concepts must be applied cautiously. The net advantage of plasticity could be zero when: a) non-adaptive plasticity reduces fitness in one environment but increases fitness in another; or b) when non-adaptive plasticity reduces fitness in both environments.