Life history as a constraint on plasticity: developmental timing is correlated with phenotypic variation in birds

Abstract

Understanding why organisms vary in developmental plasticity has implications for predicting population responses to changing environments and the maintenance of intraspecific variation. The epiphenotype hypothesis posits that the timing of development can constrain plasticity-the earlier alternate phenotypes begin to develop, the greater the difference that can result amongst the final traits. This research extends this idea by considering how life history timing shapes the opportunity for the environment to influence trait development. We test the prediction that the earlier an individual begins to actively interact with and explore their environment, the greater the opportunity for plasticity and thus variation in foraging traits. This research focuses on life history variation across four groups of birds using museum specimens and measurements from the literature. We reasoned that greater phenotypic plasticity, through either environmental effects or genotype-by-environment interactions in development, would be manifest in larger trait ranges (bills and tarsi) within species. Among shorebirds and ducks, we found that species with relatively shorter incubation times tended to show greater phenotypic variation. Across warblers and sparrows, we found little support linking timing of flight and trait variation. Overall, our results also suggest a pattern between body size and trait variation, consistent with constraints on egg size that might result in larger species having more environmental influences on development. Taken together, our results provide some support for the hypothesis that variation in life histories affects how the environment shapes development, through either the expression of plasticity or the release of cryptic genetic variation.

Mean-Variance QTL Mapping on a Background of Variance Heterogeneity

“…In reality, the residual variance (sometimes termed the environmental variance) between individuals can differ: the inherent noisiness of a phenotype can be affected by many factors, both extrinsic, such as environmental factors, and intrinsic, such as sex, or, more broadly, genetics. Environmental sources of residual variance heterogeneity have been well-documented, and include, for example, soil nitrogen and irrigation (Makumburage and Stapleton 2011), temperature (Shen et al 2014), and even the age at which young birds begin to experience the environmental insults outside of the nest (Snell-Rood et al 2015). Genetic sources of residual variance heterogeneity have attracted increasing interest, with multiple studies finding instances of the residual variance being heritable (Sorensen and Waagepetersen 2003;Hill and Mulder 2010;Sorensen et al 2015;Gonzalez et al 2016;Lin et al 2016;Mitchell et al 2016), and in some cases substantially attributable to allelic variation in individual genes (Paré et al 2010;Wolc et al 2012;Yang et al 2012;Hulse and Cai 2013;Wang et al 2014;Ayroles et al 2015;Forsberg et al 2015;Ivarsdottir et al 2017).…”

QTL Mapping on a Background of Variance Heterogeneity

“…These differences in residual variance can arise from many sources, both extrinsic, such as environmental factors, and intrinsic, such as sex, or, more broadly, genetics. Environmental sources of residual variance heterogeneity have been well-documented, and include, for example, soil nitrogen and irrigation (Makumburage and Stapleton 2011), temperature (Shen et al 2014), and even the age at which young birds begin to experience the environmental insults outside of the nest (Snell-Rood et al 2015). Genetic sources of residual variance heterogeneity have attracted increasing interest, with multiple studies finding instances of the residual variance being heritable (Sorensen and Waagepetersen 2003; Hill and Mulder 2010; Sørensen et al 2015; Gonzalez et al 2016; Lin et al 2016; Mitchell et al 2016), and in some cases substantially attributable to allelic variation in individual genes (Paré et al 2010; Wolc et al 2012; Yang et al 2012; Hulse and Cai 2013; Wang et al 2014; Ayroles et al 2015; Forsberg et al 2015; Yadav et al 2016; Ivarsdottir et al 2017).…”

Evolutionary rescue via transgenerational plasticity: Evidence and implications for conservation

“…A mismatch between parental and offspring environment can easily yield maladaptive traits (Uller, 2008), but when parents can better assess the environment that offspring will likely encounter than the offspring themselves (e.g., as when parents have better‐developed sensory capabilities), transgenerational plasticity can be more beneficial than within‐generational plasticity (Burgess & Marshall, 2014; Dyer et al, 2010; Kuijper & Hoyle, 2015). Reliable transmission of environmental information allows for faster and potentially stronger responses to environmental change than within‐generational plasticity, as cues are received early in development without the need for offspring to assess their current or future environment (Donelan et al, 2020; Snell‐Rood et al, 2015). This early response system may also mean that costs are lower for transgenerational plasticity than plasticity within a generation (Snell‐Rood et al, 2018).…”