Biology subjects

De Lisle, S. P.

Publications and source records attributed to De Lisle, S. P..

4 recordsLinked to original sources

bioRxiv2023

Genotype x Environment interaction and the evolution of sexual dimorphism: adult nutritional environment mediates selection and expression of sex-specific genetic variance in D. melanogaster

Sexual conflict plays a key role in the dynamics of adaptive evolution in sexually reproducing populations, and theory suggests an important role for variance in resource acquisition in generating or masking sexual conflict over fitness and life history traits. Here, I used a quantitative genetic genotype x environment experiment in Drosophila melanogaster, to test the theoretical prediction that variance in resource acquisition mediates variation in sex-specific component fitness. Holding larval conditions constant, I found that adult nutritional environments characterized by high protein content resulted in reduced survival of both sexes compared to an environment of lower protein content, and lower male reproductive success. Despite reduced mean fitness of both sexes in high protein environments, I found a sex*treatment interaction for the relationship between resource acquisition and fitness; estimates of the adaptive landscape indicate males were furthest from their optimum resource acquisition level in high protein environments, and females were furthest in low protein environments. Expression of genetic variance in resource acquisition and survival was highest for each sex in the environment it was best adapted to, although the treatment effects on expression of genetic variance eroded in the path from resource acquisition to total fitness. Cross-sex genetic correlations were strongly positive for resource acquisition, survival, and total fitness, and negative for mating success, although estimation error was high for all. These results demonstrate that environmental effects on resource acquisition can have predictable consequences for the expression of sex-specific genetic variance, but also that these effects of resource acquisition can erode through the life history.

evolutionary biology↗

bioRxiv2023

Predictable and divergent change in the multivariate P-matrix during parallel adaptation

AbstractAdaptation to replicated environmental conditions can be remarkably predictable, suggesting parallel evolution may be a common feature of adaptive radiation. An open question, however, is how phenotypic variation itself evolves during repeated adaptation. Here, we use a dataset of morphological measurements from 35 populations of threespine stickleback, consisting of 16 parapatric lake- stream pairs and three marine populations, to understand how phenotypic variation has evolved during transitions from marine to freshwater environments, and during subsequent diversification across the lake-stream boundary. We find statistical support for divergent phenotypic covariance (P) across populations, with most diversification of P occurring across freshwater populations. Despite a close correspondence between within-population phenotypic variation and among population divergence, we find that variation in P is unrelated to total variation in population means across the set of populations. Within lake-stream pairs, however, we find that theoretical predictions for microevolutionary change can explain over 30% of the total divergence in P matrices across the habitat boundary. Together, our results indicate that variance evolution occurs primarily in dimensions of trait space with low phenotypic integration, driven by divergence into disparate lake and stream environments, illustrating how conserved and divergent features of multivariate variation can underlie adaptive radiation.

evolutionary biology↗

bioRxiv2022

Condition-dependence resolves the paradox of missing plasticity costs

Phenotypic plasticity plays a key role in adaptation to changing environments. However, plasticity is neither perfect nor ubiquitous, implying that fitness costs must limit the evolution of phenotypic plasticity in nature. The measurement of such costs of plasticity has proved elusive; decades of experiments show that fitness costs of plasticity are often weak or nonexistent. Here, we show that this paradox can be at least partially explained by condition-dependence. We develop two models differing in their assumptions about how condition-dependence arises; both models show that variation in condition can readily mask costs of plasticity even when such costs are substantial. This can be shown simply in a model where costly plasticity itself evolves condition-dependence. Yet similar effects emerge from an alternative model where trait expression is condition-dependent. In this more complex model, average condition in each environment and genetic covariance in condition across environments both determine when costs of plasticity can be revealed. Analogous to the paradox of missing trade-offs between life history traits, our models show that variation in condition masks costs of plasticity even when costs exist, and suggests this conclusion may be robust to the details of how condition affects trait expression. Our models demonstrate that condition dependence can also account for the often-observed pattern of elevated plasticity costs inferred in stressful environments, the maintenance of genetic variance in plasticity, and provides insight into experimental and biological scenarios ideal for revealing a cost of phenotypic plasticity.

evolutionary biology↗

bioRxiv2022

Rapid evolution of ecological sexual dimorphism driven by resource competition

Sex differences in ecologically-important traits are common in animals and plants, and prompted Darwin to first propose an ecological cause of sexual dimorphism. Despite theoretical plausibility and Darwins original notion, a role for ecological resource competition in the evolution of sexual dimorphism has never been directly demonstrated and remains controversial. I used experimental evolution in Drosophila melanogaster to test the hypothesis that resource competition can drive the evolution of sex differences in diet. Following just three generations of adaptation, offspring from flies evolved in low-resource, high-competition environments show elevated sexual dimorphism in diet preference compared to both the ancestor and populations evolved on high resource availability. These results provide the first real-time direct evidence for evolution of sexual dimorphism driven by an ecological cause. One sentence summarySex differences in fly diet evolved rapidly under elevated competition, demonstrating ecological cause of sex differences.

evolutionary biology↗