A biophysical interpretation of temperature-dependent body size in Drosophila aldrichi and D. buzzatii.

The temperature-size rule, the observation that most ectotherms grow faster but reach smaller size at higher temperatures, has defied a general explanation. Here, the temperature-size rule in Drosophila aldrichi and Drosophila buzzatii is investigated, using data on development rate and adult dry weight at nine temperatures. In both species the linear regression of dry weight on temperature is negative.

Heritability of sperm length in the bumblebee Bombus terrestris.

Sperm length is highly variable, both between and within species, but the evolutionary significance of this variation is poorly understood. Sexual selection on sperm length requires a significant additive genetic variance, but few studies have actually measured this. Here we present the first estimates of narrow sense heritability of sperm length in a social insect, the bumblebee Bombus terrestris.

Evolution of phenotypic plasticity: patterns of plasticity and the emergence of ecotypes.

Phenotypic plasticity itself evolves, as does any other quantitative trait. A very different question is whether phenotypic plasticity causes evolution or is a major evolutionary mechanism. Existing models of the evolution of phenotypic plasticity cover many of the proposals in the literature about the role of phenotypic plasticity in evolution.

A genetic analysis of avian personality traits: correlated, response to artificial selection.

Individuals in a range of species consistently differ in their behavior towards mild challenges, over age and time. Differences have been found for several personality traits in a range of species. In great tits these traits have a genetic basis and are phenotypically correlated.

Latitudinal clines in Drosophila melanogaster: body size, allozyme frequencies, inversion frequencies, and the insulin-signalling pathway.

Many latitudinal clines exist in Drosophila melanogaster: in adult body size, in allele frequency at allozyme loci, and in frequencies of common cosmopolitan inversions. The question is raised whether these latitudinal clines are causally related. This review aims to connect data from two very different fields of study, evolutionary biology and cell biology, in explaining such natural genetic variation in D.

Antagonistic pleiotropy for life-history traits at the gene expression level.

Life-history trade-offs prevent different components of fitness from being maximized simultaneously. Although the existence of trade-offs has been clearly demonstrated, the 'classical' mechanism of adaptive resource allocation that should underlie them has recently received criticism. In this study, we explore the molecular mechanisms of life-history trade-offs by applying a quantitative genomic approach.

Experimental evolution in Drosophila melanogaster: interaction of temperature and food quality selection regimes.

In Drosophila, both the phenotypic and evolutionary effect of temperature on adult size involves alterations to larval resource processing and affects other life-history traits, that is, development time but most notably, larval survival. Therefore, thermal evolution of adult body size might not be independent of simultaneous adaptation of larval traits to resource availability. Using experimental evolution lines adapted to high and low temperatures at different levels of food, we show that selection pressures interact in shaping larval resource processing.

Covariation of larval gene expression and adult body size in natural populations of Drosophila melanogaster.

Understanding adaptive phenotypic variation is one of the most fundamental problems in evolutionary biology. Genes involved in adaptation are most likely those that affect traits most intimately connected to fitness: life-history traits. The genetics of quantitative trait variation (including life histories) is still poorly understood, but several studies suggest that (1) quantitative variation might be the result of variation in gene expression, rather than protein evolution, and (2) natural variation in gene expression underlies adaptation.

DENSITY DEPENDENCE AND UNPREDICTABLE SELECTION IN A HETEROGENEOUS ENVIRONMENT: COMPROMISE AND POLYMORPHISM IN THE ESS REACTION NORM.

In quantitative genetic models of the evolution of reaction norms, an individual is selected in the habitat in which it develops; as a consequence, selection leads to the optimum phenotype in each habitat. Here, individuals are assumed to experience unpredictable habitat change between development and selection, so that the environment in which an individual is selected may differ from the environment in which it developed. The model reveals that unpredictability of the selection an individual actually faces leads to the evolutionarily stable bet-hedging reaction norm constituting a compromise between the phenotypic optima in the different patches.