Schematic representation of STR mutations and their possible impact on phenotype. STR mutations frequently arise from misalignment of DNA strands. Strand misalignment may lead to expansions or contractions in repeat copy number depending on which strand the loop forms on (four different mechanisms are represented on top). Many STRs show length-dependent mutation rates, which can result in bimodal allele length distributions (bottom left). STRs positioned upstream of a gene's transcription start site are depicted at the bottom. Green boxes indicate STR units and black boxes indicate SNPs. The number of green boxes shows the STR copy number of different alleles. This variation serves as the y-axis of the gene expression graph and the phenotype graph on the right side.

Haldane's rule: when hybrids from one sex are absent, rare or sterile, that sex is always the heterogametic sex.

Biased sex ratio appears to create an opportunity for a rare allele to increase, but it does not mean that drift is directional if you do the maths.

Divergent artificial selection experiment on male courtship song parameter Inter-Pulse-Interval (IPI) in Drosophila mahican allowed us to test the effect of divergence on other fitness and behavioral traits.

Genetic differentiation and plastic responses of the southern population of landmarks affecting genetic and plastic wing shape difference. The arrows show how each landmark changes in direction.

We studied head shape variation in natricine snakes with respect to ecology. Using a phylogenetic framework, we test the hypotheses that natricine head shape variation is explained by variation in habit and diet and evaluate evidence for ecomorphs within the group. We quantified morphological similarity and disparity in head shape among 191 of the ca. 250 currently recognized natricine species and applied phylogenetic comparative methods to test for convergence. Natricine head shape is largely correlated with habit but in some burrowers is better explained by dietary specialism. Convergence in head shape is especially strong for aquatic burrowing, semiaquatic and terrestrial ecomorphs and less strong for aquatic and burrowing ecomorphs.

Female with black scarring from an abdominal wound inflicted by a male during a sexual interaction.

When comparing somatic growth thermal performance curves (TPCs), higher somatic growth across experimental temperatures is often observed for populations originating from colder environments. Such countergradient variation has been suggested to represent adaptation to seasonality. Using modelling, we show that this conclusion is based on assumptions that may not always be satisfied. We illustrate this by quantifying TPCs for three populations of Daphnia magna where detailed information can be used to predict how somatic growth TPCs may translate into population growth TPCs.

We investigated the predictors of the genetic diversity (GD) in crabs (Brachyura) by analysing 16992 cytochrome c oxidase subunit I (COI) sequences across the crab tree of life. We tested the effect of life-history and demographic variables (fecundity, body size, propagule size, number of larval stages and larval development time, signals of population expansion, maximum longevity, and habitat) that potentially influence GD across species. Our results indicate that population size fluctuation represents the most critical trait predicting GD, with species that have undergone bottlenecks followed by population expansion showing lower GD. Egg size, pelagic larval duration, and habitat might play a role probably because of their association with how species respond to disturbances.

In large populations, disadvantageous mutants can persist around a steady state, determined by the rate of mutant production and the selective disadvantage (selection-mutation balance). In a fragmented system that consists of subpopulations connected by migration, a steady-state persistence of disadvantageous mutants is also observed, which, however, is fundamentally different from the mutation-selection balance and characterized by higher mutant levels.

Habitat influence in acoustic divergence.

Sex differences in lifespan are ubiquitous across the tree of life, and exhibit broad taxonomic patterns that remain a puzzle. Here, we first analysed sex differences in lifespan across 136 species of birds, mammals, reptiles and amphibians to show that genetic determination system is clearly linked with the sex gap in lifespan (Figure). Bars above the black line (the red ring) indicate that females live longer than males, while bars below the black line (the blue ring) indicate that males live longer than females; the log transformed ratio of female and male lifespan (lnR) is plotted for each species. ZW systems are coloured in blue and XY systems are coloured in red. Across six independent origins of both ZW (blue circles) and XY (red circles) systems, females tend to live longer lifespans in species with XY systems and vice versa in ZW systems. Second, we analysed whether the relative sizes of the sex chromosomes co-vary with sex-specific ageing. In line with the idea that sex differences in lifespan can be driven by the degeneration of the heteromorphic sex chromosome (the toxic Y hypothesis), we found that the relative size of the Y is negatively associated with male lifespan in mammals, so that small Y size correlates with increased male lifespan.