Time constraints cause strong selection on life-history traits, because populations need to complete their life cycles within a shorter time. We therefore expect lower genetic variation in these traits in high- than in low-latitude populations, since the former are more time-constrained. The aim was to estimate life-history traits and their genetic variation in an obligately univoltine damselfly along a latitudinal gradient of 2730 km. Populations were grown in the laboratory at temperatures and photoperiods simulating those at their place of origin. In a complementary experiment, individuals from the same families were grown in constant temperature and photoperiod that mimicked average conditions across the latitude. Development time and size was faster and smaller, respectively, and growth rate was higher at northern latitudes. Additive genetic variance was very low for life-history traits, and estimates for egg development time and larval growth rate showed significant decreases towards northern latitudes. The expression of genetic effects in life-history traits differed considerably when individuals were grown in constant rather than simulated and naturally variable conditions. Our results support strong selection by time constraints. They also highlight the importance of growing organisms in their native environment for correct estimates of genetic variance at their place of origin. Our results also suggest that the evolutionary potential of life-history traits is very low at northern compared to southern latitudes, but that changes in climate could alter this pattern.

In order to predict evolutionary responses to environmental changes one needs to identify the evolutionary potential in terms of genetic variation of traits and of the traits' plasticity. We studied genetic variance in life history traits and their reaction norms in response to manipulated photoperiods in central, northern, and northernmost peripheral populations of the damselfly Lestes sponsa (Hansemann). After the central‐marginal hypothesis, it is predicted that central populations will express the highest genetic variance. Northern and northernmost populations showed the highest development and growth rates. All populations expressed shorter development and accelerated growth when raised in a northern compared with a central latitude photoperiod. The slopes of reaction norms differed between regions resulting in a region‐by‐photoperiod interaction. There was genetic variation in development time; however, it did not differ across regions. There was no genetic variation in growth rate or in the plasticity of development time and growth rate to photoperiod. Results did not support the central‐marginal hypothesis. However, evidence was found that the development time has the potential to evolve at similar rates across study regions. In contrast, the growth rate seems to be genetically constrained for further evolution, probably because of a strong past directional selection on this trait. The presence of low genetic variation in the slope of the reaction norms could be a result of stabilising selection imposed by seasonality.

It is well recognised in psychology that music has affective connotations and that musical stimuli can modify affective states. The aim of this study was to assess the affective connotations of 120 fifteen-second musical excerpts, covering both modern musical genres such as pop, rock, jazz, rap/R&B and electronic music (5 x N = 20), and classical music ( N = 20). Expert judges used predetermined criteria to select excerpts with positive or negative valence that induced high arousal or low arousal. The excerpts were assessed by 50 undergraduate students (25 women) from different academic departments, aged between 18 and 28 years ( M = 21.46 years, SD = 1.85). They listened to all 120 fragments and rated them with respect to six dimensions: valence, arousal, dominance, origin, subjective significance and imageability. Analyses showed that ratings were reliable, with high split-half correlations and Cronbach’s alpha estimates. We did not identify any gender differences concerning affective reactions to the music. Some music genre specificity was found for all measures, and initial music preference appeared to shape affective ratings. The results presented here will be of interest to researchers working on musical perception and the influence of music on affective outcomes and emotional regulation.