The traits involved in sexual selection, such as male secondary sexual characteristics and female mate choice, often co-evolve which can promote population differentiation. However, the genetic architecture of these phenotypes can influence their evolvability and thereby affect the divergence of species. The extraordinary diversity of East African cichlid fishes is often attributed to strong se...

Differences in seasonal migration might promote reproductive isolation and differentiation by causing populations in migratory divides to arrive on the breeding grounds at different times and/or produce hybrids that take inferior migratory routes. We examined this question by quantifying divergence in song, colour, and morphology between sister pairs of North American migratory birds. We predic...

Adaptive speciation occurs when frequency-dependent ecological interactions generate conditions of disruptive selection to which lineage splitting is an adaptive response. Under such selective conditions, evolution of assortative mating mechanisms enables the break-up of the ancestral lineage into diverging and reproductively isolated descendent species. Extending previous studies, I investigat...

Crossing experiments indicate that hybrid sterility barriers frequently have developed within diploid, circumpolar plant species of the genus Draba. To gain insight into the rapid evolution of postzygotic reproductive isolation in this system, we augmented the linkage map of one of these species, D. nivalis, and searched for quantitative trait loci (QTLs) associated with reproductive isolation....

Knowing how hosts respond to parasite infection is paramount in understanding the effects of parasites on host populations and hence host-parasite co-evolution. Modification of life-history traits in response to parasitism has received less attention than other defence strategies. Life-history theory predicts that parasitised hosts will increase reproductive effort and accelerate reproduction. ...

Introduction. Cow longevity is one of the most economically important traits in the beef cow. Longevity is inter-related to other important traits, and, therefore, it is difficult to separate the importance of longevity, itself, from the importance of traits that are related to longevity. For example, reproductive performance is usually part of the culling criteria. It is often stated that repr...

this is the first description of the polymorphisms of arylalkylamine-n-acetyltransferase (aa-nat) gene in indian goats with different reproductive traits (twinning percentage and age of sexual maturity). based on the important role of aa-nat in reproduction, it is considered as a possible candidate gene for this trait. two novel synonymous snps, c825t (exon2) and c1249t (exon3) were identified....

This is the first description of the polymorphisms of arylalkylamine-N-acetyltransferase (AA-NAT) gene in Indian goats with different reproductive traits (twinning percentage and age of sexual maturity). Based on the important role of AA-NAT in reproduction, it is considered as a possible candidate gene for this trait. Two novel synonymous SNPs, C825T (exon2) and C1249T (exon3) were identified....

Many studies have attempted to account for variation in male reproductive success by quantifying a single trait such as an ornament or a behavior, but male reproductive performance may be determined by a number of interacting traits. Although developmental nutrition is often a major determinant of adult body size and secondary sexual trait expression, other factors—such as residual shape variat...