Most natural populations of Drosophila melanogaster are polymorphic for two major electrophoretic variants at the esterase-6 locus. The frequency of the EST 6F allozyme is greatest in populations in warmer latitudes, whereas the EST 6S allozyme is predominant in colder latitudes. Latitudinal clines in electromorph frequencies are found on three continents. Purified preparations of the allozymes...

Species living in seasonal environments often adaptively time their reproduction in response to photoperiod cues. We characterized the expression of genes in the flowering-time regulatory network across wild populations of the common sunflower, Helianthus annuus, that we found to be adaptively differentiated for photoperiod response. The observed clinal variation was associated with changes at ...

Multiple stress resistance traits were investigated in the cactophilic fly Drosophila buzzatii. Adults from seven populations derived from North-Western Argentina were compared with respect to traits relevant for thermal stress resistance and for resistance to other forms of environmental stress. The populations were collected along an altitudinal gradient spanning more than 2000 m in height, s...

The association between fitness-related phenotypic traits and an environmental gradient offers one of the best opportunities to study the interplay between natural selection and migration. In cases in which specific genetic variants also show such clinal patterns, it may be possible to uncover the mutations responsible for local adaptation. The malaria vector, Anopheles gambiae, is associated w...

An analysis of sequence variation of 250 bp of the mitochondrial cytochrome b gene of 1278 Atlantic cod Gadus morhua ranging from Newfoundland to the Baltic shows four high-frequency (>8%) haplotypes and a number of rare and singleton haplotypes. Variation is primarily synonymous mutations. Natural selection acting directly on these variants is either absent or very weak. Common haplotypes show...

The objective of this study is to analyze patterns of genetic variation at genic expressed sequence tag – simple sequence repeats (EST-SSRs) and at chloroplast DNAmarkers in populations of American chestnut (Castanea dentata Borkh.) to assist in conservation and breeding efforts. Allelic diversity at EST-SSRs decreased significantly from southwest to northeast along the Appalachian range, sugge...

Traits related to local adaptation by definition show high phenotypic differentiation. The underlying genetic patterns could be clines at individual loci or small effects and extensive linkage disequilibrium at the underlying loci. In any case, including many populations in an analysis provides more information, but may simultaneously induce problems due to genetic structure. Even if the neutra...

Aim The goal of this study was to quantify levels of variation in spectral reflectance within and among populations of Dendrobates pumilio, the strawberry poison frog from the Bocas del Toro Archipelago. Location This study was carried out in the Bocas del Toro Archipelago, in the Republic of Panama, Central America. Methods Spectral reflectance was measured for samples of individuals from fift...

Parasitoid wasps are taxonomically and biologically extremely diverse. A conceptual framework has recently been developed for understanding life-history evolution and diversification in these animals, and it has confirmed that each of two linked life-history traits - the mode of larval development and the temporal pattern of egg maturation - acts as an organiser of life-history. The framework h...