We analyzed two morpho-species, Astyanax aeneus and Astyanax caballeroi , coexisting in Lake Catemaco, with ecological differences previously associated with different trophic niches. While A. aeneus is a widely distributed species, A. caballeroi is endemic to Lake Catemaco. Due to the contrasting morphology between these two sympatric species, they were originally assigned to different genera, but little is known about their...

Genic copy number differences can have phenotypic consequences, but so far this has not been studied in detail in natural populations. Here, we analysed the natural variation of two families of tandemly repeated regulatory small nucleolar RNAs (SNORD115 and SNORD116) in the house mouse ( Mus musculus ). They are encoded within the Prader‐Willi Syndrome gene region, known to be involved in behavioural, metabolic, and osteogenic...

Pupation site choice of Drosophila third‐instar larvae is critical for the survival of individuals, as pupae are exposed to various biotic and abiotic dangers while immobilized during the 3–4 days of metamorphosis. This singular behavioural choice is sensitive to both environmental and genetic factors. Here, we developed a high‐throughput phenotyping approach to assay the variation in pupation height in Drosophila melanogaster...

Poleward range expansions are commonly attributed to global change, but could alternatively be driven by rapid evolutionary adaptation. A well‐documented example of a range expansion during the past decades is provided by the European wasp spider A rgiope bruennichi . Using ecological niche modeling, thermal tolerance experiments and a genome‐wide analysis of gene expression divergence, we show that invasive populations have a...

The identification of the genes involved in morphological variation in nature is still a major challenge. Here, we explore a new approach: we combine 178 samples from a natural hybrid zone between two subspecies of the house mouse ( Mus musculus domesticus and Mus musculus musculus ), and high coverage of the genome (~ 145K SNPs) to identify loci underlying craniofacial shape variation. Due to the long history of recombination...

The evolutionary divergence of cues for mate recognition can contribute to early stages of population separation. We compare here two allopatric populations of house mice ( M us musculus domesticus ) that have become separated about 3000 years ago. We have used paternity assignments in semi‐natural environments to study the degree of mutual mate recognition according to population origin under conditions of free choice and ove...

Poleward range expansions are observed for an increasing number of species, which may be an effect of global warming during the past decades. However, it is still not clear in how far these expansions reflect simple geographical shifts of species ranges, or whether new genetic adaptations play a role as well. Here, we analyse the expansion of the wasp spider A rgiope bruennichi into N orthern E urope during the last century. W...

Homoploid hybridization after secondary contact between related species can lead to mixtures of genotypes which have the potential for rapid adaptation to new environmental conditions. Here, we focus on a case where anthropogenic changes within the past 200 years have allowed the hybridization between two fish species ( Cottus rhenanus and Cottus perifretum ) in the Netherlands. Specifically, we address the question of the dyn...

Recent advances in sequencing technology promise to provide new strategies for studying population differentiation and speciation phenomena in their earliest phases. We focus here on the black carrion crow ( Corvus [corone] corone ), which forms a zone of hybridization and overlap with the grey coated hooded crow ( Corvus [corone] cornix ). However, although these semispecies are taxonomically distinct, previous analyses based...

Mechanisms and processes of ecologically driven adaptive speciation are best studied in natural situations where the splitting process is still occurring, i.e. before complete reproductive isolation is achieved. Here, we present a case of an early stage of adaptive differentiation under sympatric conditions in the fire salamander, Salamandra salamandra, that allows inferring the underlying processes for the split. Larvae of S....

In order to assess the significance of local adaptation relative to environmental plasticity on the evolution of life history traits, we analysed the possible genetic basis of differences between pond‐ and stream‐breeding fire salamanders ( Salamandra salamandra ) in Germany. These salamanders typically deposit their larvae in small streams, where they grow until they are sufficiently large to metamorphose. However, some popul...

There is a long tradition of artificially stocking lakes and rivers with fish in the hope to increase the quality and amount of fish that can be harvested. The animals used for stocking often originate in distant hatcheries or hatcheries that breed fish from remote regions. This stocking practice could have effects on the genetic integrity of resident populations. We have analysed here a case of the influence of stocking on Al...

Although there is mounting evidence that speciation can occur under sympatric conditions, unambiguous examples from nature are rare and it is almost always possible to propose alternative allopatric or parapatric scenarios. To identify an unequivocal case of sympatric speciation it is, therefore, necessary to analyse natural settings where recent monophyletic species flocks have evolved within a small and confined spatial rang...

Representatives of the genus Salamandra occur in Europe, Northern Africa and the Near East. Many local variants are known but species and subspecies status of these is still a matter of dispute. We have analysed samples from locations covering the whole expansion range of Salamandra by sequence analysis of mitochondrial D‐loop regions. In addition, we have calibrated the rate of divergence of the D‐loop on the basis of geologi...