The Iceland population of Anguilla eels contains an elevated frequency of fish with vertebral numbers lower than those typical of European localities. Several distinct hypotheses have been advanced to account for these morphologically atypical fish: for example, they could represent (1) genetically "pure" American expatriates, (2) genetically "pure" European types with ontogenetic abnormalities...

Hermaphrodite tropical freshwater snails provide a good opportunity to study the effects of mating system and genetic drift on population genetic structure because they are self-fertile and they occupy transient patchily distributed habitats (ponds). Up to now the lack of detectable allozyme polymorphism prevented any intrapopulation studies. In this paper, we examine the consequences of selfin...

The study of the European plethodontid salamander Hydromantes strinatii using allozyme and mitochondrial markers showed a strong geographical genetic structure. This was likely the outcome of different evolutionary mechanisms leaving their signature despite the effects of the genetic drift due to the low population size typical of this species. Two highly divergent clades were identified in the...

The E and Z pheromone strains of the European corn borer (ECB) provide an exceptional model system for examining the genetic basis of sexual isolation. Differences at two major genes account for variation in female pheromone production and male behavioral response, components of the pheromone communication system known to be important for mate recognition and mate choice. Strains of ECB are mor...

Understanding the origin, maintenance and significance of phenotypic variation is one of the central issues in evolutionary biology. An ongoing discussion focuses on the relative roles of isolation and selection as being at the heart of genetically based spatial variation. We address this issue in a representative of a taxon group in which isolation is unlikely: a marine broadcast spawning inve...

Most tributaries of the Río Fuerte in northwestern Mexico contain one or more clones of allotriploid fish of the genus Poeciliopsis. We used multilocus allozyme genotypes and mitochondrial DNA (mtDNA) haplotypes to examine several potential modes of origin of these gynogenetic all-female fish. The allozyme studies corroborated earlier morphological work revealing the hybrid constitution of two ...

DNA samples from 980 plants of Avena barbata from 48 ecologically diverse sites in California and Oregon were assayed to determine their genotype for two duplicated loci governing rDNA variants. More than 40 different rDNA genotypes were observed among which 5 made up 96% of our sample in environmentally homogeneous sites; predominant genotypes were less frequent and recombinant genotypes were ...

Physalaemus pustulosus, a small leptodactylid frog with South American affinities, ranges across northern South America through Middle America to southern Mexico. To investigate its geographic variation and evolutionary origins, we analysed the presumptive gene products of 14 allozyme loci and sequenced a portion of the mitochondrial COI gene from individuals sampled throughout the distribution...

Population genetic characteristics of mummichog, Fundulus heteroclitus, from the heavily industrialized Elizabeth River and nearby York River (Virginia USA) were assessed relative to sediment PAH concentrations. Allozyme genotype frequencies for all loci were consistent with random mating expectations at each locality and age class. Fish from all sites had comparable levels of enzyme polymorphi...

Identifying the amino acid changes responsible for electrophoretic variants is essential to understanding the significance of allozyme polymorphism in adaptation. The amino acid mutations responsible for the common G6PD allozyme polymorphisms in Drosophila melanogaster have been recently described. This study characterizes the amino acid changes associated with 11 rare electrophoretic G6PD vari...