Genetic differentiation of Rana temporaria from the Pyrenean and Cantabrian mountains in Spain was studied by means of allozyme electrophoresis. 24 loci were analysed in 104 specimens from 15 populations: nine populations from the Pyrenean massif, five populations from the area of the Cantabrian mountain chain (regions of Galicia, Asturias, and Basque Country), and one population from Germany. Three distinct clusters were distinguished by phenetic analysis: (a) the Pyrenean samples and the single population from the Basque Country, (b) the populations from Galicia and Asturias) and (c) the German population. Ordination (PCA) resulted in one principle component (PC1) that separated Cantabrian from Pyrenean populations, and in a second one (PC2) that separated the single German population from the Iberian ones. PC1 indicated introgression that was corroborated by west-east clines in several alleles along the Cantabrian chain. The rather clear separation of the Cantabrian and Pyrenean clusters (mean genetic distance 0.121) suggests that two genetically different subspecies of R. temporaria may be distinguished in Spain. The absence of fixed allelic differences between populations refutes recent hypotheses of the existence of syntopic sibling species within R. temporaria in Spain. Biogeographically, the Pyrenean and Cantabrian populations possibly originated in two separate colonisation events starting from different glacial refuges. The strong morphological differentiation of Pyrenean R. temporaria populations is not paralleled by genetic divergence, and may better be explained by ecological factors such as climate, altitude and vegetation.
The hexaploid barbel population of the species Labeobarbus fritschi
which lives in the Allal El Fassi dam reservoir in the north of Morocco showed an absence of males among a sample of 597 individuals analyzed in a first survey and among the 39 fish analyzed in this study. A possible explanation is that this population may be composed of females only and that
they reproduce either by gynogenesis or hybridogenesis, two processes triggered by hybridization with a sexually incompatible species (possibly the
sympatric barbel Luciobarbus setivimensis in this case). We used molecular markers to collect any information that could explain the phenomenon. To do this, numerous nuclear loci were screened (more than 50) in search of polymorphism. Genetic diversity was low as a possible consequence of clonal reproduction: only three allozymic and two intronic loci presented a sufficient level of polymorphism to be exploited. The existence of several copies of the same multilocus genotypes (1/3 of the fish) – with some showing a significantprobability of not being derived from sexual reproduction – provided evidence of unisexual reproduction. Deviations from panmixia as well as linkage equilibrium were also observed. Although preliminary, the data supports the hypothesis of the unisexual reproduction of females by way of gynogenesis rather than hybridogenesis.
The genetic structure and phenotypic diversity of two populations of Cheilosia aff. longula (Diptera: Syrphidae) in Lapland, Finland, were examined using DNA sequencing, protein electrophoresis, and geometric morphometrics. The morphological identification of the species were verified using partial sequences of mitochondrial cytochrome c oxidase subunit I (COI mtDNA), and the nuclear ribosomal internal transcribed region 2 (ITS2 rDNA), and comparing the corresponding sequences of Cheilosia aff. longula and the closely related C. longula. Two and three haplotypes of the genes COI mtDNA and ITS2 rDNA were identified in the two populations. Analysis of 12 isozyme loci showed an extremely low genetic variability in the populations originating from Utsjoki and Kevo. Discriminant analysis combined with canonical variate analysis revealed inter-population divergence in wing shape. Variation among genetically diverse individuals, both within- and among studied populations was studied, and directional (DA) and fluctuating asymmetry (FA) estimated using landmarks in the framework of geometric morphometrics. It is likely that the documented DA and FA asymmetry in both wing shape and size reflects the developmental instability of the individuals studied. By using Procrustes ANOVA the locations of particular landmarks responsible for the variation in shape were determined. The decomposition of the components of variance accorded to each landmark showed that the landmarks differed in the percentage of variation they accounted for (DA, FA and variation among individuals). In the discussion the implications of the reduced genetic diversity and asymmetry in wing traits for conservation is considered.
In this paper I review genetic studies of black grouse to date. The topics cover different areas such as reproductive biology, mating system and, more recently, conservation genetics. The accumulated evidence shows that in the western part of the range of the species, populations are genetically differentiated. Furthermore, small and isolated populations have lost genetic variation due to increased levels of inbreeding and genetic drift. So far the vast majority of studies have been based on microsatellites. More recent investigations have employed sequence data as well as methods to study quantitative trait variation. These latter studies may aid in resolving the issue of whether local populations show any evidence of being adapted to local conditions. This is an important consideration in conservation biology since it determines the extent to which populations are interchangeable and which populations should be used for restocking if such are considered of value.
Mice belonging to the Mus musculus species complex from the north-eastern Iranian Plateau (Khorasan province) have been genetically characterised for allozymic variation, mitochondrial DNA and Y chromosome type and compared with samples from other geographic regions. The present study shows the existence of a transition zone between pure M. m. musculus in the North and animals related to M. m. castaneus in the South. The origin of this transition (primary or secondary contact) and the various biogeographic scenarios about its origin are discussed in the light of these new data sets. The possible role of the Harirud valley in the geographic connection between Central Asia and the Middle East is discussed.
Genetic variation among populations of commensal house mice was studied across the territories of the Czech and Slovak Republics and in some adjacent areas of Germany. We used six diagnostic allozyme loci (Es-2, Gpd-1, Idh-1, Mpi, Np, Sod-1) and the following molecular markers: B1 insertion in the Btk gene (X chromosome), Zfy2 18-bp deletion (Y chromosome), BamH I restriction site in the mt-Nd1 gene (mtDNA) and Hba-4ps 16-bp insertion (diagnosing the presence of t haplotypes). In total, 544 individuals taken from 49 localities were examined. Almost the entire territories of the Czech Republic and Slovakia were found to be occupied by Mus musculus, the only exception being the westernmost parts of the Czech Republic, where M. musculus meets the range of M. domesticus and forms a narrow belt of hybrid populations. Despite this, domesticus-type alleles of some allozyme markers (notably Es-2) were also found at sites well within the range of M. musculus, either tens or hundreds of kilometres behind the hybrid zone. This provides evidence of either: (1) introgression of some markers into the species’ genome due to free gene flow through the zone, or (2) human-mediated long-distance migrations, or (3) incomplete lineage sorting. Conversely, variants of molecular markers typical for M. domesticus in Btk, Zfy2 and mt-Nd1were only found in the westernmost populations studied. t haplotypes were quite frequent in some populations, irrespective of whether M. domesticus, M. musculus or their hybrids, yet no t/t homozygotes were found. The mean frequency of t/+ heterozygotes found within the study populations was 13%.
An analysis of morphometric and bionomic data (as well as the genetic evidence discussed in a companion paper) clearly shows that Meligethes matronalis Audisio & Spornraft, 1990 and M. subaeneus Sturm, 1845 (members of the Meligethes coracinus complex: Coleoptera, Nitidulidae, Meligethinae), recently synonymised by Kirejtshuk (1997), are distinct species. The two species are also compared with the closely related M. coracinus Sturm, 1845. Meligethes matronalis is strictly associated with Hesperis matronalis L. (Brassicaceae) in early Summer, whereas the larvae of the frequently syntopic M. subaeneus develop on Cardamine spp. (Brassicaceae) in Spring; M. coracinus is a more polyphagous species, developing from early Spring to late Summer mostly on Brassica spp., Sinapis spp., Barbarea spp. and Sisymbrium spp. (Brassicaceae).
The phylogenetic relationships among Palaearctic species of the ant genus Tetramorium and its social parasites of the genera Strongylognathtus, Anergates and Teletomyrmex, were investigated electrophoretically at 21 presumptive enzyme loci. The data set comprising 33 species was analysed with distance (UPGMA, Neighbor-joining and least squares statistics) and parsimony methods (independent allele, minimum turnover and mutation coding) in order to rule out analysis-dependent effects. Several groupings were consistently resolved by all procedures. Observed branching patterns support the placement of the three parasite genera and their hosts into the Palaearctic species group of Tetramorium (tribe Tetramoriini). The genus Strongylognathus forms a monophyletic group in which the slave-makers of the S. huberi group constitute the sister group of the inquilines S. testaceus and S. karawajewi (S. testaceus group). Most species of the S. huberi group show very low genetic differentiation. However, little consensus has been found with regard to which Tetramorium species are the closest relatives of Strongylognathus.
According to the electrophoretic data, social parasitism in Palaearctic tetramoriine ants has evolved independently at least twice. Though inquilinism once arose from slave-making ancestors in Strongylognathus, the extreme inquilines Anergates atratulus and Teleutomyrmex schneideri are clearly set apart from the Strongylognathus clade in phylogenetic analyses. Thus, extreme inquilinism cannot be regarded as the endpoint of a single parasitic lineage in the Tetramoriini. In these highly advanced inquilines, evolutionary rates at allozyme loci appear to be higher than those of their Tetramorium hosts. The results do not unambiguously reveal whether Anergates and Teleutomyrmex arose jointly or independently from Tetramorium ancestors. However, a combined analysis using all available evidence supports the former hypothesis. The finding that the Tetramorium parasites are not the closest relatives of their respective host species is discussed in relation to current theories for the evolution of social parasitism.