RESUMO
The aoudad or Barbary sheep (Ammotragus lervia) is a threatened ungulate emblematic of North Africa, whose population structure and subspecific taxonomy have not been examined genetically. This knowledge is essential and urgently needed to inform ongoing conservation and management efforts. We analysed the mitochondrial cytochrome b gene and four nuclear genes (casein kappa, spectrin beta nonerythrocytic 1, thyroglobulin, thyrotropin subunit beta) for the first phylogeographic survey of the aoudad, and uncovered a deep Mediterranean-Saharan mitochondrial split separating two highly distinct evolutionary lineages. Their level of divergence is greater than or comparable to those observed between several pairs of congeneric species of different caprine genera. The split was estimated to have occurred in the Early Pleistocene, about 1.3 million years ago. None of the four nuclear genes surveyed, chosen because they have been used in phylogeographic and species-level phylogenetic studies of bovids, allowed us to detect, likely due to their slow evolutionary rate, the substantial and geographically coherent subdivision revealed by mitochondrial DNA. This study is evidence and testament to the ability of mitochondrial DNA, probably unrivalled by any other single-locus marker, as an exploratory tool for investigating population genealogy and history and identifying potential evolutionarily significant units for conservation in animals.
Assuntos
Ruminantes/genética , África do Norte , Animais , Evolução Biológica , Classificação , Conservação dos Recursos Naturais , DNA Mitocondrial/genética , Espécies em Perigo de Extinção , Mitocôndrias/genética , Filogeografia , Ruminantes/classificaçãoRESUMO
Phylogenetic relationships and biogeographical patterns of the genus Luciobarbus in Algeria were investigated by analysing the complete cytochrome b sequence variation. With regard to species of the Maghreb Province and the Iberian Peninsula, phylogenetic analysis resulted in five strongly supported clades and a non-monophyletic origin for the Algerian populations. The present study supports the existence of two distinct lineages of L. setivimensis which could have diverged posterior to the emplacement of the Kabylides onto the African margin. Analysis of the 48 haplotypes detected within populations showed a clear phylogeographic structure strongly correlated with species' geographical distribution. Two haplotypes were found to be shared between different species attesting the possibility that an introgression would have occurred within the genus Luciobarbus in Algeria. The divergence time estimate suggests a rapid radiation of the genus Luciobarbus in Algeria and a pattern of distribution of populations shaped under paleogeographic conditions such as the tectonic dynamics which have led to the change in the geographic configuration of North Africa at the end of Miocene, the formation of the current fluvial basins' net in the Pliocene as well as the end of the Tell System building in the Pleistocene which seems to have played an important role in the speciation of this genus.
Assuntos
Cyprinidae/genética , DNA Mitocondrial/genética , Filogenia , Polimorfismo Genético , Animais , Cyprinidae/classificação , Especiação Genética , Haplótipos , FilogeografiaRESUMO
Traditional subspecies call attention to differences between geographic populations with research potential, but their value is often in need of revision. Genetic data can be useful for evaluating the taxonomic validity of historical species and subspecies designations or for identifying morphologically cryptic divergent lineages worthy of further in-depth taxonomic study. The desert hedgehog (Paraechinus aethiopicus) has a wide but fragmented distribution in arid and semi-arid habitats from the northwest to the northeast of Africa and southwestern Asia, and its taxonomy is still unclear. We used mitochondrial (cytochrome b, Cyt b, and 12S ribosomal RNA, 12S) and nuclear (breast cancer type 1 susceptibility protein, BRCA1, and apolipoprotein B, Apob) DNA sequence data to assess the degree of genetic divergence between two of its three major proposed subspecies: Arabian (P. a. dorsalis) and Northwest African (P. a. deserti); this is the first molecular evaluation of the taxonomy of P. aethiopicus. Phylogenetic analyses, comparison of interspecific and intraspecific genetic distances observed across hedgehog species, and molecular species delimitation methods (distance-based clustering and tree-based), all indicate a level of genetic differentiation between dorsalis and deserti that is compatible with their taxonomic separation. Their divergence in the studied genes were consistently comparable to, or greater than, several intrageneric and a few intergeneric distances in hedgehogs. The Cyt b net Kimura 2-parameter distance between dorsalis and deserti was 10.8±1.3%, which is about the mean between congeneric species in reviews of Cyt b distances for mammals. This study, as a test of the genetic distinctiveness of dorsalis and deserti, suggests that they represent evolutionarily significant units and flags them for future phylogeographic and taxonomic investigations.
Assuntos
Especiação Genética , Ouriços/genética , África , Animais , Apolipoproteínas B/genética , Proteína BRCA1/genética , Citocromos b/genética , Evolução Molecular , Ouriços/classificação , Filogenia , RNA Ribossômico/genéticaRESUMO
The common frog Rana temporaria is characterised by a large variety of colorations and dorsal patterns manifested by a V-shaped spot, which differs in the form, the number of elements and in the regularity. Some populations of R. temporaria are polymorphic for B-chromosome. V-shaped spot asymmetry and B-chromosome occurrence was studied in seven R. temporaria populations inventoried from Belarus country. The analysis of the dorsal V-shaped spot pattern asymmetry in brown frog populations implies that the persistence of additional chromosomes in populations may be one of the factors disturbing the developmental stability of some individuals. Although, Bs may confer some selective advantage to their carriers, which makes them react differently to environmental changes from do non-carriers.