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Distinct Evolutionary Lineages (distinct + evolutionary_lineage)
Selected AbstractsPopulation structure and history of southern African scrub hares, Lepus saxatilisJOURNAL OF ZOOLOGY, Issue 2 2004U. Kryger Abstract Genetic differentiation among populations of the South African scrub hare Lepus saxatilis was examined using hypervariable mitochondrial DNA control region I (CR-I) sequences. Neighbour-joining analysis revealed a pattern that did not correspond to the current subspecies delineations. The CR-I sequence data delimit scrub hares into three major maternal lineages. The three phylogenetic assemblages exhibited different geographical distributions. AMOVA analyses and exact tests for population differentiation confirmed this phylogeographic partitioning. One lineage (SW) was confined to the south-western Cape, the second lineage (N) was exclusively found in the northern part of South Africa and in the neighbouring countries, and the third lineage (C) was predominant in the central parts of South Africa. This spatial distribution did not coincide with the ranges of the 10 described subspecies covered by our sampling regime. The lineages C and N overlapped in an area including eastern parts of South Africa and southern Namibia. The presence of both lineages in that area of overlap was interpreted as the result of secondary contact due to recent range expansions after the two lineages had undergone a population restriction approximately 18 000 years ago. Analyses of contemporary gene flow disclosed an exchange of migrants between N and C, which was biased towards a movement from C to N. The SW group represents a very distinct evolutionary lineage that has been isolated for more than 45 000 years. It does not exchange female migrants with the other two groups. Mismatch distribution analyses indicated sudden population size expansions in the history of all three populations. [source] Polymorphisms in the sequences of Marteilia internal transcribed spacer region of the ribosomal RNA genes (ITS-1) in Spain: genetic types are not related with bivalve hostsJOURNAL OF FISH DISEASES, Issue 6 2005B Novoa Abstract Marteilia refringens is a protozoan parasite causing a disease notifiable to the Office International des Epizooties (OIE) and its distribution has implications for the transfer of live animals. The internal transcribed spacer-1 (ITS-1) from Marteilia clones contains polymorphism. Digestion with HhaI reveals two different restriction profiles, previously referred as ,O' (Marteilia from oyster or Marteilia refringens) and ,M' (Marteilia from mussels or Marteilia maurini). The aim of the present work was to determine whether the two previously described Marteilia molecular types (O and M) exist in the Iberian Peninsula and the strictness of the association with their bivalve host species. The sequence variability in the ITS-1 of Marteilia species was studied in mussels, Mytilus galloprovincialis, and flat oysters, Ostrea edulis, from different geographical locations in Spain, to establish the existence and the distribution of different species or molecular types. Although there were two distinct evolutionary lineages that corresponded more or less strictly with the ,M' and ,O' types, it was evident from the estimated phylogeny that some ,O' types have switched to ,M' type, and vice versa. Moreover, ,O' types were found in mussels and ,M' types were found in oysters, which suggests that there have been several cross-species transmissions of Marteilia between mussels and oysters. [source] Evolutionary history of lamprey paired species Lampetra fluviatilis (L.) and Lampetra planeri (Bloch) as inferred from mitochondrial DNA variationMOLECULAR ECOLOGY, Issue 9 2007RUTE ESPANHOL Abstract A remarkable trend in the evolution of lampreys is the occurrence in most genera of ,paired species', in which the parasitic anadromous lampreys are believed to have given rise to nonparasitic freshwater resident populations. The present work examines the phylogeography of the European paired species Lampetra fluviatilis and Lampetra planeri, in an attempt to elucidate species pair evolutionary history. We studied sequence variation in cytochrome b and ATPase 6, 8 mitochondrial genes in 63 individuals from 21 localities of the paired species throughout their distribution range. Results from the phylogenetic and nested clade analyses were largely consistent, suggesting the existence of three major evolutionary lineages: lineage I and possibly lineage II are widespread throughout Europe, while the most ancestral lineage III is apparently restricted to the Iberian Peninsula. The high genetic diversity observed in the Iberian Peninsula is probably the result of refugial persistence and subsequent accumulation of variation over several ice ages, whereas the low levels of genetic diversity observed in central and northern Europe should reflect a rapid postglacial colonization. Results suggest that L. planeri originated within at least two distinct evolutionary lineages, rejecting the single origin hypothesis. The observed lack of taxa monophyly within lineage I may be the result of ongoing gene flow if the two taxa are alternate life-history forms of a single species. However, structure within lineage I is also consistent with the hypothesis of divergence of taxa after postglacial dispersion (around 2000 generations ago) with incomplete lineage sorting. Further testing of the alternative hypotheses is warranted. [source] Testing hypotheses of speciation in the Plethodon jordani species complex with allozymes and mitochondrial DNA sequencesBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2006DAVID W. WEISROCK Salamander populations of the Plethodon jordani species complex form a challenging system for applying the general lineage concept of species to diagnose population-level lineages. The present study reports and analyses mitochondrial-DNA haplotypes (,1200 nucleotide bases from the genes encoding ND2, tRNATrp, and tRNAAla from 438 salamanders) from 100 populations representing six species of the P. jordani complex (Plethodon amplus, Plethodon cheoah, Plethodon jordani, Plethodon meridianus, Plethodon metcalfi, and Plethodon montanus) with comparative analyses of previously published allozymic data to reconstruct the evolutionary history of this group and to diagnose species lineages. Analyses of mitochondrial haplotypic data include nested-cladistic analysis of phylogeography, analysis of molecular variance, hierarchical analysis of nucleotide-diversity measures, and likelihood-based estimates of recent temporal changes in population size. New analyses of allozymic data include multidimensional scaling and principal component analyses, and both data sets are analysed and compared for congruent genetic structure using Mantel correlation tests. These analyses in combination identify the six named species as distinct evolutionary lineages despite sporadic genetic exchanges among them and some discordance between mitochondrial DNA and allozymic markers. Sexual isolation is not complete for any pair of these six species, but they replace each other geographically and appear to block the geographical spreading of their neighbours. The P. jordani complex is a strong study system for investigating the genetic and ecological processes responsible for vicariant speciation. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 89, 25,51. [source] | ||||||||||