Search results for "gene flow"

Origin and phylogeography of the Chagas disease main vector Triatoma infestans based on nuclear rDNA sequences and genome size

2004

For about half of all Chagas disease cases T. infestans has been the responsible vector. Contributing to its genetic knowledge will increase Our understanding of the capacity of geographic expansion and domiciliation of triatomines. Populations of all infestans subcomplex species, T. infestans, T. delpontei, T. platensis and T. melanosoma and the so-called T. infestans "dark morph", from many South American countries were studied. A total of 10 and 7 different ITS-2 and ITS-1 haplotypes, respectively, were found. The total intraspecific ITS-2 nucleotide variability detected in T. infestans is the highest hitherto known in triatomines. ITS-1 minisatellites, detected for the first time in tri…

Geographic distribution and seasonal variation of mitochondrial DNA haplotypes in the aphidRhopalosiphum padi(Hemiptera: Aphididae)

1997

AbstractThis study examines the spatial and seasonal patterning of mitochondrial DNA diversity in French populations of the bird cherry-oat aphid,Rhopalosiphum padi(Linnaeus), on both its primary and secondary hosts. Our results confirm the presence of two major mitochondrial lineages that are generally associated with the breeding system variation (cyclic and obligate parthenogenesis) shown by this species. The strength of this relationship varies regionally, being most evident in the south and west. Cyclically parthenogenetic populations show no significant regional or seasonal genetic divergence reflecting high levels of gene flow, possibly promoted by their obligate host-alternation. Ho…

Differential Greek and northern African migrations to Sicily are supported by genetic evidence from the Y chromosome

2009

The presence or absence of genetic heterogeneity in Sicily has long been debated. Through the analysis of the variation of Y-chromosome lineages, using the combination of haplogroups and short tandem repeats from several areas of Sicily, we show that traces of genetic flows occurred in the island, due to ancient Greek colonization and to northern African contributions, are still visible on the basis of the distribution of some lineages. The genetic contribution of Greek chromosomes to the Sicilian gene pool is estimated to be about 37% whereas the contribution of North African populations is estimated to be around 6%. In particular, the presence of a modal haplotype coming from the southern…

Early human peopling of Sicily: Evidence from the Mesolithic skeletal remains from Grotta d'Oriente

2010

The site of Grotta d'Oriente, Island of Favignana, Sicily has yielded the complete skeleton of an adult female (OB) dated to the Mesolithic age. The cranial morphometry of this individual can provide us with some useful information about the peopling of Sicily in the Early Holocene period.Morphological affinities of OB and other Sicilian Mesolithic specimens were assessed to verify hypotheses concerning the early peopling of Sicily.Craniofacial metric data were employed in a comparative analysis with European Upper Palaeolithic (UP), Mesolithic, Neolithic, and Copper/Bronze age samples, and contemporary Italians. Both a model-free and a model-bound approach were used not only to calculate c…

Population differentiation in the marginal populations of the great tit (Paridae: Parus major)

2007

The major subspecies group of the great tit, Parus major, has experienced demographic and spatial expansions during the last century in several sites at the edges of its distribution range. These expansions, although temporarily very even, have resulted in dissimilar patterns of molecular diversity. Populations locating at regions of contact to other subspecies groups (in Amur, Kirghizia–Kazakhstan, and Iran) show divergence from central population by nuclear and mitochondrial markers. In Amur, gene flow from minor group could be detected based on the existence of private minor alleles in the major population. In Kirghizia and Kazakhstan, the bokharensis and major groups share almost all th…

Genetic and morphological differentiation in Tephritis bardanae (Diptera: Tephritidae): evidence for host-race formation

2003

The fruit fly Tephritis bardanae infests flower heads of two burdock hosts, Arctium tomentosum and A. minus. Observations suggest host-associated mating and behavioural differences at oviposition indicating host-race status. Previously, flies from each host plant were found to differ slightly in allozyme allele frequencies, but these differences could as well be explained by geographical separation of host plants. In the present study, we explicitly test whether genetic and morphological variance among T. bardanae are explained best by host-plant association or by geographical location, and if this pattern is stable over a 10-year period. Populations of A. tomentosum flies differed signific…

The geography of hybrid speciation in plants

2015

Population genomics of wall lizards reflects the dynamic history of the Mediterranean Basin

2021

AbstractThe Mediterranean Basin has experienced extensive change in geology and climate over the past six million years. Yet, the relative importance of key geological events for the distribution and genetic structure of the Mediterranean fauna remains poorly understood. Here, we use population genomic and phylogenomic analyses to establish the evolutionary history and genetic structure of common wall lizards (Podarcis muralis). This species is particularly informative because, in contrast to other Mediterranean lizards, it is widespread across the Iberian, Italian, and Balkan peninsulas, and in extra-Mediterranean regions. We found strong support for six major lineages within P. muralis, w…

The genetic structure of Norway

2020

AbstractThe aim of the present study was to describe the genetic structure of the Norwegian population using genotypes from 6369 unrelated individuals with detailed information about places of residence. Using standard single marker- and haplotype-based approaches, we report evidence of two regions with distinctive patterns of genetic variation, one in the far northeast, and another in the south of Norway, as indicated by fixation indices, haplotype sharing, homozygosity, and effective population size. We detect and quantify a component of Uralic Sami ancestry that is enriched in the North. On a finer scale, we find that rates of migration have been affected by topography like mountain ridg…

Widespread secondary contact and new glacial refugia in the halophilic rotifer Brachionus plicatilis in the Iberian Peninsula.

2011

Small aquatic organisms harbour deep phylogeographic patterns and highly structured populations even at local scales. These patterns indicate restricted gene flow, despite these organisms' high dispersal abilities, and have been explained by a combination of (1) strong founder effects due to rapidly growing populations and very large population sizes, and (2) the development of diapausing egg banks and local adaptation, resulting in low effective gene flow, what is known as the Monopolization hypothesis. In this study, we build up on our understanding of the mitochondrial phylogeography of the halophilic rotifer Brachionus plicatilis in the Iberian Peninsula by both increasing the number of…