Search results for " Distance"
showing 10 items of 696 documents
Adaptation to a seasonally varying environment: a strong latitudinal cline in reproductive diapause combined with high gene flow inDrosophila montana
2011
Adaptation to seasonal changes in the northern hemisphere includes an ability to predict the forthcoming cold season from gradual changes in environmental cues early enough to prepare for the harsh winter conditions. The magnitude and speed of changes in these cues vary between the latitudes, which induces strong selection pressures for local adaptation. We studied adaptation to seasonal changes in Drosophila montana, a northern maltfly, by defining the photoperiodic conditions leading to adult reproductive diapause along a latitudinal cline in Finland and by measuring genetic differentiation and the amount of gene flow between the sampling sites with microsatellites. Our data revealed a cl…
Effects of habitat fragmentation on the genetic structure of the monophagous butterfly Polyommatus coridon along its northern range margin
2004
Population genetic patterns of species at their range margin have important implications for species conservation. We performed allozyme electrophoresis of 19 loci to investigate patterns of the genetic structure of 17 populations (538 individuals) of the butterfly Polyommatus coridon, a monophagous habitat specialist with a patchy distribution. The butterfly and its larval food plant Hippocrepis comosa reach their northern distribution margin in the study region (southern Lower Saxony, Germany). Butterfly population size increased with host plant population size. The genetic differentiation between populations was low but significant (FST = 0.013). No isolation-by-distance was found. Hiera…
Microevolutionary relationships between phylogeographical history, climate change and morphological variability in the common vole (Microtus arvalis)…
2011
Aim In this study, we analyse microevolutionary processes in common voles (Microtus arvalis) through the investigation of tooth morphological structure, in order to assess the relative impact of climate and phylogeographical history. Microevolutionary studies have shown that climate change may play a role in both population phylogeography and phenotypic differentiation. However, relatively little is known about the precise relationship between phylogeography and phenotypic variability and about how organisms respond to climate change. Location France, from sea level to the Alps (5 to > 2300 m a.s.l.). Methods This morphological analysis is based on first lower molar measurements from 16 geo…
Effects of predation pressure and resource use on morphological divergence in omnivorous prey fish
2013
Background. Body shape is one of the most variable traits of organisms and responds to a broad array of local selective forces. In freshwater fish, divergent body shapes within single species have been repeatedly observed along the littoral-pelagic axes of lakes, where the structural complexity of near shore habitats provides a more diverse set of resources compared to the open-water zones. It remains poorly understood whether similar resource-driven polymorphism occurs among lakes that vary in structural complexity and predation pressure, and whether this variation is heritable. Here, we analyzed body shape in four populations of omnivorous roach (Rutilus rutilus) inhabiting shallow lakes.…
Does the genetic diversity among pubescent white oaks in southern Italy, Sicily and Sardinia islands support the current taxonomic classification?
2020
AbstractMolecular diversity analysis of deciduous pubescent oaks was conducted for populations from Calabria, Sicily and Sardinia. The aims of this study were twofold. First, to provide data on the genetic diversity of pubescent oaks from an understudied area which currently exhibits one of the highest concentrations of pubescent oak species in Europe. Second, to verify if these groups of oaks are genetically distinct and if their identification is in accordance with the current taxonomic classification. Molecular analyses of leaf material of 480 trees from seventeen populations belonging to putatively different pubescent oak species (Quercus amplifolia,Q. congesta,Q. dalechampii,Q. ichnusa…
Genetic relationships between Sicilian wild populations of Brassica analysed with RAPD markers
2001
Brassica comprises very variable species, both morphologically and genetically. Among these species, the Sicilian populations of Brassica sect. Brassica, species related to kale crops form a complex group. The genetic relationships among 15 populations occurring in Sicily and one from Calabria, representing the existing diversity, have been investigated using random amplified polymorphic DNA (RAPD) markers. This assay, carried out with 22 arbitrary primers, generated 236 polymorphic fragments, 21 of which were specific for single populations (mainly Brassica insularis, Brassica incana and Brassica macro-carpa). Jaccard's genetic distances were computed and the phylogenic tree was establishe…
Pleurotus opuntiae revisited e An insight to the phylogeny of dimitic Pleurotus species with emphasis on the P. djamor complex
2018
Abstract The name Pleurotus opuntiae is indiscriminately used for describing mushrooms with white to off-white to white-grey pilei with short or absent stipe and dimitic hyphal system, which grow on plants of the genera Opuntia, Yucca, Agave, Phytolacca etc. However, the outcome of the present study evidences that this name should be reserved for specimens deriving from the Mediterranean area only; an epitype originating from Italy on Opuntia ficus-indica is designated. Pertinent material was sequenced by using the internal transcribed spacer region (ITS) and found to be phylogenetically related to P. djamor from Kenya and Nigeria, while members of the P. djamor complex from other continent…
Whistle variation in Mediterranean common bottlenose dolphin: The role of geographical, anthropogenic, social, and behavioral factors.
2020
Abstract The studies on the variation of acoustic communication in different species have provided insight that genetics, geographic isolation, and adaptation to ecological and social conditions play important roles in the variability of acoustic signals. The dolphin whistles are communication signals that can vary significantly among and within populations. Although it is known that they are influenced by different environmental and social variables, the factors influencing the variation between populations have received scant attention. In the present study, we investigated the factors associated with the acoustic variability in the whistles of common bottlenose dolphin (Tursiops truncatu…
Fine-scale spatial genetic structure and gene dispersal in Silene latifolia
2010
Plants are sessile organisms, often characterized by limited dispersal. Seeds and pollen are the critical stages for gene flow. Here we investigate spatial genetic structure, gene dispersal and the relative contribution of pollen vs seed in the movement of genes in a stable metapopulation of the white campion Silene latifolia within its native range. This short-lived perennial plant is dioecious, has gravity-dispersed seeds and moth-mediated pollination. Direct measures of pollen dispersal suggested that large populations receive more pollen than small isolated populations and that most gene flow occurs within tens of meters. However, these studies were performed in the newly colonized rang…
Diversifying selection on MHC class I in the house sparrow (Passer domesticus).
2009
10 pages; International audience; Genes of the major histocompatibility complex (MHC) are the most polymorphic loci known in vertebrates. Two main hypotheses have been put forward to explain the maintenance of MHC diversity: pathogen-mediated selection and MHC-based mate choice. Host-parasite interactions can maintain MHC diversity via frequency-dependent selection, heterozygote advantage, and diversifying selection (spatially and/or temporally heterogeneous selection). In this study, we wished to investigate the nature of selection acting on the MHC class I across spatially structured populations of house sparrows (Passer domesticus) in France. To infer the nature of the selection, we comp…