Search results for "DISPERSAL"
showing 10 items of 465 documents
Spatial processes driving soil microbial community assembly on a wide scale
2012
International audience; Soil houses a huge biodiversity involved in ecological services through microbial community assembly. However, processes driving soil microbial community assembly are still scarcely understood, particularly the relative importance of environmental heterogeneity regarding to dispersal limitations. This can be achieved through studying the determinism of taxa-area relationship (TAR, how community composition change with geographic distance), a fundamental relationship in ecology. Here, a biogeographical approach was applied on a wide scale to evaluate TAR for soil bacterial and fungal communities and to partition their spatial variations into environmental heterogeneit…
El marcaje revela un intercambio limitado de inmaduros de tortuga boba (Caretta caretta) entre regiones en el Mediterráneo occidental
2008
Exchange of immature loggerhead sea turtles (Caretta caretta) between the northern and southern regions of the western Mediterranean was investigated using data obtained from several Spanish tagging programmes. Tagged turtles ranged in straight carapace length from 23.0 to 74.0 cm. Thirty-six turtles were recaptured after an average interval of 390.5±462.6 days (SD). As the mean dispersal distance (MDD) of a turtle population that spreads over the western Mediterranean would stabilize after 117 days (CI 95%: 98 to 149), two analyses were conducted that included data from turtles recaptured after 98 and 149 days respectively. In both analyses, turtles were recaptured more often than expected…
The phylogeny of the European high mountain genus Adenostyles (Asteraceae-Senecioneae) reveals that edaphic shifts coincide with dispersal events.
2013
UNLABELLED PREMISE OF THE STUDY Heterogeneity of edaphic conditions plays a large role in driving the diversification of many plant groups. In the Alps and other European high mountains, many closely related calcicole and calcifuge plant taxa exist. To better understand patterns and processes of edaphic differentiation, the phylogeny of the edaphically variable genus Adenostyles was studied. The genus contains three species, of which A. alpina has five subspecies. Each species and subspecies is largely confined to either calcareous or noncalcareous substrates. • METHODS We analyzed the phylogeny of Adenostyles using DNA sequences of nrITS, nrETS, nuclear chalcone synthase, and three plastid…
The acanthocephalan parasite Polymorphus minutus alters the geotactic and clinging behaviours of two sympatric amphipod hosts: the native Gammarus pu…
2005
Acanthocephala are parasites with complex life cycles involving arthropod intermediate hosts and vertebrate final hosts. They use predation as a means of transmission, and some species have developed the ability to modify behaviour of their intermediate hosts to enhance the probability of ingestion by the definitive host. Knowledge of how a single parasite species is adapted to modify the behaviour of different intermediate host species is important for the understanding of parasitic transmission in host communities. In Burgundy, the freshwater amphipod crustaceans Gammarus pulex (native species) and Gammarus roeseli (eastern European invader) are both intermediate hosts for the acanthoceph…
Evolutionary significance of the invasion of introduced populations into the native range of Meconopsis cambrica
2011
The long history of the deliberate or accidental and human-mediated dispersal of flowering plants has led to the introduction of foreign genotypes of many species into areas of Europe hitherto occupied by potentially distinct native populations. Studies of the genetic and evolutionary consequences of such changes are handicapped by the difficulty of identifying the surviving native populations of many species in the absence of clear morphological differences. We investigated the relationship between putative native and introduced populations of the herbaceous perennial Meconopsis cambrica (Papaveraceae), as the isolated native populations of this species can be identified by historical and …
What is the origin of the Scottish populations of the European endemic Cherleria sedoides (Caryophyllaceae)?
2015
Cherleria sedoides L. (Minuartia sedoides (L.) Hiern) is a montane perennial which, with some species in Minuartia sect. Spectabiles, is more closely related to Scleranthus than to other Minuartia species and is therefore best restored to the reinstated and redefined genus Cherleria. Reconstruction of the ancestral area of the clade containing C. sedoides suggests that it evolved in the Alps or the Balkan peninsula. The species now has an unusual distribution, being present in the mountains of southern Europe and Scotland but absent from the Arctic. Three historical scenarios that might have led to the presence of the species in Scotland are outlined and tested by a molecular analysis compa…
Restrictive mate choice criteria cause age-specific inbreeding in female black grouse, Tetrao tetrix
2012
Inbreeding is generally rare in large, natural populations yet mate choice often appears to be random with respect to kinship. This suggests that the risks of inbreeding may be small because passive mechanisms of inbreeding avoidance, for example dispersal, are effective at lowering inbreeding risk. Previous theoretical and empirical studies have assumed that the risks of inbreeding are constant over an individual’s life span, but in the lek-breeding black grouse, inbreeding increases with female age. To determine whether inbreeding avoidance mechanisms are also age dependent, we generated four null models of random mate choice ranging from complete randomness to more biologically realistic…
Chapter 2 Fasciola, Lymnaeids and Human Fascioliasis, with a Global Overview on Disease Transmission, Epidemiology, Evolutionary Genetics, Molecular …
2009
Abstract Fascioliasis, caused by liver fluke species of the genus Fasciola, has always been well recognized because of its high veterinary impact but it has been among the most neglected diseases for decades with regard to human infection. However, the increasing importance of human fascioliasis worldwide has re‐launched interest in fascioliasis. From the 1990s, many new concepts have been developed regarding human fascioliasis and these have furnished a new baseline for the human disease that is very different to a simple extrapolation from fascioliasis in livestock. Studies have shown that human fascioliasis presents marked heterogeneity, including different epidemiological situations and…
Correlations among fruit traits and evolution of different fruits within Melastomataceae
2000
Abstract The anatomy and morphology of nearly mature fruits in 85 mainly palaeotropical species of Melastomataceae were examined using microtome- and hand-sectioning, and differential staining. Much structural heterogeneity was observed in both capsules and berries. Multivariate analyses of 31 of the 52 characters recorded for each species, revealed that indehiscence is associated with fusion of ovary and hypanthium tissues, placenta persistence, lack of a persistent endocarp, and a dearth of sclereids in these tissues, while dehiscence is correlated with the opposite states and a persistent exocarp. Other fruit characters such as lignification or fleshiness of tissues do not show a consist…
Connectedness and connectivity of the Natura 2000 network of protected areas across country borders in the European Union
2012
Abstract We studied the spatial connectedness of Natura 2000 site boundaries and the functional connectivity of the Natura 2000 network across the 34 terrestrial borders of the European Union. Connectivity was measured by the dispersal success of 192 reptile, amphibian, invertebrate and plant species from Annex II of the European Union Habitats Directive, based on the presence of same species on both sides of the borders. Connectedness and connectivity varied greatly between state borders, with good and bad examples found in all parts of the European Union. Connectedness and connectivity were positively correlated. However, a few outlying examples showed that good connectedness is not neces…