Home About us Contact
|
Home About us Contact | ||
|
|
||
Low Dispersal Abilities (low + dispersal_ability)
Selected AbstractsPleistocene phylogeography and phylogenetic concordance in cold-adapted spring snails (Bythinella spp.)MOLECULAR ECOLOGY, Issue 5 2009M. BENKE Abstract Previous studies on Pleistocene phylogeography of European taxa are biased towards (i) vertebrates, (ii) terrestrial taxa, (iii) single species, and (iv) taxa that survived the Pleistocene in southern refugia. Relatively little is known about whether evolutionary patterns of vertebrate and terrestrial taxa are also applicable to freshwater invertebrates, whether cold-adapted freshwater species could survive in extensive permafrost areas without retreating into refugia, and whether Pleistocene phylogeographical patterns are influenced by phylogeny. Here, the widespread and species-rich European spring snail genus Bythinella Moquin-Tandon, 1856 is utilized in an attempt to mitigate this bias. These strongly cold-adapted freshwater animals mostly occur in springs , highly isolated habitats that are relatively unaffected by anthropogenic influences. Phylogenetic and phylogeographical analyses based on mitochondrial DNA and nuclear DNA sequence data were conducted in 458 specimens from 142 populations occurring throughout Europe. The study provides evidence that most Bythinella spp. survived the Pleistocene in restricted northern glacial refugia that largely correspond to refugia previously recognized for other European biota. However, survival of Bythinella spp. in extensive permafrost areas outside of refugia can likely be rejected. Low dispersal ability and the isolation and fragmentation of spring habitats, as well as the distribution of perennial springs within permafrost regions, may account for this result. Tests involving a total of 29 nominal species showed that phylogenetically closely related Bythinella species did not occupy similar refugia. This lack of phylogenetic concordance could possibly be explained by the stochasticity of survival and dispersal in spring snails. [source] Towards a more general species,area relationship: diversity on all islands, great and smallJOURNAL OF BIOGEOGRAPHY, Issue 4 2001Lomolino Aim To demonstrate a new and more general model of the species,area relationship that builds on traditional models, but includes the provision that richness may vary independently of island area on relatively small islands (the small island effect). Location We analysed species,area patterns for a broad diversity of insular biotas from aquatic and terrestrial archipelagoes. Methods We used breakpoint or piecewise regression methods by adding an additional term (the breakpoint transformation) to traditional species,area models. The resultant, more general, species,area model has three readily interpretable, biologically relevant parameters: (1) the upper limit of the small island effect (SIE), (2) an estimate of richness for relatively small islands and (3) the slope of the species,area relationship (in semi-log or log,log space) for relatively large islands. Results The SIE, albeit of varying magnitude depending on the biotas in question, appeared to be a relatively common feature of the data sets we studied. The upper limit of the SIE tended to be highest for species groups with relatively high resource requirements and low dispersal abilities, and for biotas of more isolated archipelagoes. Main conclusions The breakpoint species,area model can be used to test for the significance, and to explore patterns of variation in small island effects, and to estimate slopes of the species,area (semi-log or log,log) relationship after adjusting for SIE. Moreover, the breakpoint species,area model can be expanded to investigate three fundamentally different realms of the species,area relationship: (1) small islands where species richness varies independent of area, but with idiosyncratic differences among islands and with catastrophic events such as hurricanes, (2) islands beyond the upper limit of SIE where richness varies in a more deterministic and predictable manner with island area and associated, ecological factors and (3) islands large enough to provide the internal geographical isolation (large rivers, mountains and other barriers within islands) necessary for in situ speciation. [source] Population genetic structure of rock ptarmigan in the ,sky islands' of French Pyrenees: implications for conservationANIMAL CONSERVATION, Issue 2 2009N. Bech Abstract Expected consequences of global warming include habitat reduction in many cool climate species. Rock ptarmigan is a Holarctic grouse that inhabits arctic and alpine tundra. In Europe, the Pyrenean ptarmigan inhabits the southern edge of the species' range and since the last glacial maximum its habitat has been severely fragmented and is restricted to high-alpine zones or ,sky islands'. A recent study of rock ptarmigan population genetic in Europe found that the Pyrenean ptarmigan had very low genetic diversity compared with that found in the Alps and Scandinavia. Habitat fragmentation and reduced genetic diversity raises concerns about the viability of ptarmigan populations in the Pyrenees. However, information on population structuring and gene flow across the Pyrenees, which is essential for designing a sound management plan, is absent. In this study, we use seven microsatellites and mitochondrial control region sequences to investigate genetic variation and differentiation among five localities across the Pyrenees. Our analyses reveal the presence of genetic differentiation among all five localities and a significant isolation-by-distance effect that is likely the result of short dispersal distances and high natal and breeding philopatry of Pyrenean ptarmigan coupled with severe habitat fragmentation. Furthermore, analysis of molecular variance, principal component analysis and Bayesian analysis of genetic structuring identified the greatest amount of differentiation between the eastern and main parts of the Pyrenean chain separated by the Sègre Valley. Our data also show that the Canigou massif may host an isolated population and requires special conservation attention. We propose a management plan which includes the translocation of birds. If a sky island structure affects genetic divergence in rock ptarmigan, it may also affect the genetic structure of other sky island species having low dispersal abilities. [source] Comparative phylogeography of four Apodemus species (Mammalia: Rodentia) in the Asian Far East: evidence of Quaternary climatic changes in their genetic structureBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2010HÉLA SAKKA The phylogeography of four Apodemus species (Apodemus agrarius, Apodemus peninsulae, Apodemus latronum, and Apodemus draco) was studied in the Far East of Asia, based on sequences of the mitochondrial DNA cytochrome b gene. The results obtained show the existence of many different genetic lineages within the studied Apodemus species, suggesting the isolation and differentiation of populations in multiple refuge areas. Higher genetic diversities in some regions such as Yunnan, Sichuan (China), and eastern Russia suggest these areas are potential refuges for these species. The existence of such complex genetic structures could be linked to the presence of many biogeographic barriers (Himalaya Mountains, Tien-shan Mountains, Altai Mountains, Tibetan Plateau, Gobi desert, Yunnan Guizhou Plateau, Dzungaria basin, and others) in these regions, which were probably reinforced during the Quaternary climate changes. These barriers also played an important role concerning the low dispersal abilities of the two studied Apodemus species adapted to forest habitats (A. latronum and A. draco) with respect to colonizing regions other than China. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 797,821. [source] Dispersal distances predict subspecies richness in birdsJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 3 2000Belliure Dispersal ability has been hypothesized to reduce intraspecific differentiation by homogenizing populations. On the other hand, long-distance dispersers may have better opportunities to colonize novel habitats, which could result in population divergence. Using direct estimates of natal and breeding dispersal distances, we investigated the relationship between dispersal distances and: (i) population differentiation, assessed as subspecies richness; (ii) ecological plasticity, assessed as the number of habitats used for breeding; and (iii) wing size, assessed as wing length. The number of subspecies was negatively correlated with dispersal distances. This was the case also after correcting for potential confounding factors such as migration and similarity due to common ancestry. Dispersal was not a good predictor of ecological plasticity, suggesting that long-distance dispersers do not have more opportunities to colonize novel habitats. Residual wing length was related to natal dispersal, but only for sedentary species. Overall, these results suggest that dispersal can have a homogenizing effect on populations and that low dispersal ability might promote speciation. [source] Population structure of the peridomestic mosquito Ochlerotatus notoscriptus in AustraliaMEDICAL AND VETERINARY ENTOMOLOGY, Issue 2 2004D. H. Foley Abstract.,Ochlerotatus notoscriptus (Skuse) (Diptera: Culicidae) is the predominant peridomestic mosquito in Australia where it is the primary vector of dog heartworm, Dirofilaria immitis (Leidy), and a potentially important vector of arboviruses (Barmah Forest, Ross River) with geographical variation of vector competence. Although widespread, Oc. notoscriptus has low dispersal ability, so it may have isolated subpopulations. The identification of gene flow barriers may assist in understanding arbovirus epidemiology and disease risk, and for developing control strategies for this species. We investigated the population structure of Oc. notoscriptus from 17 sites around Australia, using up to 31 putative allozyme loci, 11 of which were polymorphic. We investigated the effect of larval environment and adult morphology on genetic variation. At least five subpopulations were found, four in New South Wales (NSW) and one unique to Darwin. Perth samples appear to be a product of recent colonization from the Australian east coast. For NSW sites, a Mantel test revealed an isolation by distance effect and spatial autocorrelation analysis revealed an area of effective gene flow of 67 km, which is high given the limited dispersal ability of this species. No consistent difference was observed between ,urban' and ,sylvan' habitats, which suggests frequent movement between these sites. However, a finer-scaled habitat study at Darwin revealed small but significant allele frequency differences, including for Gpi. No fixed allozyme differences were detected for sex, size, integument colour or the colour of species-diagnostic pale scales on the scutum. The domestic habit of Oc. notoscriptus and assisted dispersal have helped to homogenize this species geographically but population structure is still detectable on several levels associated with geographical variation of vector competence. [source] Multiple introductions promote range expansion of the mollusc Cyclope neritea (Nassariidae) in France: evidence from mitochondrial sequence dataMOLECULAR ECOLOGY, Issue 6 2006B. SIMON-BOUHET Abstract Since the 1970s, the nassariid gastropod Cyclope neritea has been extending its range north along the French Atlantic coasts from the Iberian Peninsula. This may be due to natural spread because of the recent warming of the northeastern Atlantic. However, human-mediated introductions related to shellfish culture may also be a probable explanation for this sudden range expansion. To examine these two hypotheses, we carried out a comprehensive study based on mitochondrial gene sequences (cytochrome oxidase I) of the five recently colonized French bays as well as 14 populations located in the recognized native range of the species. From a total of 594 individuals, we observed 29 haplotypes to split into three divergent clades. In the native range, we observed a low molecular diversity, strong genetic structure and agreement between geography and gene genealogies. Along the French coasts, we observed the opposite: high genetic diversity and low genetic structure. Our results show that recurrent human-mediated introductions from several geographical areas in the native range may be a source for the French Atlantic populations. However, despite the low dispersal ability of C. neritea, the isolation-by-distance pattern in France suggested that this gastropod may have been present (although unnoticed) on the French Atlantic coasts before the 1970s. As C. neritea shows characteristics of a cryptogenic species, the classification of Atlantic populations as either native or introduced is not straightforward. Cryptogenic species should be studied further to determine the status of new populations close to their recognized native range. [source] | ||||||||||