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Continuous Population (continuous + population)

Distribution by Scientific Domains

Life Sciences	85%

Selected Abstracts

Spatial Autocorrelation Analysis and the Identification of Operational Units for Conservation in Continuous Populations

CONSERVATION BIOLOGY, Issue 4 2002
José Alexandre Felizola Diniz-Filho
We show that spatial autocorrelation analysis, applied to phenotypic or molecular data, can be used to describe the geographic structure and therefore can help define optimum strategies for conserving genetic variability within species. We propose that the intercept of a spatial correlogram can be an indication of the minimum distance between samples that can conserve and assess genetic diversity with maximum efficiency at lower costs. This parameter can be used both to define units and to establish sampling strategies for conservation programs. We illustrate the utility of this approach by autocorrelation analyses applied to three data sets: isozyme variability among Eugenia dysenterica populations in Brazilian Cerrado and within populations of Adenophora glandiflora in Korea, and microsatellite variation among Ursus arctos populations in North America. Our results suggest that the intercept of spatial correlograms is a useful parameter for establishing operational units for intraspecific conservation in continuous populations, based on overall genetic or phenotypic variability, by defining the minimum geographic distance at which samples are independent. Resumen: A pesar de los avances recientes en la identificación de la estructura genética poblacional mediante la tecnología de marcadores moleculares, la definición de las unidades intraespecíficas para la conservación es aún problemática. Esto sucede particularmente cuando la variación genética y fenotípica se encuentra distribuida de manera continua en un espacio geográfico. Demostramos que el análisis de autocorrelación espacial, aplicado a los datos fenotípicos o moleculares puede ser usado para describir la estructura geográfica y, por lo tanto, puede ayudar a definir estrategias óptimas para la conservación de la variabilidad genética en las especies. Proponemos que el intercepto de un correlograma espacial puede ser un indicador de la distancia mínima entre muestras que pueden conservar y evaluar la diversidad genética con mayor eficiencia a un costo más bajo. Este parámetro puede ser usado tanto para definir unidades como para establecer estrategias de muestreo para los programas de conservación. Ejemplificamos la utilidad de este método mediante la aplicación de análisis de autocorrelación a tres grupos de datos: variabilidad de isozomas entre poblaciones de Adenophora dysenterica en el cerrado brasileño, dentro de poblaciones de Adenophora glandiflora en Korea y variación microsatélite entre poblaciones de Ursus arctos en América del Norte. Nuestros resultados sugieren que el intercepto de los correlogramas espaciales son un parámetro útil que puede establecer unidades operacionales para conservación intraespecífica en poblaciones continuas, en base a la variabilidad general genética o fenótipica, al definir la distancia geográfica mínima a la cual las muestras son independientes. [source]

Do male and female black-backed woodpeckers respond differently to gaps in habitat?

EVOLUTIONARY APPLICATIONS (ELECTRONIC), Issue 3 2010
Jennifer C. Pierson
Abstract We used population- and individual-based genetic approaches to assess barriers to movement in black-backed woodpeckers (Picoides arcticus), a fire-specialist that mainly occupies the boreal forest in North America. We tested if male and female woodpeckers exhibited the same movement patterns using both spatially implicit and explicit genetic analyses to define population structure and movement patterns of both sexes among populations. Three genetic groups were identified, a large, genetically continuous population that spans from the Rocky Mountains to Quebec, a small isolated population in South Dakota and a separate population in the western portion of their distribution (Oregon). Patterns of genetic diversity suggest extensive gene flow mediated by both males and females within the continuous boreal forest. However, male-mediated gene flow is the main form of connectivity between the continuously distributed group and the smaller populations of South Dakota and Oregon that are separated by large areas of unforested habitat, which apparently serves as a barrier to movement of female woodpeckers. [source]

Using molecular and quantitative variation for assessing genetic impacts on Nucella lapillus populations after local extinction and recolonization

INTEGRATIVE ZOOLOGY (ELECTRONIC), Issue 2 2006
Isabelle Colson
Abstract The dogwhelk Nucella lapillus is a predatory marine gastropod living on rocky shores in the North Atlantic. As with many other gastropod species, Nucella was affected by tributyltin (TBT) pollution during the 1970s and 1980s, and local populations underwent extinction. After a partial ban on TBT in the UK in 1987, vacant sites have been recolonized. Levels of genetic diversity and quantitative genetic variation in shell form were compared between recolonized sites and sites that showed continuous population at three localities across the British Isles. Overall, estimates of genetic diversity were only slightly lower in recolonized populations, suggesting that populations have recovered from previous impacts due to the relatively high levels of migration from non-impacted sites. Molecular and quantitative analyses are broadly concordant and a positive correlation was observed (although not statistically significant) between molecular and quantitative estimates of genetic diversity, indicating the potential usefulness of quantitative methods to complement molecular population genetics analyses. [source]

Deep genetic subdivision within a continuously distributed and highly vagile marine mammal, the Steller's sea lion (Eumetopias jubatus)

MOLECULAR ECOLOGY, Issue 10 2006
J. I. HOFFMAN
Abstract The Steller's sea lion Eumetopias jubatus is an endangered marine mammal that has experienced dramatic population declines over much of its range during the past five decades. Studies using mitochondrial DNA (mtDNA) have shown that an apparently continuous population includes a strong division, yielding two discrete stocks, western and eastern. Based on a weaker split within the western stock, a third Asian stock has also been defined. While these findings indicate strong female philopatry, a recent study using nuclear microsatellite markers found little evidence of any genetic structure, implying extensive paternal gene flow. However, this result was at odds with mark,recapture data, and both sample sizes and genetic resolution were limited. To address these concerns, we increased analytical power by genotyping over 700 individuals from across the species' range at 13 highly polymorphic microsatellite loci. We found a clear phylogenetic break between populations of the eastern stock and those of the western and Asian stocks. However, our data provide little support for the classification of a separate Asian stock. Our findings show that mtDNA structuring is not due simply to female philopatry, but instead reflects a genuine discontinuity within the range, with implications for both the phylogeography and conservation of this important marine mammal. [source]

Spatial autocorrelation and linkage of Mendelian RAPD markers in a population of Picea abies Karst

MOLECULAR ECOLOGY, Issue 3 2002
Gabriele Bucci
Abstract The spatial clustering of single- and di-locus genotypes in a natural, continuous population of Norway spruce was investigated using 69 Mendelian Random Amplified Polymorphic DNA (RAPD) markers that covered about 15% of the species' genome, and whose linkage relationships were known. Spatial autocorrelation techniques and randomization tests, applied to both single- and di-locus genotypes, revealed a weak, though significant, spatial structure at the scale 0,200 m (5% of single-locus and 7% of di-locus genotypes). To assess the relative importance of isolation by distance and linkage between markers on their spatial genetic structuring, we grouped joins between sampled trees into ,equivalence categories' expected to show similar, specific patterns of spatial distribution under isolation by distance. Results from both single- and di-locus analyses were consistent with the existence of patches of like homozygotes (about 8% and 11% of loci at the single- and di-locus level, respectively) surrounded by a mix of like heterozygotes. Similar structuring has been predicted by simulation models under isolation by distance and selective neutrality. Overall, linkage between markers accounted for an increase of spatial clumping of di-locus genotypes involving tightly linked loci with recombination fractions up to 0.1, a consequence of limited, stochastic spread of single-locus genotypes in space. Our results support the hypothesis that isolation by distance and linkage have a small, though significant, effect even within continuous forest tree populations. In general, the spatial distribution of multilocus genotypes within populations should be interpreted with caution when linkage relationships among the markers used are unknown. [source]

Microsatellite analysis of North American wapiti (Cervus elaphus) populations

MOLECULAR ECOLOGY, Issue 10 2000
Renee O. Polziehn
Abstract Eleven populations of wapiti (Cervus elaphus) were analysed for genetic diversity using 12 microsatellite loci. Samples were taken from Vancouver Island, British Columbia; Burwash and French River herds in Ontario; Ya Ha Tinda Ranch, Alberta; and Banff, Elk Island, Jasper, Kootenay, Riding Mountain, Yellowstone and Yoho National Parks. Overall, wapiti populations have on average three to four alleles per locus and an average expected heterozygosity that ranged from 25.75 to 52.85%. The greatest genetic distances were observed between the Vancouver population and all other populations. Using the assignment test, Roosevelt wapiti (C. e. roosevelti Merriam 1897) assigned only to the Vancouver Island population. The distance and assignment values suggest a divergence of the Roosevelt wapiti from other populations and support the subspecific status for the Vancouver Island population. No evidence was found for the existence of unique Eastern wapiti (C. e. canadensis Erxleben 1777) in the Burwash or French River herds in Ontario. The overlapping distribution of genotypes from indigenous populations from Riding Mountain, Elk Island and Yellowstone National Parks suggests that wapiti were once a continuous population before settlers decimated their numbers. The lack of differentiation between these populations raises questions about the status of Manitoban (C. e.manitobensis Millais 1915) and Rocky Mountain (C. e.nelsoni Bailey 1935) subspecies. [source]