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Fine-scale Population Structure (fine-scale + population_structure)
Selected AbstractsFine-scale population structure and dispersal in Biomphalaria glabrata, the intermediate snail host of Schistosoma mansoni, in VenezuelaMOLECULAR ECOLOGY, Issue 5 2002J. Mavárez Abstract Biomphalaria glabrata is the main intermediate host of Schistosoma mansoni in America and one of the most intensely studied species of freshwater snails, yet very little is known about its population biology. Here, we used seven highly polymorphic microsatellite loci to analyse genetic diversity in the Valencia lake basin, which represents the core of the endemic area for schistosomiasis in Venezuela. Populations were sampled at short spatial scale (a few kilometres), both inside the lake and in ponds or rivers near the lake. Our results indicate that B. glabrata essentially cross-fertilizes, with little variation in selfing rates among populations. Our markers detected considerable genetic variation, with an average heterozygosity of 0.60. More diversity per population was found within than outside the lake, suggesting an influence of connectivity among populations on the levels of genetic diversity. A marked population structure was detected and lake populations were less structured than other populations. Most individuals were assigned to their population of origin using an assignment test. No strong demographic signal (e.g. bottleneck) was detected, though lake populations are likely to experience bottlenecks more frequently than the other populations analysed. Differences in gene flow therefore seem to play an important role in population differentiation and in the restoring of genetic diversity in demographically unstable populations. [source] Long-term effects of translocation and release numbers on fine-scale population structure among coho salmon (Oncorhynchus kisutch)MOLECULAR ECOLOGY, Issue 12 2007WILLIAM H. ELDRIDGE Abstract Management actions, such as translocations, reintroductions and supportive breeding, can have both negative and positive effects on population recovery. Several studies have examined the incidence of introgression following such actions, but few studies have explored the effect of release numbers on gene flow between closely related recipient populations. We examined population structure of coho salmon in Puget Sound (Washington State, USA) to evaluate the relationship between the number of individuals transferred between rivers, and the number released within rivers, on inter- and intrariver population divergence. Eleven microsatellite loci were surveyed in 23 hatchery and wild samples collected from 11 rivers within and one hatchery outside Puget Sound. Pairwise genetic divergences between most populations were significant, but the population structure could not be explained by an isolation-by-distance model (Mantel test, P > 0.05). In contrast, we detected significant hatchery influence on population structure. The numbers of fish transferred among rivers between 1952 and 2004 was negatively correlated with differentiation between rivers (partial Mantel test, P = 0.005) but not within rivers (t -test, P = 0.41). Number of fish released from hatcheries that collect broodstock locally was negatively correlated with population structure within rivers (t -test P = 0.002), and between nearby rivers (partial Mantel P = 0.04). Our results indicate that the population structure can, to some degree, be altered by the number of individuals transferred and by local release number of individuals in ongoing artificial propagation programs. The findings presented here emphasize the need to control the number of individuals that are either inadvertently introduced, or are deliberately released under conservation scenarios. [source] Multiple paternity in loggerhead turtle (Caretta caretta) nests on Melbourne Beach, Florida: a microsatellite analysisMOLECULAR ECOLOGY, Issue 2 2002M. K. Moore Abstract Many aspects of sea turtle biology are difficult to measure in these enigmatic migratory species, and this lack of knowledge continues to hamper conservation efforts. The first study of paternity in a sea turtle species used allozyme analysis to suggest multiple paternity in loggerhead turtle (Caretta caretta) clutches in Australia. Subsequent studies indicated that the frequency of multiple paternity varies from species to species and perhaps location to location. This study examined fine-scale population structure and paternal contribution to loggerhead clutches on Melbourne Beach, FL, USA using microsatellite markers. Mothers and offspring from 70 nests collected at two locations were analysed using two to four polymorphic microsatellite loci. Fine-scale population differentiation was not evident between the sampled locations, separated by 8 km. Multiple paternity was common in loggerhead nests on Melbourne Beach; 22 of 70 clutches had more than one father, and six had more than two fathers. This is the first time that more than two fathers have been detected for offspring in individual sea turtle nests. Paternal genotypes could not be assigned with confidence in clutches with more than two fathers, leaving the question of male philopatry unanswered. Given the high incidence of multiple paternity, we conclude that males are not a limiting resource for this central Florida nesting aggregate. [source] Microsatellite variation and fine-scale population structure in the wood frog (Rana sylvatica)MOLECULAR ECOLOGY, Issue 5 2001Robert A. Newman Abstract We investigated genetic population structure in wood frogs (Rana sylvatica) from a series of Prairie Pothole wetlands in the northern Great Plains. Amphibians are often thought to exist in demographic metapopulations, which require some movement between populations, yet genetic studies have revealed strong subdivision among populations, even at relatively fine scales (several km). Wood frogs are highly philopatric and studies of dispersal suggest that they may exhibit subdivision on a scale of , 1,2 km. We used microsatellites to examine population structure among 11 breeding assemblages separated by as little as 50 m up to , 5.5 km, plus one population separated from the others by 20 km. We found evidence for differentiation at the largest distances we examined and among a few neighbouring ponds, but most populations were strikingly similar in allele frequencies, suggesting high gene flow among all but the most distant populations. We hypothesize that the few significant differences among neighbouring populations at the finest scale may be a transient effect of extinction,recolonization founder events, driven by periodic drying of wetlands in this hydrologically dynamic landscape. [source] Polymorphic dinucleotide microsatellites in tongue sole (Cynoglossus semilaevis)MOLECULAR ECOLOGY RESOURCES, Issue 6 2007X. LIAO Abstract The tongue sole, Cynoglossus semilaevis, is a rare marine flatfish distributed in Chinese coastal waters. From a (GT)n -enriched genomic library, 57 microsatellites were isolated and characterized. Seventeen of these loci were polymorphic in a test population with alleles ranging from three to 13, and observed and expected heterozygosities from 0.1613 to 1.0000 and from 0.2126 to 0.8983, respectively. Five loci deviated from the Hardy,Weinberg equilibrium in the sampled population, and linkage disequilibrium between two loci was significant after applying Bonferroni correction. Three additional fish species assessed for cross-species amplification revealed that only one locus was also polymorphic in one species. These polymorphic microsatellite loci should provide sufficient level of genetic diversity to evaluate the breeding strategy and investigate the fine-scale population structure in C. semilaevis. [source] Atlantic capelin (Mallotus villosus) tetranucleotide microsatellitesMOLECULAR ECOLOGY RESOURCES, Issue 2 2005K. GORDOS Abstract Twelve microsatellite loci developed for Atlantic capelin (Mallotus villosus) using magnetic bead hybridization enrichment for tetranucleotide microsatellites revealed five loci composed of single repeat elements and six composed of complex repeats. Forty-four beach-spawning females from three different northwestern Atlantic Newfoundland beach-spawning populations were screened at each locus. Loci were polymorphic (two to 59 alleles per locus) and all but two exhibited high heterozygosity (0.86,1). The loci are considered suitable for addressing questions related to fine-scale population structure, spawning fidelity and survivorship/kinship issues. [source] Isolation and characterization of novel tetranucleotide microsatellite DNA markers for the spotted salamander, Ambystoma maculatumMOLECULAR ECOLOGY RESOURCES, Issue 1 2003S. E. Julian Abstract Fifteen tetranucleotide microsatellite loci were identified and characterized for spotted salamanders (Ambystoma maculatum) collected from three vernal pools in the south-eastern USA. These markers revealed a high degree of genetic diversity (7,32 alleles per locus), heterozygosity (31.6,86.3%) and allelic heterogeneity (91% of comparisons were statistically significant). Considerable differentiation among populations was observed as genetic distances (chord) ranged between 0.50 and 0.65, and all FST values (0.08,0.14) were statistically significant. Moreover, genotypic assignment tests correctly classified all individuals to their respective collection. These markers should prove useful for investigating fine-scale population structure and mating system. [source] | ||||||||||