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Springsnails of the genus Pyrgulopsis are the most diverse group of freshwater gastropods in North America and current estimates show that Pyrgulopsis contains ~120 different species, many of which are at risk of extinction. Some factors contributing to their exceptional diversity include poor dispersal ability and extreme habitat specificity based on water availability, chemistry and depth. Most taxa exhibit high degrees of endemism, with many species occurring only in a single spring or seep, making springsnails ideal for studies of speciation and population structure. Here I present data from a survey of genetic variation at the mitochondrial gene cytochrome oxidase I from 37 populations and over 1000 individuals...
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Adult movement and natal dispersal data demonstrate that Northern Goshawks (Accipiter gentilis) are able to travel over long distances, suggesting a large functional population. However, these data are unable to determine whether these movements contribute to gene flow among adjacent breeding areas. We used eight microsatellite DNA loci and mitochondrial DNA control-region sequence data to assess population structure of Northern Goshawks breeding in Utah. Goshawks had moderate levels of genetic variation at microsatellite loci (observed heterozygosity = 50%), similar to levels found in other medium-sized, highly mobile birds. Overall estimates of interpopulation variance in microsatellite alleles (FST = 0.011) and...
The forest vegetation of the northern Colorado Front Range was studied using a combination of gradient analysis and classification methods. A graphical model of forest composition based on elevation and topographic-moisture gradients was constructed using 305 0.1 ha samples. To derive the topographic-moisture gradient, stands were stratified into eight 200 m elevation belts, and then ordinated by correspondence analysis using understory (<1 m) data. Each of the resultant gradients was scaled against a standard site moisture scalar derived from incident solar radiation and topographic position. Except for krummholz sites, the vegetation defined gradients fit the moisture scalar closely. Once scaled, these gradients...
Growth of smallmouth bass (Micropterus dolomieu) was described for three widely spaced areas progressing downstream in Flaming Gorge Reservoir, Wyoming-Utah. Significant differences among areas were detected only for age-1 fish. Growth in the reservoir was compared with that of populations in other lentic habitats of varying growing season lengths in North America; slow growth in the reservoir was related to the relatively short growing season (less than 90 days). Published in Western North American Naturalist, volume 53, issue 2, on pages 180 - 185, in 1993.
    map background search result map search result map Gene flow and genetic characterization of Northern goshawks breeding in Utah Gene flow and genetic characterization of Northern goshawks breeding in Utah