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Mitochondrial DNA sequence diversity and the colonization of Scandinavia by house mice from East Holstein 总被引:3,自引:0,他引:3
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SYNOPSIS Four new eimerian species are described from red-backed voles. Clethrionomys gapperi in Pennsylvania. Sporulated oocysts of Eimeria clethrionomyis sp. n. are ellipsoidal, 18.8 (16.5–21.5) × 14.9 (14.0–16.5) with elongate, ovoid sporocysts, 10.6 (9.5–12.0) × 6.1 (5.5–7.0). The oocyst wall is smooth, with 2 layers, and thins, with terminal cap at one or both ends. Polar granules, dark Stieda body and sporocyst residuum are present. The occyst residuum is absent. Sporulated oocysts of Eimeria gallatii sp. n. are ellipsoidal, 27.7 (21–32) × 19.3 (17–24) with ovoid sporocysts, 13.5 (12–15) × 8.8 (8–10). The oocyst wall is smooth, 2-layered, with a micropyle and thin wall at the end opposite the micropyle. Polar granules. Stieda body and sporocyst residuum are present. The oocyst residuum is atypical, of cobwebby material. Sporulated oocysts of Eimeria pileata sp. n. are subspherical to spherical, 25.2 (20.5–29.5) × 22.5(19.5–25.5) with ellipsoidal sporocysts, 13.4(10.5–15.0) × 8.4 (7.5–9.5). The oocyst wall is rough, pitted, striated, 2-layered, with no micropyle. Polar granules, oocyst and sporocyst residuum. Stieda body and stiedal cap are present. Sporulated oocysts of Eimeria marconii sp. n. are ellipsoidal, 13.0 (10.5–15.0) × 10.6 (9.5–12.0) with elongate, ovoid sporocysts, 7.7 (7.0–8.5) × 4.2 (3.0–4.5). The oocyst wall is smooth, single-layered, with no micropyle. Polar granules, dark Stieda body and sporocyst residuum are present. There is no oocyst residuum. 相似文献
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D. GOTTLIEB J. P. HOLZMAN Y. LUBIN A. BOUSKILA S. T. KELLEY A. R. HARARI 《Journal of evolutionary biology》2009,22(7):1526-1534
We investigated the mating system and population genetic structure of the beetle, Coccotrypes dactyliperda, with life history characteristics that suggest the presence of a stable mixed‐mating system. We examined the genetic structure of seven populations in Israel and found significant departures from the Hardy–Weinberg equilibrium and an excess of homozygosity. Inbreeding coefficients were highly variable across populations, suggesting that low levels of outbreeding occur in nature. Experiments were conducted to determine whether the observed high inbreeding in these populations is the result of a reproductive assurance strategy. Females reared in the laboratory took longer to mate with males from the same population (inbreeding) than with males from a different population (outbreeding). These results suggest that females delayed inbreeding, and were more inclined to outbreed when possible. Thus inbreeding, which predominates in most populations, may be due to a shortage of mates for outbreeding rather than a preference for inbreeding. We conclude that C. dactyliperda has a mixed‐mating system that may be maintained by a reproductive assurance strategy. 相似文献
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1. Locomotor performance of limbless vertebrates depends on the substrate through which individuals move and may result in selection on vertebral number in different habitats. To evaluate the effect of push-point density on snake locomotion, the density of vegetation and other potential push-points was quantified at two sites in California (coastal and inland), where conspecific snakes differed greatly in vertebral number (230 and 256 average total vertebrae, respectively; Arnold 1988). The coastal site had significantly higher push-point densities than the inland site.
2. Five experimental push-point densities that fell within the natural range of push-point densities were employed in laboratory trials of juvenile snake locomotion. Density of push-points significantly affected both crawling speed and head-to-tail distance (HTD), an indirect measure of lateral bending. The fastest speed was achieved at an intermediate push-point density. The shortest HTD occurred when snakes moved through the lowest push-point density.
3. Sex, total number of vertebrae and total length significantly affected HTD, regardless of push-point density. Snakes with relatively more vertebrae had a shorter HTD, suggesting they were able to achieve greater lateral bending than snakes with fewer vertebrae. Coastal and inland populations did not differ in HTD during locomotion.
4. Numbers of body and tail vertebrae significantly influenced speed at different push-point densities. In general, snakes with more body vertebrae were slower than those with fewer, while snakes with more tail vertebrae were faster than those with fewer. Snakes of greater total length were faster at all densities. Coastal snakes crawled faster than inland snakes at all push-point densities. 相似文献
2. Five experimental push-point densities that fell within the natural range of push-point densities were employed in laboratory trials of juvenile snake locomotion. Density of push-points significantly affected both crawling speed and head-to-tail distance (HTD), an indirect measure of lateral bending. The fastest speed was achieved at an intermediate push-point density. The shortest HTD occurred when snakes moved through the lowest push-point density.
3. Sex, total number of vertebrae and total length significantly affected HTD, regardless of push-point density. Snakes with relatively more vertebrae had a shorter HTD, suggesting they were able to achieve greater lateral bending than snakes with fewer vertebrae. Coastal and inland populations did not differ in HTD during locomotion.
4. Numbers of body and tail vertebrae significantly influenced speed at different push-point densities. In general, snakes with more body vertebrae were slower than those with fewer, while snakes with more tail vertebrae were faster than those with fewer. Snakes of greater total length were faster at all densities. Coastal snakes crawled faster than inland snakes at all push-point densities. 相似文献