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51.
Thirty-four juvenile loggerhead sea turtles captured by trawling from the Charleston, South Carolina (USA), shipping channel (32°42′N; −79°47′W) between May 2004 and August 2007 were tagged with satellite transmitters to assess the extent to which they remained near the capture location given their collection along a seasonal migratory corridor. Seventy-five percent of juveniles were classified as seasonal residents. Migrants predominantly swam north in the spring and nomads wandered south in the summer, but predictive indicators for non-resident status were not identified. All but one juvenile generally remained south of 34°N, within 40 km of shore, and in waters <30 m deep throughout the year. Nine of 14 loggerhead sea turtles monitored during the winter remained exclusively over the continental shelf, three briefly occurred in oceanic habitats, and two foraged extensively in oceanic habitats. Residents distributed >15 km from shore between spring and autumn were three times as likely to occur in oceanic habitats in winter. Modest seasonal movements contrasted with adults tagged at similar latitudes and with juveniles tagged further north and suggest distinct foraging groups within a regional foraging ground.  相似文献   
52.
Satellite transmitters were attached to 25 reproductively active and four inactive adult male loggerhead sea turtles (86.6–107.0 cm SCLmin) captured from the Port Canaveral, FL, USA shipping channel to assess horizontal and vertical distributions. During the breeding period, male loggerheads aggregated (44% of 755 turtle days) in a 117.6 km2 core area that encompassed the shipping channel. Median dive duration during the breeding period was 27 min (IQR = 15–42 min) and males spent 4% (IQR = 3–5%) of the time at the surface, with significantly shorter dives associated with reproductively active males. Migrant and resident males dispersed concurrently, with residents shifting > 30 km east across the continental shelf over a more protracted departure schedule than migrants. Dive duration and time spent at the surface increased through the fall. Cluster analysis revealed the strongest association for dive duration with sea state during and after the breeding period, with significantly longer dives during more turbulent conditions. In contrast, univariate associations with surface interval duration were not elucidated.  相似文献   
53.
The United Nations' Monitoring and Reporting Mechanism is charged with documenting six grave violations against children in a time of conflict, including attacks on schools. Many of these incidents, however, remain unreported across the globe. This study explores whether or not a local knowledge base of education and child protection actors in North and South Kivu Provinces, Democratic Republic of the Congo, and in Mogadishu, Somalia, could contribute to a more complete record of attacks on education in those areas. Hundreds of semi‐structured interviews were conducted with key informants across the three settings, and in total 432 attacks on education were documented. Purposive samples of these reports were verified and a large majority was confirmed. Local non‐governmental organisations and education institutions were most knowledgeable about these incidents, but most never reported them to a monitoring authority. The study concludes that attack surveillance and response were largely insufficient, and recommends investing in mechanisms that utilise local knowledge to address these shortcomings.  相似文献   
54.
Animal color patterns often reflect a compromise between natural selection for crypsis or inconspicuousness to predators and sexual selection for conspicuousness to potential mates. In leaf litter-dwelling wolf spider species like Schizocosa ocreata, body coloration often closely matches the background coloration of a generally brown environment. However, body parts used in communication should exhibit high contrast against background coloration. We used spectral analysis to examine male and female S. ocreata for matching and contrasting coloration against leaf litter. Values were plotted in multivariate color space, based on reflectivity in different frequency ranges. When viewed from above, colors of both males and females overlap with values for dead brown leaf litter and soil, suggesting cryptic coloration when viewed by potential predators. However, when viewed from a lateral perspective, both males and females show color values that are polar opposites of litter backgrounds, suggesting higher contrast when viewed by other spiders. Moreover, male secondary characters used in visual signaling by S. ocreata (tibia brushes) show the highest level of background contrast. These findings suggest that S. ocreata wolf spiders have color patterns that provide both crypsis and background contrast at the same time, depending on receiver viewing perspective.  相似文献   
55.
Love bites: male fang use during coercive mating in wolf spiders   总被引:1,自引:1,他引:0  
Evolutionary conflicts of interest between the sexes are common, as mating tactics and strategies that increase fitness benefits for one sex may incur costs for the other. As a consequence, antagonistic coevolution between the sexes often results in a complex arms race between male persistence and female resistance. Coercive mating (e.g., forced copulation) likely benefits males by increasing the probability of mating; however, costs to females may be high, including injury or even death. Here, we report on a study of the use of fangs by males of the wolf spider Schizocosa ocreata (Hentz) during forcible mating with resistant females, which results in hemolymph loss and scar tissue formation in females. Microscopic inspection revealed that fang wounds (evidenced by scar tissue) were absent on unmated (virgin) females but were found on mated females and were significantly more frequent in coercively mated females. Experimental fang immobilization studies found no difference in copulation success between experimental (fangs immobilized) and control (sham manipulation) males. However, males that had use of their fangs had significantly longer copulation duration. These findings represent a previously unknown male mating tactic in spiders and an unrecognized potential cost of mating for female spiders.  相似文献   
56.
Invertebrates containing endosymbiotic dinoflagellate algae (zooxanthellae) retain excretory nitrogen, and many are able to take up ammonium from the surrounding seawater. However, the site of assimilation and role of nitrogen recycling between symbiont and host remains unclear. In the present study, ammonium uptake by the symbiotic sea anemone Anemonia viridis (Forskål) was examined by following the pathway of assimilation using 15N-enriched ammonium. Since zooxanthellae became enriched with 15N from ammonium at up to 17 times the rate of the host, they appear to be the primary site of assimilation. In the light, the rate of zooxanthellae enrichment at 20?M was twice that at 10?M, whereas the rate of host enrichment was not significantly affected by ammonium concentration. When anemones were incubated with [15N]ammonium in the dark, after 12?h without light the rate of enrichment was lowered in both zooxanthellae and host. However, while the enrichment of the host was significantly reduced when the light level was lowered from 300 to 150?μmol photons m?2?s?1, zooxanthellae enrichment was unchanged. Low molecular weight material from the zooxanthellae became enriched at 20 times the rate of that from the host, and enrichment was detected in the amino acids glutamate, glutamine, aspartate, alanine, glycine, phenylalanine, threonine, valine, tyrosine, and leucine from zooxanthellae. In the zooxanthellae, amino acids accounted for 65% of the total enrichment of low molecular weight material. Of the amino acids detected in zooxanthellae, over 90% of the enrichment was accounted for by glutamate, glutamine and aspartate. The enrichment of the amide group of glutamine was greater than that of the amine group of glutamate or glutamine, consistent with the glutamine synthetase/glutamine 2-oxoglutarate amidotransferase cycle as the mechanism of ammonium assimilation. To examine the flux of 15N from zooxanthellae to host, anemones were pulse-labelled with [15N]ammonium and then transferred to an unlabelled chase. Over a 2?h period there was no evidence for a flux of nitrogen from zooxanthellae to host. However, during the chase period, the enrichment of low molecular weight material declined and that of high molecular weight material increased in both zooxanthellae and host, indicating that protein was synthesized using 15N from ammonium in both components of the symbiosis. Again by using a pulse-chase system, it was found that glutamate was metabolised most rapidly by zooxanthellae, followed by (in order of decreasing rate of turnover) aspartate, alanine, glycine and valine (no data are available for glutamine). Unlike these amino acids, nitrogen was transferred to the essential amino acids phenylalanine and threonine, increasing their enrichment during the chase period. While recycled nitrogen is clearly important to this symbiosis, the mechanism by which it is cycled remains to be resolved.  相似文献   
57.
Determining the influences of anthropogenic perturbations on side channel dynamics in large rivers is important from both assessment and monitoring perspectives because side channels provide critical habitat to numerous aquatic species. Side channel extents are decreasing in large rivers worldwide. Although riprap and other linear structures have been shown to reduce side channel extents in large rivers, we hypothesized that small “anthropogenic plugs” (flow obstructions such as dikes or berms) across side channels modify whole-river geomorphology via accelerating side channel senescence. To test this hypothesis, we conducted a geospatial assessment, comparing digitized side channel areas from aerial photographs taken during the 1950s and 2001 along 512 km of the Yellowstone River floodplain. We identified longitudinal patterns of side channel recruitment (created/enlarged side channels) and side channel attrition (destroyed/senesced side channels) across n?=?17 river sections within which channels were actively migrating. We related areal measures of recruitment and attrition to the density of anthropogenic side channel plugs across river sections. Consistent with our hypothesis, a positive spatial relationship existed between the density of anthropogenic plugs and side channel attrition, but no relationship existed between plug density and side channel recruitment. Our work highlights important linkages among side channel plugs and the persistence and restoration of side channels across floodplain landscapes. Specifically, management of small plugs represents a low-cost, high-benefit restoration opportunity to facilitate scouring flows in side channels to enable the persistence of these habitats over time.  相似文献   
58.
59.
A de novo case of ‘pure’ trisomy 14q21 → qter is described which was detected at amniocentesis following an abnormal ultrasound scan of a 25–year-old woman. This is apparently the largest distal 14q duplication reported in a case surviving beyond the first trimester. The infant apipeared to have an association of clinical abnormalities previously observed in distal 14q trisomy and proximal 14q trisomy/mosaic trisomy 14.  相似文献   
60.
Nucleotide variation in cytochrome c oxidase subunit I (COI) was used to examine population structure in three invasive bryozoans: Bugula neritina (Linnaeus, 1758), Watersipora subtorquata (d’Orbigny, 1852), and W. arcuata (Banta, 1969). These species are found on ship hulls and have a short (≤2 days) larval phase. Samples were collected from 1998–2001 at multiple sites in Australia, and in Hong Kong, New Zealand, Hawaii, California, Curaçao, and England. B. neritina is known to include three cryptic species, including species Type S (Davidson and Haygood in Biol Bull 196:273–280, 1999) which occurs on the east and west coasts of the USA. One haplotype recorded previously in the USA, S1, was found to be widespread, occurring throughout Australia and in Hong Kong, Curaçao, Hawaii, and England. W. subtorquata, a Caribbean–Atlantic species which has invaded southern Australia, New Zealand, and California, had low nucleotide diversity in these areas (π=0.0016±0.0014), consisting of three haplotypes connected by one or two nucleotide mutations. W. arcuata, an Eastern-Pacific native, had comparatively high diversity (π=0.0221±0.0115) in introduced populations from Australia and Hawaii. In each species, identical haplotypes were identified on separate coastlines providing evidence of widespread, rather than genetically independent, introductions. The major contrast in nucleotide diversity suggests that different propagule-source models explain introductions.  相似文献   
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