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61.
The Overberg wheatbelt population of Blue Cranes Anthropoides paradiseus in the Western Cape of South Africa is approximately half the global population of this vulnerable species. Blue Cranes are highly susceptible to collisions with overhead power lines, and a spatial model was developed to identify high‐risk lines in the Overberg for proactive mitigation. To ground‐truth this model, we surveyed 199 km of power lines. Although Blue Cranes were the most commonly killed birds found (54% of all carcasses), the model was unable to predict lines with high collision risk for Blue Cranes. Further Geographic Information System (GIS) modelling was undertaken to test a wider range of landscape and power‐line variables, but only the presence or absence of cultivated land could usefully identify lines posing a collision risk. Modelling was limited by a lack of detailed spatial habitat data and recent information on Crane numbers and distributions. We used recent carcass counts to estimate a Blue Crane collision rate, corrected for sample biases, of 0.31/km power line per year (95% CI 0.13–0.59/km/year), which means that approximately 12% (5–23%) of the total Blue Crane population within the Overberg study area is killed annually in power‐line collisions. This represents a possibly unsustainable source of mortality. There is urgent need for further research into risk factors and for mitigation measures to be more widely implemented. 相似文献
62.
New Indicator of Histocompatibility Differences <Emphasis Type="Italic">in vitro</Emphasis> 总被引:8,自引:0,他引:8
THE haemolytic plaque-forming cell (p.f.c.) response to sheep erythrocytes (SRBC) of cultures containing spleen cells from two different strains of mouse may be depressed if the mice differ sufficiently at the H-2 locus1. In our system, however, the usual result is stimulation rather than depression. We present evidence that such stimulation does not result, as has been suggested2,3, from synergism between two cell populations, but from an immune reaction based on histocompatibility differences between them. The system provides a sensitive indicator for detecting and assessing immune reactions between histoincompatible lymphoid cells and mitogenic factors released by such reactions. 相似文献
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JESSICA M. DA SILVA JOHN S. DONALDSON GAIL REEVES TERRY A. HEDDERSON 《Biological journal of the Linnean Society. Linnean Society of London》2012,105(2):293-308
Declining populations of less than 250 mature individuals are symptomatic of many Critically Endangered cycads, which, globally, comprise the most threatened group of organisms as a result of collecting and habitat loss. Survival plans focus on law enforcement, reintroduction, and augmentation programmes using plants from the wild and botanical gardens. Augmentation is one of the few remaining options for cycad populations, although the assumed benefits remain untested and there is a possibility that augmentation from different sources could compromise the genetic integrity of existing populations, especially when garden plants have no provenance data. We studied Encephalartos latifrons, a South African endemic, which is a typical Critically Endangered cycad. We studied the extent and structure of genetic diversity in wild and ex situ populations to assess the potential benefits and risks associated with augmentation programmes. We examined 86 plants using amplified fragment length polymorphisms (AFLPs). The 417 AFLP markers thus generated yielded a unique DNA ‘fingerprint’ for each plant. Wild populations retain high levels of genetic diversity and this is reflected among the ex situ holdings at the Kirstenbosch Botanical Garden. No population differentiation is evident, indicating a single panmictic population, consistent with moderately high levels of gene flow between subpopulations and a sexual mode of reproduction. Bayesian clustering identified four genotype groups in the wild, as well as a genotype group only found in ex situ collections. Our results indicate that E. latifrons would benefit from augmentation programmes, including the use of undocumented collections, and careful management of breeding plants would increase the heterogeneity of propagules. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 293–308. 相似文献
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The Hawaiian archipelago is often cited as the premier setting to study biological diversification, yet the evolution and phylogeography of much of its biota remain poorly understood. We investigated crab spiders (Thomisidae, Mecaphesa ) that demonstrate contradictory tendencies: (i) dramatic ecological diversity within the Hawaiian Islands, and (ii) accompanying widespread distribution of many species across the archipelago. We used mitochondrial and nuclear genetic data sampled across six islands to generate phylogenetic hypotheses for Mecaphesa species and populations, and included penalized likelihood molecular clock analyses to estimate arrival times on the different islands. We found that 17 of 18 Hawaiian Mecaphesa species were monophyletic and most closely related to thomisids from the Marquesas and Society Islands. Our results indicate that the Hawaiian species evolved from either one or two colonization events to the archipelago. Estimated divergence dates suggested that thomisids may have colonized the Hawaiian Islands as early as ~10 million years ago, but biogeographic analyses implied that the initial diversification of this group was restricted to the younger island of Oahu, followed by back-colonizations to older islands. Within the Hawaiian radiation, our data revealed several well-supported genetically distinct terminal clades corresponding to species previously delimited by morphological taxonomy. Many of these species are codistributed across multiple Hawaiian Islands and some exhibit genetic structure consistent with stepwise colonization of islands following their formation. These results indicate that dispersal has been sufficiently limited to allow extensive ecological diversification, yet frequent enough that interisland migration is more common than speciation. 相似文献
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stewart c. j. r. and kennedy j. h. (1998) Cytopathology 9, 38–45
Peritoneal fluid cytology in serous borderline tumours of the ovary
Peritoneal fluid cytology findings in three patients with serous borderline tumours of the ovary and peritoneal serous implants are presented. The specimens were characterized by papillary groups, acinar clusters and single neoplastic cells exhibiting cytoplasmic vacuolation and nuclear atypia of variable degree. The cytological appearances were initially considered consistent with ovarian adenocarcinoma in all cases. Histological correlation is required to avoid this diagnostic pitfall. 相似文献
Peritoneal fluid cytology in serous borderline tumours of the ovary
Peritoneal fluid cytology findings in three patients with serous borderline tumours of the ovary and peritoneal serous implants are presented. The specimens were characterized by papillary groups, acinar clusters and single neoplastic cells exhibiting cytoplasmic vacuolation and nuclear atypia of variable degree. The cytological appearances were initially considered consistent with ovarian adenocarcinoma in all cases. Histological correlation is required to avoid this diagnostic pitfall. 相似文献
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The enzymatic phosphorylation of proteins 总被引:18,自引:0,他引:18
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The function of cytidine coenzymes in the biosynthesis of phospholipides 总被引:75,自引:0,他引:75