首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   6篇
  免费   0篇
  2013年   1篇
  2010年   1篇
  2008年   1篇
  1985年   1篇
  1980年   1篇
  1947年   1篇
排序方式: 共有6条查询结果,搜索用时 15 毫秒
1
1.
2.
In the present study, we report an investigation on molecular variation in the endangered univoltine butterfly Euphydryas aurinia (Rottemburg, 1775), a species heavily affected by habitat degradation and fragmentation in Denmark. Levels of genetic variation in extant populations were estimated using six variable number tandem repeat loci and were found to be low compared to other butterfly species with low migration rates. An analysis of genetic structure, based on both allele frequencies and genotype distributions, divided the entire sample into four distinct clusters. This was partially concordant with the a priori subdivision based on collection areas. An overall FST value of 0.16 (pairwise values ranging from 0.087–0.276) indicated restrictions of gene flow. Especially two populations had higher FST values than the others, suggesting their isolation, and showed signs of bottlenecks/founder events. One population deviated significantly from Hardy–Weinberg equilibrium, suggesting a possible Wahlund effect or the presence of null alleles. The results suggest habitat fragmentation, resulting in genetic drift and possibly inbreeding. Future management is therefore recommended to increase gene flow between the remaining populations while habitats are restored in order to increase carrying capacity. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 677–687.  相似文献   
3.
4.
5.
Five species of geophilomorphs, Strigamia maritima (Leach, 1817), Geophilus flavus (De Geer, 1778), Geophilus truncorum Bergsøe and Meinert, 1866, Geophilus proximus C. L. Koch, 1847, and Pachymerium ferrugineum (C. L. Koch, 1835), from various sample sites in north‐western Europe were examined for numbers of leg‐bearing segments. Where data was adequate, mean segment numbers were correlated with latitudinal gradients for each species. Solely in S. maritima and some populations of P. ferrugineum did the results show a highly significant geographic pattern towards more leg‐bearing segments in southern populations of both sexes. As concerns G. proximus, we presented for the first time a remarkable geographic shift towards an increased number of pairs of legs in northern populations. Contrary to the conventional geographic pattern, we found that G. flavus and G. truncorum did not exhibit a north–south increase or decrease in segment number. Although there was no general/universal evidence supporting the occurrence of a significant regression slope between mean segment number and latitude/temperature, more information shows that the overall region‐to‐region segment variation was highly significant in both sexes. In S. maritima and P. ferrugineum mean segment number was correlated with the north–south temperature cline. The same was not observed in G. proximus. Parthenogenesis in G. proximus, and a series of ecological characteristics such as habitat preferences, spatial distribution, and fragmented populations could explain the presence or absence of a geographic patterning of segment number variation along a latitudinal cline. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100 , 899–909.  相似文献   
6.
Abstract. The world species of Leptofoenus (Chalcidoidea; Pteromalidae; Cleonyminae) are revised, and a key given for the six known species. One new species, rufus, is described, and two new synonymies proposed (phantasma and ashmeadi as junior synonyms of pelecinifor-mis). Lectotypes are designated for peleciniformis, westwoodi, and howardi. New distributional records are presented, including the first record of this genus from the Nearctic, rufus from Arizona and California (U.S.A.). Important characters and relationships between the species are discussed.  相似文献   
1
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号