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51.
The present study deals with the analysis of the floristic composition and plant diversity of Wadi Gimal protectorate. Its major aim is to identify community types and environmental factors that affect their growth and distribution. These quantitative data provide rangers with knowledge that is necessary for monitoring and managing plant communities within the protected areas, as well as restoration of vegetation‐depleted habitats. Twenty‐seven stands were selected along the length of Wadi and its tributaries. Thirty‐five species were recorded in Wadi Gimal; with Poaceae as the dominant family and Phanerophytes dominating over other life forms. Saharo‐Arabians were the predominant chorological element. Six vegetation groups were recognized in Wadi Gimal. Zilla spinosa (VG C) which inhabited the Wadi bed had the highest species richness, species turnover, relative evenness and relative concentration of dominance. Capparis sinaica (VG A) which inhabited the mountain slope had the lowest species richness, relative evenness and relative concentration of dominance, while Salvadora persica group had the lowest species turnover. Phoenix dactylifera–Hyphaene thebaica (VG F) which dominated the deltaic part of Wadi, had the highest salinity; whilst Acacia ehrenbergiana (VG E) which dominated the upper‐stream part of the Wadi had the lowest value of salinity.  相似文献   
52.
Although recent radiations are fruitful for studying the process of speciation, they are difficult to characterize and require the use of multiple loci and analytical methods that account for processes such as gene flow and genetic drift. Using multilocus sequence data, we combine hierarchical cluster analysis, coalescent species tree inference, and isolation‐with‐migration analysis to investigate evolutionary relationships among cryptic lineages of North American ground skinks. We also estimate the extent that gene flow has accompanied or followed diversification, and also attempt to account for and minimize the influence of gene flow when reconstructing relationships. The data best support seven largely parapatric populations that are broadly concordant with mitochondrial (mt)DNA phylogeography throughout most of the species range, although they fail to fully represent extensive mtDNA divergence along the Gulf Coast. Relationships within and among three broad geographical groups are well supported, despite evidence of gene flow among them. Rejection of an allopatric divergence model partially depends on the inclusion of samples from near parapatric boundaries in the analyses, suggesting that allopatric divergence followed by recent migration may best explain migration rate estimates. Accounting for geographical variation in patterns of gene flow can improve estimates of migration–divergence parameters and minimize the influence of contemporary gene flow on phylogenetic inference. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ?? , ??–??.  相似文献   
53.
There has been considerable discussion on the origin of the red wolf and eastern wolf and their evolution independent of the gray wolf. We analyzed mitochondrial DNA (mtDNA) and a Y‐chromosome intron sequence in combination with Y‐chromosome microsatellites from wolves and coyotes within the range of extensive wolf–coyote hybridization, that is, eastern North America. The detection of divergent Y‐chromosome haplotypes in the historic range of the eastern wolf is concordant with earlier mtDNA findings, and the absence of these haplotypes in western coyotes supports the existence of the North American evolved eastern wolf (Canis lycaon). Having haplotypes observed exclusively in eastern North America as a result of insufficient sampling in the historic range of the coyote or that these lineages subsequently went extinct in western geographies is unlikely given that eastern‐specific mtDNA and Y‐chromosome haplotypes represent lineages divergent from those observed in extant western coyotes. By combining Y‐chromosome and mtDNA distributional patterns, we identified hybrid genomes of eastern wolf, coyote, gray wolf, and potentially dog origin in Canis populations of central and eastern North America. The natural contemporary eastern Canis populations represent an important example of widespread introgression resulting in hybrid genomes across the original C. lycaon range that appears to be facilitated by the eastern wolf acting as a conduit for hybridization. Applying conventional taxonomic nomenclature and species‐based conservation initiatives, particularly in human‐modified landscapes, may be counterproductive to the effective management of these hybrids and fails to consider their evolutionary potential.  相似文献   
54.
Abstract Florida populations of the eastern tiger swallowtail butterfly, Papilio glaucus L., have unique morphological features and ecological adaptations that have contributed to their subspecies status (P. g. maynardi Gauthier). We describe geographically unique abilities for detoxification of Carolina willow, Salix caroliniana Michx. (Salicaceae), for several Florida populations of P. g. maynardi. Of all the approximately 570 worldwide species of the Papilionidae, such Salicaceae detoxification abilities exist only in the allopatric North American western and northernmost species (P. rutulus Lucas, P. eurymedon Lucas and P. canadensis Rothschild & Jordan). Females of P. glaucus collected from populations in southeastern USA were examined for oviposition preference in 5‐choice assays, and displayed a low preference for Salicaceae (<5%), but larvae from Florida populations exhibited a high survival (>60%) on these plants. Detoxification abilities have previously shown to be autosomally inherited, and can be transferred via natural or hand‐paired interspecific hybrid introgression. However, these Florida populations are at least 700–1 500 km from the nearest hybrids or the hybrid species, P. appalachiensis Pavulaan & Wright, which possess these detoxification abilities. In any case, the Z ( = X)‐linked oviposition preferences for Salicaceae are lacking in these Florida populations, illustrating genetic independence of oviposition preference determination and larval survival/performance abilities. The origins of detoxification abilities are unlikely to be due to recent climate‐driven introgression, and may represent ancestral trait carry‐overs from interglacial refugium populations of the Pleistocene epoch.  相似文献   
55.
Adult hawksbill turtles (Eretmochelys imbricata) are typically described as open-coast, coral reef and hard substrate dwellers. Here, we report new satellite tracking data on female hawksbills from several countries in the eastern Pacific that revealed previously undocumented behaviour for adults of the species. In contrast to patterns of habitat use exhibited by their Caribbean and Indo-Pacific counterparts, eastern Pacific hawksbills generally occupied inshore estuaries, wherein they had strong associations with mangrove saltwater forests. The use of inshore habitats and affinities with mangrove saltwater forests presents a previously unknown life-history paradigm for adult hawksbill turtles and suggests a potentially unique evolutionary trajectory for the species. Our findings highlight the variability in life-history strategies that marine turtles and other wide-ranging marine wildlife may exhibit among ocean regions, and the importance of understanding such disparities from an ecological and management perspective.  相似文献   
56.
Abstract The Delmarva fox squirrel (Sciurus niger cinereus) has been listed as endangered by the United States Department of Interior since 1967. A high-priority task for the recovery of this taxon is to determine its current geographic distribution. Toward this end, we have identified a microsatellite locus that unambiguously differentiates Delmarva fox squirrels from eastern gray squirrels (S. carolinensis), which frequently co-occur with Delmarva fox squirrels. Analysis of this marker in noninvasively collected hair samples will allow unequivocal identification of localities occupied by Delmarva fox squirrels with a minimum investment of funds, time, and effort because handling individuals will be unnecessary. This protocol will expedite site review in connection with the Endangered Species Act consultation process.  相似文献   
57.
 该文比较系统地综述了美国东部杜克森林76年来植物种类变化、种群动态和森林演替研究的基本情况。重点介绍了该森林内永久性森林样地的 设置和调查规范,以及最近10年来利用永久样地数据进行树木空间格局和自然干扰研究的最新进展,并将杜克森林永久样地监测规范和数据管 理方法与目前主要的森林监测网络进行了一定的比较,旨在对目前国际上蓬勃开展的长期定位植物多样性监测和空间格局研究有所启示和帮助 。  相似文献   
58.
Floristics and plant biogeography in China   总被引:1,自引:0,他引:1  
In 1998, a revolutionary system of angiosperm classification, the Angiosperm Phylogeny Group system was published.Meanwhile, another new system of classification of angiosperms, the eight-class system was proposed by C.Y. Wu and colleagues based on long term work on the flora of China. The Flora Reipublicae Popularis Sinicae project was initiated in 1959 and completed by 2004. It is the largest Flora so far completed in the world, including 31 228 species of vascular plants,or one-eighth of the global plant diversity. The English-language and updated Flora of China (FOC) is an international joint effort initiated in 1988 and accelerated in 1998. Up to now, 15 of the 24 volumes of the FOC have been published. Based on the fioristic data, the composition, characteristics, floristic divisions and affinities of the flora of China have been studied by Wu and colleagues since 1965. In the past 10years, analyses of the available floristic data have been very productive.The East Asiatic Floristic Kingdom was proposed in 1998. All 346 families of angiosperms in China, according to the eightclass system of classification, were comprehensively discussed by using knowledge of current and historical distribution of seed plants in the world, together with some morphological and molecular data. A scheme of distribution patterns or areal-types of families and genera of seed plants in China was modified and elucidated, together with a proposed scheme of areal-types of the world. Molecular phylogenetic and biogeographical studies of angiosperms in China in the past 10 yearsalso witnessed a progressive development. Integration of morphological and molecular data and fossil evidence revealed some significant results. Eastern Asia, which used to be regarded as an important center of survival during the ice age, is likely an important center of diversification of angiosperms.  相似文献   
59.
Western and eastern bluebirds (Sialia mexicana and S. sialis) are socially monogamous passerines that engage in extra‐pair copulations. We obtained microsatellites from S. mexicana and optimized and characterized 15 microsatellite DNA loci in 60 individuals of this species. Primer pairs yielded an average of 13 alleles per locus in western bluebirds (range 3–35 alleles) with an average observed heterozygosity of 0.68 (range 0.27–0.88). All 15 loci also successfully amplified in S. sialis (n = 24), with an average of 11.5 alleles per locus (range 4–26) and an average observed heterozygosity of 0.59 (range 0.22–0.90).  相似文献   
60.
The disruption of the trail-based communication system of eastern tent caterpillars (ETC) ( Malacosoma americanum ) and forest tent caterpillars (FTC) ( M. disstria ) by spraying host trees with a trail pheromone mimic caused the disintegration and collapse of young colonies. A 1-ppm formulation of 5β-cholestan-3-one or a control formulation was sprayed on trees either before or after eclosion of the caterpillars in the spring. For pre-eclosion trials, an average of 92% of the FTC colonies on control trees, but only 17% of colonies on treated trees consisted of viable, cohesive aggregates when survival was assessed 5–23 days post-spray. The remaining colonies had either completely disappeared or were reduced to small, disintegrated fragments. For the ETC, 100% of colonies on control trees and an average of 12% of colonies on treated trees consisted of cohesive aggregates inhabiting tents when survival was assessed 3–41 days post-spray. The remaining colonies were completely destroyed, reduced to scattered individuals, or to small, disintegrated, shelter-less fragments. For post-eclosion trials with the FTC in which colonies were sprayed during their first or second larval stadium, an average of 63% of individuals in control groups but only 7% in treatment groups were still on the sprayed trees 5–18 days post-spray. For the ETC, colonies were largely unaffected when trees were not sprayed until after the caterpillars had eclosed and established tents. For all trials, the loss of individuals on treated trees was largely attributable to the inability of dispersed and isolated first or second instar caterpillars to maintain secure purchase, causing them to fall from trees and perish. To our knowledge, this is the first study to investigate the potential of manipulating populations of pest species by interfering with a trail-based, chemical communication system.  相似文献   
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