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1.
Home range and association patterns of elephants Loxodonta africana in private nature reserves adjacent to the Kruger National Park, South Africa, were determined over a period of six years by using radio telemetry. The minimum convex polygon (MCP) and harmonic mean (HM) methods were used for data processing. The minimum and maximum range areas required by females were estimated at 115 and 465 km2, respectively, whilst those of males varied between 157 and 342 km2. Core areas of females comprised on average 10·1% of the range areas as calculated by the MCP method. Range areas between females in the Klaserie and Timbavati Private Nature Reserves differed significantly. A significant difference in range size was also found between the male population (pooled data) and the females of the Klaserie Private Nature Reserve. Range areas increased from the wet to the dry season. Three male elephant categories were established, namely males utilizing the same area during the study period, those who shifted their range areas and individuals with very large range areas which frequented the area on an irregular basis. A loose relationship existed between males. Association between females can be attributed to kinship and not to the overlapping of range areas. Results indicated avoidance behaviour between females in their core areas, which might partially explain the ability of elephants to tolerate high densities. It is concluded that male elephant hunting should be approached with caution.  相似文献   
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Introduced species often become ecologically dominant, displacing native species and posing a serious threat to ecosystem function and global biodiversity. Ants are among the most widespread and damaging alien species; introductions are often accompanied by population-level behavioural and genetic changes contributing to their success. We investigated the genetic structure, chemical profile and nestmate recognition in introduced populations of the invasive big-headed ant, Pheidole megacephala, in Australia. Behavioural analyses show that workers are not aggressive towards conspecifics from different nests, even at large geographical scales (up to 3000 km) and between populations encompassing a wide range of environmental conditions. By contrast, interactions with workers of other species invariably result in agonistic behaviours. Genetic analyses reveal that populations have low genetic diversity. No genetic differentiation occurs among nests of the same population; differentiation between populations, though significant, remains weak. Chemical analyses indicate that cuticular lipids are similar between colonies of a population, and that differentiation between populations is low. Altogether, these results indicate that the big-headed ant P. megacephala forms a large unicolonial population across northern/eastern Australia.  相似文献   
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To unravel the relationship between the European wild apple, Malus sylvestris (L.) Mill., and its domesticated relative M. domestica Borkh., we studied chloroplast DNA variation in 634 wild and 422 domesticated accessions originating from different regions. Hybridization between M. sylvestris and M. domestica was checked using 10 nuclear microsatellites and a Bayesian assignment approach. This allowed us to identify hybrids and feral plants escaped from cultivation. Sixty-eight genotypes belonging to 12 other wild Malus species, including 20 M. sieversii (Ledeb.) Roem. accessions were also included in the analysis of chloroplast diversity. Marker techniques were developed to type a formerly described duplication and a newly detected transversion in the matK gene. Chloroplast DNA variation was further investigated using PCR-RFLP (Polymerase Chain Reaction-Random Fragment Length Polymorphism), and haplotypes were constructed based on all mutational combinations. A closer relationship than presently accepted between M. sylvestris and M. domestica was established at the cytoplasmic level, with the detection of eight chloroplast haplotypes shared by both species. Hybridization between M. sylvestris and M. domestica was also apparent at the local level with sharing of rare haplotypes among local cultivars and sympatric wild trees. Indications of the use of wild Malus genotypes in the (local) cultivation process of M. domestica and cytoplasmic introgression of chloroplast haplotypes into M. sylvestris from the domesticated apple were found. Only one of the M. sieversii trees studied displayed one of the three main chloroplast haplotypes shared by M. sylvestris and M. domestica. This is surprising as M. sieversii has formerly been described as the main maternal progenitor of the domesticated apple. This study hereby reopens the exciting discussion on the origin of M. domestica.  相似文献   
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Background  

Nuclear insertions of mitochondrial sequences (NuMts) have been identified in a wide variety of organisms. Trafficking of genetic material from the mitochondria to the nucleus has occurred frequently during mammalian evolution and can lead to the production of a large pool of sequences with varying degrees of homology to organellar mitochondrial DNA (mtDNA) sequences. This presents both opportunities and challenges for forensics, population genetics, evolutionary genetics, conservation biology and the study of DNA from ancient samples. Here we present a case in which difficulties in ascertaining the organellar mtDNA sequence from modern samples hindered their comparison to ancient DNA sequences.  相似文献   
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Five microsatellite loci were isolated and characterized within the woolly mouse opossum (Micoureus paraguayanus), a Neotropical marsupial, using an enrichment cloning procedure. Between four and seven alleles were detected per locus, with expected heterozygosity ranging from 0.358 to 0.560. These microsatellites should provide useful markers in a variety of genetic analyses to examine parentage, inbreeding, population structure and population dynamics in fragmented forest habitats.  相似文献   
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Physical disorders are, compared to the general population, more prevalentin people with severe mental illness (SMI). Although this excess morbidityand mortality is largely due to modifiable lifestyle risk factors, the screeningand assessment of physical health aspects remains poor, even in developedcountries. Moreover, specific patient, provider, treatment and system factorsact as barriers to the recognition and to the management of physical diseasesin people with SMI. Psychiatrists can play a pivotal role in the improvementof the physical health of these patients by expanding their task from clinicalpsychiatric care to the monitoring and treatment of crucial physical parameters.At a system level, actions are not easy to realize, especially for developingcountries. However, at an individual level, even simple and very basic monitoringand treatment actions, undertaken by the treating clinician, can already improvethe problem of suboptimal medical care in this population. Adhering to monitoringand treatment guidelines will result in a substantial enhancement of physicalhealth outcomes. Furthermore, psychiatrists can help educate and motivatepeople with SMI to address their suboptimal lifestyle, including smoking,unhealthy diet and lack of exercise. The adoption of the recommendations presentedin this paper across health care systems throughout the world will contributeto a significant improvement in the medical and related psychiatric healthoutcomes of patients with SMI.  相似文献   
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H. DE  HAAN 《Freshwater Biology》1972,2(3):235-241
It this study the use of Sephadex G-25, Sephadex LH-20 and CPG-10-75 for the separation of soluble humic compoutids frotn fresh water is tested. It is shown by Sephadex G-25 gel filtration that differences in molecule-size distribution of soluble humic compounds in one lake at different titnes and between lakes can be predicted by E250 and E365 measurements.  相似文献   
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