中国人群肤纹的主成分分析

近年来 ,我国学者多将中国人群分为南、北两大类群。作者对我国 5 9个人群的肤纹进行主成分分析。结果表明 ,根据肤纹特征 ,可将中国人分为 6个族群 ,除北方族群、南方族群外 ,存在着新疆族群与西藏族群。新疆族群与北方族群相比 ,斗型率低 ,尺箕、桡箕率高 ,小鱼际区与指间区Ⅱ、Ⅲ真实花纹率高。西藏族群斗型率高、尺箕率低。北方族群与南方族群相比 ,指纹嵴线总数、小鱼际区与指间区Ⅲ真实花纹率高。此外 ,还存在南北族群间的过渡族群与南北混合族群。 8个汉族人群未能聚集 ,分散于各族群中。这表明 ,汉族与少数民族间、南北方民族间存在着肤纹基因的交流。将中华民族分为南北两大类群的观点可能过于简单化了。     

Quantitative genetic differences between populations of Drosophila melanogaster from diverse geographic origins

Crosses were made between each seven populations of Drosophila melanogaster-three of which were laboratory populations and four were recently captured populations-and a line previously selected for low sternopleural bristle number for many generations. In each of six replicate lines from each cross, selection was practised for low sternopleural bristle number; subsequently these replicates were intercrossed and reselected. Introduction of new genetic material from four populations into the selected line was achieved, indicating the presence in these populations of particular alleles which are absent from or rare in the base populations of the selected line. Introduction of new genetic material from three populations into the selected line was not achieved. Consequently, it was possible to establish two groups of populations. In each group, the populations appear to be segregating for essentially the same alleles. Differences in gene frequency rather than the presence or absence of particular alleles are mainly responsible for the differences observed between the populations.In all, 11 populations screened for genetic differences controlling sternopleural bristle number. There are widespread genetic similarities among populations of very different geographic origin. Laboratory populations as a group are not more homogeneous than recently collected populations, although the latter are genetically more variable. Drift alone could account for the reduction of variability in the laboratory populations.     

Taxonomic relationships within the pan-oriental narrow-mouth toad Microhyla ornata as revealed by mtDNA analysis (Amphibia, Anura, Microhylidae)

A molecular phylogenetic survey was conducted using mtDNA sequences of 12S and 16S rRNA, and cyt-b genes to examine taxonomic relationships among populations of the Pan-Oriental microhylid, Microhyla ornata, from India, Bangladesh, Thailand, Laos, China, Taiwan, and the Ryukyu Archipelago of Japan. Two discrete clades are recognized within this species, one consisting of populations from India and Bangladesh, and the other encompassing the remaining populations. In the latter clade, populations from the Ryukyu Archipelago are clearly split from the rest (populations from Taiwan and the continent) with considerable degrees of genetic differentiations. Each of the three lineages is judged to represent a good species, and the name Microhyla ornata is restricted to the South Asian populations. For the populations from Taiwan and a wide region from China to Southeast Asia, the name Microhyla fissipes should be applied, whereas the Ryukyu populations are most appropriately referred to as Microhyla okinavensis, although further substantial genetic differentiations are recognized among some island group populations within this last species.     

云贵高原多星韭二倍体—四倍体分布格局研究

采用染色体压片技术对云贵高原17个多星韭居群,共412株个体进行染色体数目和核型研究。结合已有的细胞学资料,对云贵高原多星韭多倍体分布格局进行了研究。9个二倍体居群、6个二倍体与四倍体混生居群分布于云南中部至西北部,12个四倍体居群分布于整个云贵高原。二倍体除香格里拉d和保山居群核型类型为3A型外,其余均为2A型,四倍体除会泽和赫章居群为2 B型外,其余均为2A型。云南西北部四倍体核型不对称指数低于其它分布区,推测该地区四倍体可能起源较早。多星韭二倍体与四倍体核型类型和形态并无明显差异,表明多星韭四倍体可能为同源多倍体。     

基于psbA-trnH分析的何首乌野生居群遗传多样性

对产自不同省区的何首乌[ Fallopia multiflora (Thunb.) Harald.] 17个野生居群85个单株的sbA-trnH序列进行了扩增和分析,在此基础上分析了居群间的遗传多样性,并采用NJ法对85个单株进行了聚类分析.结果表明:供试85个单株的psb A-trnH序列长度为384 bp;其中,变异位点为167 bp,简约信息位点为53 bp,分别占序列总长度的43.5％和13.8％.变异类型主要为碱基缺失和替换;变异位点主要集中在235～281 bp区域,根据位点变异情况可将17个居群大体分为3类.各居群间的遗传距离为0.000～0.172,其中,贵州居群与其他16个居群间的遗传距离为0.167 ～0.172,而其他16个居群间的遗传距离为0.000～0.017.17个居群间的核苷酸多样性指数(Pi)、遗传分化系数(Nst)和基因流(Nm)分别为0.028 56、0.918 68和0.04;除贵州居群外其他16个居群的Pi、Nst和Nm分别为0.015 68、0.837 19和0.10;贵州局群与其周边省区(四川、云南、广西、湖南和湖北)居群的Pi、Nst和Nm分别为0.047 99、0.937 62和0.03.在NJ系统树上,17个居群可聚为4支,且大部分居群的供试单株聚在同一分支中;仅贵州居群单独聚为一支,与序列分析的划分结果基本一致.由研究结果可见:野生何首乌居群总遗传变异的91.868％来自居群间,8.132％来自居群内,居群间的基因交流较少;除贵州居群外其余16个居群的整体遗传多样性水平偏低,说明何首乌居群整体多样性水平在很大程度上受贵州居群的影响.     

Large mainland populations of South Island robins retain greater genetic diversity than offshore island refuges

For conservation purposes islands are considered safe refuges for many species, particularly in regions where introduced predators form a major threat to the native fauna, but island populations are also known to possess low levels of genetic diversity. The New Zealand archipelago provides an ideal system to compare genetic diversity of large mainland populations where introduced predators are common, to that of smaller offshore islands, which serve as predator-free refuges. We assessed microsatellite variation in South Island robins (Petroica australis australis), and compared large mainland, small mainland, natural island and translocated island populations. Large mainland populations exhibited more polymorphic loci and higher number of alleles than small mainland and natural island populations. Genetic variation did not differ between natural and translocated island populations, even though one of the translocated populations was established with five individuals. Hatching failure was recorded in a subset of the populations and found to be significantly higher in translocated populations than in a large mainland population. Significant population differentiation was largely based on heterogeneity in allele frequencies (including fixation of alleles), as few unique alleles were observed. This study shows that large mainland populations retain higher levels of genetic diversity than natural and translocated island populations. It highlights the importance of protecting these mainland populations and using them as a source for new translocations. In the future, these populations may become extremely valuable for species conservation if existing island populations become adversely affected by low levels of genetic variation and do not persist.     

The genetic structure of Drosophila ananassae populations from Asia, Australia and Samoa

Information about genetic structure and historical demography of natural populations is central to understanding how natural selection changes genomes. Drosophila ananassae is a widespread species occurring in geographically isolated or partially isolated populations and provides a unique opportunity to investigate population structure and molecular variation. We assayed microsatellite repeat-length variation among 13 populations of D. ananassae to assess the level of structure among the populations and to make inferences about their ancestry and historic biogeography. High levels of genetic structure are apparent among all populations, particularly in Australasia and the South Pacific, and patterns are consistent with the hypothesis that the ancestral populations are from Southeast Asia. Analysis of population structure and use of F-statistics and Bayesian analysis suggest that the range expansion of the species into the Pacific is complex, with multiple colonization events evident in some populations represented by lineages that show no evidence of recent admixture. The demographic patterns show isolation by distance among populations and population expansion within all populations. A morphologically distinct sister species, D. pallidosa, collected in Malololelei, Samoa, appears to be more closely related to some of the D. ananassae populations than many of the D. ananassae populations are to one another. The patterns of genotypic diversity suggest that many of the individuals that we sampled may be morphologically indistinguishable nascent species.     

菱角萤叶甲不同地理种群数量性状变异(鞘翅目:叶甲科)

采用模糊聚类、系统聚类和主成分分析的方法对中国12个不同地理种群菱角萤叶甲Galerucella birmanica Jacoby的形态数据进行了分析,探讨了其数量性状变异和地理分布间的关系,并对菱角萤叶甲亚种的分类地位进行了界定。聚类分析将我国菱角萤叶甲12个地理种群分为6个部分:其中西南云贵高原地区的保山种群为一组,华南地区的广州种群为一组,东北地区的沈阳种群为一组,华中地区的孝感种群为一组,长江以北地区的淮安、扬州、泰安和阜阳种群为一组,长江以南地区的常州、嘉兴、青浦和义乌种群为一组,可见不同地理种群菱角萤叶甲的数量性状变异与地理分布之间具有显著的相关性。主成分分析显示,菱角萤叶甲各器官的长度存在相互促进共同变异的关系,变异与性状具有显著正相关性。采用形态学测量的方法对于确定菱角萤叶甲亚种的地位是可行的。     

Microsatellite variation in autochthonous and introduced populations of the Alpine marmot (Marmota marmota) along a European west–east transect

Microsatellite variation was studied in 11 populations of the Alpine marmot along a west–east transect through the present distribution range. The samples represent five autochthonous and six introduced populations. Eleven loci were analysed in nine populations and six loci in the two populations from France. In the populations from the Western Alps, there is no indication for reduced variability as has been assumed in previous studies. However, a decrease of variation in the autochthonous populations was observed from the west to the east. The introduced populations showed a heterogeneous pattern reflecting the geographic origin of the released individuals. The population from the Spanish Pyrenees harbours a high level of variation and is genetically closest to the French populations. In Austria, three of the introduced populations have low variation and are closely related to the autochthonous populations from the western part of Austria. In contrast, two introduced populations from the central part of Austria are highly variable and resemble the populations from France. At least for one of these populations an early introduction of founder individuals from the Western Alps has been documented.     

二维Lotka-Volterra竞争系统的β持续生存与β绝灭

利用极限理论与延拓方法研究了二维Lotka-Volterra竞争务统在有限时间内的持续生存与绝灭问题,即β持续生存与β绝灭问题.给出了种群β持续生存与β绝灭的一些充分条件.所得结论表明:种群的β持续生存和β绝灭与种群的初始数量有关.在一定条件下,只要控制种群的初始数量在一定范围内,即可保证两种群永远β持续生存.     

The effects of gene flow and population isolation on the genetic structure of␣reintroduced wild turkey populations: Are genetic signatures of source populations retained?

To counter losses of genetic diversity in reintroduced populations, species sometimes are reintroduced into networks of populations with the potential to exchange individuals. In reintroduced populations connected by gene flow, patterns of genetic structure initiated by the founding event may become obscured, and populations may eventually follow an isolation-by-distance model of genetic differentiation. Taking advantage of well-documented reintroduction histories of wild turkey populations in Indiana, we assessed the degree to which gene flow among reintroduced populations has obscured genetic signatures left by the founding events. Using a suite of nuclear microsatellite loci and sequence data from the mitochondrial control region, we characterized the level of genetic diversity and degree of genetic structure within and among: (1) reintroduced populations in isolated northern Indiana Fish and Wildlife Areas, (2) reintroduced populations in southern Indiana Fish and Wildlife Areas, where the distribution of populations is more continuous, and (3) source populations used for these reintroductions. We also utilized individual-based assignment tests to determine the relative contribution of source populations to the current distribution of alleles in reintroduced populations. Our results indicate that wild turkey reintroductions in Indiana have left distinct genetic signatures on populations that are detectable even after several decades. Although we found some case-specific evidence for gene flow, particularly in regions where populations are in close proximity, our data indicate on overall paucity of gene flow at a regional scale. Such post-reintroduction genetic monitoring has immediate implications for the design of optimal strategies to reintroduce wildlife for conservation and management.     

Differential admixture shapes morphological variation among invasive populations of the lizard Anolis sagrei

The biological invasion of the lizard Anolis sagrei provides an opportunity to study evolutionary mechanisms that produce morphological differentiation among non-native populations. Because the A. sagrei invasion represents multiple native-range source populations, differential admixture as well as random genetic drift and natural selection, could shape morphological evolution during the invasion. Mitochondrial DNA (mtDNA) analyses reveal seven distinct native-range source populations for 10 introduced A. sagrei populations from Florida, Louisiana and Texas (USA), and Grand Cayman, with 2-5 native-range sources contributing to each non-native population. These introduced populations differ significantly in frequencies of haplotypes from different native-range sources and in body size, toepad-lamella number, and body shape. Variation among introduced populations for both lamella number and body shape is explained by differential admixture of various source populations; mean morphological values of introduced populations are correlated with the relative genetic contributions from different native-range source populations. The number of source populations contributing to an introduced population correlates with body size, which appears independent of the relative contributions of particular source populations. Thus, differential admixture of various native-range source populations explains morphological differences among introduced A. sagrei populations. Morphological differentiation among populations is compatible with the hypothesis of selective neutrality, although we are unable to test the hypothesis of interdemic selection among introductions from different native-range source populations.     

Genetic differentiation and habitat partition of Robertsonian house mouse populations (Mus musculus domesticus) of Tunisia

The karyological analysis of Tunisian populations of house mice revealed the existence of a Robertsonian (Rb) chromosomal race carrying nine pairs of metacentric chromosomes in central Tunisia. Divergence estimates showed that they are genetically differentiated from local all-acrocentric populations and have a reduced level of genic variability. The Rb populations are restricted to urban habitats, whereas all-acrocentric populations occur in rural areas. Contact zones between these two types of habitat yield chromosomally polymorphic populations. Analysis of gene flow indicates that it is reduced and limited to populations bordering the contact areas. The reduced genic variability and patchy distribution exhibited by the Tunisian Rb mice do not agree with results from previous studies of the European Rb populations. Two hypotheses are presented to account for this discrepancy based on local differentiation versus introduction of the Tunisian Rb race.     

State‐dependent dynamics of cycles in red grouse abundance

Fluctuating populations are frequently demonstrated to co‐vary in abundance over space, but the dynamics of coupling between populations that gives rise to this synchrony are poorly understood. Synchrony may arise through coupling that is weak and continuous, but in populations that cycle with a characteristic period, synchrony can be maintained through stronger coupling that acts only intermittently. Here, we apply a discrete Markov model that describes the state of a population trajectory to be in one of four possible states. The Markov model reveals the nature of the coupling that gives rise to the weakly synchronous cycles of red grouse abundance. Using time‐series data from 287 populations across the species range in the UK, we show that grouse populations appear mostly uncoupled through time, but that approximately one year in six, “collective forcing events” occur, where populations in a region are forced into synchrony to a significantly greater degree than would be expected if their dynamics proceeded independently. In the absence of these events, synchrony between populations dissipates within ~3 yr. Smaller, low abundance populations tend to make the less probable phase shifts required to synchronize with nearby high abundance populations, suggesting that these low abundance populations are more susceptible to the perturbations responsible for phase shifts than larger populations.     

Founding events influence genetic population structure of sockeye salmon (Oncorhynchus nerka) in Lake Clark, Alaska

Bottlenecks can have lasting effects on genetic population structure that obscure patterns of contemporary gene flow and drift. Sockeye salmon are vulnerable to bottleneck effects because they are a highly structured species with excellent colonizing abilities and often occupy geologically young habitats. We describe genetic divergence among and genetic variation within spawning populations of sockeye salmon throughout the Lake Clark area of Alaska. Fin tissue was collected from sockeye salmon representing 15 spawning populations of Lake Clark, Six-mile Lake, and Lake Iliamna. Allele frequencies differed significantly at 11 microsatellite loci in 96 of 105 pairwise population comparisons. Pairwise estimates of FST ranged from zero to 0.089. Six-mile Lake and Lake Clark populations have historically been grouped together for management purposes and are geographically proximate. However, Six-mile Lake populations are genetically similar to Lake Iliamna populations and are divergent from Lake Clark populations. The reduced allelic diversity and strong divergence of Lake Clark populations relative to Six-mile Lake and Lake Iliamna populations suggest a bottleneck associated with the colonization of Lake Clark by sockeye salmon. Geographic distance and spawning habitat differences apparently do not contribute to isolation and divergence among populations. However, temporal isolation based on spawning time and founder effects associated with ongoing glacial retreat and colonization of new spawning habitats contribute to the genetic population structure of Lake Clark sockeye salmon. Nonequilibrium conditions and the strong influence of genetic drift caution against using estimates of divergence to estimate gene flow among populations of Lake Clark sockeye salmon.     

Vital survivors: low genetic variation but high germination in glacial relict populations of the typical rock plant Draba aizoides

Glacial relict populations are isolated remnants of arctic-alpine species resulting from shifts of the distribution range during glaciations. Recently, the conservation value of relict populations has been emphasized, since they are adapted to stressful ecological conditions, which may be important for future distribution range shifts due to climate change. However, glacial relict populations have strongly been affected by historical fragmentation processes. Limited genetic variation and reduced reproduction can, therefore, be postulated for glacial relict populations. In our study we tested these assumptions. We investigated central European populations of the typical rock plant Draba aizoides from the Alps (considered as a core distribution area) and from the Swabian Alb, the Southern and Northern Franconian Jura (where its populations are considered glacial relict populations). We analysed genetic variation using molecular markers AFLPs and studied the reproduction of the populations in germination experiments. Glacial relict populations were genetically less variable and strongly differentiated, but they exhibited higher germination than populations from the Alps. From our results it can be concluded that glacial relict populations may have limited genetic variation, but they do not necessarily exhibit a limited reproductive capacity. Glacial relict populations are, therefore, vital survivors of the Pleistocene, which deserve full conservation attention, especially against the background of future climate change.     

Estimation of parameters of deleterious mutations in partial selfing or partial outcrossing populations and in nonequilibrium populations

The Deng-Lynch method was developed to estimate the rate and effects of deleterious genomic mutations (DGM) in natural populations under the assumption that populations are either completely outcrossing or completely selfing and that populations are at mutation-selection (M-S) balance. However, in many plant and animal populations, selfing or outcrossing is often incomplete in that a proportion of populations undergo inbreeding while the rest are outcrossing. In addition, the degrees of deviation of populations from M-S balance are often not known. Through computer simulations, we investigated the robustness and the applicability of the Deng-Lynch method under different degrees of partial selfing or partial outcrossing and for nonequilibrium populations approaching M-S balance at different stages. The investigation was implemented under constant, variable, and epistatic mutation effects. We found that, generally, the estimation by the Deng-Lynch method is fairly robust if the selfing rate (S) is <0.10 in outcrossing populations and if S > 0.8 in selfing populations. The estimation may be unbiased under partial selfing with variable and epistatic mutation effects in predominantly outcrossing populations. The estimation is fairly robust in nonequilibrium populations at different stages approaching M-S balance. The dynamics of populations approaching M-S balance under various parameters are also studied. Under mutation and selection, populations approach balance at a rapid pace. Generally, it takes 400-2000 generations to reach M-S balance even when starting from homogeneous individuals free of DGM. Our investigation here provides a basis for characterizing DGM in partial selfing or outcrossing populations and for nonequilibrium populations.     

Independent evolutionary origins of landlocked alewife populations and rapid parallel evolution of phenotypic traits

Alewife, Alosa pseudoharengus, populations occur in two discrete life-history variants, an anadromous form and a landlocked (freshwater resident) form. Landlocked populations display a consistent pattern of life-history divergence from anadromous populations, including earlier age at maturity, smaller adult body size, and reduced fecundity. In Connecticut (USA), dams constructed on coastal streams separate anadromous spawning runs from lake-resident landlocked populations. Here, we used sequence data from the mtDNA control region and allele frequency data from five microsatellite loci to ask whether coastal Connecticut landlocked alewife populations are independently evolved from anadromous populations or whether they share a common freshwater ancestor. We then used microsatellite data to estimate the timing of the divergence between anadromous and landlocked populations. Finally, we examined anadromous and landlocked populations for divergence in foraging morphology and used divergence time estimates to calculate the rate of evolution for foraging traits. Our results indicate that landlocked populations have evolved multiple times independently. Tests of population divergence and estimates of gene flow show that landlocked populations are genetically isolated, whereas anadromous populations exchange genes. These results support a 'phylogenetic raceme' model of landlocked alewife divergence, with anadromous populations forming an ancestral core from which landlocked populations independently diverged. Divergence time estimates suggest that landlocked populations diverged from a common anadromous ancestor no longer than 5000 years ago and perhaps as recently as 300 years ago, depending on the microsatellite mutation rate assumed. Examination of foraging traits reveals landlocked populations to have significantly narrower gapes and smaller gill raker spacings than anadromous populations, suggesting that they are adapted to foraging on smaller prey items. Estimates of evolutionary rates (in haldanes) indicate rapid evolution of foraging traits, possibly in response to changes in available resources.     

Biological effects of chronic radiation exposure on plant populations

The findings from long-term field studies on biological effects in plant populations inhabiting radioactively contaminated territories contrast in levels and compositions of dose-forming radionuclides are presented. Plant populations developing under radioactive impact show enhanced frequencies of gene and chromosome mutations, and their reproductive potential is inferior to reference populations. Even relatively low levels of technogenic impact are able to increase genetic diversity and destroy regularities inherent for intact populations. Chronic radiation exposure from a certain level appears to be an ecological factor changing genetic structure of wild populations. Data presented indicate the presence of adaptation processes in plant populations in territories with technogenic impact. Under ecological stress, there are selection processes for resistance improvement in plant populations. But an appearance and rate of this process can essentially differ in dependence on radioecological conditions.     

Variability of nonmetric traits of musk deer <Emphasis Type="Italic">Moschus moschiferus</Emphasis> L. (Moschidae,Cetartiodactyla) craniums

Variation in 15 phenotypic traits is investigated in 349 craniums of seven geographic populations. Differences between geographic populations are ascertained, and phenotypic peculiarities of the subspecies are determined by principal component analysis and cluster analysis using the measure of the contribution to variability of populations and of subspecies similarity. Variations in populations of the Siberian and Himalayan subspecies in nonmetric characters are established. Differences between the craniums from populations are shown to be manifested to a greater degree than between the craniums of subspecies. The analysis of nonmetric characters showed the lack of a rare phene as a diagnostic feature of the musk deer.