distruct: a program for the graphical display of population structure

In analysis of multilocus genotypes from structured populations, individual coefficients of membership in subpopulations are often estimated using programs such as structure . distruct provides a general method for visualizing these estimated membership coefficients. Subpopulations are represented as colours, and individuals are depicted as bars partitioned into coloured segments that correspond to membership coefficients in the subgroups. distruct , available at http://www.cmb.usc.edu/~noahr/distruct.html , can also be used to display subpopulation assignment probabilities when individuals are assumed to have ancestry in only one group.     

多异瓢虫种群动态及捕食功能的研究

采用田间调查和室内实验。研究了多异瓢虫的种群消长规律和捕食功能，表明该虫在棉田发生量大，发生时间长、幼虫、成虫对棉蚜的功能反应为Ｈｏｌｌｉｎｇ－Ⅱ型，并随着幼虫的生长其捕食量逐渐增大。     

Genetic population structure of the Dakota skipper (Lepidoptera: Hesperia dacotae): A North American native prairie obligate

A range-wide survey of Dakotaskipper (Hesperia dacotae) populationsassessed levels of genetic variability andgeographic scale of population structure inthis species of conservation concern. Thisspecies exists on isolated patches of nativetall- and mixed-grass prairie within a highlymodified landscape dominated by agriculture. It has been extirpated from the southernportion of its range and has sufferedrange-wide declines. Nine populations weresampled from western Minnesota, eastern SouthDakota, and southern Manitoba. Starch gelelectrophoresis was used to resolve 21 isozymeloci in 278 Dakota skippers. Dakota skipperpopulations were approximately as variable asother lepidopterans found in isolated habitats. Genetic distances indicated that Manitobapopulations were somewhat distinct from ones inMinnesota and South Dakota. Isolation-by-distance was detected range-wideand among the seven southern-most populations. Genetically effective immigration rates weresmall at both range-wide and regional scalesand effective populations sizes were lowsuggesting that Dakota skipper populations aregenetically isolated from one another, althoughthey were likely more connected in the recentpast. Genotype assignment tests revealed twoclusters of populations in Minnesota and SouthDakota that were not apparent from theisolation-by-distance results. Significantheterozygote deficiencies relative toHardy-Weinberg expectations and high inbreedingcoefficients suggest structure within samplelocations. Management recommendations includethe maximization of effective population sizein each Dakota skipper population to offset theeffects of drift and habitat corridors in somecases. Habitat management should consider thewithin-site population structure and possibletemporal population structure detected in thisstudy.     

A comparison of attack rates in a native and an introduced population of the parasitoid Cotesia glomerata

The attack rate of a population of the braconid parasitoid Cotesia glomerata, introduced into the USA over 100 years ago as a parasitoid of Pieris rapae, was compared with that of a native British population, which normally attacks P. brassicae, and with that of a P. rapae specialist, Cotesia rubecula. British C. glomerata attacked P. brassicae at a much higher rate than it attacked P. rapae. In comparison with British C. glomerata, C. rubecula showed a higher attack rate with P. rapae. American C. glomerata attacked P. rapae at a slightly higher rate than did British C. glomerata, but not at as high a rate as that achieved by C. rubecula. The differences in each comparison were statistically significant. The possible causes of the differences between British and American C. glomerata attacking P. rapae are discussed. They may be due to genetic or environmental effects. Egg load did not appear to be a factor limiting the number of hosts parasitized under the conditions of the experiments.     

一株AEC^hrL—赖氨酸产生菌

从乳糖发酵短杆菌Brevibacterium Lactofermentum2645菌株出发选育L-赖氨酸产生菌,经分离复壮后,用硫酸二乙酯(DES)诱变处理,由添加S-(2-氨基乙基)—L—半胱氨酸(AEC)和L-苏氨酸的药物平板定向筛选,最后获得了一株L—赖氨酸高产菌E_(16-2)(AHV~(hr)SAM~gAEC~(hr))。进而通过正交试验、工艺条件试验最终获得了该菌株的最佳发酵条件,并考查了在此条件下的L-赖氨酸发酵过程,结果表明该菌具有生长、耗糖、产酸速度快、发酵周期短的明显特点。     

Cranial growth in Saimiri sciureus (Cebidae) and its alteration by nutritional factors: A longitudinal study

Ten male Saimiri sciureus boliviensis (Cebidae), born at the Centro Argentino de Primates (CAPRIM), were grown in captivity. At weaning (6 months old), five individuals were fed ad libitum on a 20% protein diet (controls). The other five animals were fed ad libitum on a 5% protein diet (malnourished). Animals were radiographed monthly. The length, width, and height of the anterior, middle, and posterior components of the neurocranium, and those of the masticatory, respiratory, and optic components of the face were measured. A pattern of high growth rate was observed in both the three facial and the middle neural components. The anterior and posterior neural components showed a pattern of low rate of growth. The growth behavior of each variable was also different. Lengths grew more than widths and heights in the facial components, whereas widths grew more than heights and lengths in the neurocranium. Malnutrition delayed growth in size and altered the normal shape changes. High-patterned variables, such as masticatory and respiratory lengths, and the anterior and middle neural widths were particularly affected. The masticatory and the middle neural components underwent the greatest growth arrest. The optic and the respiratory components suffered a mild effect. The anterior and the posterior neural components were affected to a lesser degree. Am J Phys Anthropol 102:545–554, 1997. © 1997 Wiley-Liss, Inc.     

Sex pheromone of a North American population of the spotted tentiform leafminer, Phyllonorycter blancardella

The major sex pheromone compound of the spotted tentiform leafminer, Phyllonorycter blancardella (F.) (Lepidoptera: Gracillariidae), from Ontario, Canada, was identified as (10E)‐dodecen‐1‐yl acetate (E10‐12:Ac) using chemical analysis and field trapping experiments. The minor compounds (10E)‐dodecen‐1‐ol (E10‐12:OH) (4.6%), dodecan‐1‐ol (12:OH) (2.3%), and (10Z)‐dodecen‐1‐yl acetate (Z10‐12:Ac) 1.6% were also identified. The dienic acetate (4E,10E)‐dodecadien‐1‐yl acetate (E4,E10‐12:Ac), a compound reported to be attractive to P. blancardella, was not found in the glands of this population. A two‐component blend of the major and one of each the three minor compounds, in ratios similar to those found in the sex pheromone gland, did not increase the attractiveness of traps baited with synthetic pheromone. The minor compounds E10‐12:OH and 12:OH were not attractive to P. blancardella when tested individually. Z10‐12:Ac was attractive to P. blancardella, although traps baited with this compound captured only 2% of the moths that were captured in traps baited with the main compound. A four‐component blend of the major and each of the three minor compounds (100 : 1 : 1 : 1) was not more attractive than the major compound alone. The related species Phyllonorycter mespilella was captured in traps baited with E10‐12:Ac.     

Admixture analysis of a rural population of the state of Guerrero, Mexico

We studied 156 individuals of Native American descent from the city of Tlapa in the state of Guerrero in western Mexico. Most individuals' ethnicity was either Nahua, Mixtec, or Tlapanec, but self-identified Mestizos and individuals of mixed ethnicities were also included in the sample. We typed 24 autosomal, one Y-chromosome, and four mitochondrial ancestry-informative markers (AIMs) to estimate group and individual admixture proportions, and determine whether the admixture process involved directional gene flow between parental groups. When genetically defined (GD) Mestizos were excluded from the analysis, Native American ancestry represented approximately 98% of the population's gene pool, while European and West African ancestry represented approximately 1% each. Maternally inherited markers also showed an exceptionally high Native American contribution (98.5%), as did the paternally inherited marker, DYS199 (90.7%). We did not detect genetic structure in this population using these AIMs, which appears consistent with the homogeneity of the sample in terms of admixture proportions. The addition of GD Mestizos to the sample did not produce a considerable change in admixture estimates, but it had a major effect on population structure. These results show that the population of Tlapa in Guerrero, Mexico, has experienced little admixture with Europeans and/or West Africans. They also show that the impact of a small number of admixed individuals on an otherwise homogeneous population might have profound implications on subsequent ancestry/phenotype analysis and mapping strategies. We suggest that heterogeneity is a major characteristic of Mexican populations and, as a consequence, should not be disregarded when designing epidemiological studies of Mexican and Mexican American populations.     

A nucleic acid biosensor for the detection of a short sequence related to the hepatitis B virus using bis(benzimidazole)cadmium(II) dinitrate as an electrochemical indicator

A novel hybridization indicator, bis(benzimidazole)cadmium(II) dinitrate (Cd(bzim)(2)(NO(3))(2)), was utilized to develop an electrochemical DNA biosensor for the detection of a short DNA sequence related to the hepatitis B virus (HBV). The sensor relies on the immobilization and hybridization of the 21-mer single-stranded oligonucleotide from the HBV long repeat at the glassy carbon electrode (GCE). The hybridization between the probe and its complementary sequence as the target was studied by enhancement of the peak of the Cd(bzim)(2)(2+) indicator using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Numerous factors affecting the probe immobilization, target hybridization, and indicator binding reactions were optimized to maximize the sensitivity and speed of the assay time. With this approach, a sequence of the HBV could be quantified over the range from 1.49x10(-7)M to 1.06x10(-6)M, with a linear correlation of r=0.9973 and a detection limit of 8.4x10(-8)M. The Cd(bzim)(2)(2+) signal observed from the probe sequence before and after hybridization with a four-base mismatch containing sequence was lower than that observed after hybridization with a complementary sequence, showing good selectivity. These results demonstrate that the Cd(bzim)(2)(2+) indicator provides great promise for the rapid and specific measurement of the target DNA.     

Genetic relationships and population structure within taxa of the endemic Sideritis pusilla (Lamiaceae) assessed using RAPDs

RAPD analysis has been performed for 15 plant populations, covering eight different infraspecific taxa of Sideritis pusilla (Lange) Pau, member of the Lamiaceae endemic to southeastern Spain, and their putative parental species Sideritis hirsuta L. and Sideritis Uucantha Cav. Genetic distances, together with the presence of numerous fixed molecular markers differentiating S. pusilla from its putative ancestors, indicate that it should be considered as a true species. Cladistic and populational analysis led to the allocation of S. pusilla populations into three major groups– osteoxylla, jlavovirens and pusilla/almeriensis –which include taxa previously described as ranging from the varietal to the specific level. Low genetic differentiation among groups revealed by a reduced number of specific molecular markers justify their assignment under the infraspecific range. Moreover, the existence of both morphological and biogeographical differences, supports a status for these groups as subspecies of S. pusilla. Highly significant ( P <0.002) variance partitioning data (AMOVA) extracted from the analysis of individuals within S. pusilla populations show that, of the total genetic diversity, 68.8% was attributable to individual differences within populations, 19.9% to populational differences within groups, and only 11.3% to divergence between groups. This distribution is in agreement with the outcrossing nature of these plants. Comparative analysis of variance within populations reveals a reduced genetic variation for the osteoxylla group, thus supporting its previous consideration as an endangered taxon.     

Impact of released Eurasian otters on a population of American mink: a test using an experimental approach

Competition is considered to be a major evolutionary driving force within assemblages of related and morphologically similar species, but it is notoriously difficult to test and quantify especially amongst species that cannot be easily manipulated in a laboratory or in the field. By exploiting a re-introduction of Eurasian otters ( Lutra lutra ) in the Upper Thames catchment (UK) in 1999 we performed an experiment to test whether there was evidence of competition between otters and American mink ( Mustela vison ). Mink and otters are semi-aquatic mustelids belonging to the same guild. Otters are expected to be the dominant competitor because they are larger and better adapted at exploiting aquatic resources. Our hypothesis was that mink declines when the density of otters increases. We measured the effect of competition at the population level, by observing whether mink distribution and densities changed in an area of 1353 km² in association with the arrival of its putative competitor. We estimated distribution and densities by means of sign surveys and trapping. The results showed that otters were associated with a significant and rapid reduction in the densities of mink, while mink occupancy remained approximately the same in an area of 2464 km² that was used as a control. We observed that the spatial distribution of the mink population throughout its decline was influenced by the yearly cycle of mink activities, with areas being temporarily re-colonized during the dispersal season. Mink is an invasive species in the UK threatening the survival of some native species. Our findings suggest that the re-establishment of otter populations is likely to lead to a decline of mink that may, in turn, be beneficial to native species threatened by this invasive.     

柿树新害虫──柿树真绵蚧的研究

柿树真绵蚧Eupulrinariacitricola（Kuwana）的报道在国内尚属首次。近年来该虫在河北省部分柿产区日趋严重,成为柿树的一种重要害虫。该虫在当地1年发生1次。以2龄若虫在当年生枝条上越冬,第二年3月上旬越冬虫体复苏,4月20～25日成虫交配,5月20～25日雌成虫产卵,6月10～20日若虫孵化后,固定在叶片上越夏,9月下旬越夏若虫蜕皮进入2龄,并转移到当年生枝条上越冬。农药防治结果表明：久效磷、氧乐果等有机内吸剂的防治效果很好,防治的最佳时间是6月中旬。该虫在当地的主要天敌有红点瓢虫ChilocoruskuwanaeSilvestri、黑缘红瓢虫C.rubidusHope和一种寄生蜂。     

Evaluation of the population dynamics of the forage legume (Lotus corniculatus), using matrix population models

The population dynamics of perennial crop plants are influenced by numerous factors, including management practices. Conditions in the field vary from year to year, and matrix population models are useful for evaluating population behaviour in relation to environmental variability. In Missouri, the stand persistence of birdsfoot trefoil ( Lotus corniculatus ), a perennial legume, is often limited by disease and poor seed production. A stage-based, matrix population model was developed to evaluate the population dynamics of birdsfoot trefoil in relation to clipping treatment. The plant growth stages represented in the model were seeds, seedlings, mature vegetative and reproductive plants. Two phases of population growth were evaluated in clipped and unclipped stands. Establishment-phase populations were characterized by relatively high mortality and low reproduction. Elasticity analysis indicated that growth of these populations was most sensitive to the survival of vegetative plants. Mature vegetative plants and seeds comprised the majority of surviving individuals in clipped and unclipped populations, respectively; however, establishment-phase populations under both management treatments tended toward extinction. Populations in the post-establishment phase of growth were characterized by relatively low mortality and high reproduction. Population growth in this phase of growth was most sensitive to seed production, and most individuals in these populations were at the seed stage.     

A parentage evaluation test in North American Elk (Wapiti) using microsatellites of ovine and bovine origin

DNA microsatellites originally detected in sheep and cattle are also detectable in North American elk (Wapiti) using polymerase chain reactions. We have developed a parentage test in elk using eleven microsatellite markers that are highly polymorphic and informative.     

生物电阻抗法测定广西京族的体成分

本文利用生物电阻抗法对广西京族的体成分进行了测定,初步分析了其体成分形成的原因。研究组于2020年12月在广西壮族自治区东兴市“京族三岛”测定了430例京族成人（男182例,女248例）的16项指标。结果表明,京族男、女性的体质量、总肌肉量、躯干肌肉量、推定骨量、总能量代谢与年龄呈显著负相关。体成分随年龄增长而发生的变化,主要是自然的生理变化和劳动强度下降所致。随着年龄增长,男性的体脂率升高,这主要是躯干脂肪增多造成的。京族男性的体质量、总肌肉量、推定骨量、总能量代谢、水分率、四肢和躯干肌肉量均大于女性,而体脂率、四肢和躯干脂肪率均小于女性。京族男性比女性拥有更大的体质量和更高比例的骨骼肌,这两方面因素再加上劳动强度的差异,可能导致男性肌肉量、骨量、脂肪率等体成分与女性存在差异。总体来看,京族成人身体偏胖,脂肪含量较高,身体含水量基本正常,体成分特征与同为南亚语系或同在沿海地区的其他中国族群并不相似,而相对更接近于中国蒙古族,并且表现在体质量、体脂率、水分率等方面接近。生活环境、社会经济、日常饮食和劳动强度等因素是导致京族成人体质量及体脂率较高的原因。