共查询到20条相似文献，搜索用时 0 毫秒
1.
盐桦（Betula halophila Ching ex P.C.Li）是我国120个极小种群野生植物之一,仅分布于我国新疆阿勒泰地区。为了解其在迁地保护过程中对环境的适应性和沿海强风环境等对幼苗生长的影响,以山东烟台迁地保护基地内两个盐桦居群为材料,对其3年的生长量、果实性状、叶性状以及叶片生态化学计量等进行研究,利用独立样本t检验和贝叶斯方差分析对山东迁地保护两个居群和新疆迁地保护居群进行比较分析。结果显示,经过3年的生长,盐桦在烟台地区适应性良好,能在一个生长周期结出果实,设置风障以后盐桦生长速度显著升高,表明在幼苗敏感期设置风障可以为幼苗越冬提供保障,同时风障营造的相对稳定的环境提高了盐桦对资源环境的利用能力。 相似文献
2.
3.
黄梅秤锤树(Sinojackia huangmeiensis J.W.GeX.H.Yao)是我国120个极小种群野生植物之一。本研究运用独立样本t检验和贝叶斯方差分析比较黄梅秤锤树仅存的1个迁地保护种群和1个野生种群的环境条件、果实形态性状和果实元素含量。结果显示,迁地保护种群和野生种群同处于亚热带地区,年均温和年降水量基本一致。迁地保护种群的果实长度、宽度和长宽比均显著大于野生种群;2个种群在果实重量上呈现相同的趋势,但差异不显著。迁地保护种群在果实形态性状方面,种内变异程度不低于野生种群;土壤和果实中绝大多数元素(Ni元素除外)的含量在2个种群间的变化规律不一致。研究结果表明该物种的迁地保护基本成功,但存在迁地保护种群较小的问题。 相似文献
4.
Snakes are a particularly threatened vertebrate taxon, with distributions of many species and populations becoming increasingly fragmented. At present, little is known about the degree of genetic differentiation that exists between isolated populations even though such information may be critical to their survival and conservation. As an example of how recently developed RAPD genetic markers can be used in conservation genetics, we present preliminary results from a study which used these DNA-based markers to assess population divergence in two threatened Canadian snakes, the black rat snake ( Elaphe o. obsoleta ) and the eastern massasauga rattlesnake ( Sistrurus c. catenatus ). We present information on the levels of variation and reliability of amplification for fragments generated from five primers. We then use a recently developed analytical technique to estimate levels of nucleotide diversity within populations and sequence divergence between populations. Our results show that intrapopulation levels of divergence as estimated by the methods of Clark & Lanigan ( Molecular Biology and Evolution 1993, 10 , 1096–1111) approximate those found for mtDNA in vertebrates and that diversity between snake populations is small and non-significant when tested using randomization procedures. Thus, our study provides an example of how RAPDs can be applied to conservation genetic studies of vertebrates and suggest that the snake populations we examined have only recently become isolated and maybe considered genetically equivalent from a conservation perspective, although this conclusion needs to be confirmed with other DNA-based markers. 相似文献
5.
采用随机扩增多态 DNA(RAPD)分析研究了中国3种珍稀濒危兰科植物硬叶兜兰(Paphiopedilum micranthum Tang et Wang)、麻栗坡兜兰(P. malipoense S.C.Chen et Tsi)和独花兰(Changnienia amoena Chien)的遗传多样性与群体遗传结构.12个RAPD引物在2种兜兰中共扩增出131条带.对4个硬叶兜兰群体的检测表明其物种水平的多态条带百分率(PPB)为 71.6%,Nei 的基因多样度(h)为 0.217 1,Shannon多样性指数 (I) 为 0.330 1;4个群体的平均多样性水平为 PPB = 45.2%,h = 0.145 7,I = 0.220 4,低于远交兰花的平均水平.在总遗传变异中,群体间遗传变异占20.31%,略高于远交物种的平均水平.在物种水平上,麻栗坡兜兰的PPB为49.5%,h为0.117 4,I为0.176 4,均大大低于硬叶兜兰.对11个独花兰群体采用16个RAPD引物共扩增出119条带.物种水平PPB=76.5%,h=0.194 1,I=0.305 8;在群体水平上,上述3个指标的平均值则分别为37.2%、0.119 7和0.181 0,均低于远交兰花的平均水平.群体间的遗传变异占45.27%,遗传分化明显高于远交物种的平均水平.导致3个物种遗传多样性偏低而群体间遗传分化较高的主要原因在于人为的过度采挖和生境的片断化.研究结果为兰花保护策略和措施的制定提供了理论基础. 相似文献
6.
The status of a fish population is a reflection of the overall condition of the aquatic environment in which that population resides. As such, fish population characteristics can be used as indicators of environmental health. Simple and inexpensive methods to follow fish population responses to environmental degradation are lacking. This paper outlines a protocol whereby environmental impacts on fish populations are classified by five patterns based on characteristics such as mean age, fecundity and condition factor. The patterns summarize population changes and describe responses to exploitation, recruitment failure, the presence of multiple stressors, food limitation and niche shifts. Classification is best based on the selection, and appropriate sampling, of a comparable reference population. Population characteristics can be used to examine ecosystems exposed to stressors for evidence of long-term damage, and when used with biochemical indicators, can be a powerful tool for ecosystem health assessment. The five responses are illustrated using published data on a number of species challenged by increased predation pressure, acidification, eutrophication, mine waste and reservoir impoundment. Application of this scheme will aid in directing and focusing research efforts on crucial aspects impacted by changing conditions. 相似文献
7.
Constantinos Mannouris Diane L. Byers 《Biological journal of the Linnean Society. Linnean Society of London》2013,108(1):55-67
Loss and fragmentation of the native prairies in the Midwestern United States have resulted in isolated and smaller habitats and populations. The populations remaining in these prairies are expected to show a decline in the extent of genetic variation and an increase in genetic drift load (accumulation of deleterious recessive alleles due to genetic drift) in fitness‐related traits. Using complementary greenhouse experiments, we tested whether these expected changes have occurred in the native annual prairie plant Chamaecrista fasciculata. In the first experiment, open pollinated C. fasciculata seeds from 12 prairie fragments representing a range in area of habitat were grown in competition with Schizachyrium scoparium to determine if there are changes in plant vigour with changes in fragment size and corresponding changes in population size. Plants from smaller prairie fragments exhibited a slight but significant decline in biomass, suggesting an increase in genetic drift load. In the second experiment, a formal genetic crossing design of four prairie fragment populations was used to estimate quantitative genetic diversity and genetic drift load. We did not find extensive quantitative genetic variation, but we did find a strong effect of genetic drift load on five traits in this experiment. Our overall conclusion is that a decline in relative‐fitness traits in smaller prairie fragments is probably associated with fixation of deleterious alleles due to more isolated and smaller populations, i.e. genetic drift load. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ?? , ??–??. 相似文献
8.
Helen V. Senn Muhammad Ghazali Jennifer Kaden David Barclay Ben Harrower Ruairidh D. Campbell David W. Macdonald Andrew C. Kitchener 《Evolutionary Applications》2019,12(3):399-414
The degree of introgressive hybridization between the Scottish wildcat and domestic cat has long been suspected to be advanced. Here, we use a 35‐SNP‐marker test, designed to assess hybridization between wildcat and domestic cat populations in Scotland, to assess a database of 295 wild‐living and captive cat samples, and test the assumptions of the test using 3,097 SNP markers generated independently in a subset of the data using ddRAD. We discovered that despite increased genetic resolution provided by these methods, wild‐living cats in Scotland show a complete genetic continuum or hybrid swarm structure when judged against reference data. The historical population of wildcats, although hybridized, clearly groups at one end of this continuum, as does the captive population of wildcats. The interpretation of pelage scores against nuclear genetic data continues to be problematic. This is probably because of a breakdown in linkage equilibrium between wildcat pelage genes as the two populations have become increasingly mixed, meaning that pelage score or SNP score alone is poor diagnostic predictors of hybrid status. Until better tools become available, both should be used jointly, where possible, when making management decisions about individual cats. We recommend that the conservation community in Scotland must now define clearly what measures are to be used to diagnose a wildcat in the wild in Scotland, if future conservation action is to be effective. 相似文献
9.
DÁNAE CABRERA‐TOLEDO JORGE GONZÁLEZ‐ASTORGA ANDREW P. VOVIDES 《Botanical journal of the Linnean Society. Linnean Society of London》2008,158(3):436-447
Dioon caputoi is a long‐lived cycad known from only four populations that range in size from 50 to 120, mostly adult individuals. Dioon caputoi has the most narrow geographical range of all Dioon spp. (less than 10 km), existing completely within the boundaries of the Tehuacán–Cuicatlán Biosphere Reserve, Mexico. Negative inbreeding values were found in all four populations (FIT = ?0.242) and within subpopulations (FIS = ?0.379). Only c. 10% of the total genetic variation was partitioned among populations (FST = 0.099). We also found that most mean values of genetic variation (A = 1.91 ± 0.12; P = 78.9 ± 10.2; HE = 0.35 ± 0.01) are within the range reported for other Dioon species with larger populations and with wider geographical ranges. These results support recent findings that rare plant species maintain high levels of genetic diversity. The heterozygote excess found at all loci is discussed in detail from a neutral evolutionary perspective, leaving arguments as working hypotheses for further research. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 436–447. 相似文献
10.
11.
D. Martínez-Torres R. Carri A. Latorre J. C. Simon A. Hermoso A. Moya 《Journal of evolutionary biology》1997,10(4):459-477
A method is presented for the estimation of nucleotide diversity and genetic structure of populations from RAPD (random amplified polymorphic DNA) data. It involves a modification of the technique developed by Lynch and Crease (1990) for the case of restriction sites as survey data. As new elements the method incorporates (i) dominance correction, (ii) values of asexual reproduction of the populations sampled, and (iii) an analytical variance of the number of nucleotide substitutions per site. Sampling was carried out at two geographic scales for three aphid species. At a macrogeographic scale, populations of Rhopalosiphum padi did not show statistical genetic differentiation. Aphis gossypii and Myzus persicae, which were sampled at a microgeographic scale, showed a higher genetic differentiation than R. padi, it being statistically significant in M. persicae. The major sources of sampling variance within- and between-populations were found to be nucleotide (i.e., the number of alleles used as a function of the number of primers used) and population (i.e., sample size) sampling. Extremely low estimates of nucleotide diversity were obtained for the species studied here. This result is consistent with previous reports on genetic diversity for the same or other aphid species which were based on allozyme polymorphism, mitochondrial DNA variation and qualitative analyses of RAPDs. 相似文献
12.
极小种群野生植物黄梅秤锤树群落结构与动态 总被引：2，自引：0，他引：2
本文以极小种群野生植物黄梅秤锤树(Sinojackia huangmeiensis)当前唯一的野生种群为依托建立了1 ha的固定样地, 研究了黄梅秤锤树野生植物群落的物种组成、优势种的径级结构、黄梅秤锤树的空间分布格局、种内与种间空间关联性和种群更新特征。样地内共记录到胸径 ≥ 1.0 cm的木本植物31种, 隶属于21科28属。群落更新良好, 样地中所有1,225株个体中小径木占比为67.18%。群落优势种为麻栎(Quercus acutissima)、枸骨(Ilex cornuta)、朴树(Celtis sinensis)和黄梅秤锤树。麻栎的径级结构呈单峰型, 为衰退型种群; 枸骨、朴树和黄梅秤锤树的径级结构呈倒“J”型或偏倒“J”型, 表明更新良好。黄梅秤锤树的空间分布格局在小尺度上呈聚集分布, 在大尺度上呈随机或均匀分布, 并且与其他3个优势种(麻栎、枸骨、朴树)在空间上主要呈负关联性。黄梅秤锤树的成树和幼苗、幼树和幼苗都是在小尺度上呈负关联性, 在大尺度上关联性不显著, 而成树和幼树在整体上关联性不显著。黄梅秤锤树的萌蘖现象非常明显, 萌蘖数与母株胸径具有极显著的正相关性(R2 = 0.330, P < 0.001), 萌蘖率与相对幼苗密度具有极显著的负相关性(R2 = 0.438, P < 0.001)。总体来说, 高比例的小径木和普遍的种间负关联均表明该群落处于演替的早中期, 物种组成和群落结构还未达到稳定阶段。作为长江中下游冲积平原区具有代表性的残存风水林, 该野生植物群落在生物多样性维持和珍稀植物保护方面具有重要的作用, 应加强保护和管理。 相似文献
13.
The autogamous annual Microseris bigelovii occurs in isolated populations along a narrow strip of land along the Pacific Coast from Southern California to Victoria, B. C. — Thirteen inbred strains were derived from 11 representative populations. Nuclear DNA from these strains was amplified using single arbitrary 10-base-pair primers. 194 amplification products were obtained with 22 primers. Of these, 44 were shared by all strains, 32 were present or absent in only one of the strains. The remaining 118 amplification products were shared by 2 to 11 strains. Attempts to construct a cladogram of the 13 inbred genotypes revealed 5 monophyletic groups. Two of these consist of duplicate isolates from two populations each, two comprise two strains each derived from neighboring populations, and one comprises the three populations from Victoria, B. C., which are postulated to be the result of local differentiation after a single founder event. The Victoria populations share the only known chloroplast mutation in M. bigelovii with a strain from the San Mateo County south of San Francisco. Beyond the local groups of strains we found more or less random allele associations rather than cladistic groupings, with overall genetic distances (UPGMA) more or less related to geographic distance. Achene transport, too rare for direct observationmust be effective to allow gene flow among populationsin M. bigelovii. 相似文献
14.
We investigated the genetic outcome of successful invasion by an alien species, the marsh frog Rana ridibunda, in Britain. Twelve adults translocated from Hungary into Kent (Romney) in 1935 resulted rapidly in a large localized population. A further successful translocation in 1973 from Romney to Sussex (Lewes), together with other range extensions, provided an opportunity to test bottleneck effects during colonization events. Romney and Lewes frogs had similar genetic diversities to those in Hungary at 14 random amplified polymorphic DNA marker (RAPD) and five microsatellite loci. The introduced populations were, however, differentiated genetically from each other and from a reference population in Hungary. Fitness assessments (larval growth and survival) revealed no differences between the Lewes and Romney populations. Despite starting with few founders, significant bottleneck effects on R. ridibunda in Britain were therefore undetectable, presumably because population expansions were rapid immediately after the translocations. 相似文献
15.
Michel C. Milinkovitch Ricardo Kanitz Ralph Tiedemann Washington Tapia Fausto Llerena Adalgisa Caccone James P. Gibbs Jeffrey R. Powell 《Evolutionary Applications》2013,6(2):377-383
A species of Galápagos tortoise endemic to Española Island was reduced to just 12 females and three males that have been bred in captivity since 1971 and have produced over 1700 offspring now repatriated to the island. Our molecular genetic analyses of juveniles repatriated to and surviving on the island indicate that none of the tortoises sampled in 1994 had hatched on the island versus 3% in 2004 and 24% in 2007, which demonstrates substantial and increasing reproduction in situ once again. This recovery occurred despite the parental population having an estimated effective population size <8 due to a combination of unequal reproductive success of the breeders and nonrandom mating in captivity. These results provide guidelines for adapting breeding regimes in the parental captive population and decreasing inbreeding in the repatriated population. Using simple morphological data scored on the sampled animals, we also show that a strongly heterogeneous distribution of tortoise sizes on Española Island observed today is due to a large variance in the number of animals included in yearly repatriation events performed in the last 40 years. Our study reveals that, at least in the short run, some endangered species can recover dramatically despite a lack of genetic variation and irregular repatriation efforts. 相似文献
16.
J. Sugardjito C. H. Southwick J. Supriatna A. Kohlhaas S. Baker J. Erwin J. Froehlich N. Lerche 《American journal of primatology》1989,18(4):285-301
A field survey of 25 sites in Sulawesi Utara (north Sulawesi) in 1987 and 1988 found macaques in 16 of these sites. The most viable population of Macaca nigra was found in the Tangkoko reserve at an estimated density of 76.2 monkeys/km2, which is less than one-third the abundance reported in the late 1970s by the MacKinnons. The adjacent reserves of Batuangus and Duasudara had only 22 monkeys/km2, yielding a population estimate for these three contiguous reserves of only 3,655 individuals. Maccaca nigrescens were found in the central and western portions of Dumoga-Bone National Park in densities of 15.5 and 16.4 monkeys/km2, significantly below the density of 27/km2 reported by the MacKinnons. The more peripheral areas of Dumoga-Bone had only 8.15 monkeys/km2, yielding a population estimate of M. nigrescens in Dumoga-Bone of less than 34,000. Our total population estimate for M. nigra and M. nigrescens combined is less than 50,000 individuals, which is considerably below that reported in recent litreture. M. hecki were observed in only two locations, Tangale and Panua Reserves, at low densities of 3.3 to 5.2 monkeys/km2, suggesting its range and abundance have declined since the observations of Groves (pp. 84–124 in THE MACAQUES: STUDIES IN ECOLOGY, BEHAVIOR AND EVOLUTION. D. G. Lindburg, ed. New York, Van Nostrand Reinhold, 1980). Several factors have contributed to population decline in these species: habitat shrinkage, increasing human population pressure, and drought conditions. Group sizes were significantly smaller in our study than in previous ones, and we found a shortage of juveniles and infants. 相似文献
17.
Janelle L. Thomas Meghan Cullen Danielle O'Leary Caroline Wilson James A. Fitzsimons 《Ecological Management & Restoration》2021,22(1):100-105
Volunteers and citizen scientists can make an important contribution to bird monitoring and threatened species conservation projects. Members of BirdLife Australia’s Threatened Bird Network (TBN), a programme which encouraged community participation in conservation projects for threatened birds, were surveyed in 2013 to gain an insight into their demographics and volunteering motivation and preferences. In the 2013 survey, a large proportion of survey respondents were aged between 55 and 74 years old and over half were retired, representing a higher proportion of retired participants than found in a similar study of TBN members in 2000. A large proportion (69%) of respondents had volunteered with TBN projects (occasionally or at least once per year), despite being involved with other environmental groups. Respondents that volunteered mostly preferred short‐term (one day) field‐based volunteer activities, with nearly half also preferring to travel 50 km or less to participate in a project. Less than one third of respondents had never volunteered with TBN projects; this was attributed to not enough projects close to home, time restrictions and lack of transport. Preferences of volunteers in the 2013 survey were similar to those undertaken in 2000 for the majority of responses, including the preference for the activity occurring outdoors, the importance of regular feedback from the organiser, the moderate importance placed on seeing target species and the lack of importance for the provision of transport. A higher importance was placed on the following factors in the 2013 survey responses compared to 2000 (potentially influenced by the higher number of retirees): Having activities closer to home, the activity not being too physically demanding, the opportunity for free time during the activity, good weather was predicted on the day of the activity, existing skills were adequate for the activity, and accommodation was provided if required. 相似文献
18.
Nicola J. Marlow Neil D. Thomas Andrew A. E. Williams Brian Macmahon John Lawson Yvette Hitchen John Angus Oliver Berry 《Ecological Management & Restoration》2015,16(2):131-141
European Red Fox (Vulpes vulpes) baiting with 1080 poison (sodium fluoroacetate) is undertaken in many Australian sites to reduce fox abundance and to protect vulnerable native species from predation. The longest continuous use of fox baiting for fauna conservation commenced in south‐west Western Australia in the 1980s and includes baiting Dryandra Woodland and Tutanning Nature Reserve. The trap success of the Woylie (Bettongia penicillata) in these two reserves initially increased more than 20‐fold after the commencement of baiting and was maintained until 2000. Woylie captures then decreased rapidly, despite ongoing fox baiting, so the long‐term efficacy of 1080 baiting was questioned. Here, fox density and probabilities of detection, re‐detection and survival between replicated baited and unbaited sites were compared by modelling capture–recapture of individual foxes. These were identified from microsatellite DNA genotypes obtained non‐invasively from hair, scat and saliva samples. The frequency and duration of fox residencies were also quantified. Remote cameras were used to determine the fate of baits but uptake by foxes was low, whereas nontarget species' bait uptake was high. Nevertheless, foxes inhabiting baited reserves had significantly higher mortality, shorter residency times, and 80% lower density than foxes inhabiting unbaited reserves. Baiting continues to significantly reduce fox abundance after more than 25 years of continuous use. This has positive implications for fox control programmes throughout Australia but reduced fox abundance may facilitate increased predation by feral Cats (Felis catus). 相似文献
19.
T. R. Allnutt A. C. Newton A. Lara † A. Premoli ‡ J. J. Armesto § R. Vergara† M. Gardner¶ 《Molecular ecology》1999,8(6):975-987
Fitzroya cupressoides (alerce, Cupressaceae) is a large and exceptionally long-lived conifer, endemic to a restricted area of southern Chile and neighbouring areas of Argentina. As a result of its high economic value, the species has been severely exploited for timber, and remnant populations are fragmented and often highly disturbed. The species is thought to have undergone a major range contraction during the last glaciation. In order to assess the extent of genetic variation using DNA markers within and between populations of this species, samples were obtained from throughout the natural range and analysed for random amplified polymorphic DNA (RAPD) variation. Eight 10-mer and three 15-mer primers were used to produce a total of 54 polymorphic bands. Shannon's diversity estimates were calculated to provide an estimate of the degree of variation within each population. Values varied from 0.343 to 0.636 with only the lowest value differing significantly from the others (Spop = 0.547). This indicated that there is a significant degree of variation within each population, and did not provide evidence for genetic 'bottle-neck' effects within the species. A pairwise distance measure calculated from the RAPD data was used as an input for principal coordinate (PCO) and AMOVA analyses. The first three principal coordinates of RAPD distances described 8.3, 5.9 and 5.4% of the total variance, respectively, and a degree of clustering of samples according to their geographical origin was detectable. AMOVA analysis indicated that although most of the variation (85.6%) was found within populations, a significant proportion (P < 0.002) was attributable to differences between populations. An UPGMA dendrogram constructed using phi ST values derived from AMOVA produced a pattern broadly similar to that produced by the PCO, highlighting differences between three main groups of populations within Chile: those from the northern Coastal Range, the southern Coastal Range and Central Depression, and the Andes. Populations from Argentina also emerged as significantly different from those in Chile. These results are interpreted in the context of the postglacial history of the species, and their implications for the development of conservation strategies for Fitzroya are discussed. 相似文献
20.
No genetic variation detected within isolated relict populations of Saxifraga cernua in the Alps using RAPD markers 总被引：9，自引：0，他引：9
Genetic variation in seven relict populations of Saxifraga cernua from three regions of the Alps was investigated using RAPD (random amplified polymorphic DNA) markers. No variation, either within the populations or within the regions, could be demonstrated. Nevertheless, each alpine region was characterized by a unique RAPD phenotype. Absence of genetic variation in these relict populations is attributed to population bottlenecks and founder effects during or following the ice ages. Contrasting hypotheses about the history of these populations, either as survivors of the glacial period or as products of postglacial immigration, are discussed in the light of the data presented. 相似文献