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1.
    
  1. Similar to many small, range‐restricted elasmobranchs, the Brazilian sharpnose shark (Rhizoprionodon lalandii) is listed as ‘data deficient’ by the International Union for the Conservation of Nature (IUCN). Data on stock assessment and sustainability are scarce, and there is no information on population structure. This constitutes a management problem because this shark comprises approximately 50% of the catch of small coastal sharks in Brazil.
  2. In this study, populations of R. lalandii distributed from the Caribbean to southern Brazil were investigated using sequences from the mitochondrial DNA control region. Analysis of molecular variance revealed strong structuring between population samples from the Caribbean and those from the Brazilian coast (ФST = 0.254, P < 0.0001). Significant differences in the rates of genetic diversity between these major areas were also detected. The observed levels of population structuring are likely to be driven by female phylopatry.
  3. Therefore, the identification of both mating and nursery areas with parallel ban/restriction of fishing in these areas may be critical for the long‐term sustainability of these populations.
Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

2.
李琪 《中国水产科学》2006,13(3):502-509
微卫星DNA由于具有高度多态性、共显性遗传、基因组中含量丰富且随机分布等特点,目前已成为最有效的分子标记之一,并应用于种群分化研究、血缘分析、基因连锁分析、进化以及生态学研究等许多领域。近年来,海洋贝类微卫星的研究报道日益增多。本文对海洋贝类微卫星分离方法、开发现状、遗传学特性以及在种群遗传、家系分析、遗传多样性评价等方面的最新研究进展进行了综述,并分析了微卫星分析中无效等位基因、“结巴”带、短等位基因显性和等位基因“扩增丢失”现象的产生原因以及对微卫星基因型判读带来的影响。  相似文献   

3.
    
Genetic differentiation in aquatic systems is often driven by geographic distance (isolation by distance) due to the linear and hierarchical distribution of populations, but habitat fragmentation often exacerbates this effect by decreasing population connectivity, leading to isolation by resistance. Stronghold populations of the Kentucky Arrow Darter (Etheostoma spilotum) in the South Fork Kentucky River system within the Daniel Boone National Forest of eastern Kentucky, USA have a high population structure not explained by distance alone. Higher than expected levels of genetic differentiation among proximate populations were hypothesized to be driven by land-use change, but this was not previously tested. Here we use a riverscape genetics approach to test for the effects of natural landscape features including slope, elevation and stream size, and anthropogenically altered habitat features, including specific conductance (conductivity), culverts and forest cover, on population connectivity and genetic diversity of E. spilotum. We found isolation of populations among all tributary systems and a strong, positive relationship between genetic and geographic distances as expected. However, high conductivity levels due to surface coal mining best explain the population structure observed. We also found signatures of low genetic diversity overall and indicators that culverts may limit upstream movements of E. spilotum. This study provides a novel fine-scale view of the effects of instream and landscape features on connectivity among, and genetic diversity within populations of an imperilled, small-bodied, benthic fish.  相似文献   

4.
Abstract Population genetic studies can be useful for informing conservation and management. In Atlantic salmon, Salmo salar L., population structuring frequently occurs between river systems, but contrasting patterns occur within rivers, highlighting the need for catchment‐specific studies to inform management. Here, population structure of Atlantic salmon was examined in the River Tamar, United Kingdom, using 12 microsatellite loci. Gene diversity and allelic richness ranged from 0.80 to 0.84 and from 8.96 to 10.24, respectively. Some evidence of genetic structure was found, including significant genetic differentiation between samples in different subcatchments (pairwise θ and tests of genic differentiation), results from assignment tests and a pattern of isolation by distance. Conversely, structure revealed only one population cluster, and an analysis of molecular variance showed no significant variation between subcatchments. Evidence of population bottlenecks depended on the mutation model assumed and is discussed with reference to catchment‐specific studies of stock abundance. Implications for implementing management actions are considered.  相似文献   

5.
    
The genetic structure of the gadiform fish species, burbot Lota lota L., was investigated across Germany to derive management options for facilitating the preservation of genetic diversity. Sequence analysis of the mitochondrial control region (n = 244) and microsatellite analysis (n = 861) of specimens from 20 sites revealed genetic structuring between major river basins, and particularly between lake and river habitats. The admixture zone between the Eurasian and West European phylogenetic clades in Lake Constance was confirmed and expanded to include the drainage basins of the rivers Rhine and Schlei/Trave. Haplotype distribution and private haplotypes in single river basins indicated population differentiation and imply that German burbot constituted an important part of the entire species' diversity. The derived genetic structuring has implications for future stocking programmes and the preservation of the adaptive potential of burbot, a guiding species for oligotrophic lakes in Europe.  相似文献   

6.
Groupers are a valuable fishery resource of reef ecosystems and are among those species most vulnerable to fishing pressure because of life history characteristics including longevity, late sexual maturation and aggregation spawning. Despite their economic importance, few grouper fisheries are regularly monitored or managed at the species level, and many are reported to be undergoing declines. To identify major threats to groupers, the International Union for Conservation of Nature (IUCN) Red List criteria were applied to all 163 species. Red List assessments show that 20 species (12%) risk extinction if current trends continue, and an additional 22 species (13%) are considered to be Near Threatened. The Caribbean Sea, coastal Brazil and Southeast Asia contain a disproportionate number of Threatened species, while numerous poorly documented and Near Threatened species occur in many regions. In all, 30% of all species are considered to be Data Deficient. Given that the major threat is overfishing, accompanied by a general absence and/or poor application of fishery management, the prognosis for restoration and successful conservation of Threatened species is poor. We believe that few refuges remain for recovery and that key biological processes (e.g. spawning aggregations) continue to be compromised by uncontrolled fishing. Mariculture, through hatchery‐rearing, increases production of a few species and contributes to satisfying high market demand, but many such operations depend heavily on wild‐caught juveniles with resultant growth and recruitment overfishing. Better management of fishing and other conservation efforts are urgently needed, and we provide examples of possible actions and constraints.  相似文献   

7.
Four microsatellite markers and a mitochondrial DNA (mtDNA) fragment were used to investigate two possible explanations for a reported decline in productivity of genetically improved farmed tilapia (GIFT) in Fiji: (i) a decline in genetic diversity (GD) and (ii) genetic introgression from feral tilapia populations. Genetic diversity was estimated using θ and allelic richness, while Bayesian clustering was used to assign individuals to genetic groups (K=2 or 3) to test for introgression. Differentiation among groups was estimated using FST analysis. Results indicate that genetic diversity had declined compared with a GIFT reference stock from WorldFish Centre, while there was little evidence for introgression from feral tilapia populations. Loss of genetic diversity most probably resulted from practices that have not actively managed genetic resources in the hatchery. While GIFT is considered to be an improved line of Nile tilapia (Oreochromis niloticus), mtDNA analysis here revealed haplotypes assigned previously to three discrete Oreochromis species (O. niloticus, Oreochromis mossambicus and Oreochromis aureus) in both the Fijian strain and the WorldFish Centre strain. Possible sources for the three divergent lineages are discussed. Results have implications for the management and future expansion of the tilapia culture industry in Fiji as well as in other Pacific island nations.  相似文献   

8.
    
  1. Freshwater mussels of the family Unionidae are one of the most threatened groups worldwide and have suffered severe decline over recent decades. Although the freshwater duck mussel, Anodonta anatina (Linnaeus, 1758), is still widespread, this species has shown evidence of recent declines and is already protected in some European countries.
  2. Informed conservation efforts must take into account patterns in genetic diversity and phylogeography. In the present study, 20 newly developed polymorphic loci were described and tested in seven populations of A. anatina, belonging to three previously detected divergent mtDNA lineages. The genetic diversity patterns, within and among A. anatina populations, were evaluated to test their congruence with those lineages.
  3. A high genetic differentiation (FST) was found among all populations, with the exception of those in Central Europe (Germany) and the UK, which were not strongly structured.
  4. The present study confirms the division of the species into three evolutionarily significant units corresponding to the three previously detected mtDNA lineages, which should be managed independently. Furthermore, owing to the high differentiation among southern European populations, the establishment of distinct management units for the Guadalquivir, Guadiana and Douro populations in the Iberian Peninsula is also proposed.
Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

9.
采用聚合酶链式反应和直接测序的方法研究了中国海矮拟帽贝(Patelloida pygmaea) 13个地理种群环境因子对其遗传多样性的影响。137个样本的COI部分序列(601 bp)中共发现217个多态位点,转换颠换比1. 25,界定30个单倍型。汕头种群呈现较高的遗传多样性,威海种群呈现较低的遗传多样性。与环境因子相关性分析发现,矮拟帽贝遗传多样性与年均温度、年均降水量、年均水汽压呈显著正相关(P <0. 05),与纬度、年均温度变异系数、日照百分率、日照时数呈显著负相关(P <0. 05)。形态主成分分析矮拟帽贝长重比(L/DW)、宽重比(W/DW)、高重比(H/DW)为形态变异主成分,且与年均降水量变异系数呈显著负相关(P <0. 05)。温度、降水、日照、水汽压是影响中国海矮拟帽贝遗传多样性的主导因子,南方种群比北方种群有更高的遗传多样性。  相似文献   

10.

11.
    
  1. Population structure of highly mobile marine organisms can be complex and difficult to study, but it is important to understand how populations partition themselves within their environment for accurate assessment of both natural and anthropogenic impacts and successful management. The 2010 Deepwater Horizon oil spill negatively impacted common bottlenose dolphins (Tursiops truncatus) within Mississippi Sound and the surrounding north central Gulf of Mexico (GOMx); however, little was known about their underlying population structure in these waters. Thus, it was unclear how many demographically independent populations were affected by the spill.
  2. Common bottlenose dolphin samples were collected throughout inshore waters of Mississippi Sound and coastal waters of the north-central GOMx. Mitochondrial DNA control region sequence data and 19 nuclear microsatellite loci were analysed to determine how many populations are present and characterize their range throughout these waters.
  3. Bayesian clustering and migration analyses identified two genetically distinct and demographically independent populations: one predominantly inhabiting Mississippi Sound and adjacent coastal waters, and a second population extending generally from offshore of Mobile Bay, Alabama, east along the Florida Panhandle. Neither of these populations align with the currently delineated management stocks previously used to estimate impacts from the oil spill on common bottlenose dolphins in this portion of the GOMx.
  4. These results suggest that revisions may be necessary so that management stocks accurately represent the demographically independent populations present in these waters. Furthermore, better comprehension of underlying population structure will enhance impact assessments on common bottlenose dolphins and provide more appropriate baseline data to support future restoration and conservation objectives.
  相似文献   

12.
    
Abstract  Genetic variation within and among stone loach, Barbatula barbatula L., populations inhabiting anthropogenically degraded watercourses in Flanders (northern part of Belgium) was assessed using five microsatellite markers. High levels of genetic diversity were observed at all sampling sites, (MNA: 6.2–11.2; H O: 0.64–0.75; H E: 0.67–0.85). Estimates of the effective population size varied between 1535 and 3021 individuals and there were no indications of recent severe bottlenecks. Significant genetic differentiation was observed among sites belonging to different river systems and drainage basins. These results suggest human activities, such as pollution and river engineering, have not impacted significantly on genetic variability in the stone loach populations investigated. It is possible that this lack of genetic erosion may be attributed to species-specific characteristics such as pollution tolerance and ecological flexibility.  相似文献   

13.
    
Application of environmental DNA (eDNA) analysis has attracted the attention of researchers, advisors and managers of living marine resources and biodiversity. The apparent simplicity and cost‐effectiveness of eDNA analysis make it highly attractive as species distributions can be revealed from water samples. Further, species‐specific analyses indicate that eDNA concentrations correlate with biomass and abundance, suggesting the possibility for quantitative applications estimating abundance and biomass of specific organisms in marine ecosystems, such as for stock assessment. However, the path from detecting occurrence of an organism to quantitative estimates is long and indirect, not least as eDNA concentration depends on several physical, chemical and biological factors which influence its production, persistence and transport in marine ecosystems. Here, we provide an overview of basic principles in relation to eDNA analysis with potential for marine fisheries application. We describe fundamental processes governing eDNA generation, breakdown and transport and summarize current uncertainties about these processes. We describe five major challenges in relation to application in fisheries assessment, where there is immediate need for knowledge building in marine systems, and point to apparent weaknesses of eDNA compared to established marine fisheries monitoring methods. We provide an overview of emerging applications of interest to fisheries management and point to recent technological advances, which could improve analysis efficiency. We advise precaution against exaggerating the present scope for application of eDNA analysis in fisheries monitoring, but also argue that with informed insights into strengths and limitations, eDNA analysis can become an integrated tool in fisheries assessment and management.  相似文献   

14.
    
  1. The European cave salamander, Proteus anguinus, or proteus, is the largest obligate cave animal in the world. It is an endangered and charismatic species of high conservation importance for subterranean waters. Conservation genetic studies are hampered by the extreme size and repetitiveness of its nuclear genome.
  2. The aim of the study was to develop and characterize the first microsatellite markers for proteus, and test their informativeness at the level of individuals, populations and between populations in the Postojna and Planina caves in Slovenia.
  3. Twenty‐three novel polymorphic microsatellite markers were amplified in 201 individuals from both caves using three multiplex reactions. The number of alleles per locus varied from three to nine. The loci are largely unlinked and conform to Hardy–Weinberg genotype frequencies. Genetic equilibrium and an FST value of 0.0024 suggest a nearly panmictic population in both caves separated by some 10 km of subterranean river course, while Bayesian clustering detected weak genetic structure.
  4. The microsatellites described fill the gap of urgently needed nuclear markers in Proteus that can be applied in genetic mark–recapture studies, population monitoring and identification of management units to assist conservation efforts.
  相似文献   

15.
    
Abstract Population‐genetic structure and average long‐term effective size of yellowtail snapper, Ocyurus chrysurus (Bloch), sampled offshore from the Florida Keys and four localities in the US Caribbean, were investigated using nuclear‐encoded microsatellites and a fragment of the mitochondrially encoded ND‐4 gene. Analysis of spatial genetic variation revealed occurrence of up to four groupings (stocks) of yellowtail snapper: one in the Florida Keys, one along the west coast of Puerto Rico, one that includes the east coast of Puerto Rico and St. Thomas and one offshore of St. Croix. The observed genetic differences among localities are not strong, and additional sampling to examine whether the observed patterns of population structure are temporally stable is warranted. Levels of genetic variability and estimates of average, long‐term effective size (Ne) indicate that yellowtail snapper at all five localities have, at present, sufficient genetic variation to maintain long‐term integrity and sustainability.  相似文献   

16.
为研究滆湖鲌类国家级水产种质资源保护区主要保护对象的种质遗传状况,通过PCR和测序技术,获得保护区翘嘴鲌(Culter alburnus)、达氏鲌(Culter dabryi)、蒙古鲌(Culter mongolicus)等3种鲌属鱼类的细胞色素b(Cytb)基因序列,并分析了其遗传多样性和群体结构。结果显示,3种鲌鱼的Cytb基因全长为1 141 bp,碱基组成相似,均表现为A+T的含量(56.4%)高于G+C的含量(43.6%)。翘嘴鲌的Cytb基因有16个变异位点,定义14种单倍型,单倍型和核苷酸多样性分别为0.907和0.002 4;蒙古鲌的Cytb基因有8个变异位点,定义6种单倍型,单倍型和核苷酸多样性分别为0.863和0.002 4;达氏鲌的Cytb基因有10个变异位点,定义7种单倍型,单倍型和核苷酸多样性分别为0.573和0.001 2。整体来看,3种鲌鱼均具有高单倍型多样性和低核苷酸多样性的遗传多样性模式,暗示3种鲌鱼群体在历史上经历过种群扩张,与中性检验结果和歧点分布图分析结果相一致。翘嘴鲌和蒙古鲌的种内遗传距离为0～0.006,达氏鲌的种内遗传距离为0～0.004,...  相似文献   

17.
    
  1. South American fur seals, Arctocephalus australis, were intensively hunted for centuries, leaving the species at the edge of extinction. After the cessation of commercial hunting in the 20th century the overall population has increased to an estimated population of 250 000–300 000 individuals, with Guafo Island being the largest breeding colony in Southern Chile with Guafo Island in Southern Chile being the largest breeding colony.
  2. The genetic diversity of the South American fur seal population on Guafo Island and the possible genetic connectivity among populations from the Atlantic and Pacific oceans were studied in order to assess the importance of the Southern Chile Pacific population for the management of the species. Mitochondrial DNA sequences from the Guafo Island population were compared with those from various Atlantic (Brazil, Uruguay, and Argentina) and Pacific (Peru) populations previously studied.
  3. The results indicate the occurrence of historical and/or current gene flow among the populations of Guafo Island in the Pacific Ocean and the populations of the Atlantic Ocean, displaying a lack of genetic structure within these areas. In contrast, the Peruvian population is highly divergent compared with the Chilean and Atlantic populations.
  4. The lack of genetic structure of Guafo Island fur seals suggests that this group is connected to populations in the Atlantic Ocean. Thus, the significant genetic diversity pool harboured by the Guafo Island population represents the northernmost point of expansion of this species from the Atlantic Ocean to the Pacific Ocean, which could be important for the eventual dispersal of the species to more northern areas of the Pacific and to the future adaptation of the species to changing environmental conditions on the Pacific coasts.
  相似文献   

18.
    
  1. Ruppia species are distantly related to seagrasses and occur in saltwater coastal and inland lagoons, mostly as monospecific beds. The diversity of euryhaline Ruppia populations from different continents recently became better understood from a suite of chloroplast sequences but limited nuclear markers. These revealed a high complexity from hybridization, introgression, polyploidy and haplotypic divergence.
  2. Because of this complexity within the genus and multiple allelic states in polyploids, three multiplexed sets of 24 nuclear microsatellites were developed from four Ruppia provenances and cross‐amplified on 130 individuals from a wide range of taxa in various aquatic habitats on different continents.
  3. Secondly, pure R. cirrhosa and R. maritima individuals could be unambiguously identified from their introgressed hybrids and from other known or yet unidentified taxa, using diagnostic markers that referred to autotetraploid individuals in R. cirrhosa and allotetraploidy in an ancient hybrid complex ‘haplogroup E’.
  4. Thirdly, a phenetic barcoding approach of trnH‐psbA chloroplast haplotypes taking into account insertion–deletion variations, revealed lineages of recently described taxa from lagoons in different continents (i.e. R. sinensis, R. brevipedunculata, R. mexicana) in addition to separate lineages of hybrid origin. Congruence between pollination mode and diversification of lineages, allows one to hypothesize whether selfing underwater leads to clearly separated lineages whereas outcrossing at the water surface allows hybridization and extensive introgression with potential chloroplast capture.
  5. This study raises a renewed interest in cryptic lineages, hybrid taxa and shallow phylogenies of Ruppia lineages, thereby critically questioning worldwide distributions of least concern species. Recognition and monitoring of unique Ruppia lineages will support further studies on connectivity, survival strategies and movement ecology to aid in determining the conservation status of a wide variety of lagoon and coastal wetland habitats.
  相似文献   

19.
    
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20.
ABSTRACT:   Polymerase chain reaction (PCR) restriction fragment length polymorphism analysis of mitochondrial DNA was applied to the genetic structure and evolutionary history of the more ancestral Pangasianodon hypophthalmus ( n  = 82), and the recently speciated catfish Pangasius bocourti ( n  = 90) from the Cambodian Mekong River. Both pangasiids were characterized by a lack of genetic population structure that may result from high levels of contemporary gene flow. Genetic diversity was lower in P. hypophthalmus than in P. bocourti . However, a different evolutionary history was inferred for both species based on genealogical and demographic analyses (mismatch analysis, Tajima's D- and Fu's F S-tests). The genetic profile of the more ancestral P. hypophthalmus shows indications of a recent population bottleneck, whereas the recently speciated P. bocourti shows signatures of historical population expansion. This study stresses the importance of preserving the migration routes in the Cambodian Mekong basin in order to maintain the genetic diversity and long-term integrity of both species.  相似文献   

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