Genetic Structure Of Wild Populations Research Articles

Mitochondrial DNA supports the low genetic diversity of Tursiops truncatus (Artiodactyla: Delphinidae) in Bocas del Toro, Panama and exhibits new Caribbean haplotypes

Introduction: The common bottlenose dolphin (Tursiops truncatus) is one of the most studied cetaceans worldwide; however, information about the genetic structure of wild populations is scarce in some regions like Central America and the Caribbean. There are two known genetic forms identified in the Caribbean based on mitochondrial DNA Control Region (mtDNA-CR) data: the ‘inshore (or coastal) form’ and the ‘Worldwide distributed form’. In general, the inshore form refers to coastal and highly philopatric populations that show low genetic diversity. Worldwide distributed form refers to highly mobile populations with coastal and oceanic individuals that do not show philopatry and usually display high genetic diversity.
 Objective: To determine the preliminary genetic status of common bottlenose dolphins in La Guajira, Colombian Caribbean, using a hypervariable portion of mtDNA-CR. The obtained haplotypes were compared with samples collected in Panama (likely ‘inshore form’) and with haplotypes previously found in other areas of the Caribbean.
 Methods: In 2016, a total of 26 skin samples were obtained by remote biopsy system (PAXARMS) in two locations, La Guajira (Colombia, N=7) and Bocas del Toro (Panama, N=19). DNA was extracted, samples sexed, and a segment of mtDNA-CR (~550-750 bp) was amplified by PCR. The successfully amplified DNA sequences were manually reviewed and cleaned, and subsequently compared with 44 haplotypes previously reported for the Caribbean.
 Results: The mtDNA-CR sequences from Bocas del Toro shared the same unique inshore haplotype previously reported for this population, while the samples from La Guajira represented six novel haplotypes, five belonging to the Worldwide distributed form and one to the ‘inshore form.’ Population structure analysis revealed two phylogroups for the Caribbean (FST=0.1353, ΦST=0.3330) with high haplotype diversity: Panama(Bocas del Toro)-Bahamas-Cuba-Mexico (h=0.8489, π=4.2536 %) and Colombia-Costa Rica-Honduras-Puerto Rico (h=0.8837, π=4.2423 %).
 Conclusions: These findings support the results previously reported for common bottlenose dolphins in Bocas del Toro-Panama and reinforce the need to protect this vulnerable ‘inshore’ population by treating it as a unique population management unit. Mitochondrial DNA analysis of samples collected from La Guajira dolphins provide the first insight into the genetic diversity of common bottlenose dolphins in this region, indicating the presence of both inshore and Worldwide distributed genetic forms. The potential connectivity of this last form among La Guajira-Colombia, Costa Rica, and Honduras in Central America highlights the need for more genetic and ecological studies to determine the appropriate management units for this species in Central America and the Caribbean.

Towards a standardised set of data analyses for long-term genetic monitoring of grouse using non-invasive sampling: a case study on western capercaillie

Genetic monitoring has become a popular instrument in the conservation of endangered species, allowing to estimate size and genetic structure of wild populations. Long-term monitoring projects are essential to recognize demographic changes and impact of human activities. Since 2011, an extensive monitoring project on the population size and trends, as well as spatial distribution and survival rates, of two grouse species including the western capercaillie, Tetrao urogallus, has been conducted in Tyrol, in the eastern part of the European Alps, where T. urogallus males are huntable under specific regulations. In this case study, we aimed to compile a set of analyses to be employed in evaluating data from dropping and feather samples for conservation studies. Using eleven microsatellite and two sex markers, we genotyped 251 faeces and feathers of T. urogallus collected in East Tyrol in spring 2019. We analysed population structure and mobility patterns, including sex differences in genetic diversity and mobility. The relationship between habitat parameters and genetic diversity was investigated using multiple linear regressions. We showed that the investigated T. urogallus population is well mixed and likely well connected to neighbouring populations. We also found sex-specific mobility patterns that support female-biased dispersal. As the last step, we demonstrated the general feasibility of a modelling approach using habitat parameters. With this pilot study, further analysis of data is possible for the whole monitoring project, giving a better insight in the grouse populations in Tyrol.

Mapping the geographic origin of captive and confiscated Hermann’s tortoises: A genetic toolkit for conservation and forensic analyses

The illegal trade has been threatening tortoise populations worldwide for decades. Nowadays, however, DNA typing and forensic genetic approaches allow us to investigate the geographic origin of confiscated animals and to relocate them into the wild, providing that suitable molecular tools and reference data are available. Here we assess the suitability of a small panel of microsatellite markers to investigate patterns of illegal translocations and to assist forensic genetic applications in the endangered Mediterranean land tortoise Testudo hermanni hermanni. Specific allelic ladders were created for each locus and tested on several reference samples. We used the microsatellite panel to (i) increase our understanding of the population genetic structure in wild populations with new data from previously unsampled geographic areas (overall 461 wild individuals from 28 sampling sites); (ii) detect the presence of non-native individuals in wild populations; and (iii) identify the most likely geographic area of origin of 458 confiscated individuals hosted in Italian seizure and recovery centers. Our analysis initially identified six major genetic clusters corresponding to different geographic macro-areas along the Mediterranean range. Long-distance migrants among wild populations, due to translocations, were found and removed from the reference database. Assignment tests allowed us to allocate approximately 70 % of confiscated individuals of unknown origin to one of the six Mediterranean macro-areas. Most of the assigned tortoises belonged to the genetic cluster corresponding to the area where the respective captivity center was located. However, we also found evidence of long-distance origins of confiscated individuals, especially in centers along the Adriatic coast and facing the Balkan regions, a well-known source of illegally traded individuals. Our results clearly show that the microsatellite panel and the reference dataset can play a beneficial role in reintroduction and repatriation projects when confiscated individuals need to be re-assigned to their respective macro-area of origin before release, and can assist future forensic genetic applications in detecting the illegal trade and possession of Testudo hermanni individuals.

Isolation and characterization of 15 new microsatellite markers for the globally endangered Lear's macaw Anodorhynchus leari.

A set of 16 microsatellite markers was characterized for Lear's macaw (Anodorhynchus leari) using DNA samples from captive individuals. Extending this molecular toolkit, including the use of samples from wild individuals, is expected to provide the required power of resolution for pedigree inference of both wild and captive individuals, and could support research on the genetic structure of wild populations.We characterize a set of 15 microsatellite markers optimized for the Lear's macaw, developed from a microsatellite-enriched library in a three-step procedure. Primer pairs were initially designed for 62 microsatellites with > 7 tandem repetitions. After amplification of DNA of five wild individuals from different localities, 22 loci seemed to be polymorphic and were further tested on 12 wild nestling samples. Fifteen unlinked loci showed unambiguous peaks and low to moderate polymorphism levels. The combination of the four most polymorphic markers allowed individual identification even of putative sibs.These markers complement previously described microsatellites developed for A. leari and constitute a fundamental genetic toolkit for the investigation of the genetics of both wild and captive populations, thus assisting integrated management plans for the conservation of this globally endangered species.

Anthropogenic disturbance drives dispersal syndromes, demography, and gene flow in amphibian populations

AbstractThere is growing evidence that anthropogenic landscapes can strongly influence the evolution of dispersal, particularly through fragmentation, and may drive organisms into an evolutionary trap by suppressing dispersal. However, the influence on dispersal evolution of anthropogenic variation in habitat patch turnover has so far been largely overlooked. In this study, we examined how human‐driven variation in patch persistence affects dispersal rates and distances, determines dispersal‐related phenotypic specialization, and drives neutral genetic structure in spatially structured populations. We addressed this issue in an amphibian, Bombina variegata, using an integrative approach combining capture–recapture modeling, demographic simulation, common garden experiments, and population genetics. B. variegata reproduces in small ponds that occur either in habitat patches that are persistent (i.e., several decades or more), located in riverine environments with negligible human activity, or in patches that are highly temporary (i.e., a few years), created by logging operations in intensively harvested woodland. Our capture–recapture models revealed that natal and breeding dispersal rates and distances were drastically higher in spatially structured populations (SSPs) in logging environments than in riverine SSPs. Population simulations additionally showed that dispersal costs and benefits drive the fate of logging SSPs, which cannot persist without dispersal. The common garden experiments revealed that toadlets reared in laboratory conditions have morphological and behavioral specialization that depends on their habitat of origin. Toadlets from logging SSPs were found to have higher boldness and exploration propensity than those from riverine SSPs, indicating transgenerationally transmitted dispersal syndromes. We also found contrasting patterns of neutral genetic diversity and gene flow in riverine and logging SSPs, with genetic diversity and effective population size considerably higher in logging than in riverine SSPs. In parallel, intrapatch inbreeding and relatedness levels were lower in logging SSPs. Controlling for the effect of genetic drift and landscape connectivity, gene flow was found to be higher in logging than in riverine SSPs. Taken together, these results indicate that anthropogenic variation in habitat patch turnover may have an effect at least as important as landscape fragmentation on dispersal evolution and the long‐term viability and genetic structure of wild populations.

Multiple decades of stocking has resulted in limited hatchery introgression in wild brook trout (Salvelinus fontinalis) populations of Nova Scotia.

Many populations of freshwater fishes are threatened with losses, and increasingly, the release of hatchery individuals is one strategy being implemented to support wild populations. However, stocking of hatchery individuals may pose long‐term threats to wild populations, particularly if genetic interactions occur between wild and hatchery individuals. One highly prized sport fish that has been heavily stocked throughout its range is the brook trout (Salvelinus fontinalis). In Nova Scotia, Canada, hatchery brook trout have been stocked since the early 1900s, and despite continued stocking efforts, populations have suffered declines in recent decades. Before this study, the genetic structure of brook trout populations in the province was unknown; however, given the potential negative consequences associated with hatchery stocking, it is possible that hatchery programs have adversely affected the genetic integrity of wild populations. To assess the influence of hatchery supplementation on wild populations, we genotyped wild brook trout from 12 river systems and hatchery brook trout from two major hatcheries using 100 microsatellite loci. Genetic analyses of wild trout revealed extensive population genetic structure among and within river systems and significant isolation‐by‐distance. Hatchery stocks were genetically distinct from wild populations, and most populations showed limited to no evidence of hatchery introgression (<5% hatchery ancestry). Only a single location had a substantial number of hatchery‐derived trout and was located in the only river where a local strain is used for supplementation. The amount of hatchery stocking within a watershed did not influence the level of hatchery introgression. Neutral genetic structure of wild populations was influenced by geography with some influence of climate and stocking indices. Overall, our study suggests that long‐term stocking has not significantly affected the genetic integrity of wild trout populations, highlighting the variable outcomes of stocking and the need to evaluate the consequences on a case‐by‐case basis.

Population genetic structure and variability in Lindera glauca (Lauraceae) indicates low levels of genetic diversity and skewed sex ratios in natural populations in mainland China.

Lindera glauca (Lauraceae) is a tree of economic and ecological significance that reproduces sexually and asexually via apomictic seeds. It is widely distributed in the low-altitude montane forests of East Asia. Despite the potential implications of a mixed reproductive system in terms of genetic diversity, few studies have focused on this aspect. In this study, the genetic structure of wild populations of L. glauca was investigated via genetic analyses. Overall, 13 nuclear microsatellites (nSSRs) and five chloroplast microsatellites (cpSSRs) were used to genotype 300 individual plants, taken from 20 wild populations (a small sample size in some wild populations is due to the limitation of its specific reproduction, leading to certain limitations in the results of this study) and two cultivated populations ranging across nearly the entire natural distribution of mainland China. The populations exhibited low levels of genetic diversity (nSSR: AR = 1.75, Ho = 0.32, He = 0.36; cpSSR: Nb = 2.01, Hrs = 0.40), and no significant effect of isolation by distance between populations existed, regardless of marker type (nSSR: R2 = 0.0401, P = 0.068; cpSSR: R2 = 0.033, P = 0.091). Haplotype networks showed complex relationships among populations, and the H12 haplotype was predominant in most populations. Analyses of molecular variance obtained with nuclear markers (Fsc = 0.293, FST = 0.362) and chloroplast markers (Fsc = 0.299, FST = 0.312) were similar. The migration ratio of pollen flow versus seed flow in this study was negative (r = −1.149). Results suggest that weak barriers of dispersal between populations and/or the similarity of founders shared between neighbors and distant populations are indicative of the gene flow between populations more likely involving seeds. Wild L. glauca in mainland China was inferred to have highly skewed sex ratios with predominant females. In addition, some populations experienced a recent bottleneck effect, especially in Gujianshan, Chongqing, and southwest China (population GJS). It is suggested that few wild male individuals should be conserved in order to maintain overall genetic diversity in the wild populations of this species. These findings provide important information for the sustainable utilization and preservation of the overall genetic diversity of L. glauca.

Hatchery-reared enhancement program for silver carp (Hypophthalmichthys molitrix) in the middle Yangtze River: monitoring the effectiveness based on parentage analysis.

IntroductionA hatchery-reared silver carp (Hypophthalmichthys molitrix) program has been intensively carried out since 2010 to enhance the rapidly declining fisheries production in the middle Yangtze River. However, only a little information regarding the effectiveness of the enhancement program has been reported. In this context, this study investigates on an enhancement program through monitoring the efficacy based on parentage analysis.MethodsA total of 1,529 hatchery-reared fish and 869 larvae were sampled from the middle Yangtze River in 2016 and 2017 and were genotyped by thirteen microsatellite loci. Based on the results of parentage analysis the larvae were divided into three populations: (1) larvae population with both parents being hatchery-reared fish (=R), (2) larvae population with only a male or a female parent being hatchery-reared fish (=H), and (3) larvae population with no hatchery-reared fish parent (=W). The following analyses were also carried out: (1) assessing the contribution of hatchery-reared offspring to larval resources, and (2) evaluating the genetic effect of stock enhancement on the wild population.ResultsIn total, 10.37% and 11.56% of larvae were identified as the offspring produced by hatchery-reared fish released in 2016 and 2017, respectively. In 2017, some of the larvae were assigned unambiguously to hatchery-reared fish released in 2016. In terms of the number of offspring produced, the hatchery-reared fish have shown significant variations. No significant differences were found among all the larvae populations concerning genetic parameters for diversity. High levels of genetic diversity of all larvae populations were obtained. Low FSTvalues obtained from pairwise FST analysis, as well as the analysis of molecular variance (AMOVA), revealed high genetic structural similarity among all the larvae populations. The genetic composition of the W larvae population in 2017 was different from that of all other larvae populations (all larvae populations in 2016, and R and H larvae populations in 2017), as demonstrated from the results of STRUCTURE and PCA analyses.ConclusionIt was demonstrated that hatchery-reared fish are successful in producing the offspring in the natural environment during multiple years, which might assist in increasing the abundance of larvae. The hatchery-reared fish had variations in terms of the success rates on reproduction. Also, the hatchery-reared enhancement program had no significant effect on the genetic diversity or the genetic structure of wild populations. However, the genetic component of the W larvae population in 2017 was changed as compared to 2016, which was not due to the hatchery-reared enhancement program for silver carp. This could be due to flooding, but the specific causes need further studies. Our results clearly show the necessity to continuously inspect the genetic impact of the enhancement program so that historical information can be utilized for further research.

Assessment of genetic structure of wild populations of mrigal carp, Cirrhinus cirrhosus by microsatellite DNA markers

The genetic structure of mrigal carp, Cirrhinus cirrhosus was analysed using six microsatellite DNA markers (MFW1, MFW2, MFW17, Bgon22, Barb54, and Bgon17) to detect genetic variations among fish samples from the three rivers, the Halda, the Padma, and the Jamuna in Bangladesh. All the populations showed polymorphism at all loci except Bgon17. Genetic richness of the Halda and Padma populations was indicated by the presence of rare alleles, two in Halda at MFW2 (160 bp) and MFW17 (201 bp), and one in Padma at Bgon22 (96 bp). The highest average number of allele (2.8) was observed in the Halda followed by the Padma (2.6) and the Jamuna (2.4). The observed heterozygosity (Hₒ) was highest (0.400) in the Padma followed by the Halda (0.383) and the Jamuna (0.377). The highest (0.0257) population differentiation (FST) value was observed between the Halda and Padma populations and the lowest (0.0143) between the Padma and Jamuna populations. The highest gene flow (Nₘ) was recorded between the Padma and Jamuna populations (17.1756) and the lowest between the Halda and Padma populations (9.4832). The highest (0.037) genetic distance (D) was observed between the Halda and Padma populations and the lowest (0.0195) between the Jamuna and Padma populations. The results indicated a low level of genetic variation regarding allelic richness and heterozygosity among wild stocks of C. cirrhosus and indicated it might be advisable to take necessary measures for the conservation and enhancement of C. cirrhosus genetic resources.

Population Genetic Structure of an Endangered Endemic Primate (Leontopithecus chrysomelas) in a Highly Fragmented Atlantic Coastal Rain Forest

This study evaluated the genetic structure of wild populations of the endangered primate, Leontopithecus chrysomelas. We tested the assumption that populations of L. chrysomelas, given their larger population size and a higher degree of habitat continuity, would have higher genetic diversity and less genetic structuring than other lion tamarins. We used 11 microsatellites and 122 hair samples from different locations to assess their genetic diversity and genetic structure, and to make inferences about the isolation by distance. The overall expected heterozygosity (0.51 ± 0.03) and the average number of alleles (3.6 ± 0.2) were relatively low, as is the case in other endangered lion tamarins. Genetic clustering analyses indicated two main clusters, whereas the statistical analyses based on genotype similarities and F_st suggested further substructure. A Mantel test showed that only 34% of this genetic differentiation was explained by the linear distance. In addition to linear distance, structural differences in the landscape, physical barriers and behavioural factors may be causing significant genetic structuring. Overall, this study suggests that these populations have a relatively low genetic diversity and a relatively high population genetic structure, putting in question whether the presence of agroforest systems (known locally as cabruca) is enough to fully re-establish functional landscape connectivity.

Genetic diversity of wild Zacco platypus populations among four river systems in Henan Province analyzed by mitochondrial CO I gene

PDF HTML阅读 XML下载 导出引用 引用提醒 河南境内四水系宽鳍鱲野生群体的遗传多样性 DOI: 作者: 作者单位: 河南师范大学 水产学院, 河南省水产动物养殖工程技术研究中心, 河南 新乡 453007 作者简介: 刘慧芬(1985-),女,讲师,博士,研究方向为鱼类繁殖生理学和分子生态学.E-mail:huifen_liu@126.com 通讯作者: 中图分类号: S931 基金项目: 河南省科技攻关重点项目（142102110057，162102310443，162102110147，172102310751）；河南省高校科技创新团队支持计划（14IRTSTHN013）；河南省创新型科技团队支持计划（CXTD2016043）. Genetic diversity of wild Zacco platypus populations among four river systems in Henan Province analyzed by mitochondrial CO I gene Author: Affiliation: College of Fisheries, Henan Normal University, Engineering Technology Reasearch Center of Henan Province for Aquatic Animal Cultivation, Xinxiang 453007, China Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为准确掌握河南野生宽鳍鱲（）群体遗传结构，本研究利用线粒体CO I基因检测了海河、黄河、淮河和长江水系宽鳍鱲群体的遗传多样性和种群分化情况。110个样品共检测出40个单倍型，平均单倍型多样性为0.92077，平均核苷酸多样性为0.02439。AMOVA分析显示，大多数遗传变异存在于宽鳍鱲群体间（60.59%），群体内的遗传变异为37.67%。系统发育树结果表明，长江水系宽鳍鱲群体遗传分化较大，一部分群体单独聚为一支，另外一部分群体与海河、黄河、淮河水系宽鳍鱲聚在一起，没有显示出明显的南北分化格局。种群历史动态结果推测宽鳍鱲群体经历过瓶颈效应，且该过程可能与第四纪中更新世气候波动有关。建议对河南境内的宽鳍鱲种群，特别是遗传多样性低的种群（海河水系）进行保护。 Abstract:To correctly determine the genetic structure of wild populations from Haihe, Yellow, Huaihe, and Yangtze River basins in Henan Province, we analyzed the population genetic diversity and differentiation of the species using mitochondrial CO I gene. A total of 110 individuals were sequenced, which have defined 40 distinct haplotypes. The average haplotype diversity and nucleotide diversity were 0.92077 and 0.02439, respectively. Analysis of molecular variance (AMOVA) indicated that most of the genetic variation existing among populations (60.59%), and the remaining 37.67% of genetic variation was attributed to differentiation within populations. The assignment of populations based on Neighbor-Joining (NJ) method revealed that populations from Yangtze River divided into two distinct mitochondrial DNA lineages, one clustered from the ZY population and the other clustered individuals from Haihe River, Yellow River and Huaihe River. This phylogenetic pattern is not consistent with the previous reported North and South Clades. Demographical history analysis indicated that populations had undergone a bottleneck which coincided with the middle Pleistocene and suffered from climate changes. Considering the genetic and phylogeographic results obtained in this study, appropriate measures are proposed to conserve population, especially for those with low genetic diversity in Haihe River basin. 参考文献 相似文献 引证文献

Comparative assessment of SSR and SNP markers for inferring the population genetic structure of the common fungus Armillaria cepistipes

During the last years, simple sequence repeats (SSRs, also known as microsatellites) and single-nucleotide polymorphisms (SNPs) have become the most popular molecular markers for describing neutral genetic variation in populations of a wide range of organisms. However, only a limited number of studies has focused on comparing the performance of these two types of markers for describing the underlying genetic structure of wild populations. Moreover, none of these studies targeted fungi, the group of organisms with one of the most complex reproductive strategies. We evaluated the utility of SSRs and SNPs for inferring the neutral genetic structure of Armillaria cepistipes (basidiomycetes) at different spatial scales. For that, 407 samples were collected across a small (150 km2) area in the Ukrainian Carpathians and a large (41 000 km2) area in the Swiss Alps. All isolates were analyzed at 17 SSR loci distributed throughout the whole genome and at 24 SNP loci located in different single-copy conserved genes. The two markers showed different patterns of structure within the two spatial scales studied. The multi-allelic SSR markers seemed to be best suited for detecting genetic structure in indigenous fungal populations at a rather small spatial scale (radius of ~50-100 km). The pattern observed at SNP markers rather reflected ancient divergence of distant (~1000 km) populations that in addition are separated by mountain ranges. Despite these differences, both marker types were suitable for detecting the weak genetic structure of the two A. cepistipes populations investigated.

Use of molecular and environmental analyses for integrated in situ and ex situ conservation: The case of the Mexican prairie dog

An important step in species conservation is to identify populations that significantly contribute to it. Considering both in situ and ex situ populations provides an integrated approach to the preservation of a species' evolutionary potential. The joint use of molecular and environmental analyses allows conservation schemes to be implemented when reintroducing captive populations, and wild populations to be prioritized for conservation purposes. We used genetic data and environmental analyses to select candidate areas for the reintroduction of a captive population of the Mexican prairie dog, Cynomys mexicanus, and prioritize wild populations for the conservation of this endangered endemic species. We estimated the levels of genetic diversity and differentiation of the captive population and compared them with those of six wild populations. We used species distribution modeling (SDM) to perform forecasts under future climate change scenarios and identify areas with suitable environmental conditions for the populations to persist in the medium to long term. The captive population showed high levels of genetic diversity (Hd=0.692, HE=0.52), but was genetically differentiated from the wild populations. The genetic structure of wild populations should therefore be considered when reintroducing captive Mexican prairie dogs. In the wild populations, we found a correlation between colony area and nuclear genetic diversity, suggesting that genetic drift and/or inbreeding have been stronger in smaller colonies. The occupied climate space was well differentiated among wild colonies. The impact of agriculture and roads was stronger in the northeastern area of the species range, where SDM forecasts suggest that environmental conditions may remain suitable in the future. Finally, we identified three colonies as conservation priorities based on both genetic and ecological criteria.

Temporal sampling helps unravel the genetic structure of naturally occurring populations of a phytoparasitic nematode. 2. Separating the relative effects of gene flow and genetic drift.

Studying wild pathogen populations in natural ecosystems offers the opportunity to better understand the evolutionary dynamics of biotic diseases in crops and to enhance pest control strategies. We used simulations and genetic markers to investigate the spatial and temporal population genetic structure of wild populations of the beet cyst nematode Heterodera schachtii on a wild host plant species, the sea beet (Beta vulgaris spp. maritima), the wild ancestor of cultivated beets. Our analysis of the variation of eight microsatellite loci across four study sites showed that (i) wild H. schachtii populations displayed fine‐scaled genetic structure with no evidence of substantial levels of gene flow beyond the scale of the host plant, and comparisons with simulations indicated that (ii) genetic drift substantially affected the residual signals of isolation‐by‐distance processes, leading to departures from migration–drift equilibrium. In contrast to what can be suspected for (crop) field populations, this showed that wild cyst nematodes have very low dispersal capabilities and are strongly disconnected from each other. Our results provide some key elements for designing pest control strategies, such as decreasing passive dispersal events to limit the spread of virulence among field nematode populations.

Evidence of Natural Hybridization in Brazilian Wild Lineages of Saccharomyces cerevisiae.

The natural biology of Saccharomyces cerevisiae, the best known unicellular model eukaryote, remains poorly documented and understood although recent progress has started to change this situation. Studies carried out recently in the Northern Hemisphere revealed the existence of wild populations associated with oak trees in North America, Asia, and in the Mediterranean region. However, in spite of these advances, the global distribution of natural populations of S. cerevisiae, especially in regions were oaks and other members of the Fagaceae are absent, is not well understood. Here we investigate the occurrence of S. cerevisiae in Brazil, a tropical region where oaks and other Fagaceae are absent. We report a candidate natural habitat of S. cerevisiae in South America and, using whole-genome data, we uncover new lineages that appear to have as closest relatives the wild populations found in North America and Japan. A population structure analysis revealed the penetration of the wine genotype into the wild Brazilian population, a first observation of the impact of domesticated microbe lineages on the genetic structure of wild populations. Unexpectedly, the Brazilian population shows conspicuous evidence of hybridization with an American population of Saccharomyces paradoxus. Introgressions from S. paradoxus were significantly enriched in genes encoding secondary active transmembrane transporters. We hypothesize that hybridization in tropical wild lineages may have facilitated the habitat transition accompanying the colonization of the tropical ecosystem.

Assessment of Genetic Structure in Wild Populations of Panulirus homarus (Linnaeus, 1758) across the South Coast of Sri Lanka Inferred from Mitochondrial DNA Sequences

Scalloped spiny lobster ( Panulirus homarus , Palinuridae) is an economically and ecologically important food species. Population structure of the scalloped spiny lobster across the southern coast of Sri Lanka (SCSL) (in Indian Ocean) was investigated using mitochondrial DNA (mtDNA) markers. Four sites belonging two regions were sampled (Hikkaduwa, Weligama in the southwest and Godawaya, Kirinda in the southeast) and DNA was isolated from tissues of pereiopod and used for PCR amplification. Genetic variation in DNA sequences were examined for two mtDNA gene regions; Cytochrome Oxidase I (COI) and Cytochrome B (CytB). High levels of haplotype diversity and nucleotide diversity were detected in all populations and estimated average fixation index (-0.026285 ( p < 0.01)) indicated essential homogeneity among population. Results of AMOVA analysis confirmed an absence of signi?cant population structure among sites. Tests of neutral evolution and analysis of mismatch distribution suggested that P. homarus populations across the SCSL might have experienced a recent population expansion. Information emerged from the current study could be utilized when people design appropriate management strategies for conserving this vital wild marine resource.

Genetic structure of a commercially exploited bivalve, the great scallop Pecten maximus, along the European coasts

The great scallop Pecten maximus is harvested in several European countries and fisheries targeting this species are severely regulated by fishing quotas. In addition, hatchery-based population enhancement has been developed in some countries to provide alternative or complementary production. The genetic structure of wild populations of P. maximus and the potential impact of aquaculture on the genetic diversity of this species remains poorly documented. In this study, we explored the genetic structure of P. maximus using 12 microsatellite markers, considering 14 populations sampled from Galicia (Spain) to the North of Norway, and one population of Pecten jacobaeus (L., 1758) from the Lion Gulf (Mediterranean Sea). Results indicated a clear differentiation between Norwegian and Atlantic (from Ireland to Spain) populations, but very little to no difference between populations within these two groups. A decrease of the genetic diversity was observed with latitude. No significant reduction of the genetic diversity was observed in the Bay of Brest, where hatchery-based population enhancement has been performed intensively since 1983. Our results are discussed in the light of the inferred recent evolutionary history, phylogeography and connectivity of populations in Europe, and of the phenotypic variability reported in previous studies between northern and southern populations.

Genetic structure of captive and free-ranging okapi (Okapia johnstoni) with implications for management

Breeding programs for endangered species increasingly use molecular genetics to inform their management strategies. Molecular approaches can be useful for investigating relatedness, resolving pedigree uncertainties, and for estimating genetic diversity in captive and wild populations. Genetic data can also be used to evaluate the representation of wild population genomes within captive population gene-pools. Maintaining a captive population that is genetically representative of its wild counterpart offers a means of conserving the original evolutionary potential of a species. Okapi, an even-toed ungulate, endemic to the Democratic Republic of Congo, have recently been reclassified as Endangered by the IUCN. We carried out a genetic assessment of the ex-situ okapi (Okapia johnstoni) population, alongside an investigation into the genetic structure of wild populations across their geographic range. We found that while levels of nuclear (12 microsatellite loci) genetic variation in the wild, founder and captive okapi populations were similar, mitochondrial (833 bp of Cyt b, CR, tRNA-Thr and tRNA-Pro) variation within captive okapi was considerably reduced compared to the wild, with 16 % lower haplotype diversity. Further, both nuclear and mitochondrial alleles present in captivity provided only partial representation of those present in the wild. Thirty mitochondrial haplotypes found in the wild were not found in captivity, and two haplotypes found in captivity were not found in the wild, and the patterns of genetic variation at microsatellite loci in our captive samples were considerably different to those of the wild samples. Our study highlights the importance of genetic characterisation of captive populations, even for well-managed ex-situ breeding programs with detailed studbooks. We recommend that the captive US population should be further genetically characterised to guide management of translocations between European and US captive populations.

Identification of quantitative genetic components of fitness variation in farmed, hybrid and native salmon in the wild.

Feral animals represent an important problem in many ecosystems due to interbreeding with wild conspecifics. Hybrid offspring from wild and domestic parents are often less adapted to local environment and ultimately, can reduce the fitness of the native population. This problem is an important concern in Norway, where each year, hundreds of thousands of farm Atlantic salmon escape from fish farms. Feral fish outnumber wild populations, leading to a possible loss of local adaptive genetic variation and erosion of genetic structure in wild populations. Studying the genetic factors underlying relative performance between wild and domesticated conspecific can help to better understand how domestication modifies the genetic background of populations, and how it may alter their ability to adapt to the natural environment. Here, based upon a large-scale release of wild, farm and wild x farm salmon crosses into a natural river system, a genome-wide quantitative trait locus (QTL) scan was performed on the offspring of 50 full-sib families, for traits related to fitness (length, weight, condition factor and survival). Six QTLs were detected as significant contributors to the phenotypic variation of the first three traits, explaining collectively between 9.8 and 14.8% of the phenotypic variation. The seventh QTL had a significant contribution to the variation in survival, and is regarded as a key factor to understand the fitness variability observed among salmon in the river. Interestingly, strong allelic correlation within one of the QTL regions in farmed salmon might reflect a recent selective sweep due to artificial selection.

Genetic structure of brown and Iberian hare populations in northern Iberia: Implications for conservation of genetic diversity

ABSTRACTHares in the northern Iberian Peninsula have been managed by local authorities primarily as a game species for hunting. Over the last 4 decades, populations have been restocked by means of translocation from other regions. We examined the genetic structure of wild populations of 2 species living in the northern Iberian Peninsula: the brown hare (Lepus europaeus) and the Iberian hare (L. granatensis) to assess their genetic uniqueness and distinctiveness, and thus determine if these populations have been altered by anthropogenic translocations. We analyzed 215 sequences of the mitochondrial DNA (mtDNA) control region and 6 microsatellite markers in 157 individuals from northern Iberia. We detected 3 distinct mtDNA types in L. europaeus (timidus, granatensis, and europaeus mtDNA lineages) and 2 mtDNA types in L. granatensis, (timidus and granatensis lineages). The high and homogeneous prevalence of a north European timidus mtDNA lineage in both L. europaeus and L. granatensis may be the result of an ancient introgression during the last glacial period. The homogeneous distribution of the granatensis mtDNA lineage in L. europaeus may also be the result of gene flow between species in a contact zone. In contrast, both the low prevalence of the europaeus mtDNA lineage and its highly localized presence in the center of Guipúzcoa are strongly indicative of the recent incorporation of non‐Iberian L. europaeus into the local population. The data derived from microsatellite markers revealed that L. europaeus populations from the center of Guipúzcoa had a much higher assignment probability to eastern European populations than the rest of northern Iberian populations, which presented high assignment probabilities to the populations from protected areas of Cantabria and Huesca. Strict adherence to International Union for Conservation of Nature (IUCN) criteria strongly suggests that these translocations may not be beneficial, in that they compromise the genetic integrity of the native population of L. europaeus in the northern Iberian Peninsula. For this reason, we strongly recommend 1) translocations of L. europaeus individuals from non‐Iberian populations into Iberian populations be avoided; 2) restocking the center of Guipúzcoa with autochthonous L. europaeus individuals; 3) carrying out periodic genetic surveys of L. europaeus throughout the study area; and 4) increasing our knowledge of the genetic structure of L. granatensis under natural conditions. © 2014 The Wildlife Society.