45 resultados para Population genetic strcuture
em Aquatic Commons
Resumo:
A new method of finding the optimal group membership and number of groupings to partition population genetic distance data is presented. The software program Partitioning Optimization with Restricted Growth Strings (PORGS), visits all possible set partitions and deems acceptable partitions to be those that reduce mean intracluster distance. The optimal number of groups is determined with the gap statistic which compares PORGS results with a reference distribution. The PORGS method was validated by a simulated data set with a known distribution. For efficiency, where values of n were larger, restricted growth strings (RGS) were used to bipartition populations during a nested search (bi-PORGS). Bi-PORGS was applied to a set of genetic data from 18 Chinook salmon (Oncorhynchus tshawytscha) populations from the west coast of Vancouver Island. The optimal grouping of these populations corresponded to four geographic locations: 1) Quatsino Sound, 2) Nootka Sound, 3) Clayoquot +Barkley sounds, and 4) southwest Vancouver Island. However, assignment of populations to groups did not strictly reflect the geographical divisions; fish of Barkley Sound origin that had strayed into the Gold River and close genetic similarity between transferred and donor populations meant groupings crossed geographic boundaries. Overall, stock structure determined by this partitioning method was similar to that determined by the unweighted pair-group method with arithmetic averages (UPGMA), an agglomerative clustering algorithm.
Resumo:
In order to carry out Biometric studies, 75 samples were caught from 3 locations ( Tajan river, Sefidrud and Shirud) using Salic and the length (±1 mm) and weights (± 5 gr) of samples were determined. Using One-way ANOVA by SPPSS software, there wasn’t significant difference between locations in length and fecondity (P ≥0.01(, but there was significant difference between Shirud and tajan samples with sefidrud in weight ) P≤0.01(. In order to carry out genetic variation studies, 210 fish were caught from 3 different regions of the Iranian coastline (Khoshkrud, Tonekabon, Gorganrud) and 1 region in Azerbaijan (Waters of the Caspian Sea close to Kura River mouth) during 2008-2009 . Genomic DNA was extracted of fin using the phenol-chloroform. The quantity and quality of DNA from samples were assessed by spectrophptometer and 1% agarose gel electro-phoresis. PCR was carried out using 15 paired microsatellite primers. PCR products were separated on 8% polyacrylamide gels that were stained using silver nitrate. Molecular weight calculate using UVTech software. The recorded microsatellite genotypes were used as input data for the GENALEX software version 6 package in order to calculate allele and genotype frequencies, observed (Ho) and (He) expected heterozygosities and to test for deviations from Hardy-Weinberg equilibrium. Genetic distance between two populations was estimated from Nei standard genetic distance and genetic similarity index (Nei, 1972). Genetic differentiation between populations was also evaluated by the calculation of pairwise estimates of Fst and Rst values. From 15 SSR markers were used in this investigation, 9 of them were polymorph. Average of expected and observed heterozygosity was 0.54 and 0.49 respectively. Significant deviations from Hardy-Weinberg expectations were observed in all of location except Anzali lagoon- autumn in AF277576 and EF144125, Khoshkrud in EF144125 and Gorganrud and Kura in AF277576. Using Fst and Rst there was significant difference between locations ) P≤0.01(. According to Fst , the highest population differentiation (Fst= 0.217) was between Gorganrud and Khoshkrud that have the lowest Nm and the lowest (Fst= 0.086) was between Gorganrud and Tonekabon that have the highest Nm. Using Rst the highest population differentiation (Rst= 0.271) was between Tonekabon and spring Anzali lagoon and the lowest (Rst= 0.026) was between Tonekabon and Autumn Anzali 159 lagoon. Also the difference between Spring Anzali lagoon and Autumn Anzali lagoon was noticeable (Fst=0.15). AMOVA analysis with consideration of 2 sampling regions (Iran and Azerbaijan) and 7 sampling locations (Iran: Khoshkrud, Tonekabon, Gorganrud, Spring Anzali lagoon and Autumn Anzali lagoon ; Azerbaijan: the Kura mouth) revealed that almost all of the variance in data namely 83% )P≤0.01( was within locations, Genetic variances among locations was 14% )P≤0.01( and among regions was 3% )P≤0.01(. The genetic distance was the highest (0.646) between Gorganrud and Autumn Anzali lagoon populations, whereas the lowest distance (0.237) was between Gorganrud and Tonekabon River. Result obtained from the present study show that at least 2 different population of Rutilus frissi kutum are found in the Caspian sea,which are including the kura river population and the southern Caspian sea samples and it appears that there is more than one population in southern Caspian sea that should be attantioned in artifical reproduction Center and stoke rebilding.
Resumo:
Ngege, Oreochromis esculentus, originally formed the mainstay of the Lake Victoria Region (LVR) fisheries. Together with its indigenous congener O. variabilis, it was displaced from Lakes Victoria and Kyoga of LVR and was found to survive as isolated small populations within the peripheral minor lakes and reservoirs around the two lakes. Displacement of the two LVR indigenous tilapiines was thought to be principally driven by changed lake environment and predation by the introduced Nile perch, but also competition and genetic swamping by the closely related introduced and comparatively more ecologically versatile tilapine species. In a study carried out in the LVR between 1993 and 2003, micro satellites and RAPD markers were used to analyse the remnant populations so as to establish the population structure and extant genetic diversity of O. esculentus. Analyses indicated that the surviving O. esculentus retained a high proportion of genetic diversity with high differentiation between units an indication of genetic exchange between indigenous and introduced Nile tilapia where the two forms co-existed. While this heightened concern for genetic swamping of the remnant population units by the introduced tilapiines it was noteworthy that in a few of the satellite lakes where the O. esculentus was dominant evidence for introgression was weak.
Resumo:
Sardines and other Microfilidae have very important ecological role in marine ecosystems because they are first consumers in marine food chain and they are the main food of valuable species as tuna. So decries in their population will decline fishing of these spices. There are 10 genus of Clupeidae in south of Iran and Sardinella is the one of the most abundant of them. In this study we investigated about morphological and genetically differences in population of 3 species: Sardinella sindensis, Sardinella abella, Dussomieria acuta. About 65 specimens of Sardinella sindensis, 61 specimens of Sardinella albella and 63 specimens of, Dussomieria acuta from three regions of their distribution: Jask (Oman Sea), Qeshm (Hormoz) and Lengeh (Pearsian Gulf) have been collected. Morphological research of their characters and statistical studies were done. To determine the genetically structure of specie's population we sequenced 500 bp of mitochondrial control region. Genetical studies determine meaningful difference in alleles and heterozigosity frequency of Sardinella sindensis. This must be the result of divergence in population of this species. Morphological investigation of Sardinella albella shows the meaningful difference. But detailed studies diffused it. Genetical studies show a meaningful variance in allele and heterosigosity frequency. This may be an aspect of sardine tendency to live in estuaries. Morphological research of Dussomieria acuta in Jask and Lengeh show a meaningful variance in these regions. Such a situation might be result of Monsoon, upwelling and better weather which occur in Oman Sea in spite of Persian Gulf.
Resumo:
Neogobius caspius is a small benthic fish that is native to the Caspian Sea. The importance of this fish is because of it is role as a main food resource of the sturgeon fish. The genetic diversity of N. caspius population in the Caspian Sea was studied using PCR- RFLP technique. A total of 135 samples of N. caspius were collected from coastal line in the north Caspian sea, including specimens from coasts of Anzali , Torkman Port and Chalus. Genomic DNA was extracted by phenol-chloroform method and then was amplified using a pair primer of cytochrom b gene, 2 tRNA gene and the control region sequences by a thermal cycler. D2 (5'-CCGGAGTATGTAGGGCATTCTCAC-3'), CY1 (5'-YYTAACCRRGACYAATGACTTGA-3') 12 restriction enzyme were used to digest the target gene region including: Alul HincII —Tas1 —Rsa1 -MboI -DraI -BSeNI(BSRI) Alw261(BsmAI). Bsul 51 Hin11 Bsh12851- BsuRI(HaeIII) digested PCR products were observed by silver staining method followed by Polyacrylamide gel electrophoresis (PAGE). The results were shown the same pattern among the species. There was no polymorphism and no differentiation in population in the Neogobius caspius fish and all individuals have shown homogenous genotype.
Resumo:
Rougheye rockfish (Sebastes aleutianus) and shortraker rockfish (Sebastes borealis) were collected from the Washington coast, the Gulf of Alaska, the southern Bering Sea, and the eastern Kamchatka coast of Russia (areas encompassing most of their geographic distribution) for population genetic analyses. Using starch gel electrophoresis, we analyzed 1027 rougheye rockfish and 615 shortraker rockfish for variation at 29 proteincoding loci. No genetic heterogeneity was found among shortraker rockfish throughout the sampled regions, although shortraker in the Aleutian Islands region, captured at deeper depths, were found to be significantly smaller in size than the shortraker caught in shallower waters from Southeast Alaska. Genetic analysis of the rougheye rockfish revealed two evolutionary lineages that exist in sympatry with little or no gene f low between them. When analyzed as two distinct species, neither lineage exhibited heterogeneity among regions. Sebastes aleutianus seems to inhabit waters throughout the Gulf of Alaska and more southern waters, whereas S. sp. cf. aleutianus inhabits waters throughout the Gulf of Alaska, Aleutian Islands, and Asia. The distribution of the two rougheye rockfish lineages may be related to depth where they are sympatric. The paler color morph, S. aleutianus, is found more abundantly in shallower waters and the darker color morph, Sebastes sp. cf. aleutianus, inhabits deeper waters. Sebastes sp. cf. aleutianus, also exhibited a significantly higher prevalence of two parasites, N. robusta and T. trituba, than did Sebastes aleutianus, in the 2001 samples, indicating a possible difference in habitat and (or) resource use between the two lineages.
Resumo:
Executive Summary: Tropical marine ecosystems in the Caribbean region are inextricably linked through the movement of pollutants, nutrients, diseases, and other stressors, which threaten to further degrade coral reef communities. The magnitude of change that is occurring within the region is considerable, and solutions will require investigating pros and cons of networks of marine protected areas (MPAs), cooperation of neighboring countries, improved understanding of how external stressors degrade local marine resources, and ameliorating those stressors. Connectivity can be broadly defined as the exchange of materials (e.g., nutrients and pollutants), organisms, and genes and can be divided into: 1) genetic or evolutionary connectivity that concerns the exchange of organisms and genes, 2) demographic connectivity, which is the exchange of individuals among local groups, and 3) oceanographic connectivity, which includes flow of materials and circulation patterns and variability that underpin much of all these exchanges. Presently, we understand little about connectivity at specific locations beyond model outputs, and yet we must manage MPAs with connectivity in mind. A key to successful MPA management is how to most effectively work with scientists to acquire the information managers need. Oceanography connectivity is poorly understood, and even less is known about the shape of the dispersal curve for most species. Dispersal kernels differ for various systems, species, and life histories and are likely highly variable in space and time. Furthermore, the implications of different dispersal kernels on population dynamics and management of species is unknown. However, small dispersal kernels are the norm - not the exception. Linking patterns of dispersal to management options is difficult given the present state of knowledge. The behavioral component of larval dispersal has a major impact on where larvae settle. Individual larval behavior and life history details are required to produce meaningful simulations of population connectivity. Biological inputs are critical determinants of dispersal outcomes beyond what can be gleaned from models of passive dispersal. There is considerable temporal and spatial variation to connectivity patterns. New models are increasingly being developed, but these must be validated to understand upstream-downstream neighborhoods, dispersal corridors, stepping stones, and source/sink dynamics. At present, models are mainly useful for providing generalities and generating hypotheses. Low-technology approaches such as drifter vials and oceanographic drogues are useful, affordable options for understanding local connectivity. The “silver bullet” approach to MPA design may not be possible for several reasons. Genetic connectivity studies reveal divergent population genetic structures despite similar larval life histories. Historical stochasticity in reproduction and/or recruitment likely has important, longlasting consequences on present day genetic structure. (PDF has 200 pages.)
Resumo:
HIGHLIGHTS FOR FY 2008 1. Completed the first of a two-year Gulf sturgeon population study on the Choctawhatchee River, Florida. The sub adult and adult Gulf sturgeon population was estimated at 2,800 fish. 2. Gulf sturgeon eggs were collected at three hard bottom sites in the Apalachicola River, Florida; two sites were previously confirmed spawning areas and one was a newly confirmed spawning area. 3. Documented 55 potential environmental threats to Gulf sturgeon spawning habitat in the Pea River, Florida and Alabama. 4. Assigned the Eglin AFB Road-Stream Crossing Working Group to guide the closure, repair and maintenance of roads and road stream crossings that impact threatened and endangered species. 5. Conducted 81 assessments of fish and stream invertebrates on and in watersheds surrounding Eglin AFB. 6. Provided technical support for the 5-year status review and reclassification proposed rule for the Okaloosa darter. 7. Initiated an intensive population genetic analysis of the Okaloosa darter throughout its range. Tissues from over 200 Okaloosa darters were collected and analyzed. 8. Established a GIS database to serve as a host for data from any sites sampled for mussels in Northeast Gulf of Mexico drainages. 9. Conducted habitat surveys at 115 locations in the Apalachicola River to assess the effects of drought-related mussel mortality and strandings, evaluate habitat conditions, and assess population demography. 10. A land use/aerial imagery threats assessment data analysis was completed for the Chipola River. A total of 266 impoundments/borrow pits and 471 unpaved road crossings were identified among the threats. 11. Okaloosa darters marked with elastomeric dyes were monitored in Mill Creek, Eglin AFB, to determine movement and habitat use following completion of a fish passage project. 3 12. Partners for Fish and Wildlife funded a streambank and riparian restoration project on Econfina Creek consisting of 3,900 feet of streambank fencing to exclude cattle access. One acre of riparian floodplain was planted with native trees. 13. We provided design and on-the-ground assistance for restoring surface hydrology at St. Vincent NWR. The project restored approximately 1.5 miles of tidal stream and 100 acres of wetlands. 14. A study was completed on 11 coastal streams to document large wood debris relationships with fluvial geomorphic characteristics. 15. We developed a Population Viability Analysis model for the fat threeridge mussel to determine current and future risk of extinction. 17. A Gulf Sturgeon Friends Group, “Gulf Sturgeon Preservation Society” was organized in FY 08. 18. Multiple outreach projects were completed to detail aquatic resource conservation needs and opportunities, including National Fishing Week, Earth Day, several festivals and school outreach.
Resumo:
In this paper we present livestock breeding developments that could be taken into consideration in the genetic improvement of farmed aquaculture species, especially in freshwater fish. Firstly, the current breeding objective in aquatic species has focused almost exclusively on the improvement of body weight at harvest or on growth related traits. This is unlikely to be sufficient to meet the future needs of the aquaculture industry. To meet future demands breeding programs will most likely have to include additional traits, such as fitness related ones (survival, disease resistance), feed efficiency, or flesh quality, rather than only growth performance. In order to select for a multi-trait breeding objective, genetic variation in traits of interest and the genetic relationships among them need to be estimated. In addition, economic values for these traits will be required. Generally, there is a paucity of data on variable and fixed production costs in aquaculture, and this could be a major constraint in the further expansion of the breeding objectives. Secondly, genetic evaluation systems using the restricted maximum likelihood method (REML) and best linear unbiased prediction (BLUP) in a framework of mixed model methodology could be widely adopted to replace the more commonly used method of mass selection based on phenotypic performance. The BLUP method increases the accuracy of selection and also allows the management of inbreeding and estimation of genetic trends. BLUP is an improvement over the classic selection index approach, which was used in the success story of the genetically improved farmed tilapia (GIFT) in the Philippines, with genetic gains from 10 to 20 per cent per generation of selection. In parallel with BLUP, optimal genetic contribution theory can be applied to maximize genetic gain while constraining inbreeding in the long run in selection programs. Thirdly, by using advanced statistical methods, genetic selection can be carried out not only at the nucleus level but also in lower tiers of the pyramid breeding structure. Large scale across population genetic evaluation through genetic connectedness using cryopreserved sperm enables the comparison and ranking of genetic merit of all animals across populations, countries or years, and thus the genetically superior brood stock can be identified and widely used and exchanged to increase the rate of genetic progress in the population as a whole. It is concluded that sound genetic programs need to be established for aquaculture species. In addition to being very effective, fully pedigreed breeding programs would also enable the exploration of possibilities of integrating molecular markers (e.g., genetic tagging using DNA fingerprinting, marker (gene) assisted selection) and reproductive technologies such as in-vitro fertilization using cryopreserved spermatozoa.
Resumo:
The population structure of walleye pollock (Theragra chalcogramma) in the northeastern Pacific Ocean remains unknown. We examined elemental signatures in the otoliths of larval and juvenile pollock from locations in the Bering Sea and Gulf of Alaska to determine if there were significant geographic variations in otolith composition that may be used as natural tags of population affinities. Otoliths were assayed by using both electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (ICP-MS). Elements measured at the nucleus of otoliths by EPMA and laser ablation ICP-MS differed significantly among locations. However, geographic groupings identified by a multivariate statistical approach from EPMA and ICP-MS were dissimilar, indicating that the elements assayed by each technique were controlled by separate depositional processes within the endolymph. Elemental profiles across the pollock otoliths were generally consistent at distances up to 100 μm from the nucleus. At distances beyond 100 μm, profiles varied significantly but were remarkably consistent among individuals collected at each location. These data may indicate that larvae from various spawning locations are encountering water masses with differing physicochemical properties through their larval lives, and at approximately the same time. Although our results are promising, we require a better understanding of the mechanisms controlling otolith chemistry before it will be possible to reconstruct dispersal pathways of larval pollock based on probe-based analyses of otolith geochemistry. Elemental signatures in otoliths of pollock may allow for the delineation of fine-scale population structure in pollock that has yet to be consistently revealed by using population genetic approaches.
Resumo:
Atlantic menhaden (Brevoortia tyrannus), through landings, support one of the largest commercial fisheries in the United States. Recent consolidation of the once coast-wide reduction fishery to waters within and around Chesapeake Bay has raised concerns over the possibility of the loss of unique genetic variation resulting from concentrated fishing pressure. To address this question, we surveyed variation at the mitochondrial cytochrome c oxidase subunit I (COI) gene region and seven nuclear microsatellite loci to evaluate stock structure of Atlantic menhaden. Samples were collected from up to three cohorts of Atlantic menhaden at four geographic locations along the U.S. Atlantic coast in 2006 and 2007, and from the closely related Gulf menhaden (B. patronus) in the Gulf of Mexico. Genetic divergence between Atlantic menhaden and Gulf menhaden, based on the COI gene region sequences and microsatellite loci, was more characteristic of conspecific populations than separate species. Hierarchical analyses of molecular variance indicated a homogeneous distribution of genetic variation within Atlantic menhaden. No significant variation was found between young-of-the-year menhaden (YOY) collected early and late in the season within Chesapeake Bay, between young-of-the-year and yearling menhaden collected in the Chesapeake Bay during the same year, between YOY and yearling menhaden taken in Chesapeake Bay in successive years, or among combined YOY and yearling Atlantic menhaden collected in both years from the four geographic locations. The genetic connectivity between the regional collections indicates that the concentration of fishing pressure in and around Chesapeake Bay will not result in a significant loss of unique genetic variation.
Resumo:
Genetic structure of hatchery population of Thai pangas (Pangasius hypophthalmus) of Jessore region, Bangladesh has been investigated from 1 January 2004 to 31 December 2004. Samples for this study were collected from five fish hatcheries viz. Asrom, Banchte Shekha, Chowdhury, Maola and Rezaul Haque. The enzymes were encoded by 15 gene loci: Adh-1*, Est-1*, G3pdh-2*, Gpi-1*, Gpi-2*, Idhp-1*, Idhp-2*, Ldh-1*, Ldh-2*, Mdh-1*, Mdh-2*, Pgm*, Sdh-1*, Sdh-2* and Sod*. Among them four (Est-1*, G3pdh-2*, Gpi-2*and Pgm*) were found to be polymorphic in different populations but only Gpi-2* was polymorphic in all the sampled populations. The mean proportion of polymorphic loci per population was the highest (26.7%) in Banchte Shekha hatchery while the mean proportion of heterozygous loci was 13.33% per individual in Banchte Shekha and Maola hatcheries. The UPGMA dendrogram of Nei's (1972) genetic distances indicated a relationship between the genetic distance and geographical difference. High genetic variability in stocks of Thai pangas was observed in the Banchte Shekha and Maola hatcheries and less variability was found in the other three hatcheries.
Resumo:
For study the genetic diversity of Caspian brown trout population in five rivers in the southern part of Caspian Sea in Iran 182 number generators in the fall and winter of 1390 were collected in Chalus, Sardab Rud, Cheshmeh Kileh, Kargan Rud and Astara rivers. Then about 3-5 g of soft and fresh tissue from the bottom fin fish removed and were fixed in ethanol 96°. Genomic DNA was extracted by using ammonium acetate, then quantity and quality of the extracted DNA were determined by using spectrophotometry and horizontal electrophoresis in 1% agarose gel. The polymerase chain reaction was performed by using 16 SSR primers and sequencing primers (D-Loop) and the quality of PCR products amplified by SSR method were performed by using horizontal electrophoresis in 2% agarose gel. Alleles and their sizes were determined by using vertical electrophoresis in 6% polyacrylamide gel and silver nitrate staining method. Gel images were recorded by gel documentarian, the bands were scored by using Photo- Capt software and statistical analysis was performed by using Gene Alex and Pop Gene software. Also the PCR sequencing products after quality assessment by usinghorizontal electrophoresis in 1.5% agarose gel were purified and sent to South Korea Bioneer Corporation for sequencing. Sequencing was performed by chain termination method and the statistical analysis was performed by using Bio- Edit, Mega, Arlequin and DNA SP software. The SSR method, 5 pairs of primers produced polymorphic bands and the average real and effective number of alleles were calculated 5.60±1.83 and 3.87±1.46 in the Cheshmeh Kileh river and 7.60±1.75 and 5.48±1.32 in the Karganrud river and the mean observed and expected heterozygosity were calculated 0.44 ±0.15 and 0.52 ±0.16 in the Cheshmeh Kileh river and 0.50 ±0.11 and 0.70±0.13 in the Karganrud river. Analysis of Molecular Variance results showed that significant differences in genetic diversity between and within populations and between and within individuals in the studied rivers (P<0.01). The sequencing method identified 35 different haplotype, the highest number of polymorphic position (251) and haplotype (14) were observed in the Chalus river. The highest mean observed number of alleles (2.24±0.48) was calculated in the Sardabrud river, the highest mean observed heterozygosity (1.00±0.03) was calculated in the Chalus river and the highest mean nucleotide diversity (0.13±0.07) was observed in the Sardabrud river and mean haplotype diversity was obtained (1) in three studied rivers. The overall results show that there are no same population of this fish in the studied rivers and Karganrud and Chalus rivers in the SSR and sequencing methods had the highest levels of genetic diversity.