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1.
Preservation of rare genetic stocks requires continual monitoring of populations to avoid losses of genetic variability. Genetic variability can be described using genealogical and molecular parameters characterizing variation in allelic frequencies over time and providing interesting information on differentiation that occurred after the foundation of a conservation program. Here we analyze the pedigree of the rare Xalda sheep breed (1851 individuals) and the polymorphism of 14 microsatellites in 239 Xalda individuals. Individuals were assigned to a base population (BP) or 4 different cohorts (from C1 to C4) according to their pedigree information. Genetic parameters were computed at a genealogical and molecular level, namely inbreeding (F), observed (Ho) and expected (He) heterozygosity, individual coancestry coefficients (f and fm), average relatedness (AR), mean molecular kinship (Mk), average number of allele per locus (A), effective number of ancestors (fa), effective population size (Ne and Ne(m)) and founder genome equivalents (Ng and Ng(m)). In general, the computed parameters increased with pedigree depth from BP to C4, especially for the genealogical information and molecular coancestry-based parameters (fm, Mk and Ng(m)). However, Ho and He showed the highest values for C1 and the molecular heterozygote deficiency within population (FIS(m)) showed the lowest value for C1, thus indicating that loss of genetic variability occurs very soon after the implementation of conservation strategies. Although no genealogical or molecular parameters are sufficient by themselves for monitoring populations at the beginning of a conservation program, our data suggests that coancestry-based parameters may be better criteria than those of inbreeding or homozygosity because of the rapid and strong correlation established between f and f(m). However, the obtaining of molecular information in well-established conservation programs could not be justified, at least in economic terms.  相似文献   

2.
《African Zoology》2013,48(1):30-38
The residency and small-scale movements of early juveniles (<175 mm fork length) of three sparid fish species were examined in the shallow subtidal zone along a 500 m stretch of rocky coastline near Schoenmakerskop (Eastern Cape Province, South Africa). A total of 12 blacktail (Diplodus capensis), 12 zebra (Diplodus hottentotus) and six white musselcracker (Sparodon durbanensis) were tagged using visible implant elastomer (VIE) tags. Underwater observations in four shallow rocky subtidal gullies and adjacent areas were made using snorkeling gear on a total of 37 days spanning 13 field trips over spring low tide periods between January and August 2006. The VIE tagging method was well suited to individually tag small juvenile fish with minimum disturbance. In general, the degree of residency of juveniles in the shallow rocky subtidal zone was species specific and dependent on the size of individuals. Juvenile zebra displayed the highest degree of residency followed by white musselcracker and blacktail, with re-sightings recorded on 53%, 40% and 10% of observation days, respectively. The high degree of residency by early juvenile sparids renders them vulnerable to localized coastal perturbations and climate change.  相似文献   

3.
Polymorphisms for seven microsatellite loci in three red deer subspecies (9 populations) found in XinJiang were detected by polymerase chain reaction (PCR), 12% nondenaturation polyacrylamide gel electrophoresis and the Sanguinetti silver staining method. Numbers of alleles, average effective numbers of alleles (E) and the average rate of homozygosity, allelic frequencies of seven microsatellite loci, polymorphism information content (PIC), mean heterozygosity (H) and genetic distances among the populations were calculated for each population. Dendrograms were constructed based on genetic distances by the neighbor‐joining method (NJ), utilizing molecular evolutionary genetics analysis software PHYLIP (3.6). The phylogenetic tree was constructed based on allelic frequencies using maximum likelihood (ML); the bootstrap value was estimated by bootstrap test in the tree. Lastly, phylogenesis was analyzed. The results showed that four of the seven microsatellite loci were highly polymorphic, but BMS2508 and Celjp0023 showed no polymorphism and BM5004 was a neutral polymorphism. It is our conclusion that the four microsatellite loci are effective DNA markers for the analysis of genetic diversity and phylogenetic relationships among the three red deer subspecies. The mean PIC, H and E‐values across the microsatellite loci were 0.5393, 0.5736 and 2.64, which showed that these microsatellite loci are effective DNA markers for the genetic analysis of red deer. C.e. songaricus populations from Regiment 104, 151 and Hami are clustered together. C.e. yarkandensis populations from Regiment 35, Xaya and Alaer are clustered together. These two clusters also cluster together. Lastly, C.e. sibiricus populations from Burqin, Regiment 188 and the first two clusters were clustered together. The phylogenetic relationship among different red deer populations is consistent with the known origin, history of breeding and geographic distributions of populations.  相似文献   

4.
《African Zoology》2013,48(2):291-298
The amphibian Amietophrynus regularis is distributed throughout equatorial Africa, with presumed introduced populations in the Cape Verde archipelago. Portions of the 12S and 16S rRNA mitochondrial regions of 30 specimens from Kenya, Uganda, Niger, Mali, Burkina-Faso, Ghana, Guinea-Bissau and Cape Verde were used to assess genetic diversity and to identify the most probable geographic origin for the introduction of this toad on the latter archipelago. Two lineages with 1.4% genetic divergence between them were identified in western and eastern Africa. All sequences from the different Cape Verde Islands were identical to each other and to the Guinea-Bissau samples, indicating, together with other historical evidences, that an anthropogenic introduction event probably occurred, possibly from Guinea-Bissau, but further work is needed to confirm this. As previously noted, several individuals from previous genetic studies seem to have been misidentified.  相似文献   

5.
The study characterized genetic diversity and genetic structure of five indigenous pig populations (Ha Lang, Muong Te, Mong Cai, Lung and Lung Pu), two wild pig populations (Vietnamese and Thai wild pigs) and an exotic pig breed (Yorkshire) using FAO/ISAG recommended 16 microsatellite markers in 236 samples. All estimated loci were very polymorphic indicated by high values of polymorphism information content (from 0.76 in S0225 to 0.92 in Sw2410). Indigenous populations had very high level of genetic diversity (mean He = 0.75); of all indigenous breeds, Lung Pu showed highest mean number of alleles (MNA = 10.1), gene diversity (He = 0.82), allele richness (5.33) and number of private alleles (10). Thirteen percentage of the total genetic variation observed was due to differences among populations. The neighbour‐joining dendrogram obtained from Nei's standard genetic distance differentiated eight populations into four groups including Yorkshire, two wild populations, Mong Cai population and a group of four other indigenous populations. The Bayesian clustering with the admixture model implemented in Structure 2.1 indicated seven possible homogenous clusters among eight populations. From 79% (Ha Lang) to 98% (Mong Cai). individuals in indigenous pigs were assigned to their own populations. The results confirmed high level of genetic diversity and shed a new light on genetic structure of Vietnam indigenous pig populations.  相似文献   

6.
The Cape river crab, Potamonautes perlatus, is widely distributed in streams and rivers of the Western Cape where it exhibits considerable morphological variation. Recent genetic work on populations in the Olifants River system has demonstrated the existence of a new cryptic species of river crab, while populations of P. perlatus in the nearby Berg River system remained uninvestigated. Six populations of P. perlatus were collected from along the length of the Berg River system (125 km) and the genetic structure was investigated using allozyme electrophoresis. Results from 14 allozyme loci showed that the populations were genetically invariant across the river system. It is suggested that gene flow may be responsible for the poor genetic differentiation amongst populations in the Berg River system. The implication for future management of the system is briefly discussed.  相似文献   

7.
Four populations of the bushveld rain frog, Breviceps adspersus, representing three northern populations (B. adspersus adspersus), and a southern population (B. adspersus pentheri), were analysed by electrophoresis to assess the extent of genetic variation and differentiation amongst them. Eighteen protein-coding loci were resolved of which 11 loci (61 %) displayed polymorphism. A low mean heterozygosity ranging between H = 0.009 to H = 0.062 was estimated. Greater genetic differentiation was observed between the B. adspersus pentheri and B. adspersus adspersus populations, than between the three B. adspersus adspersus populations. This supports the subspecific status of both taxa.

Key words: allozymes, anura, speciation, taxonomy.  相似文献   

8.
Though important, CO2 effluxes from non-agricultural ecosystems are poorly characterised. Given that thicket vegetation is prevalent in Eastern Cape, South Africa, we monitored soil CO2 effluxes from an intact thicket, degraded thicket (DT) and grassland (G) over 10 months, as affected by temperature, moisture and penetration resistance (PR). High soil moisture (16%) reduced PR (4?kg cm?2), which raised winter effluxes (1.2 µmol m?2 s?1), while low moisture (2%) resulted in hard dry soil (14?kg cm?2) that suppressed spring effluxes (0.2 µmol m?2 s?1). There was good interaction between PR and moisture (r = ?0.53), with seasonal effluxes increasing with increasing moisture (r = 0.9, p = 0.0001) and decreasing PR (r = ?0.66, p = 0.02). Temperature effects were significant under unlimited moisture supply. Thus high summer temperature (40 °C) gave lower effluxes in DT and G (<1 µmol m?2 s?1) due to limited moisture (<10%), whereas high autumn temperature (48 °C) and good moisture (16%) accelerated CO2 emissions (averaging 2 µmol m?2 s?1) from all covers. Although semi-arid ecosystems are limited by low moisture and sandy soils, they contribute to CO2 emissions under high moisture and increasing temperature. Keywords: Eastern Cape, grassland, soil carbon dioxide effluxes, soil organic carbon, thicket  相似文献   

9.
不同生态型芦苇生境适应性的遗传差异   总被引:1,自引:0,他引:1  
以甘肃省临泽县内的4种生态型芦苇为材料,采用随机扩增多态DNA技术和等位酶多态性分析技术初步探讨了不同生态型芦苇对各自生境适应性的遗传差异。RAPD-PCR(随机扩增多态DNA聚合酶链式反应)采用10碱基随机引物,筛选出16条重复性高并产生明显多态性产物的引物,共扩增了559条谱带,其中489条谱带具有多态性,多态性百分数为87.5%。等位酶分析选用了12个等位酶系统,其中9个基因位点显示了多态性,多态位点平均百分数为34.1%。试验结果表明,不同生态型芦苇之间具有显著的分子遗传差异和等位酶表达差异,同时属于同一生态型的个体和群体之间的遗传差异很小,这与不同生态型芦苇在适应各自生境的过程中所形成的形态学和生理学方面的差异是一致的,说明各个生态型之间的差异是遗传分化的结果。  相似文献   

10.
The spatial genetic structure is a topical issue in the studies of various aspects of ecology and evolution. Using the multilocus autocorrelation method with hypervariable microsatellite genetic markers, we investigated a fine-scale pattern of genetic structure in 5 local populations of the common shrew Sorex araneus separated by distances of 300–1000 m (the Moscow chromosomal race). Spatial genetic autocorrelation analysis based on 5 microsatellite loci (expected heterozygosity >0.79) with 90 alleles revealed a consistent pattern of significant positive genetic structure. By testing the autocorrelation at multiple scales from 25 to 500 m, we found that positive spatial genetic structure is detectable in distance classes of <500 m. The weaker spatial genetic structure positively correlated with a higher ratio of nonresident individuals to residents’ activity (number of captures). In contrast to nonresident animals, the residents demonstrated prominent genetic structure. Genetic difference (FST) between the populations was significant (0.016–0.051) and comparable with that between populations of different races analyzed previously (0.016–0.038). FST was not associated with geographic distance. These demographic patterns allowed us to propose a scheme of genetic-structure dynamics involving periodic appearance of more related local groups and renewal of allelic profiles from а common pool where the alleles are mixed. The scheme predicts fluctuating genetic structure and random similar differences among local populations.  相似文献   

11.
The tortoise tick Amblyomma marmoreum was collected from large numbers of reptiles and other animals during the course of numerous surveys conducted in South Africa. A total of 1229 ticks, of which 550 were adults, were recovered from 309 reptiles belonging to 13 species, with leopard tortoises, Geochelone pardalis being the most heavily infested. The 269 birds sampled harboured 4901 larvae, 217 nymphs and no adult ticks, and the prevalence of infestation was greatest on helmeted guineafowls, Numida meleagris. Only two larvae were recovered from 610 rodents, including 31 spring hares, Pedetes capensis, whereas 1144 other small mammals yielded 1835 immature ticks, of which 1655 were collected from 623 scrub hares, Lepus saxatilis. The 213 carnivores examined harboured 2459 ticks of which none were adult. A single adult tick and 6684 larvae and 62 nymphs were recovered from 656 large herbivores, and a total of 4081 immature ticks and three adults were collected from 1543 domestic animals and 194 humans. Adult male and female A. marmoreum were most numerous on reptiles during January and February, and larvae during March. The largest numbers of larvae were present on domestic cattle and helmeted guineafowls in the Eastern Cape Province during March or April respectively, whereas larvae were most numerous on helmeted guineafowls, scrub hares and the vegetation in north-eastern Mpumalanga Province during May. In both provinces nymphs were most numerous between October and December. Amblyomma marmoreum appears to be most prevalent in the western regions of the Western and Eastern Cape and Free State provinces, and the north-eastern regions of the Northern Cape, KwaZulu-Natal, Mpumulanga and Limpopo provinces.  相似文献   

12.
Information is presented on the genetic diversity and relationship among six Indian sheep breeds/populations belonging to the Southern peninsular and Eastern agroecological zones, based on microsatellite markers. Parameters of genetic variation, viz., allele diversity, observed heterozygosity, gene diversity and population inbreeding estimates, were calculated for the six breeds. The allele diversity ranged from 6.40 to 7.92, whereas the gene diversity varied from 0.617 to 0.727. The highest allele and gene diversity was observed for Nellore sheep, while the lowest was exhibited by Garole breed. Within population inbreeding estimate (F IS) revealed a significant deficit of heterozygotes in Deccani, Madgyal, Nellore and Garole, whereas Ganjam and Chhotanagpuri sheep showed an excess of heterozygotes. The contribution of each breed to the total diversity of the breeds was quantified by the Weitzman approach. The marginal loss of diversity incurred with removal of Nellore and Garole breeds was higher (>27%), whereas removal of Deccani breed resulted in lowest loss of diversity (3.84%) from the set. Estimation of the genetic differentiation (F ST) and genetic distance (D A) between the pairs of breeds revealed a close relationship between Deccani and Madgyal sheep (F ST = 0.017; D A = 0.080) and greatest demarcation between Madgyal and Garole breeds (F ST = 0.110; D A = 0.622). The information generated would help in shaping genetic management and conservation programs for the sheep breeds under consideration.  相似文献   

13.
In this study, we compare the level and distribution of genetic variation between South African conserved and village chicken populations using microsatellite markers. In addition, diversity in South African chickens was compared to that of a reference data set consisting of other African and purebred commercial lines. Three chicken populations Venda, Ovambo and Eastern Cape and four conserved flocks of the Venda, Ovambo, Naked Neck and Potchefstroom Koekoek from the Poultry Breeding Resource Unit of the Agricultural Research Council were genotyped at 29 autosomal microsatellite loci. All markers were polymorphic. Village chicken populations were more diverse than conservation flocks. structure software was used to cluster individuals to a predefined number of 2 ≤ K ≤ 6 clusters. The most probable clustering was found at K = 5 (95% identical runs). At this level of differentiation, the four conservation flocks separated as four independent clusters, while the three village chicken populations together formed another cluster. Thus, cluster analysis indicated a clear subdivision of each of the conservation flocks that were different from the three village chicken populations. The contribution of each South African chicken populations to the total diversity of the chickens studied was determined by calculating the optimal core set contributions based on Marker estimated kinship. Safe set analysis was carried out using bootstrapped kinship values calculated to relate the added genetic diversity of seven South African chicken populations to a set of reference populations consisting of other African and purebred commercial broiler and layer chickens. In both core set and the safe set analyses, village chicken populations scored slightly higher to the reference set compared to conservation flocks. Overall, the present study demonstrated that the conservation flocks of South African chickens displayed considerable genetic variability that is different from that of the assumed founder populations (village chickens).  相似文献   

14.
South American camelids (SACs) have a major role in the maintenance and potential future of rural Andean human populations. More than 60% of the 3.7 million llamas living worldwide are found in Bolivia. Due to the lack of studies focusing on genetic diversity in Bolivian llamas, this analysis investigates both the genetic diversity and structure of 12 regional groups of llamas that span the greater part of the range of distribution for this species in Bolivia. The analysis of 42 microsatellite markers in the considered regional groups showed that, in general, there were high levels of polymorphism (a total of 506 detected alleles; average PIC across per marker: 0.66), which are comparable with those reported for other populations of domestic SACs. The estimated diversity parameters indicated that there was high intrapopulational genetic variation (average number of alleles and average expected heterozygosity per marker: 12.04 and 0.68, respectively) and weak genetic differentiation among populations (FST range: 0.003–0.052). In agreement with these estimates, Bolivian llamas showed a weak genetic structure and an intense gene flow between all the studied regional groups, which is due to the exchange of reproductive males between the different flocks. Interestingly, the groups for which the largest pairwise FST estimates were observed, Sud Lípez and Nor Lípez, showed a certain level of genetic differentiation that is probably due to the pattern of geographic isolation and limited communication infrastructures of these southern localities. Overall, the population parameters reported here may serve as a reference when establishing conservation policies that address Bolivian llama populations.  相似文献   

15.
In this study we examined the genetic diversity of yak populations in the northernmost part of their current global distribution. Five Mongolian and one Russian yak populations as well as one Chinese yak population from the Qinghai–Tibetan Plateau, the putative centre of yak domestication, were analysed with 15 microsatellite loci to determine the level of genetic variation within populations as well as the genetic differentiation and relationship between populations. A total of 116 microsatellite alleles were identified. The mean number of alleles per locus (MNA) across populations was 7.73 ± 1.98 and the mean expected heterozygosity (HE) was 0.696 ± 0.026. The relative magnitude of gene differentiation (FST) among populations was 4.1%, and all genetic differentiations (FST) between populations were significant (p < 0.001). A significant inbreeding effect (FIS) was detected in the Hovsgol yak (p < 0.01). There was no indication of a recent bottleneck in any of the populations studied. The results showed that yak populations in Mongolia and Russia have maintained high genetic diversity within populations and a low, although significant, genetic differentiation between populations. Both phylogenetic and principal component analyses support a close genetic relationship between the Gobi Altai, south Gobi and north Hangai populations, and between the Hovsgol and Buryatia populations respectively. Our results indicate that these yak populations should be considered as distinct genetic entities in respect of conservation and breeding programmes.  相似文献   

16.
Influenza A viruses (IAVs) are negative‐sense, single‐stranded and segmented RNA viruses of the Orthomyxoviridae family that may cause acute respiratory disease in a wide range of birds and mammals. Susceptibility of several species within the family Mustelidae to IAVs has been reported as a result of natural or experimental infections. The objectives of this study were to assess whether free‐ranging American mink populations from Northern Spain were infected with IAV and try to define the role of this species in the epidemiology of IAV. Sera from 689 American mink from Northern Spain captured between 2011 and 2014 were tested for the presence of antibodies against IAVs using a commercial competition cELISA. Positive sera were further analysed with haemagglutination inhibition (HI) assay. Fifteen of the 689 (2.2%, 1.3–3.6 CI95%) of the American minks analysed were ELISA positive. No significant differences were observed between years of capture, provinces, river basins, sexes or ages of the animals. All seropositive sera resulted negative to the panel strains used in the HI assay, showing that the most relevant strains circulating in swine, the most relevant avian subtypes (H5 and H7) and the H10N4 subtype isolated in minks have not been circulating in this free‐ranging exotic carnivore from Spain. In the light of these results, the free‐range American mink from Northern Spain do not seem to have an important role in the epidemiology of IAVs.  相似文献   

17.
An analysis of morphological and allozyme variation in the Namaqua gecko, Pachydactylus namaquensis from southern Africa is presented. Three separately evolving lineages, well defined by morphology and allozyme variation, are identified. The isolated southern population, occurring on the southern escarpment and Cape Fold Mountains surrounding the western Little Karoo, is named P. kladamderma sp. nov., and is characterized by a slit-like ear opening, low number of granules bordering the mental (3-6) and mental and adjacent infralabials (513), the frequent (79%) occurence of the supralabial entering the nostril, and its drab brown base colouration. A northern population, occurring in southern Namibia and the Richtersveld is named P. haackei sp. nov., and is characterized by its more rounded or squared ear opening; high number of granules bordering the mental and adjacent infralabials (11-19), the general exclusion of the supralabial from the nostril (only 3.7% entry), and brighter, lighter colouration. It is further differentiated from P. kladaroderma on the basis of fixed differences at 11 allozyme loci. Both new species differ from P. namaquensis, which is mainly restricted to Little Namaqua- land, but is sympatric with P. haackei in the Lower Orange River region, by their more heterogenous dorsal scalation, smaller cloacal spurs, lack of spine-like tubercles on the lateral surfaces of the tail, and more fragile skin. The type locality of P. namaquensis is restricted to ‘the vicinity of Springbok, Little Namaqualand, Northern Cape Province, South Africa’.  相似文献   

18.
The influence of bush density on the grass component of the herbaceous layer was investigated for three savanna veld types (Molopo Thornveld, Mixed Vaalbos Thornveld, and the Eastern Grass and Bushveld) in the Northern Cape and North-West Province of South Africa. Relationships between bush density and the density, species composition and phytomass production of the grass component were determined over a four-year period. Bush encroachment had an adverse influence on the density and production of the grass component, but not on the species composition. Fluctuations in seasonal rainfall appeared to be the most important factor governing changes in the species composition of the grass component. Bush enchroachment (2 500 tree equivalents ha?l) decreased the potential grazing capacity by as much as 331%, 149% and 58% in the Molopo Thornveld, the Mixed Vaalbos Thornveld and the Eastern Grass Bushveld, respectively, In comparison to sites with tree densities of less than 400 tree equivalents ha?1. In the encroached condition grazing capacities of 15, 13 and 10 ha LSU?1 are recommended for the Molopo Thornveld, the Mixed Vaalbos Thornveld and the Eastern Grass and Bushveld, respectively. The implementation of bush control measures in all problem areas is proposed in order to restore the productivity of these areas in the long term.  相似文献   

19.
A herd of 15 Chinese elephants attracted international attention during their 2021 northward trek, motivating the government to propose establishment of an Asian elephant national park. However, planning is hampered by a lack of genetic information on the remaining populations in China. We collected DNA from 497 dung samples from all 5 populations encompassing the entire range of elephants in China and used mitochondrial and microsatellite markers to investigate their genetic and demographic structure. We identified 237 unique genotypes (153 females, 84 males), representing 81% of the known population. However, the effective population size was small (28, range 25–32). Historic demographic contraction appeared to account for low haplotype diversity (Hd = 0.235), but moderate nucleotide and nuclear diversity (π = 0.6%, He = 0.55) was attributable to post-bottleneck recovery involving recent population expansion plus historical gene exchange with elephants in Myanmar, Lao PDR, and Vietnam. The 5 populations fell into 3 clusters, with Nangunhe elephants differing consistently from the other 4 populations (FST = 0.23); elephants from Mengyang, Simao, and Jiangcheng belonged to a single population (henceforth, MSJ), and differed from the Shangyong population (FST = 0.11). Interpopulation genetic variation reflected isolation by distance and female-biased dispersal. Chinese elephants should be managed as 2 distinct units: Nangunhe and another combining Shangyong and MSJ; their long-term viability will require restoring gene flow between Shangyong and MSJ, and between elephants in China and neighboring countries. Our results have the potential to inform conservation planning for an iconic megafaunal species.  相似文献   

20.
Investigation of genetic structure on the basis of pedigree information requires indicators adapted to the specific context of the populations studied. On the basis of pedigree‐based estimates of diversity, we analysed genetic diversity, mating practices and gene flow among eight cat populations raised in France, five of them being single breeds and three consisting of breed groups with varieties that may interbreed. When computed on the basis of coancestry rate, effective population sizes ranged from 127 to 1406, while the contribution of founders from other breeds ranged from 0.7 to 16.4%. In the five breeds, FIS ranged between 0.96 and 1.83%, with this result being related to mating practices such as close inbreeding (on average 5% of individuals being inbred within two generations). Within the three groups of varieties studied, FIT ranged from 1.59 to 3%, while values were estimated between 0.04 and 0.91%, which was linked to various amounts of gene exchanges between subpopulations at the parental level. The results indicate that cat breeds constitute populations submitted to low selection intensity, contrasting with relatively high individual inbreeding level caused by close inbreeding practices.  相似文献   

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