古丈县南方红豆杉天然群体的遗传多样性研究

通过对分布于湖南省古丈县的南方红豆杉(Taxus chinensis)天然群体中30个个体的功能叶片的过氧化物酶(POD)和酯酶(EST)同工酶谱带的分析,研究了该天然群体的遗传多样性水平.结果表明:30个个体中都存在有迁移率相同的谱带(4条),占酶谱带总数的26.7%;两个酶系统共检出15条酶谱带,等位基因位点数4个,其中多态位点数3个,单态位点数1个,多态位点百分数P=75%,平均每个位点的等住基因数A=3,平均有效等位基因数Ae=2.75,平均期望杂合度He=60.7%,平均实际杂合度Ho=22.2%,表明该群体有较丰富的遗传多样性.     

Development and characterization of microsatellite markers for Emmenopterys henryi (Rubiaceae), a rare tree from China

? Premise of the study: Compound microsatellite primers were developed for Emmenopterys henryi, an endangered deciduous tree endemic to China, to assess its genetic diversity and population structure as well as its evolutionary history. ? Methods and Results: Using the compound microsatellite marker technique, 10 pairs of polymorphic microsatellite primers were isolated and characterized in E. henryi. Levels of polymorphism were tested across a total of 63 individuals from three natural populations. Allele numbers varied from 10 to 20 per locus, with an average of 14.50 alleles per locus. The observed heterozygosity per locus ranged from 0.125 to 0.962, and the expected heterozygosity ranged from 0.377 to 0.903. ? Conclusions: The highly polymorphic markers developed and characterized in this study will facilitate evolutionary and population genetic studies in E. henryi.     

Characterization of microsatellite markers for Thoropa taophora (Anura, Cycloramphidae), a frog endemic to the Brazilian Atlantic Rain Forest

Here we characterize nine microsatellite loci for Thoropa taophora collected from a coastal and an island population in southeastern Brazil. The number of alleles per locus ranged from three to 11 for the coastal population and from two to eight for the island population. Observed heterozygosities ranged from 0.308 to 0.778 for the coastal population and from zero to 0.737 for the island population. One locus did not conform to Hardy-Weinberg expectations on the coast, while two were in disequilibrium on the island. These markers are currently being used to examine genetic differentiation and patterns of dispersal in T. taophora.     

Dependence of expected heterozygosity on locus number with stabilizing selection and drift

I determine expected levels of heterozygosity in two allele multilocus models with mutation, stabilizing selection and drift. In the range 2 to 32 loci, the per locus heterozygosity can depend on the locus number. The per locus heterozygosity for ten loci can be as low as three fourths of the per locus heterozygosity in the limit, as the number of loci gets large. Simulations indicate that this dependence on locus number is not due to the population approaching equilibria at which the mean differs from the optimum, but is due to changes in the substitution rate as a function of the number of loci.     

Isolation and characterization of microsatellite loci in the whale shark (Rhincodon typus)

In preparation for a study on population structure of the whale shark (Rhincodon typus), nine species-specific polymorphic microsatellite DNA markers were developed. An initial screening of 50 individuals from Holbox Island, Mexico found all nine loci to be polymorphic, with two to 17 alleles observed per locus. Observed and expected heterozygosity per locus ranged from 0.200 to 0.826 and from 0.213 to 0.857, respectively. Neither statistically significant deviations from Hardy-Weinberg expectations nor statistically significant linkage disequilibrium between loci were observed. These microsatellite loci appear suitable for examining population structure, kinship assessment and other applications.     

Eight new polymorphic microsatellite loci for genetic analyses in the endangered common hamster (Cricetus cricetus L.)

We developed primers for eight polymorphic microsatellite loci in the endangered common hamster (Cricetus cricetus L.). Population genetic parameters were analysed on the basis of 70 adult individuals captured from a single population. Allele numbers per locus ranged from eight to 17. Expected and observed heterozygosities per locus ranged from 0.67 to 0.91 and from 0.41 to 0.8, respectively.     

Development and characterization of eight polymorphic microsatellite loci from Pistacia lentiscus L. (Anacardiaceae)

We have developed a set of eight polymorphic nuclear microsatellite markers for the Mediterranean shrub Pistacia lentiscus by means of an enriched library method. Characterization for the eight loci was carried out on 42 individuals from two populations sampled in southern Spain. The overall number of alleles detected was 59, ranging from three to 13 per locus. Expected heterozygosity per locus and population ranged from 0.139 to 0.895. Two loci albeit only in one population (Seville) departed significantly from Hardy-Weinberg equilibrium expectations and no linkage disequilibrium between pairs of loci was detected. These markers will be used in studies of gene flow across a fragmented landscape.     

Polymorphic chloroplast microsatellite loci in Nelumbo (Nelumbonaceae)

? Premise of the study: To study population genetics, phylogeography, and hybridization of Nelumbo (Nelumbonaceae), chloroplast microsatellite markers were developed. ? Methods and Results: Seventeen microsatellite loci were identified from the chloroplast genomes of N. nucifera and N. lutea. Polymorphisms were assessed in three populations of N. nucifera and one population of N. lutea. Nine loci were found to be polymorphic in N. nucifera, and all 17 loci were found to be polymorphic in N. lutea. In N. nucifera, the number of alleles per locus ranged from two to six, and the unbiased haploid diversity per locus ranged from 0.198 to 0.790. In N. lutea, the number of alleles ranged from two to four, and the unbiased haploid diversity per locus ranged from 0.245 to 0.694. ? Conclusions: The identified chloroplast simple sequence repeat markers will be useful for the study of genetic diversity, phylogeography, and identification of Nelumbo cultivars.     

Development and characterization of microsatellite markers for the endangered northern riffleshell mussel Epioblasma torulosa rangiana (Bivalvia: Unionidae)

Primers for six polymorphic microsatellite loci were developed for the endangered northern riffleshell Epioblasma torulosa rangiana from the Sydenham River, Ontario, Canada. These loci along with an additional nine microsatellite loci, developed from other unionoid species, available in the literature, were tested and characterized on individuals from two populations in the Allegheny River; one population in French Creek, PA, USA, and one population from the Sydenham River. Allelic diversity ranged from two to 28 alleles per locus and averaged 13.7 per locus. These primers are being used in a rangewide study on the conservation genetics of remaining extant populations of the northern riffleshell.     

Isolation and characterization of the first microsatellite loci from the order Psocoptera in the economically important pest insect Liposcelis decolor (Pearman) and cross‐species amplification

A total of 11 microsatellite loci from the invasive insect pest Liposcelis decolor were isolated and characterized of which six loci were polymorphic. A population survey involving a total of 30–192 individuals per locus from five populations revealed a range of four to seven alleles per locus and moderate observed heterozygosities (0.183–0.565), highlighting the utility of these loci in further population genetic studies. Cross‐species amplifications were successful for two to 11 loci in five other Liposcelis species also of international economic importance.     

Development of microsatellite markers for the dove tree, Davidia involucrata (Nyssaceae), a rare endemic from China

? Premise of the study: Microsatellite primers were developed for the endangered Davidia involucrata to assess the population genetics and infer its evolutionary history. ? Methods and Results: Using both the modified magnetic bead hybridization method and the dual-suppression PCR method, we isolated and characterized 12 polymorphic microsatellite loci using 134 individuals from five populations in southwestern China. The number of alleles per locus ranged from six to 21 (mean = 10.8). The expected heterozygosity per locus ranged from 0.404 to 0.918 and observed heterozygosity ranged from 0.015 to 0.821. ? Conclusions: All of the 12 microsatellite markers developed for D. involucrata are polymorphic, and lay a solid foundation for further studies of the population genetics of this famous tree.     

Isolation and characterization of 12 dinucletiotide microsatellite loci in Paratrechalea galianoae (Araneae, Trechaleidae), a nuptial gift-spider

Twelve microsatellite loci from the Neotropical spider Paratrechalea galianoae were isolated from a microsatellite-enriched genomic library, and were tested in a sample of 27 individuals from a population that occurs in Brazil. All loci were polymorphic and three to 14 (mean 7.58) alleles per locus were identified. The observed and expected heterozygosities per locus ranged from 0.417 to 0.885 and from 0.595 to 0.878, respectively. Two loci deviated significantly from Hardy-Weinberg equilibrium and one pair showed evidence of linkage disequilibrium. These loci are being used to study the population structure and genetic diversity in P. galianoae.     

Isolation and characterization of microsatellite loci in the plant-ant Pseudomyrmex ferrugineus (Formicidae: Pseudomyrmecinae) and cross-testing for two congeneric species

To investigate the population structure of the obligate plant-ant Pseudomyrmex ferrugineus, we developed primers for 12 microsatellite loci. We tested the variability of the markers on 11 individuals from each of two populations (totalling 22 individuals) and found two to 12 alleles per locus and population. No deviations from Hardy-Weinberg equilibrium were detected. Observed and expected heterozygosities at each locus ranged from 0.00 to 0.50 and from 0.08 to 0.46, respectively. We also investigated suitability of these primers in two congeneric species.     

Microsatellite markers isolated from the flightless cormorant (Phalacrocorax harrisi)

Eight polymorphic microsatellite DNA loci were isolated from the flightless cormorant (Phalacrocorax harrisi) for future population genetic studies. Genetic variability was assessed using at least 38 individuals from two populations. Allele numbers ranged from three to nine per locus. Mean observed heterozygosity varied from 0.27 to 0.78. No locus deviated from Hardy-Weinberg (HW) or linkage equilibria in either population. The high levels of detected polymorphism indicate the utility of these markers for population genetic studies of this Galápagos species.     

Isolation and characterization of microsatellite loci from Lochmaea suturalis, the heather beetle (Coleoptera: Chrysomelidae), a pest in Europe and a biocontrol agent in New Zealand

The heather beetle Lochmaea suturalis which is native to northwest Europe has been released as a biocontrol agent for heather in New Zealand. We have isolated and optimized eight microsatellite loci from New Zealand beetles. These loci provide markers with high polymorphism ranging from four to 20 alleles per locus. Observed heterozygosity averaged 0.631 per locus. These results suggest the markers are useful for population studies that will contribute to assessment of L. suturalis as a biocontrol agent.     

Development of 10 microsatellite loci for Yellow-billed Magpies (Pica nuttalli) and corvid ecology and West Nile virus studies

We developed 10 polymorphic microsatellite loci for Yellow-billed Magpies (Pica nuttalli). The primers were tested across a population of 57 Central California Yellow-billed Magpies and displayed an average of 3.9 alleles per locus. Forty-one American Crows (Corvus brachyrhynchos) from California were polymorphic for seven of the loci with an average of 2.9 alleles per locus. One additional microsatellite-containing locus displayed diagnostic allele sizes and may be useful to distinguish between the two species. These corvid specific microsatellites will aid ecological studies of the population-level effects of diseases, such as West Nile virus.     

An estimator for pairwise relatedness using molecular markers

I propose a new estimator for jointly estimating two-gene and four-gene coefficients of relatedness between individuals from an outbreeding population with data on codominant genetic markers and compare it, by Monte Carlo simulations, to previous ones in precision and accuracy for different distributions of population allele frequencies, numbers of alleles per locus, actual relationships, sample sizes, and proportions of relatives included in samples. In contrast to several previous estimators, the new estimator is well behaved and applies to any number of alleles per locus and any allele frequency distribution. The estimates for two- and four-gene coefficients of relatedness from the new estimator are unbiased irrespective of the sample size and have sampling variances decreasing consistently with an increasing number of alleles per locus to the minimum asymptotic values determined by the variation in identity-by-descent among loci per se, regardless of the actual relationship. The new estimator is also robust for small sample sizes and for unknown relatives being included in samples for estimating allele frequencies. Compared to previous estimators, the new one is generally advantageous, especially for highly polymorphic loci and/or small sample sizes.     

Isolation and characterization of microsatellite DNA loci from the peanut worm, Sipunculus nudus

Sipunculus nudus, the peanut worm, is the best known species in its genus. This unsegmented subtidal marine worm is consumed in some parts of Asia and is also used as fish bait. We found 20 microsatellite DNA markers for S. nudus. The number of alleles per polymorphic locus ranged from two to seven in a sample of 39 individuals. Observed and expected heterozygosities per polymorphic locus varied from 0.103 to 1.000 and from 0.307 to 0.771, respectively. Five loci showed significant departure from Hardy-Weinberg equilibrium after sequential Bonferroni's correction. No significant linkage disequilibrium between pairs of loci was found. These microsatellite markers will provide useful tools for investigating genetic population structure, population history and conservation management of S. nudus.     

Polymorphic microsatellite markers for the Florida scrub lizard (Sceloporus woodi)

The Florida scrub lizard (Sceloporus woodi) is one of a suite of species restricted to Florida scrub, a threatened ecosystem. We characterized eight microsatellite loci from scrub lizards based on screening of 75–91 individuals per locus. Polymorphism was high (8–20 alleles per locus). Observed and expected heterozygosities ranged from 0.32–0.83 and 0.77–0.91, respectively. These markers will be useful for population‐level analyses and can contribute to a genetic foundation for conservation strategies for this endemic species.     

Nine polymorphic microsatellite loci for the northern leopard frog (Rana pipiens)

We describe the cloning and characterization of nine microsatellite loci from the northern leopard frog. Seven loci consist of tetranucleotide repeats, one locus consists of a dinucleotide repeat and one locus consists of a GT repeat juxtaposed with a GATA repeat. In a sample of 36 frogs from a natural population, polymorphism at these loci ranged from two to 13 alleles per locus with expected heterozygosities ranging from 0.5 to 0.91. These loci will be useful to researchers since this species is used for a broad range of studies.