摘要:

AbstractMicrosatellite loci are regions of DNA containing tandem repeats of a short sequence motif; they occur abundantly in all eukaryotic genomes and have been shown to be a rich source of highly polymorphic genetic markers in humans and other mammals. These loci are particularly suitable for population studies because they can be relatively easily scored using a combination of polymerase chain reaction (PCR) amplification of each locus followed by electrophoresis to separate alleles. This paper details a method for finding these loci in any species. This method demonstrates that trinucleotide microsatellite loci are abundant and highly polymorphic in the social waspPolistes annularis, whereas allozyme electrophoresis reveals very little polymorphism. The first six loci examined were all polymorphic with a mean observed heterozygosity of 0.62; in comparison average heterozygosity of 33 allozymes was 0.035. We suggest that this method can be used to detect variation where other methods have failed, making it an ideal tool for population and conservation geneticists who must deal with populations lacking other types of genetic variability.

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1993.tb00102.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractSpatial genetic structure in populations of mosquitofish (Gambusia) sampled throughout the south‐eastern United States was characterized using mitochondrial (mt) DNA and allozyme markers. Both sets of data revealed a pronounced genetic discontinuity (along a broad path extending from south‐eastern Mississippi to north‐eastern Georgia) that corresponds to a recently recognized distinction between the nominal formsG. affinisto the west andG. holbrookito the east. However, several populations from the general contact region exhibited unusual allelic associations in high frequency, suggestive of evolutionary processes within a zone of introgressive hybridization. These involve: (i) cytonuclear profiles representing combinations of nuclear and mitochondrial genotypes that tended to be more nearly species‐specific and concordant elsewhere; and (ii) significant nuclear gametic disequilibria, perhaps attributable to positive assortative mating and/or differential fitnesses of homospecific vs. recombinant genotypes. However, outside this suspected hybrid region, ‘heterospecific’ genetic markers also appeared in low frequency, thus complicating interpretations. These discordant alleles on a broader geographic scale may reflect: (a) the retention of polymorphisms from an ancestral gene pool; (b) occasional evolutionary convergence (especially with respect to electrophoretic mobility of allozyme alleles); (c) the ‘footprints’ of a moving hybrid zone; or (d) differential introgressive penetrance across the curren

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1993.tb00103.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractRandomly amplified polymorphic DNA (RAPD) markers were used to analyse genetic diversity within and betweenHordeum spontaneumpopulations sampled from Israel. Nei's index of genetic differentiation was used to partition diversity into within and between population components. Fifty‐seven per cent of the variation detected was partitioned within 10H. spontaneumpopulations. Using principal component and multiple regression analysis, part of the variation detected between populations was seen to be associated with certain ecogeographical factors. Fifty‐eight per cent of the distribution of the phenotypic frequencies of three RAPD phenotypes detected using a single primer in 20H. spontaneumpopulations could be accounted for by four ecogeographical variables, suggesting adaptive variation at certain RAPD l

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1993.tb00104.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA phylogeny of mainland eastern Australian scrubwrens (Sericornis citreogularis, S. frontalis, S. keri, S. tnagnirostrisandS. beccarii) was constructed using presence or absence of phylogenetically informative restriction sites in 15 mitochondrial DNA (mtDNA) haplotypes. MtDNA sequence divergences between species were generally large (mostly between 10 and 18%) emphasizing the antiquity of this radiation. Phylogenetic analysis of the mtDNA resulted in a strongly supported phylogeny concordant with relationships suggested by a previous study of allozyme variation, but conflicting with concepts based on morphological similarity. The mtDNAs grouped the species into two lineages, one containingbeccariiandtnagnirostrisand the other comprisingcitreogularis, frontalisandkeri.The mtDNAs ofbeccariiandtnagnirostriswere paraphyletic with a northern variant oftnagnirostrisbeing more similar tobeccariithan othermagnirostris.The mtDNA fromkeriwas most closely related to that offrontalisand thencitreogularis.The strongly corroborated molecular phylogeny confirms and extends the previous (Christidiset al.1988;Auk105>616) reinterpretation of morphological and ecological shifts in the group. This suggests considerable plasticity and parallelism in the plumage characters previously used to associate species. The low divergence and close relationship between the montane rain‐forest specialistkeriand the widely distributed generalistfrontalisdemonstrate the capacity for evolutionarily rapid and dramatic shifts in habitat use. This contrasts with the assumption of fixed habitat preference that underlies refuge‐based models of diversification of rain‐forest

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1993.tb00105.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractProkaryotes can exchange chromosomal and plasmid genes via extracellular DNA in a process termed genetic transformation. This process has been observed in the test tube for several bacterial species living in the environment but it is not clear whether transformation occurs in natural bacterial habitats. A major constituent of terrestrial environments are solid particles such as quartz, silt and clay, which have considerable surface areas and which make up the solid‐liquid interfaces of the habitat. In previous experiments the adsorption of DNA to chemically purified quartz and clay minerals was shown and the partial protection of adsorbed DNA against DNAase I. In a microcosm consisting of natural groundwater aquifer material (GWA) sampled directly from the environment and groundwater (GW) both linear duplex and supercoiled plasmid DNA molecules bound rapidly and quantitatively to the minerals. The divalent cations required to form the association were those present in the GWA/GW microcosm. The association was stable to extended elution over one week at 23°C. Upon adsorption, the DNA became highly resistant against enzymatic degradation. About 1000 times higher DNAase I concentrations were needed to degrade bound DNA to the same extent as DNA dissolved in GW. Furthermore, chromosomal and plasmid DNA bound on GWA transformed competent cells ofBacillus subtilis.However, in contrast to DNA in solution, on GWA the chromosomal DNA was more active in transformation than the plasmid DNA. The studies also revealed that in the transformation ofB. subtilisMg2+can be replaced by Na+, K+or NH4The observations suggest that in soil and sediment environments, mineral material with inorganic precipitates and organic matter can harbour extracellular DNA leaving it available for genetic transformati

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1993.tb00106.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

The details of mitochondrial DNA (mtDNA) phylogenetic structure of the northern grasshopper mouseOnychomys leucogasterwere examined using populations from a postulated area of endemism that includes three arid regions (Colorado Plateaus, Interior Plains, and Wyoming Basins) in western North America. Fifteen tetra‐ and heptanucleotide restriction enzymes were used to assay restriction‐site variation in a 2150‐bp PCR‐amplified fragment of mtDNA representing the ND2 and part of the COI gene regions. A total of 18 mtDNA haplotypes were detected. Although overall genetic divergence among these haplotypes was low (average = 1.1%), phylogeographic structuring was apparent. Notably, a clear phylogenetic split separated one group of haplotypes restricted to the Wyoming Basins from all others. This phylogenetic split was further corroborated by examination of nucleotide sequence variation from a 270‐bp stretch of the mtDNA cytochromebgene. Overall geographic and phylogenetic patterns suggest a complex history of geographic structuring and subsequent mixing of populations of grasshopper mice throughout the late Pleistocene. These patterns of variation are evaluated relative to alternative hypotheses about biotic responses to Quaternary climatic oscillations in western North American ari

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1993.tb00107.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1993.tb00108.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY