摘要:

AbstractWe developed RAPD DNA markers useful in distinguishing the fire antsSolenopsis invictaandS. richteri.An initial survey of 200 primers revealed seven informative markers; family studies allowed us to determine expression patterns and to confirm Mendelian inheritance of these markers. The seven RAPD markers, one of which is inherited as a codominant marker, were employed along with three allozyme markers to describe the structure of a hybrid zone that has formed between the two species in the USA, where they have been introduced. The data suggest minor introgression of alleles from one parental species (S. richteri) into the other (S. invicta), which most likely reflects the documented recent movement of this hybrid zone. This pattern is interpreted as interspecific introgression rather than shared intraspecific polymorphism on the basis of comparisons with samples from native, non‐hybridizing populations in South America that lack such polymorphism. The data further reveal that the structure of the hybrid zone in the USA varies geographically. One parental species (S. invicta) and the hybrids exhibit a mosaic distribution in the east; a gradual transition between the parental species occurs in the centre, with a large intervening area of hybrid genotypes only; and there is apparent contact between parental populations with a small or no intervening zone of hybridization in the west. These differing patterns in the structure of the hybrid zone presumably reflect the unique histories of colonization in different parts of the range of introduced fire ant

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1994.tb00084.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe tassel‐eared squirrel,Sciurus aberti, includes six subspecies which occupy restrictive and apparently identical habitats in Ponderosa pine forests in the south‐western United States and Mexico; the strict habitat requirement of this species is based on dietary requirements which are only fulfilled in these forests. To examine evolutionary relationships among certain subspecies ofS. aberti, we obtained estimates of nucleotide diversity within subspecies as well as nucleotide divergence between subspecies using mitochondrial DNA (mtDNA) analysis. Restriction site polymorphisms were identified in samples of the four US subspecies:S. a. aberti(Abert),S. a. kaibabensis(Kaibab),S. a. ferreus(Ferreus), andS. a. chuscensis(Chuska) Fourteen mtDNA clones were resolved that were, with one exception, uniquely subspecific. Dendrograms constructed by neighbour‐joining and maximum parsimony methods revealed two major assemblages: (1) an Abert/Kaibab group; and (2) a Ferreus/Chuska group. The Abert vs. Ferreus clones exhibited the greatest net nucleotide divergence, with a lineage separation estimate approximating 572 000 years ago assuming a nucleotide substitution rate of 7.15 × 10‐9/year/site. Five out of ten Chuska squirrels shared a clone with one Abert sample; the relative sizes of these two populations and their respective ranges as well as their close proximity support the proposal for relatively recent intermixing of Abert and Chuska populations resulting in what appears to be Abert → Chuska migration. Nucleotide diversity within subspecies ranked as Kaibab

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1994.tb00085.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractJapanese sika deer (Cervus nippon nippon) were introduced to Scotland around 80 years (20 generations) ago. The sika phenotype is expanding its range and hybridizing extensively with native red deer (Cervus elaphus) leading to the establishment of a hybrid zone. This zone is currently moving and cannot be considered to be at equilibrium. Cervid genotypes and mitochondrial haplotypes were mapped across the sika phenotype range, using diagnostic protein isozymes, microsatellite nuclear DNA markers and RFLPs in mtDNA. These were analysed to estimate heterozygote deficits and nuclear linkage disequilibria and cytonuclear disequilibria in relation to gene frequencies and time since contact. Introgression was found in both taxa and strong linkage disequilibria and heterozygote deficits characterize the populations longest exposed to hybridization. Populations further from the introduction site, where hybridization is facilitated by the dispersal of sika‐like stags, show low values for linkage disequilibria and heterozygote deficit. The observed patterns in genotype are explained in terms of assortative mating and a selective advantage of the sika genotype. The genetic integrity of the Scottish mainland red deer is shown to be at risk from the invasion of sik

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1994.tb00086.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractIn colonies of bluegillLepomis macrochirus, some males provide parental care for broods in nests, whereas other males steal fertilizations and do not provide parental care. Using experimental pond populations of bluegill of known genotype (determined through protein electrophoresis), we demonstrate that cuckolder males successfully fertilize eggs in parental male nests. Using electrophoretic techniques to assess the fertilization success of nesting parental male bluegill in Lake Opinicon, Ontario, we demonstrate that paternity of these males ranges from 41% to 100% among four colonies studied. This difference among colonies is related to the density of cuckolder males.

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1994.tb00087.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe large‐scale inoculation of selected beneficial ectomycorrhizal fungi in forest nurseries has generated renewed interest in the ecology of these symbiotic fungi. However, information on the dissemination and persistence of introduced symbionts is scarce due to the limitation of the current identification methods. To identify ectomycorrhizal fungi on single root tips, we investigated the polymorphism of the PCR‐amplified ribosomal DNA intergenic spacer (IGS) from a wide range of ectomycorrhizal fungi. To investigate the reliability of this molecular approach in large‐scale surveys, the dissemination and persistence on Douglas fir seedlings of the introducedLaccaria bicolorS238N were assessed in a forest nursery in the Massif Central (France). Several hundred ectomycorrhizas and fruiting bodies were sampled from plots where control and L.bicolorinoculated‐Douglas fir seedlings were grown for 1.5 years. PCR typing of mycorrhizas indicated that trees inoculated withL. bicolorS238N remained exclusively colonized by that isolate (or sexually derived isolates) for the entire test period. In contrast, control seedlings were infected by indigenous isolates ofLaccaria laccataandThelephora terrestris.The molecular evidence for the persistence of the introduced mycobiont despite the competition from indigenous isolates of the same species provides further illustration of the potential of exotic species for large‐scale microbial ap

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1994.tb00088.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractRandom amplified polymorphic DNA (RAPD) phenotypes generated by 13 primers were scored for 101 individuals in 14 populations of the endangered red‐cockaded woodpeckerPicoides borealis.Although no population‐specific markers were found, the frequencies of several markers differed significantly among populations. Application of the recently developedamovamethod (analysis of molecular variance; Excoffier, Smouse&Quattro 1992) showed that more than 90% of phenotypic variance occurred among individuals within populations; of the remaining variance, half was attributed among groups of geographically adjacent populations and half among populations within those groups. The statistical significance of these patterns was supported by Monte Carlo sampling simulations and permutation tests. Estimation of allele frequencies from phenotypes provided somewhat weaker evidence for population structure, although among‐population variance in allele frequencies was detectable (Fst= 0.19; x2169= 509.3,P<0.0001). Upgmacluster analyses based on Rogers' (1972) genetic distance revealed grouping of some geographically proximate populations. A Mantel test indicated a positive (r = 0.16), although not significant, correlation between geographic and genetic distances. We compared a subset of our RAPD data with data from a previous study that used allozymes (Stangel, Lennartz&Smith 1992). RAPD (n= 75) and allozyme (n= 245) results based on samples from the same ten populations showed similar patterns. Our study indicates that RAPDs can be helpful in differentiating populations at the phenotypic level even when small sample sizes, estimation bias, and inability to test for Hardy‐Weinberg equilibrium complicate the genotypic interpretation. Lack of large differences among populations of red‐cockaded woodpeckers may allow flexibility in overpopulation translocations, provided factors such as habitat preference, latitudinal direction of translocation, and status of donor populations are c

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1994.tb00089.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe identification of genes of large effect on ecologically important traits is an important aim of molecular ecology. Theperiodgene ofDrosophilais a candidate for a gene with a large influence on premating isolation betweenDrosophilaspecies, as it determines species specific aspects of courtship behaviour. Strains ofD. melanogasterare available which have been genetically transformed with theperiodgene of eitherD. melanogasterorD. simulans.Here we show thatD. melanogasterfemales do not discriminate between two such strains. This suggests thatperiodmay only make a small contribution to total premating isolation between these species. We discuss the use of genetically transformed strains in assessing the influence of single genes on complex traits.

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1994.tb00090.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1994.tb00091.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY