摘要:

AbstractNumbers of light‐footed clapper railsRallus longirostris levipes, an endangered bird inhabiting southern California salt marshes, have substantially declined from historic levels. RAPD (randomly amplified polymorphic DNA) analysis was employed to assess the genetic variability within and among four of the largest remaining light‐footed clapper rail populations. A single, larger population of the endangered Yuma clapper railRallus longirostris yumanensiswas used for comparison.A total of 325 RAPD primers were tested on DNA from a subset of five clapper rails composed of a single representative for each of the four light‐footed clapper rail populations and a representative for the single Yuma clapper rail population. Of the 1338 amplified bands (loci) surveyed in these five representative birds, approximately 1% were polymorphic, indicating the level of differentiation across all loci is quite low. Nine primers yielding these 16 polymorphic bands were used to analyse 48 individuals from five populations. Five of these bands were polymorphic in both subspecies, six were polymorphic only within the light‐footed clapper rails, and five were polymorphic only within the Yuma clapper rail samples. Considering the few bands that were polymorphic among the light‐footed clapper rail populations, a surprisingly high level of population differentiation (GST=0.28) was found. This is in accord with the results of AMOVA analyses which show that a fairly high percentage of the limited variability among the rails is due to either differences between subspecies or differences between the light‐footed rail populations. Because inbreeding depression is suspected and overall genetic distances between populations are low, movement of light‐footed clapper rails from larger populations into smaller ones might be considered as a management strategy. Employing RAPDs as one of a series of assays is useful in revealing the population structure of genetically depaup

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1996.tb00339.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractMitochondrial (mt) DNA sequences were analysed to resolve the phylogeography and population genetic structure of Atlantic and Mediterranean populations of green turtles (Chelonia mydas). Analysis of sequence variation over 487 base pairs of the control (D‐loop) region identified 18 haplotypes among 147 individuals from nine nesting populations. Pairwise comparisons of haplotype frequencies distinguished most nesting colonies, indicating significant genetic differentiation among rookeries and a strong propensity for natal homing behaviour by nesting females. Comparison of control region sequence data to earlier restriction fragment length polymorphism (RFLP) data for the same individuals demonstrates approximately a sixfold higher substitution rate in the 5′ end of the control region. The sequence data provide higher resolution both in terms of the number of mtDNA genotype variants and the phylogeographic relationships detected within the Atlantic region, and reveal a gene genealogy that distinguishes two groups of haplotypes corresponding to (i) the western Caribbean and Mediterranean, and (ii) eastern Caribbean, South Atlantic and West Africa. The data suggest that phylogeographic patterns in the Atlantic Ocean may be interpreted in terms of female nest site fidelity and episodic dispersal events. The distribution of mtDNA haplotypes within the region is thus explained by the geological and climatic alternations (glacial and interglacial) over the last million ye

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1996.tb00340.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractGenetic individuals, or genets, ofArmillariaand other root‐infecting basidiomycetes are usually found in discrete patches that often include the root systems of several adjacent trees. Each diploid individual is thought to arise in an unique mating event and then grow vegetatively in an expanding territory over a long period of time. Our objective in this study was to describe the population from which such genetic individuals are drawn. In a sample including 274 collections representing 121 genetic individuals ofA. gallica(synonymA. bulbosa) from two sites in each of four regions of eastern North America, genotype frequencies at seven nuclear loci were not significantly different from Hardy‐Weinberg expectations. Furthermore, allele frequencies at the seven loci were not significantly different between regions. Additional allelic data from four non‐contiguous regions of mitochondrial DNA showed little or no population subdivision over the four regions. Analysis of the distribution of multilocus mtDNA haplotypes revealed some clonal transmission of mtDNAs between genets and nonrandom mating within sites. Despite the sharing of mtDNA types by some individuals, the overall sample contained a high level of genotypic diversity. The apparent linkage equilibrium between some pairs of loci and the high level of phylogenetic inconsistency among all four loci suggest the occurrence heteroplasmy and recombination among mtDNAs ofA. gallicain nature. In laboratory matings of two haploid strains with different mtDNA types, a low frequency of recombination in mtDNA was det

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1996.tb00341.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThe genetic structure ofMycosphaerella fijiensispopulations around the world was examined using DNA restriction fragment length polymorphism (RFLP) markers. Allele frequencies at 19 nuclear RFLP loci were estimated in a sample of 136M. fijiensisisolates from five geographical populations representative of banana‐producing areas (South‐East Asia including the Philippines and Papua New Guinea, Africa, Latin America and Pacific Islands). Within each population, gametic disequilibrium tests between the 19 nuclear RFLP loci were mainly non significant (P>0.05), indicating that random sexual reproduction occurred in these populations. AllM. fijiensispopulations had a high level of genotypic and allelic diversity (H, gene diversity: 0.25–0.59). The highest levels of gene diversity were found in the two South‐East Asian populations (H: 0.57 and 0.59). Most of the alleles (>88%) detected in Africa, Latin America and Pacific Islands populations were also detected in South‐East Asian populations. Furthermore, a high and significant (P<0.05) level of genetic differentiation was observed amongM. fijiensisgeographical populations (overall estimate ofFst: 0.32). These results were consistent with the hypothesis thatM. fijiensisoriginated in South‐East Asia and spread recently to other parts of the world. The level of allelic diversity inM. fijiensispopulations from regions other than South‐East Asia was drastically reduced, indicating founder effects. The data also suggested rare occurrence of migration ofM. fijiensisbetwe

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1996.tb00342.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractComplex eusocial insect societies are generally matrifilial, suggesting kin selection has been of importance in their development. For simpler social systems, factors favouring their existence, in particular kin selection, have rarely been studied. Communal nesting is one of these simple social organizations, and is found in a diversity of insect species. To examine whether kin selection may play a role in the evolution and maintenance of communality, we estimated genetic relatedness of nestmate females of the facultatively communal bee,Andrena jacobi. Microsatellite loci were developed for this species and used to analyse individuals from two populations. Loci were variable, they were in heterozygote deficit and showed positive inbreeding coefficients. This may arise from nonrandom mating; previous observations (Paxton&Tengö 1996) indicate that a large proportion of females mate intranidally with nestmate males in their natal nests before first emerging. Nestmate relatedness was low, no different from zero for all loci in one population and for three of four loci in the other population. The large number of nestmates sharing a common nest (up to 594) may explain the low relatedness estimates, although relatedness was also independent of the number of females sharing a nest. Lack of inclusive fitness payoffs could constrain social evolution in this communal species

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1996.tb00343.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractAmphibians in the south‐western United States are currently experiencing population declines. Causal explanations for these population changes as well as the implementation of sound management practices requires an understanding of the genetic structure of natural amphibian populations. To this end, we estimated genetic differences within and among seven isolated populations of northern leopard frogs,Rana pipiens, from Arizona and southern Utah using random amplified polymorphic DNA (RAPD) analyses. Fourteen arbitrarily designed primers detected 38 polymorphic loci in 85 individual frogs. Three types of population structure were observed in this study, (i) Two populations showed low genetic diversity (D= 0.10 and 0.04) and may have been established by relatively recent events, (ii) Two were not genetically distinct and exhibited a high degree of within‐population diversity (D= 0.35). The possibility of gene flow between these populations is high due to their geographical proximity and their shared genetic structure, (iii) Three populations were genetically distinct from each other and the other populations, and exhibited intermediate within‐population variation (D= 0.19, 0.17, 0.14). Genetic distances among the seven populations ranged from 0.00 to 0.20, suggesting that some of these leopard frog populations are genetically distinct. Although based on relatively small samples, these data suggest that leopard frog populations in the south‐west are likely to represent unique genetic entities worthy of conservation. The management implications of these results are that isolated leopard frog populations should be evaluated on an individual basis to best preser

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1996.tb00344.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractData are presented on allozyme variation between 15 populations of the stenophagous capitulum weevil,Larinus cynarae, and three populations of its congener,L. latus, that had been collected throughout the northern mediterranean range of these species. A phenetic analysis of these data revealed no direct relationship between genetic variation and host‐plant association withinL. cynarae, but there was a strong geographical structuring of allozyme patterns. Most of the genetic variation was due to differences between geographical regions and variation within these was small. Wright'sFSTvalues showed that Italian and Greek populations ofL. cynaraewere most distinct fromL. latus, with southern Iberian, northern Spanish and French populations increasingly less so. This pattern was associated with a cline in the frequencies of certain alleles along this geographical arc from France to Greece. A phenogram of Nei's genetic distances indicated the close genetic relationship between the two species ofLarinusand separated the populations ofL. cynaraeinto three allopatric groups. These groups have different host‐plant spectra — dominated byCynara cardunculusin Italy and Greece,Cynara humilis/Onopordumin southern Iberia andOnopordumspp. in France/Northern Spain — and can be considered to be host biotypes ofL. cynarae. L. latus, which occurs in Greece and further east is also anOnopordumspecialist. An analysis of the phylogeny of this group ofLarinusindicates a primary separation into eastern (L. latus) and western (L. cynarae) taxa, with further branching of theL. cynaraelineage into the putative host‐biotypes. An hypothesis for the evolution of these taxa is given, based on the evolutionary history of host‐plant taxa and geographical

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1996.tb00345.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractPolymorphisms in the chloroplast genome of the argan tree (Sapotaceae), an endemic species of south‐western Morocco, have been detected by restriction site studies of PCR‐amplified fragments. A total of 12 chloroplast DNA (cpDNA) and two mitochondrial DNA (mtDNA) fragments were amplified and digested with a single restriction enzyme (HinfI). Polymorphisms were identified in six of the cpDNA fragments, whereas no mtDNA polymorphisms were detected in a survey of 95 individuals from 19 populations encompassing most of the natural range of the species. The cpDNA polymorphisms allowed the identification of 11 haplotypes. Two lineages, one in the south‐east and the other in the north‐west, divide the range of the argan tree into two distinct areas. The level of genetic differentiation measured at the haplotype level (GSTc= 0.60) (i.e. with unordered haplotypes) was smaller than when phylogenetic relationships were taken into account (NSTc= 0.71‐0.74) (ordered haplotypes), indicating that population history must be considered in the study of the geographical distribution of cpDNA lineages in this species. If contrasted with the level of nuclear genetic differentiation measured in a previous study with isozymes (GSTn= 0.25), the results indicate a relatively high level of gene flow by seeds, or conversely a relatively low level of gene flow by pollen, as compared with other tree species. Goats and camels could have played an important role in disseminating the fruits of

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1996.tb00346.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Mitochondrial DNA variation was used to examine population structure in a widespread, marine‐dispersed species,Birgus latro. Crabs were collected from eight locations throughout the species' Indo‐Pacific distribution. Purified mtDNA from 160 individuals was cut with five restriction enzymes, revealing high haplotype diversity (0.96) and moderate nucleotide diversity (0.75%). Island populations from the Indian Ocean (Christmas I.) and Pacific Ocean were significantly different (GST= 0.37) and had distinct mtDNA lineages with a net sequence divergence of 1.4%. Pacific island populations had diverged in a manner consistent with isolation by distance, with only the most peripheral populations being significantly different. The results for mtDNA are largely concordant with those from allozymes, although estimates of gene flow between the Indian and Pacific Oceans were much lower when based on mtDNA. The mtDNA phylogeny also permitted a deeper examination of the evolutionary and demographic history ofBirgus latro. Long‐term separation of populations is evident in the complete phylogenetic subdivision of mtDNA lineages between the Indian and Pacific Ocean populations sampled. The starlike phylogeny of alleles from the Pacific suggests a rapid population expansion in the Pacific during the Pleistocene. Including information about allele phylogeny, as well as distribution and frequency, obscured contemporary population structure, but provided unique insights into the evolutionary history of the sp

ISSN:0962-1083    

DOI:10.1046/j.1365-294X.1996.00125.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

摘要:

Fifteen microsatellites were isolated from a beluga whaleDelphinapterus leucas, genomic library. The microsatellites were amplified in 100 beluga obtained from two widely separated locations. An average of 8.6 alleles per locus were detected and the average heterozygosity was 0.65 with a range of 0.27–0.86. All microsatellites were polymorphic and 13 of the genotype distributions observed were in Hardy‐Weinberg equilibrium. It was possible with these microsatellites to assign correctly individual whales to their stock‐of‐origin 98% of the time. Microsatellites were amplified in 15 other cetaceans with these beluga‐derive

ISSN:0962-1083    

DOI:10.1046/j.1365-294X.1996.00109.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY