bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reproductive biology and genetic diversity of a cryptoviviparous mangrove Aegiceras corniculatum (Myrsinaceae) using allozyme and intersimple sequence repeat (ISSR) analysis
Authors: Ge X. J. , Sun M. 
Published: March 2003

AbstractMangroves consist of a group of taxonomically diverse species representing about 20 families of angiosperms. However, little is known about their reproductive biology, genetic structure, and the ecological and genetic factors affecting this structure. Comparative studies of various mangrove species are needed to fill such gaps in our knowledge. The pollination biology, outcrossing rate, and genetic diversity of Aegiceras corniculatum were investigated in this study. Pollination experiments suggested that the species is predominantly pollinator‐dependent in fruit setting. A quantitative analysis of the mating system was performed using progeny arrays assayed for intersimple sequence repeat (ISSR) markers. The multilocus outcrossing rate (tm) was estimated to be 0.653 in a wild population. Both allozyme and ISSR were used to investigate genetic variation within and among populations. The combined effects of founder events and enhanced local gene flow through seedling dispersal by ocean currents apparently played an important role in shaping the population genetic structure in this mangrove species. Both allozyme variation (P = 4.76%, A = 1.05, HE = 0.024) and ISSR diversity (P = 16.18%, A = 1.061, HE = 0.039) were very low at the species level, in comparison with other woody plants with mixed‐mating or outcrossing systems. Gene differentiation among populations was also low: allozyme GST = 0.106 and ISSR GST = 0.178. The unusually high genetic identities (0.997 for allozyme and 0.992 for ISSR loci), however, suggest that these populations are probably all descended from a common ancestral population with low polymorphism.
Comparative genetic diversity of parasites and their hosts: population structure of an urban cockroach and its haplo‐diploid parasite (oxyuroid nematode)
Authors: Jobet E. , Durand P. , Langand J. , Müller‐Graf C. D. M. , Hugot J.‐P. , Bougnoux M.‐E. , Rivault C. , Cloarec A. , Morand S. 
Published: March 2003

AbstractFew studies have investigated the genetic structure of both host and parasite populations at a level of populations and at a level of individuals. We investigated the genetic structure of the urban cockroach Blattella germanica and its oxyuroid parasite Blatticola blattae. Random amplified polymorphic DNA (RAPD) markers were used to quantify genetic diversity between and within four populations (from two cities in France) of the host and its parasite. Diversity based on phenotypic frequencies was calculated for each RAPD marker using Shannon‐Wiener’s index. We used multivariate analyses to test the significance of genetic differentiation between host and parasite populations. Analysis of molecular variance was also used. Both methods gave similar results. Diversity between pairs of individuals was estimated by Nei & Li’s index. Genetic diversity was higher within host or parasite populations (80% and 82%, respectively, of explained diversity) than between host or parasite populations (20% and 18%, respectively, explained diversity). The genetic distances between pairs of parasite populations (or individuals) were not correlated with the genetic distances between the corresponding pairs of host populations (or individuals).
Parentage analysis with incomplete sampling of candidate parents and offspring
Authors: Neff B. D. , Repka J. , Gross M. R. 
Published: March 2003

AbstractMany breeding systems include ‘multiple mating’ in which males or females mate with multiple partners. We identify two forms of multiple mating: ‘single‐sex’, where the next‐generation individuals (NGIs) are the product of multiple mating by one sex; and ‘two‐sex’, where the NGIs are the product of multiple mating by both sexes. For both mating systems we develop models that estimate the proportion of NGIs that is fathered (paternity) or mothered (maternity) by the putative parents. The models only require genetic data from the parent or parents in question and the sample of NGIs, as well as an estimate of population allele frequencies. The models provide unbiased estimates, can accommodate loci with many alleles and are robust to violations of their assumptions. They allow researchers to address intractable problems such as the parentage of seeds found on the ground, juvenile fish in a stream, and nestlings in a communal breeding bird. We demonstrate the models using genetic data from a nest of the bluegill sunfish Lepomis macrochirus, where the NGIs may be from multiple females that have spawned with multiple males from different life histories (cuckolder and parental).
Genetic structure of Camellia japonica L. in an old‐growth evergreen forest, Tsushima, Japan
Authors: Ueno S. , Tomaru N. , Yoshimaru H. , Manabe T. , Yamamoto S. 
Published: March 2003

AbstractThe spatial genetic structure of Camellia japonica was investigated, using microsatellite markers, in a 4‐ha permanent plot within an old‐growth forest. Spatial distribution of individuals was also assessed to obtain an insight into spatial relationships between individuals and alleles. Morisita’s index of dispersion showed that 518 C. japonica individuals in the plot were clumped, and Moran’s I spatial autocorrelation coefficient revealed weak genetic structure, indicating a low level of allele clustering. Average I correlograms showed that there was stronger genetic structure over short‐distance classes. The clumped distribution of individuals and the positive autocorrelation over short‐distance classes may result from the limited seed dispersal and microsite heterogeneity of the stand, while the genetic structure may be weakened by overlapping seed shadow and extensive pollen flow, mediated by animal vectors, and the high outcrossing rate found in C. japonica.
Phylogeography and genetic structure of northern populations of the yellow warbler (Dendroica petechia)
Authors: Milot Emmanuel , Gibbs H. Lisle , Hobson Keith A. 
Published: March 2003

AbstractPhylogeographic patterns of intraspecific variation can provide insights into the population‐level processes responsible for speciation and yield information useful for conservation purposes. To examine phylogeography and population structure in a migratory passerine bird at both continental and regional geographical scales, we analysed 344 bp of mitochondrial DNA (mtDNA) control region sequence from 155 yellow warblers (Dendroica petechia) collected from seven locations across Canada and from Alaska. There is a major subdivision between eastern (Manitoba to Newfoundland) and western (Alaska and British Columbia) populations which appears to have developed during the recent Pleistocene. Some localities within these two regions also differ significantly in their genetic composition, suggesting further subdivision on a regional geographical scale. Eastern and western birds form distinct phylogeographic entities and the clustering of all western haplotypes with two eastern haplotypes suggests that the western haplotypes may be derived from an eastern lineage. Analyses based on coalescent models support this explanation for the origin of western haplotypes. These results are consistent with important features of Mengel’s model of warbler diversification. From a conservation perspective they also suggest that individual populations of migrant birds may form demographically isolated management units on a smaller scale than previously appreciated.
A direct regional scale estimate of transgene movement from genetically modified oilseed rape to its wild progenitors
Authors: Wilkinson M. J. , Davenport I. J. , Charters Y. M. , Jones A. E. , Allainguillaume J. , Butler H. T. , Mason D. C. , Raybould A. F. 
Published: March 2003

AbstractOne of the major environmental concerns over genetically modified (GM) crops relates to transgene movement into wild relatives. The pattern of hybridization ultimately affects the scale and rapidity of ecological change and the feasibility of containment. A new procedure for quantifying hybrid formation over large areas is described. Remote sensing was used to identify possible sites of sympatry between Brassica napus and its progenitor species across 15 000 km2 of south‐east England in 1998. Two sympatric populations with B. rapa and one with B. oleracea were found over the entire survey area. Every newly recruited plant in these populations in 1999 was screened for hybrid status using flow cytometry and molecular analyses. One hybrid was observed from the 505 plants screened in the B. rapa populations but none of the nine B. oleracea recruits were hybrids. Measures to minimize gene flow are suggested, and a procedure for the post‐release evaluation and containment of GM cultivars is proposed.
Biogeography of a southern hemisphere freshwater fish: how important is marine dispersal?
Authors: Waters Jonathan M. , Dijkstra Lucette H. , Wallis Graham P. 
Published: March 2003

AbstractGalaxias maculatusis one of the world’s most widely distributed freshwater fish. This species has a marine‐tolerant juvenile phase, and a geographical range extending through much of the southern hemisphere. We conducted phylogeographic analyses of 163 control region haplotypes ofG. maculatus, including samples from New Zealand (five locations), Tasmania (one location) and Chile (one location). A lack of genetic structure among New Zealand samples suggests that marine dispersal facilitates considerable gene flow on an intra‐continental scale. The discovery of a Tasmanian‐like haplotype in one of 144 New Zealand samples indicates that inter‐continental marine dispersal occurs but is insufficient to prevent mitochondrial DNA differentiation among continents. The sister relationship of Tasmanian and New Zealand clades implies that marine dispersal is an important biogeographical mechanism for this species. However, a vicariant role in the divergence of eastern and western PacificG. maculatuscannot be rejected.
Microsatellite analysis of genetic structure in the mangrove species Avicennia marina (Forsk.) Vierh. (Avicenniaceae)
Authors: Maguire T. L. , Saenger P. , Baverstock P. , Henry R. 
Published: March 2003

AbstractThe level of genetic variation throughout the entire worldwide range of the mangrove species Avicennia marina (Forsk.) Vierh. was examined using microsatellite markers. Three microsatellite loci detected high levels of allelic diversity (70 alleles in total), essential for an accurate estimation of population genetic parameters. The informativeness of the microsatellite loci tended to increase with increasing average number of repeats. The levels of heterozygosity detected for each population, over all loci, ranged from 0.0 to 0.8, with an average of 0.407, indicating that some populations had little or no genetic variation, whereas others had a large amount. Populations at the extremes of the distribution range showed reduced levels of heterozygosity, and significant levels of inbreeding. This is not unexpected as these populations may be subject to founder effects and environmental constraints. The presence of genetic structure was tested in A. marina populations using three models: (i) a single panmictic model; (ii) the discrete subpopulation model; and (iii) the isolation by distance model. The discrete subpopulations model was supported by the overall measures of population differentiation based on the infinite alleles model (F‐statistics), and the stepwise mutation model (R statistics). In addition, an analysis of molecular variance (amova), using both theoretical models, found that most of the variation was between populations (41–71%), and within individuals in the total population (31–49%). There was little variation among individuals within populations (0–10%). There was no significant isolation by distance. The high levels of genetic differentiation observed among populations of A. marina may be due to environmental and ecological factors, particularly past sea level and climatic changes.
Phylogeography of Peromyscus furvus (Rodentia; Muridae) based on cytochrome b sequence data
Authors: Harris Danny , Rogers Duke S. , Sullivan Jack 
Published: March 2003

AbstractWe conducted phylogenetic analyses of cytochrome b sequence data to assess genetic variation within and among the three allopatric segments of the distribution of Peromyscus furvus from the Sierra Madre Oriental in eastern Mexico. We identified 24 unique haplotypes among the 54 individuals examined and genetic distances ranged up to 0.078 substitutions per site. Populations from the central portion of the range formed a monophyletic unit, whereas samples from the southern distributional unit were polyphyletic. Furthermore, the southernmost population sampled may represent a distinct species. This high degree of genetic differentiation among populations, currently recognized as conspecific, mirrors the result of other genetic studies of highland rodents in Mesoamerica. Together these studies indicate that the region, already considered hyperdiverse on the basis of species diversity and endemism, may contain considerably greater diversity than is currently appreciated.
Genetic diversity and introgression in the Scottish wildcat
Authors: Beaumont M. , Barratt E. M. , Gottelli D. , Kitchener A. C. , Daniels M. J. , Pritchard J. K. , Bruford M. W. 
Published: March 2003

AbstractThis paper describes a genetic analysis of wild‐living cats in Scotland. Samples from 230 wild‐living Scottish cats (including 13 museum skins) and 74 house cats from England and Scotland were surveyed for nine microsatellite loci. Pelage characteristics of the wild‐living cats were recorded, and the cats were then grouped into five separate categories depending on the degree to which they conformed to the characteristics attributed toFelis silvestrisSchreber, 1775. Allele frequency differences between the morphological groups are greater than those among the three house cat samples. Analysis of genetic distances suggests that more of the differences between individuals can be explained by pelage than geographical proximity, and that pelage and geographical location are not confounded. Ordination of the genetic distances suggests two main groups of wild‐living cats, with intermediates, and one group is genetically very similar to the house cats, while the other group contains all cats taxonomically identified as wildcat based on morphology. A genetic mixture analysis gives similar results to the ordination, but also suggests that the genotypes of a substantial number of cats in the wildcat group are drawn from a gene pool with genotypes in approximately equilibrium proportions. We argue that this is evidence that these cats do not have very recent domestic ancestry. However, from the morphological data it is highly likely that this gene pool also contains a contribution from earlier introgression of domestic cat genes.
rbcL sequences reveal multiple cryptic introductions of the Japanese red alga Polysiphonia harveyi
Authors: McIvor Lynne , Maggs Christine A. , Provan Jim , Stanhope Michael J. 
Published: March 2003

AbstractIn Europe, the last 20 years have seen a spectacular increase in accidental introductions of marine species, but it has recently been suggested that both the actual number of invaders and their impacts have been seriously underestimated because of the prevalence of sibling species in marine habitats. The red alga Polysiphoniaharveyi is regarded as an alien in the British Isles and Atlantic Europe, having appeared in various locations there during the past 170 years. Similar or conspecific populations are known from Atlantic North America and Japan. To choose between three competing hypotheses concerning the origin of P. harveyi in Europe, we employed rbcL sequence analysis in conjunction with karyological and interbreeding data for samples and isolates of P. harveyi and various congeners from the Pacific and North Atlantic Oceans. All cultured isolates of P. harveyi were completely interfertile, and there was no evidence of polyploidy or aneuploidy. Thus, this biological species is both morphologically and genetically variable: intraspecific rbcL divergences of up to 2.1% are high even for red algae. Seven rbcL haplotypes were identified. The four most divergent haplotypes were observed in Japanese samples from Hokkaido and south‐central Honshu, which are linked by hypothetical ‘missing’ haplotypes that may be located in northern Honshu. These data are consistent with Japan being the centre of diversity and origin for P. harveyi. Two non‐Japanese lineages were linked to Hokkaido and Honshu, respectively. A single haplotype was found in all North Atlantic and Mediterranean accessions, except for North Carolina, where the haplotype found was the same as that invading in New Zealand and California. The introduction of P. harveyi into New Zealand has gone unnoticed because P. strictissima is a morphologically indistinguishable native sibling species. The sequence divergence between them is 4–5%, greater than between some morphologically distinct red algal species. Two different types of cryptic invasions of P. harveyi have therefore occurred. In addition to its introduction as a cryptic sibling species in New Zealand, P. harveyi has been introduced at least twice into the North Atlantic from presumed different source populations. These two introductions are genetically and probably also physiologically divergent but completely interfertile.
Contrasting patterns of mitochondrial DNA and microsatellite introgressive hybridization between lineages of lake whitefish (Coregonus clupeaformis); relevance for speciation
Authors: Lu G. , Basley D. J. , Bernatchez L. 
Published: March 2003

AbstractWe performed a combined analysis of mitochondrial DNA (mtDNA) and microsatellite loci among lake whitefish (Coregonus clupeaformis) populations in order to assess the levels of congruence between both types of markers in defining patterns of genetic structuring, introgressive hybridization and inferring population origins in the hybrid zone of the St. John River basin. A second objective was to test the hypothesis that secondary contact between glacial lineages always resulted in the occurrence of sympatric dwarf and normal whitefish ecotypes. Fish were sampled from 35 populations and polymorphism was screened at mtDNA and six microsatellite loci for a total of 688 and 763 whitefish, respectively. Four lakes harbouring a single whitefish population of normal ecotype admixed with mtDNA haplotypes of different lineages were found. This confirmed that secondary contact between whitefish evolutionary lineages did not always result in the persistence of reproductively isolated ecotypes. Microsatellites further supported the definition of distinct glacial lineages by identifying lineage‐specific allelic size groups. They also further supported the hypothesis that ecotypes originated from either a single founding lineage (sympatric divergence) or following secondary contacts between lineages (allopatric divergence), depending on the lake. In general, however, the pattern of population differentiation and introgressive hybridization observed at microsatellites was in sharp contrast with that depicted by mtDNA variation. Both factorial correspondence analysis and analysis of admixture proportion revealed a much more pronounced pattern of introgressive hybridization than depicted by mtDNA analyses. Variable levels of introgression indicated that environmental differences may be as important as the historical contingency of secondary contact in explaining the persistence of sympatric ecotypes and the differential pattern of introgressive hybridization among lakes. Whitefish populations from the St. John River basin hybrid zone represent a rare illustration of a continuum of both morphological and genetic differentiation within a given taxon, spanning from complete introgression to possibly complete reproductive isolation, depending on lakes. Thus, each lake may be viewed as a different temporal snapshot taken throughout the gradual process of speciation.
Fragmentation of riverine systems: the genetic effects of dams on bull trout (Salvelinus confluentus) in the Clark Fork River system
Authors: Neraas Lukas P. , Spruell Paul 
Published: March 2003

AbstractMigratory bull trout (Salvelinus confluentus) historically spawned in tributaries of the Clark Fork River, Montana and inhabited Lake Pend Oreille as subadult and adult fish. However, in 1952 Cabinet Gorge Dam was constructed without fish passage facilities disrupting the connectivity of this system. Since the construction of this dam, bull trout populations in upstream tributaries have been in decline. Each year adult bull trout return to the base of Cabinet Gorge Dam when most migratory bull trout begin their spawning migration. However, the origin of these fish is uncertain. We used eight microsatellite loci to compare bull trout collected at the base of Cabinet Gorge Dam to fish sampled from both above and further downstream from the dam. Our data indicate that Cabinet Gorge bull trout are most likely individuals that hatched in above‐dam tributaries, reared in Lake Pend Oreille, and could not return to their natal tributaries to spawn. This suggests that the risk of outbreeding depression associated with passing adults over dams in the Clark Fork system is minimal compared to the potential genetic and demographic benefits to populations located above the dams.
Origin of honeybees (Apis mellifera L.) from the Yucatan peninsula inferred from mitochondrial DNA analysis
Authors: Clarke Kylea E. , Oldroyd Benjamin P. , Javier J. , Quezada‐Euán G. , Rinderer Thomas E. 
Published: March 2003

AbstractHoneybees (Apis mellifera L.) sampled at sites in Europe, Africa and South Ámerica were analysed using a mitochondrial DNA restriction fragment length polymorphism (RFLP) marker. These samples were used to provide baseline information for a detailed analysis of the process of Africanization of bees from the neotropical Yucatan peninsula of Mexico. Radical changes in mitochondrial haplotype (mitotype) frequencies were found to have occurred in the 13‐year period studied. Prior to the arrival of Africanized bees (1986) the original inhabitants of the Yucatan peninsula appear to have been essentially of southeastern European origin with a smaller proportion having northwestern European ancestry. Three years after the migration of Africanized bees into the area (1989), only very low levels of maternal gene flow from Africanized populations into the resident European populations had occurred. By 1998, however, there was a sizeable increase in the proportion of African mitotypes in domestic populations (61%) with feral populations having 87% of mitotypes classified as African derived. The results suggest that the early stages of Africanization did not involve a rapid replacement of European with African mitotypes and that earlier studies probably overestimated the prevalence of African mitotypes.