bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microsatellite variation in Daphnia pulex from both sides of the Baltic Sea
Authors: Pálsson Snæbjörn 
Published: March 2003

AbstractDespite large genetic differentiation among neighbouring populations of many freshwater zooplankton species, a macrogeographical homogeneity of allozyme variation is generally observed. A study on breeding systems in Scandinavian populations of Daphnia pulex suggested a latitudinally related cline in breeding system with both diploid cyclic parthenogens and diploid obligate parthenogens at the latitude of 60–61°N. Variation at neutral markers may be more affected by selection at linked loci in such species than in strictly sexual species. In this paper I present a study of variation at five microsatellite loci in a total of 34 populations from small ponds and rockpools on both sides of the Baltic Sea at 60–61°N. Two major groups, which may represent different species of the D. pulex complex, are defined with the microsatellites. Neighbouring populations show both similar and well differentiated genetic composition. Populations separated by larger geographical distances show only a large differentiation and a macrogeographic pattern. The large differentiation observed at small distances can be explained with small effective population size: variation at the microsatellite loci has been shaped by population bottlenecks followed with expansion in size, and possibly by selection. No conclusive evidence is found for obligative parthenogenesis.
Chloroplast DNA haplotype variation and population differentiation in Sorbus aucuparia L. (Rosaceae: Maloideae)
Authors: Raspé O. , Saumitou‐Laprade P. , Cuguen J. , Jacquemart A.‐L. 
Published: March 2003

AbstractIntra‐specific chloroplast DNA (cpDNA) variation was studied in Sorbus aucuparia L., an entomophilous, mid‐or early successional tree producing fleshy fruits. Eight PCR‐amplified fragments of the chloroplast genome were screened for restriction fragment length polymorphisms, using one or two 4 bp‐cutter restriction endonucleases. cpDNA variation was investigated on two geographical scales: (1) among four regions in France and Belgium; and (2) within the Belgian region. A total of 150 individuals from six populations were analysed. Fourteen polymorphisms were detected in six of the cpDNA fragments. All polymorphisms probably resulted from insertions or deletions, and allowed the identification of 12 haplotypes. The level of genetic differentiation computed on the basis of haplotype frequencies was similar on the two geographical scales considered (GSTc = 0.286 among regions, GSTc = 0.259 among populations within the Belgian region). These values are much lower than those obtained in nine previously studied temperate tree species, which are all wind‐pollinated, late‐successional species producing dry fruits. These results might primarily be accounted for by the contrasting life history traits of S. aucuparia. In order to obtain insights into the relative contribution of pollen and seeds to gene flow, GSTc was also compared with previously obtained GST estimates based on allozyme data.
Genetic analysis and conservation of 31 surviving individuals of a rare New Zealand tree, Metrosideros bartlettii (Myrtaceae)
Authors: Drummond R. S. M. , Keeling D. J. , Richardson T. E. , Gardner R. C. , Wright S. D. 
Published: March 2003

Abstract Metrosideros bartlettii (Myrtaceae) is a distinctive and extremely rare tree, endemic to New Zealand, first discovered in 1975. Prior to this study, a total of 19 adult individuals of the species had been reported; these are located in three small forest remnants in the far north of the North Island of New Zealand. Here we describe a total of 31 adult M. bartlettii at the three sites, including 12 individuals newly discovered by us. We analyse the genetic diversity of the species, using microsatellites to examine the chloroplast genome and amplified fragment length polymorphisms (AFLPs) to monitor nuclear variation. The results clearly demonstrate that M. bartlettii is a unique species, distinct from its two closest relatives M. robusta and M. excelsa. Analysis of genetic diversity within the 31 remaining individuals of M. bartlettii showed an average heterozygosity (< H >) of 0.18 and a proportion of polymorphic genes (< P >) of 0.44. Population structure, as shown by 286 AFLP loci, varied between the three geographical sites; the site with fewest individuals, containing two trees, showed some separation from the populations at the other two locations. These two latter sites, by contrast, had highly overlapping AFLP population diversity profiles. The implications of these results for conservation of the species are discussed.
Evolutionary genetics of metamorphic failure using wild‐caught vs. laboratory axolotls (Ambystoma mexicanum)
Authors: Voss S. R. , Shaffer H. B. 
Published: March 2003

AbstractIn many organisms metamorphosis allows for an ecologically important habitat‐shift from water to land. However, in some salamanders an adaptive life cycle mode has evolved that is characterized by metamorphic failure (paedomorphosis); these species remain in the aquatic habitat throughout the life cycle. Perhaps the most famous example of metamorphic failure is the Mexican axolotl (Ambystoma mexicanum), which has become a focal species for developmental biology since it was introduced into laboratory culture in the 1800s. Our previous genetic linkage mapping analysis, using an interspecific crossing design, demonstrated that a major gene effect underlies the expression of metamorphic failure in laboratory stocks of the Mexican axolotl. Here, we repeated this experiment using A. mexicanum that were sampled directly from their natural habitat at Lake Xochimilco, Mexico. We found no significant association between the major gene and metamorphic failure when wild‐caught axolotls were used in the experimental design, although there is evidence of a smaller genetic effect. Thus, there appears to be genetic variation among Mexican axolotls (and possibly A. tigrinum tigrinum) at loci that contribute to metamorphic failure. This result suggests a role for more than one mutation and possibly artificial selection in the evolution of the major gene effect in the laboratory Mexican axolotl.
Across the Southern Alps by river capture? Freshwater fish phylogeography in South Island, New Zealand
Authors: Waters Jonathan M. , Wallis Graham P. 
Published: March 2003

AbstractWe used DNA analysis of galaxiid fish to test a hypothesis of localized headwater capture in South Island, New Zealand. The restricted western, but widespread eastern, distributions of three nonmigratory freshwater fish species suggest that part of the east‐flowing Waiau River has been captured by the west‐flowing Buller River. However, mitochondrial control region (Kimura 2‐parameter distance = 4.1–5.4%) and microsatellite flanking sequences do not support a relationship between Waiau (N = 4 fish sequences) and western populations (N = 8) of Galaxias vulgaris. Instead, the point of capture is probably to the north‐east, perhaps the Nelson lakes region. Phylogenetic analysis indicates that western populations, along with populations in the north‐east (N = 18), represent a previously unidentified monophyletic Evolutionarily Significant Unit, possibly a cryptic species. We suggest a general caveat for zoogeographic conclusions based on distributional data alone.
Variation of haplotype distributions of two genomic regions of Citrus tristeza virus populations from eastern Spain
Authors: D’Urso F. , Sambade A. , Moya A. , Guerri J. , Moreno P. 
Published: March 2003

AbstractGenetic variation in natural populations of Citrus tristeza virus (CTV) was studied using haplotypes detected by single‐strand conformation polymorphism (SSCP) analysis of two genomic regions (p20 gene and segment A, located in ORF1a). Analysis of 254 samples from 125 trees, collected at 12 different sites, yielded 8 different haplotypes for p20 and 5 for segment A. The most frequent haplotype of p20 was predominant at all sites, but several sites differed in the predominance of segment A haplotypes. At most sites, the homozygosity observed for the p20 gene tended to be higher than expected in a neutral evolution, whereas the opposite was true for segment A. Comparison of the populations at different sites showed that 44 of the 66 possible population pairs were genetically distinct for segment A, but only six pairs differed for the p20 gene. Analysis of molecular variance grouping trees by site, scion variety, rootstock or age, showed that variation in segment A was significantly affected by site, tree age and rootstock, and that variation between trees in each group and within trees was even more important. In contrast, variation in p20 was affected only by site and rootstock, each factor contributing to < 2% of the variation. The data suggest that sequence variations in segment A must be functionally less important and that it has less evolutionary constraints than p20. Detection of different haplotypes in neighbour trees or in samples from the same tree may help explain part of the variability observed in CTV symptom expression.
Tripartite genetic subdivisions in the ornate shrew (Sorex ornatus)
Authors: Maldonado Jesus E. , VilÀ Carles , Wayne Robert K. 
Published: March 2003

AbstractWe examined cytochromebsequence variation in 251 ornate shrews (Sorex ornatus) from 20 localities distributed throughout their geographical range. Additionally, vagrant (S. vagrans) and montane (S. monticolus) shrews from four localities were used as outgroups. We found 24 haplotypes in ornate shrews from California (USA) and Baja California (Mexico) that differed by 1–31 substitutions in 392 bp of mitochondrial DNA (mtDNA) sequence. In a subset of individuals, we sequenced 699 bp of cytochromebto better resolve the phylogeographic relationships of populations. The ornate shrew is phylogeographically structured into three haplotype clades representing southern, central and northern localities. Analysis of allozyme variation reveals a similar pattern of variation. Several other small California vertebrates have a similar tripartite pattern of genetic subdivision. We suggest that topographic barriers and expansion and contraction of wetland habitats in the central valley during Pleistocene glacial cycles account for these patterns of genetic variation. Remarkably, the northern ornate shrew clade is phylogenetically clustered with another species of shrew suggesting that it may be a unique lowland form of the vagrant shrew that evolved in parallel to their southern California counterparts.
Divergence betweenDrosophila santomeaand allopatric or sympatric populations ofD. yakubausing paralogous amylase genes and migration scenarios along the Cameroon volcanic line
Authors: Cariou M.‐L. , Silvain J.‐F. , Daubin V. , Da Lage J.‐L. , Lachaise D. 
Published: March 2003

AbstractWe have used two paralogous genes (AmyrelandAmy) of the amylase multigene family to reconstruct the phylogeny of the nineDrosophila melanogastersubgroup sister species, includingD. santomea, the newly discovered endemic from São Tomé island. The evolutionary divergence of these genes is of special interest as it is suspected to result from physiological evolution via gene duplication. This paper describes the relationship between the geographical origin of the various strains and the patterns of mating and phylogeny, focusing on the evolution ofD. santomeaand its relationship to other species and their niches. TheAmyrelandAmydata indicate that, contrary to expectations, the sympatric insularD. yakubapopulation is less closely related toD. santomeathan allopatric mainland ones, suggesting that the extant insularD. yakubapopulation on São Tomé results from a recent secondary colonization. Data for sympatric and allopatricD. yakubasuggest thatD. santomeaarose from a mainlandD. yakubaparental stock when montane habitats of the Cameroon volcanic line extended to lower altitudes during colder and less humid periods. Despite their different modes of evolution and different functions, theAmyrelandAmygenes provide remarkably consistent topologies and hence reflect the same history, that of the species.
Genetic variation and clonal diversity in four clonal sedges (Carex) along the Arctic coast of Eurasia
Authors: Stenström Anna , Jonsson B. Olle , Jónsdóttir Ingibjörg S. , Fagerström Torbjörn , Augner Magnus 
Published: March 2003

AbstractWe studied the structure of genetic variation (at both ramet‐ and genet‐level) and clonal diversity within and among populations in the four closely related arctic clonal sedges Carex bigelowii, C. ensifolia, C. lugens and C. stans by use of allozyme markers. Compared to other sedges and arctic plants, the studied taxa all had high levels of genetic variation, both within populations and taxa. These taxa contained most of the total gene diversity (HT) within populations and a small part of the diversity among populations (GST ranged 0.05–0.43). Carex bigelowii had genetic variation (HS = 0.173, mean for populations) at a comparable level to other outbreeding arctic plants and to other widespread, rhizomatous and mainly outbreeding Carex species. In contrast, C. ensifolia (HS = 0.335), C. lugens (HS = 0.339) and C. stans (HS = 0.294) had within‐population variations that were higher than in most other studied Carex species and for arctic plants in general. Genetic variation was not related to any tested environmental variable, but it was lower in areas deglaciated only 10 000 years

bp compared to areas deglaciated 60 000 years

bp or not glaciated at all during the Weichselian. All the populations were multiclonal, except for two populations of C. stans that were monoclonal. In contrast to genetic variation, clonal diversity decreased with latitude and did not differ between areas with different times of deglaciation. In accordance with previous studies, C. bigelowii and C. lugens were found to be outbreeding, while C. ensifolia and C. stans had mixed mating systems.
Correspondence between genet diversity and spatial distribution of above‐ and below‐ground populations of the ectomycorrhizal fungus Hebeloma cylindrosporum
Authors: Guidot A. , Debaud J.‐C. , Marmeisse R. 
Published: March 2003

AbstractPopulation studies of ectomycorrhizal fungal species have largely relied upon fruit body (the reproductive organ) sampling. Analysis of the fruit bodies alone supposes that they reflect the present and spatial organization of all below‐ground genets (mycorrhizas and extramatrical mycelia). The relation between fruit bodies and ectomycorrhizas was investigated for the basidiomycete agaric Hebeloma cylindrosporum in four Pinus pinaster stands in south‐west France. Genet identification was based on the comparison of polymorphisms within a hypervariable segment of the ribosomal intergenic spacer amplified by polymerase chain reaction (PCR) using a H. cylindrosporum species‐specific primer. Mycorrhizas were sorted from soil samples collected underneath patches of fruit bodies or patches where fruit bodies had or had not been observed during the years prior to mycorrhiza collection. On average 65% of the 1026 mycorrhizas collected underneath fruit bodies were formed by H. cylindrosporum, whereas only 2% of the 954 collected in places from where fruit bodies were absent were formed by this species. All genotypes identified above ground were also identified below ground. In patches where one genotype formed all or more than 90% of the fruit bodies, the same genotype formed all or a large majority of the mycorrhizas. In patches occupied by several different fruiting genotypes, additional nonfruiting ones could be present on the root systems. In all cases, the mycorrhizas of one genotype were found no more than 10–20 cm away from its corresponding fruit bodies, and fruit body disappearance at a given place was associated with the disappearance of the corresponding mycorrhizas within 1 year. Although there was not a strict coincidence between the total numbers of genets present below ground and of those forming fruit bodies, fruit body analysis for H. cylindrosporum appears to reflect both the genetic diversity and the spatial structure of its below‐ground populations. The results obtained also illustrate the rapid turnover of ectomycorrhizal fungal species on the root systems in the absence of any obvious major disturbance of the ecosystem.
Conservation genetics of peripheral populations of the mygalomorph spider Atypus affinis (Atypidae) in northern Europe
Authors: Pedersen A. AA. , Loeschcke V. 
Published: March 2003

AbstractGenetic diversity and differentiation were studied in peripheral populations of the recently rediscovered purse‐web spider Atypus affinis in Denmark and Sweden using allozyme electrophoresis. Because of the very narrow environmental niche exploited by this species, only a limited number of potential habitats are available. Furthermore, fragmentation has reduced the number and size of potential habitats within the last century. The level of genetic diversity in A. affinis was intermediate compared with other nonsocial spiders, but low compared with invertebrates in general. Significant genetic differentiation was found within distances of only 1–10 km with FST estimates ranging from 0.020 to 0.075. Within distances of 30–60 km FST ranged from 0.081 to 0.312. Hierarchical FST revealed that genetic variability was partitioned at 89.8% within populations, 9.5% among populations within regions and only 0.7% among the four main regions in Denmark and Sweden. Comparing the result of the genetic analysis with the life history of A. affinis, it is concluded that the level of successful dispersal is low, and that the species has not recently reinvaded northern Europe but prevailed undiscovered for several decades. Finally, it is suggested that the genetic scenario found for A. affinis might represent that for a wide range of other arthropods with similar life history characteristics.
Phylogeography of the yucca moth Tegeticula maculata: the role of historical biogeography in reconciling high genetic structure with limited speciation
Authors: Segraves K. A. , Pellmyr O. 
Published: March 2003

Abstract Tegeticula maculata is one of the most ancient and morphologically variable lineages within the yucca moths, yet has apparently undergone little diversification in comparison with much younger yucca moth lineages that have rapidly diversified. A phylogeographic approach was used to determine the number of independent lineages within T. maculata and to examine whether these patterns corresponded with morphological differences between its subspecies maculata and extranea. Phylogenetic analysis of mitochondrial DNA sequence variation indicated that the two subspecies are in separate clades, but there was also an equally deep split within subspecies maculata. There was no evidence for gene flow among regions and there was considerable substructure within clades. The phylogeographic structure of moth populations among and within subspecies can be explained in part by historical biogeographic boundaries and increasingly patchy postglacial distribution of the exclusive host plant, Hesperoyucca whipplei. Local specialization and co‐adaptation would be possible in the absence of apparent gene flow, yet gross morphological divergence is limited to the very old split between the subspecies. Sorting of ancient mitochondrial lineages followed by local genetic differentiation may explain the pattern of high genetic structure with limited speciation.
Species boundaries and genetic diversity among Hawaiian crickets of the genus Laupala identified using amplified fragment length polymorphism
Authors: Parsons Y. M. , Shaw K. L. 
Published: March 2003

AbstractCrickets of the genus Laupala represent one of the many morphologically cryptic groups of insects, with the most closely related species distinguished only by the male calling song. Cryptic groups provide a challenge in determining the genetic boundaries between closely related populations and species. We have addressed the question of species boundaries in the Hawaiian cricket, Laupala, using nuclear DNA patterns sampled by the amplified fragment length polymorphism (AFLP) technique. This method has been used widely by plant researchers to facilitate the rapid assessment of genetic diversity in very closely related species and varieties. The AFLP technique is simple and robust, can be applied to any organism, and overcomes problems associated with cost, development time, information content and reproducibility that can plague other marker systems. Our results support previously hypothesized taxonomic relationships among sympatric populations and suggest close genetic relationships among allopatric, conspecific populations.
Insights into recently fragmented vole populations from combined genetic and demographic data
Authors: Tallmon D. A. , Draheim H. M. , Mills L. Scott , Allendorf F. W. 
Published: March 2003

AbstractWe combined demographic and genetic data to evaluate the effects of habitat fragmentation on the population structure of the California red‐backed vole (Clethrionomys californicus). We analysed variation in the mitochondrial DNA (mtDNA) control region and five nuclear microsatellite loci in small samples collected from two forest fragments and an unfragmented control site in 1990–91. We intensively sampled the same forest fragments and two different control sites in 1998 and 1999. Vole abundances fluctuated greatly at sizes below 50 individuals per fragment. Fragment populations had significantly lower mtDNA allelic diversity than controls, but not nuclear heterozygosity or numbers of alleles. The use of only trapping and/or mtDNA marker data would imply that fragment populations are at least partially isolated and vulnerable to inbreeding depression. In contrast, the abundance estimates combined with microsatellite data show that small fragment populations must be linked to nearby forests by high rates of migration. These results provide evidence for the usefulness of combining genetic and demographic data to understand nonequilibrium population structure in recently fragmented habitats.
Community genetics in the Northwestern Atlantic intertidal
Authors: Wares J. P. 
Published: March 2003

AbstractOur ability to make inferences about the processes acting upon a biological system can be dramatically improved through integration of information from other fields. In particular, this is true of the field of phylogeography, a discipline that attempts to describe geographical variation in species using neutral genetic diversity as a correlate of time. Through comparisons of information from multiple species, as well as background information about the abiotic environment and how it has changed over time, we should be able to reassemble many of the forces that were important in assembling the communities and community interactions found in a given region. Here I review the information available for coastal species in the northwestern Atlantic, and argue that an integration of ecological, genetic, geological and oceanographic information can illustrate emergent patterns of community genetics.
Extreme microallopatric divergence in a cichlid species from Lake Malawi
Authors: Rico C. , Turner G. F. 
Published: March 2003

AbstractWe demonstrate significant population structuring on an extremely small spatial scale between adjacent demes of a Lake Malawi haplochromine cichlid species of the mbuna group, Pseudotropheus callainos, separated by only 35 m of habitat discontinuity. This substantiates further the notion that intralacustrine allopatric divergence may help to explain the high level of species richness of the mbuna in comparison to other Malawian cichlids, as well as of the Malawian haplochromines as a whole.