bluuebunny/crossref_metadata_2025_split huggingface dataset:
Combining paternally and maternally inherited mitochondrial DNA for analysis of population structure in mussels
Authors: Krebs Robert A. 
Published: May 2004

AbstractSequence divergence for a fragment of the 16S rRNA gene was compared to identify the advantages in using mitochondrial genes that descend separately through the female and male lineages to examine population structure. The test compared divergence among four local species of freshwater mussels (Unionidae) and was extended to multiple populations of one species, Pyganodon grandis. For the same gene, the male‐inherited sequences diverged at a faster rate, producing longer branch lengths in the phylogenies. Of particular use were sequences extracted from P. grandis populations from the southern region of the Lake Erie watershed (Ohio, USA); five male‐inherited haplotypes were found. Only one change was observed in the female‐inherited form in this region. Therefore, more rapid evolution has occurred in the male form of the gene, and this form provided stronger evidence of geographical isolation among populations. A combination of analyses on haplotypes derived through males and females creates complementary opportunities to identify evolutionary relationships caused by drift and migration in mussels.
Genetic diversity in Tetrachaetum elegans, a mitosporic aquatic fungus
Authors: Laitung Beryl , Chauvet Eric , Feau Nicolas , Fève Katia , Chikhi Lounès , Gardes Monique 
Published: May 2004

Abstract Tetrachaetum elegans Ingold is a saprobic aquatic hyphomycete for which no sexual stage has yet been described. It occurs most commonly during the initial decay of tree leaves in temperate freshwater habitats and typically sporulates under water. Dispersal of the aquatic fungus takes place primarily in the water column and has a large passive component. Differences in substrate composition (e.g. quality of leaf litter) may also play a role in the distribution of different species or genotypes. The population genetic structure of T. elegans was studied using amplified fragment length polymorphism (AFLP) multilocus fingerprints. The populations were isolated from the leaf litter of three different tree genera, sampled in nine streams distributed throughout a mixed deciduous forest. Molecular markers were developed for 97 monosporic isolates using four selective primer pairs. A total of 247 fragments were scored, of which only 32 were polymorphic. Significant stream differentiation was detected for the isolates considered in this study. Analysis of molecular variance revealed that 20% of the genetic variation observed was the result of differences between streams. No correlation between genetic and geographical distances was found but a few multilocus genotypes were observed in different locations. Altogether these results suggest that environmental barriers play a role in the population structure of this aquatic fungus. No clear‐cut effect of leaf litter composition on genetic variation could be demonstrated. Finally, tests of linkage disequilibrium between the 32 polymorphic AFLP loci as well as simulations did not provide a final answer regarding clonality in T. elegans. Indeed, it was possible to reject linkage equilibrium at different sampling levels and show that full linkage was unlikely.
Habitat age, breeding system and kinship in the antFormica fusca
Authors: Hannonen Minttumaaria , Helanterä Heikki , Sundström Liselotte 
Published: May 2004

AbstractIn polygyne ants (multiple queens per colony) factors that affect the distribution and survival of queens may play a key role in shaping the population‐wide mating system and colony kin structure. The aim of this paper was to study the breeding system in two populations of different age in the facultatively polygyne antFormica fusca.Both the observed numbers of queens, and the relatedness patterns among queens, workers and colony fathers were compared in two adjacent populations (ages 17 years and > 100 years) in Southern Finland. The results showed that both the mating system and colony kin structure differed between the study populations. In the old population the relatedness among workers, queens and colony fathers was high. The queens were also related to their mates, resulting in significant inbreeding in workers, but not in queens. Finally, the number of queens per colony fluctuated between years, suggesting queen turnover, and nest‐mate queens shared their reproduction unequally (reproductive skew). In the younger population relatedness among queens and workers was lower than in the old population, and the colony fathers were unrelated. Furthermore, inbreeding was absent, and no conclusive evidence was found for reproductive skew among nest‐mate queens. Finally, the number of queens per colony appeared more stable between years, although queen turnover occurred also in this population. The observed differences in dispersal and mating behaviour are discussed in the light of a potential connection between population age and habitat saturation.
Genetic evidence for sex‐biased dispersal in resident bottlenose dolphins (Tursiops aduncus)
Authors: Möller Luciana M. , Beheregaray Luciano B. 
Published: May 2004

AbstractIn most mammals males usually disperse before breeding, while females remain in their natal group or area. However, in odontocete cetaceans behavioural and/or genetic evidence from populations of four species indicate that both males and females remain in their natal group or site. For coastal resident bottlenose dolphins field data suggest that both sexes are philopatric to their natal site. Assignment tests and analyses of relatedness based on microsatellite markers were used to investigate this hypothesis in resident bottlenose dolphins, Tursiops aduncus, from two small coastal populations of southeastern Australia. Mean corrected assignment and mean relatedness were higher for resident females than for resident males. Only 8% of resident females had a lower probability than average of being born locally compared to 33% of resident males. Our genetic data contradict the hypothesis of bisexual philopatry to natal site and suggest that these bottlenose dolphins are not unusual amongst mammals, with females being the more philopatric and males the more dispersing sex.
Prevalence of interspecific hybrids amongst asexual fungal endophytes of grasses
Authors: Moon C. D. , Craven K. D. , Leuchtmann A. , Clement S. L. , Schardl C. L. 
Published: May 2004

Abstract Epichloë endophytes are fungal symbionts of grasses that span a continuum including asexual mutualists that are vertically transmitted, obligately sexual pathogens that are horizontally transmitted, and mixed‐strategy symbionts with both mutualistic and pathogenic capabilities. Here we show that processes of genome evolution differ markedly for the different symbiont types. Genetic and phylogenetic analysis was conducted of a broad taxonomic, ecological and geographical sample of sexual and asexual isolates, in which were identified and sequenced alleles of genes for β‐tubulin (tub2) and translation elongation factor 1‐α (tef1), and microsatellite alleles were identified by length polymorphisms. The majority of asexual isolates had two or three alleles of most loci, but every sexual isolate had only single alleles for each locus. Phylogenetic analysis of tub2 and tef1 indicated that in all instances of multiple alleles in an isolate, the alleles were derived from different sexual species. It is concluded that, whereas horizontally transmissible species had haploid genomes and speciation occurred cladistically, most of the strictly seedborne mutualists were interspecific hybrids with heteroploid (aneuploid or polyploid) genomes. Furthermore, the phylogenetic evidence indicated that, in at least some instances, hybridization followed rather than caused evolution of the strictly seedborne habit. Therefore, the abundance of hybrid species among grass endophytes, and their prevalence in many host populations suggests a selective advantage of hybridization for the mutualistic endophytes.
Ecological determinants of genetic diversity in an expanding population of the shrub Myrica cerifera
Authors: Erickson David L. , Hamrick J. L. , Kochert Gary D. 
Published: May 2004

AbstractThe ecological mechanisms that contribute to the acquisition of genetic diversity in an expanding population of the shrub, Myrica cerifera, on an island habitat were investigated. Genealogical reconstruction was used to assess the contribution of early reproductive colonists to subsequent recruitment. In addition, through determination of parentage, the source of recruiting seedlings was identified and the contribution of seed and pollen dispersal into the colonizing sites was inferred. The relative contribution of different sources of gene flow was determined directly and an investigation was made into how variability in breeding patterns may have contributed to observed levels of genetic variability. It was expected that early colonists that could flower would contribute to subsequent recruiting cohorts, and that the limited number of such early reproductive colonists would lead to variance in mating success, inbreeding, or bottlenecks which could reduce genetic diversity and increase genetic differentiation among subsequent recruiting cohorts. Analyses of parentage (with paternity exclusion probability > 95%) for all recruiting plants demonstrated that in fact, there was little contribution by the early reproductive colonists to subsequent cohorts, and that immigration from outside the study sites in the form of seed dispersal accounted for over 94% of the recruitment in the study plots, with pollen dispersal accounting for less than 3% gene flow. No genetic bottleneck or evidence of reproductive skew in the recruiting cohorts were found, suggesting that propagule dispersal was from many source individuals in other established populations.
Mitochondrial DNA phylogeography of western lowland gorillas (Gorilla gorilla gorilla)
Authors: Clifford Stephen L. , Anthony Nicola M. , Bawe‐Johnson Mireille , Abernethy Kate A. , Tutin Caroline E. G. , White Lee J. T. , Bermejo Magdelena , Goldsmith Michelle L. , McFarland Kelley , Jeffery Kathryn J. , Bruford Michael W. , Wickings E. Jean 
Published: May 2004

AbstractThe geographical distribution of genetic variation within western lowland gorillas (Gorilla gorilla gorilla) was examined to clarify the population genetic structure and recent evolutionary history of this group. DNA was amplified from shed hair collected from sites across the range of the three traditionally recognized gorilla subspecies: western lowland (G. g. gorilla), eastern lowland (G. g. graueri) and mountain (G. g. beringei) gorillas. Nucleotide sequence variation was examined in the first hypervariable domain of the mitochondrial control region and was much higher in western lowland gorillas than in either of the other two subspecies. In addition to recapitulating the major evolutionary split between eastern and western lowland gorillas, phylogenetic analysis indicates a phylogeographical division within western lowland gorillas, one haplogroup comprising gorilla populations from eastern Nigeria through to southeast Cameroon and a second comprising all other western lowland gorillas. Within this second haplogroup, haplotypes appear to be partitioned geographically into three subgroups: (i) Equatorial Guinea, (ii) Central African Republic, and (iii) Gabon and adjacent Congo. There is also evidence of limited haplotype admixture in northeastern Gabon and southeast Cameroon. The phylogeographical patterns are broadly consistent with those predicted by current Pleistocene refuge hypotheses for the region and suggest that historical events have played an important role in shaping the population structure of this subspecies.
Tracing back seed and pollen flow within the crop–wild Beta vulgaris complex: genetic distinctiveness vs. hot spots of hybridization over a regional scale
Authors: Viard Frédérique , Arnaud Jean‐François , Delescluse Maxime , Cuguen Joël 
Published: May 2004

AbstractHybrids between transgenic crops and wild relatives have been documented successfully in a wide range of cultivated species, having implications on conservation and biosafety management. Nonetheless, the magnitude and frequency of hybridization in the wild is still an open question, in particular when considering several populations at the landscape level. The Beta vulgaris complex provides an excellent biological model to tackle this issue. Weed beets contaminating sugar beet fields are expected to act as a relay between wild populations and crops and from crops‐to‐crops. In one major European sugar beet production area, nine wild populations and 12 weed populations were genetically characterized using cytoplasmic markers specific to the cultivated lines and nuclear microsatellite loci. A tremendous overall genetic differentiation between neighbouring wild and weed populations was depicted. However, genetic admixture analyses at the individual level revealed clear evidence for gene flow between wild and weed populations. In particular, one wild population displayed a high magnitude of nuclear genetic admixture, reinforced by direct seed flow as evidenced by cytoplasmic markers. Altogether, weed beets were shown to act as relay for gene flow between crops to wild populations and crops to crops by pollen and seeds at a landscape level.
Genetic evidence reveals density‐dependent mediated success of alternative mating behaviours in the European bitterling (Rhodeus sericeus)
Authors: Reichard M. , Smith C. , Jordan W. C. 
Published: May 2004

AbstractThe reproductive success of alternative mating behaviours may vary within and among populations in relation to environmental factors and demographic parameters. We used behavioural and genetic data to investigate how male density affects reproductive success of territoriality and sneaking in the European bitterling (Rhodeus sericeus, Cyprinidae), a freshwater fish that spawns on the gills of living freshwater mussels. Keeping the number of spawning sites constant, we manipulated male densities in laboratory and mesocosm experiments. We showed that sneaked fertilizations were common in R. sericeus, and that they increased significantly with male density. Territorial mating was almost 17 times more successful than sneaking at the lowest male density treatment, and still 2–3 times more successful at intermediate densities. However, both behaviours conferred the same fitness pay‐off at the highest male density. While the success of territorial males declined with male density, the success of individual sneaking males remained constant across densities. Notably, the capacity of territorial males to outcompete sneakers by preoviposition sperm loading was the best predictor of male reproductive success, rather than aggression, body size or postoviposition ejaculation.
Accuracy, efficiency and robustness of four algorithms allowing full sibship reconstruction from DNA marker data
Authors: Butler K. , Field C. , Herbinger C. M. , Smith B. R. 
Published: May 2004

AbstractIn the problem of reconstructing full sib pedigrees from DNA marker data, three existing algorithms and one new algorithm are compared in terms of accuracy, efficiency and robustness using real and simulated data sets. An algorithm based on the exclusion principle and another based on a maximization of the Simpson index were very accurate at reconstructing data sets comprising a few large families but had problems with data sets with limited family structure, while a Markov Chain Monte Carlo (MCMC) algorithm based on the maximization of a partition score had the opposite behaviour. An MCMC algorithm based on maximizing the full joint likelihood performed best in small data sets comprising several medium‐sized families but did not work well under most other conditions. It appears that the likelihood surface may be rough and presents challenges for the MCMC algorithm to find the global maximum. This likelihood algorithm also exhibited problems in reconstructing large family groups, due possibly to limits in computational precision. The accuracy of each algorithm improved with an increasing amount of information in the data set, and was very high with eight loci with eight alleles each. All four algorithms were quite robust to deviation from an idealized uniform allelic distribution, to departures from idealized Mendelian inheritance in simulated data sets and to the presence of null alleles. In contrast, none of the algorithms were very robust to the probable presence of error/mutation in the data. Depending upon the type of mutation or errors and the algorithm used, between 70 and 98% of the affected individuals were classified improperly on average.
Polyandry and fitness in the western harvester ant,Pogonomyrmex occidentalis
Authors: Wiernasz Diane C. , Perroni Christina L. , Cole Blaine J. 
Published: May 2004

AbstractUsing four highly polymorphic microsatellite markers (12–28 alleles), we gentoyped workers from 63 colonies ofPogonomyrmex occidentalis. Colonies have a single, multiply mated queen, and an average number of 6.3 patrilines per colony. Colony growth was measured over an 8‐year period in the study population. Intracolonial relatedness and colony growth are correlated negatively, indicating a substantial fitness benefit to multiple mating.
Hybridization and asymmetric reproductive isolation between the closely related bryophyte taxa Polytrichum commune and P. uliginosum
Authors: Van Der Velde M. , Bijlsma R. 
Published: May 2004

AbstractBased on genetic differentiation, the haploid dioecious bryophyte taxa Polytrichum commune and P. uliginosum have been inferred to be completely reproductively isolated. However, analysing diploid sporophytes from a sympatric population for three diagnostic microsatellite markers, we show here that reproductive isolation between these taxa is far more complex and highly asymmetric. Isolation between ♀‐P. commune×♂‐P. uliginosum seems to be complete and prezygotic (or early postzygotic) as no hybrid sporophytes were observed on P. commune females. In the other direction (♀‐P. uliginosum×♂‐P. commune) isolation was clearly postzygotic as high frequencies of hybrid sporophytes were found on P. uliginosum females. However, during maturation these sporophytes showed irregular development, indicating that hybrid sporophytes are unlikely to produce ripe spores. Mechanisms possibly underlying this asymmetric reproductive isolation pattern are discussed. Notwithstanding hybrid offspring being unlikely, the high frequency of hybrid sporophytes observed suggests that viable spores may be formed occasionally through such rare processes as chromosome nondisjunction, possibly giving rise to allodiploids. Allodiploids have been reported in Polytrichum (and other bryophyte genera). Studies such as the one presented here will therefore help to elucidate the evolutionary importance of interspecific hybridization and allodiploidization in bryophyte speciation.
Adaptive divergence vs. environmental plasticity: tracing local genetic adaptation of metamorphosis traits in salamanders
Authors: Weitere Markus , Tautz Diethard , Neumann Dietrich , Steinfartz Sebastian 
Published: May 2004

AbstractIn order to assess the significance of local adaptation relative to environmental plasticity on the evolution of life history traits, we analysed the possible genetic basis of differences between pond‐ and stream‐breeding fire salamanders (Salamandra salamandra) in Germany. These salamanders typically deposit their larvae in small streams, where they grow until they are sufficiently large to metamorphose. However, some populations in Western Germany use ponds as larval habitat. Because habitat quality of streams differs from that of ponds one expects life history differences in the pond animals, which may result either from a plastic response or through genetic differentiation (i.e. local adaptation). Using a phylogeographical analysis of mitochondrial D‐loop sequences, we show that both stream and pond populations in Western Germany are derived from a single lineage that recolonized following the last glaciation. This finding suggests that pond breeding originated very recently. Our studies of habitat quality and metamorphic behaviour of larvae in natural ponds and streams disclosed that pond larvae experience a significantly reduced food supply and greater risk of drying than do stream larvae. Pond larvae metamorphose earlier at the cost of reduced mass. Common‐environment experiments with pond and stream larvae show that metamorphic behaviour of pond larvae under limited‐food conditions is determined genetically and is not simply a plastic response to the differing habitat conditions. These results show that phenotypic plasticity is less important than local adaptation in explaining differences in ecological diversification within this species and suggests the possibility of rapid evolution of genetic adaptations when new habitats are exploited.
Genetic detection of sex‐specific dispersal in historical and contemporary populations of anadromous brown trout Salmo trutta
Authors: Bekkevold Dorte , Hansen Michael M. , Mensberg Karen‐Lise D. 
Published: May 2004

AbstractThe study of sex‐biased dispersal has attracted considerable attention in birds and mammals, but less in other taxa, including fishes. We analysed sex‐specific dispersal in historical (1910s and 1950s) and contemporary (1990s) samples of anadromous brown trout Salmo trutta. We tested the hypothesis that dispersal is unbiased using information from microsatellite DNA and applying an assignment index for 11 temporally and spatially separated samples. Our results are most consistent with brown trout dispersal being male biased, and provide no evidence of female bias. We found no evidence that dispersal patterns changed over time, indicating that stocking with hatchery strains did not affect sex‐specific dispersal.
Mitochondrial phylogeography of the moor frog, Rana arvalis
Authors: Babik W. , Branicki W. , Sandera M. , Litvinchuk S. , Borkin L. J. , Irwin J. T. , Rafiński J. 
Published: May 2004

AbstractThe moor frog Rana arvalis is a lowland species with a broad Eurasiatic distribution, from arctic tundra through forest to the steppe zone. Its present‐day range suggests that glacial refugia of this frog were located outside southern European peninsulas. We studied the species‐wide phylogeographical pattern using sequence variation in a 682 base pairs fragment of mtDNA cytochrome b gene; 223 individuals from 73 localities were analysed. Two main clades, A and B, differing by c. 3.6% sequence divergence were detected. The A clade is further subdivided into two subclades, AI and AII differing by 1.0%. All three lineages are present in the Carpathian Basin (CB), whereas the rest of the species range, including huge expanses of Eurasian lowlands, are inhabited solely by the AI lineage. We infer that AII and B lineages survived several glacial cycles in the CB but did not expand, at least in the present interglacial, to the north. The geographical distribution and genealogical relationships between haplotypes from the AI lineage indicate that this group had two glacial refugia, one located in the eastern part of the CB and the other probably in southern Russia. Populations from both refugia contributed to the colonization of the western part of the range, whereas the eastern part was colonized from the eastern refugium only. The effective population size as evidenced by θML is an order of magnitude higher in the AI lineage than in the AII and B lineages. Demographic expansion was detected in all three lineages.