bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stream‐bank shade and larval distribution of the Philippine malaria vector Anopheles flavirostris
Authors: Foley D. H. , Torres E. P. , Mueller I. 
Published: March 2003

Abstract The principal malaria vector in the Philippines, Anopheles flavirostris (Ludlow) (Diptera: Culicidae), is regarded as ‘shade‐loving’ for its breeding sites, i.e. larval habitats. This long‐standing belief, based on circumstantial observations rather than ecological analysis, has guided larval control methods such as ‘stream‐clearing’ or the removal of riparian vegetation, to reduce the local abundance of An. flavirostris. We measured the distribution and abundance of An. flavirostris larvae in relation to canopy vegetation cover along a stream in Quezon Province, the Philippines. Estimates of canopy openness and light measurements were obtained by an approximation method that used simplified assumptions about the sun, and by hemispherical photographs analysed using the program hemiphot©. The location of larvae, shade and other landscape features was incorporated into a geographical information system (GIS) analysis.Early larval instars of An. flavirostris were found to be clustered and more often present in shadier sites, whereas abundance was higher in sunnier sites. For later instars, distribution was more evenly dispersed and only weakly related to shade. The best predictor of late‐instar larvae was the density of early instars. Distribution and abundance of larvae were related over time (24 days). This pattern indicates favoured areas for oviposition and adult emergence, and may be predictable. Canopy measurements by the approximation method correlated better with larval abundance than hemispherical photography, being economical and practical for field use.Whereas shade or shade‐related factors apparently have effects on larval distribution of An. flavirostris, they do not explain it completely. Until more is known about the bionomics of this vector and the efficacy and environmental effects of stream‐clearing, we recommend caution in the use of this larval control method.
Peer‐reviewed publication following presentation at a regional surgical meeting
Authors: Bowrey David J , Morris‐Stiff Gareth J , Clark Geoffrey W B , Carey P Declan , Mansel Robert E 
Published: March 2003

Objectives The aim of the study was to investigate the proportion of publications arising from work presented at a regional surgical meeting.Design A list of all presentations to the Welsh Surgical Society 1983–95 was compiled and a detailed search made of the Medline Database. The surgical topic of each presentation, the date of presentation, the date of publication and the journal of publication were recorded.Setting University Hospital of Wales.Results Four hundred and ninety‐six papers were presented to the society, of which 402 (81%) were by trainees. The most frequent topics of presentation were colorectal (15%), vascular (15%) and hepato–pancreatico–biliary (11%). Two hundred and thirty‐three papers (47%) have been published in peer‐reviewed journals. The most popular journals for publication were Annals of the Royal College of Surgeons of England (19%), British Journal of Surgery (16%) and Journal of the Royal College of Surgeons of Edinburgh (8%). The median time from presentation to publication was 17·0 months (interquartile range 10·0–27·5 months).Conclusions Regional surgical meetings have an important role in the annual surgical calendar and they are the ideal initial setting for presentation by trainees.
Phylogeography of North American populations of the moss species Hylocomium splendens based on the nucleotide sequence of internal transcribed spacer 2 of nuclear ribosomal DNA
Authors: Chiang T. Y. , Schaal B. A. 
Published: March 2003

AbstractSequence variation of the internal transcribed sequence 2 (ITS2) region of nuclear ribosomal DNA (nrDNA) was investigated in 10 North American populations of Hylocomium splendens. Cladistic analyses supported the monophyly of this moss species, rooted at Hylocomiastrum and Neodolichomitra. Three geographically based groups (Great Lakes Forest, Appalachian Mountains, and Pacific Northwest) were identified by a minimum spanning network. Significant genetic differentiation was detected (FST = 0.197 − 0.390) among three geographical regions in North America. Although high genetic divergence exists within H. splendens, these results do not suggest sufficient divergence for designating sibling species.
Canonical correspondence analysis for estimating spatial and environmental effects on microsatellite gene diversity in brook charr (Salvelinus fontinalis)
Authors: Angers Bernard , Magnan Pierre , Plante Michel , Bernatchez Louis 
Published: March 2003

AbstractThe understanding of the relationships between environmental factors and evolutionary forces is of importance to preserve opportunities for the continuation of dynamic evolutionary and ecological processes. This involves the identification and quantification of the relative importance of environmental factors that may influence these processes. Nevertheless, environmental factors are generally interpreted in terms of hypothetical inferences as relationships between environmental and genetic variables are often difficult to quantify. In this study, we used a statistical framework based on canonical correspondence analysis in order to determine the relative contribution of drainage pattern and environmental factors in structuring inter‐ and intrapopulational genetic diversity among brook charr populations as depicted by microsatellite analysis. These procedures simultaneously analyse several sets of variables and determine their relative contribution. The results revealed the influence of drainage pattern, altitude and human‐induced factors on the pattern of genetic diversity and, particularly, the important role of historical events in explaining patterns of contemporary genetic diversity among populations. The statistical framework used in this study provides an efficient way to empirically relate variations of genetic diversity and descriptive variables in general.
Microsatellite and morphological analysis of population structure in the parthenogenetic freshwater snailMelanoides tuberculata: insights into the creation of clonal variability
Authors: Samadi S. , Mavárez J. , Pointier J.‐P. , Delay B. , Jarne P. 
Published: March 2003

AbstractThe distribution of variability was studied at various geographical scales in the tropical freshwater snailMelanoides tuberculata, in order to analyse the role of factors shaping this distribution, including the mating system and population dynamics. This parthenogenetic polyploid species reproduces mainly asexually, with males occurring at low frequency. About 800 individuals (38 sites) were sampled from Africa and the Middle East, where the species originated, and from recently colonized habitats in South and Central America, and especially the island of Martinique. We first described variation of general aspects and ornamentation of the shells. This analysis confirms the existence of discrete morphs. Second, individuals were studied at three microsatellite loci, showing that each morph is a genetic clone with some minor variation compatible with models of microsatellite evolution. The genetic analysis also showed much more variation within than between clones. However, two populations from Africa exhibited a large amount of variability, and a mixture of sexual and asexual reproduction might explain these genetic patterns. The worldwide distribution of variability is, therefore, compatible with the African origin of the species, and the introduction of a few clones in other parts of the world. These results also suggest that the distribution of variability in Martinique is influenced by flooding events, and that two morphs from Martinique can be interpreted as hybrids between two pre‐existing morphs, based on morphological, genetic and geographical arguments.
Microsatellites reveal clonal structure of populations of the thelytokous ant Platythyrea punctata (F. Smith) (Hymenoptera; Formicidae)
Authors: Schilder K. , Heinze J. , Gross R. , Hölldobler B. 
Published: March 2003

AbstractParthenogenesis is often thought to constitute an evolutionary dead end as compared with sexual reproduction because genetic recombination is limited or nonexistent in parthenogenetic populations. Yet there are many species to demonstrate that parthenogenesis can initially be extremely successful under certain environmental conditions. In this study we used microsatellite markers to investigate the genetic structure of four natural populations of the neotropical thelytokous parthenogenetic ant Platythyrea punctata. Ten dinucleotide microsatellites were isolated from a partial genomic library of P. punctata. Five of these were found to be polymorphic. In a subsequent analysis of 314 workers taken from 51 colonies, we detected low intraspecific levels of variation at all loci, expressed both in the number of alleles detected and heterozygosities observed. Surprisingly, we found almost no differentiation within populations. Populations rather had a clonal structure, with all individuals from all colonies usually sharing the same genotype. Only in one colony from Puerto Rico did some workers have an additional genotype. This low level of genotypic diversity probably reflects the predominance of thelytoky in P. punctata, together with genetic bottlenecks and founder effects. Cross‐species amplification of all 10 loci in 29 ant species comprising four different subfamilies yielded positive amplification products in only a limited number of species.
Intraspecific phylogeography ofLasmigona subviridis(Bivalvia: Unionidae): conservation implications of range discontinuity
Authors: King Tim L. , Eackles Michael S. , Gjetvaj Branimir , Hoeh Walter R. 
Published: March 2003

AbstractA nucleotide sequence analysis of the first internal transcribed spacer region (ITS‐1) between the 5.8S and 18S ribosomal DNA genes (640 bp) and cytochromecoxidase subunit I (COI) of mitochondrial DNA (mtDNA) (576 bp) was conducted for the freshwater bivalveLasmigona subviridisand three congeners to determine the utility of these regions in identifying phylogeographic and phylogenetic structure. Sequence analysis of the ITS‐1 region indicated a zone of discontinuity in the genetic population structure between a group ofL. subviridispopulations inhabiting the Susquehanna and Potomac Rivers and more southern populations. Moreover, haplotype patterns resulting from variation in the COI region suggested an absence of gene exchange between tributaries within two different river drainages, as well as between adjacent rivers systems. The authors recommend that the northern and southern populations, which are reproductively isolated and constitute evolutionarily significant lineages, be managed as separate conservation units. Results from the COI region suggest that, in some cases, unionid relocations should be avoided between tributaries of the same drainage because these populations may have been reproductively isolated for thousands of generations. Therefore, unionid bivalves distributed among discontinuous habitats (e.g. Atlantic slope drainages) potentially should be considered evolutionarily distinct. The DNA sequence divergences observed in the nuclear and mtDNA regions among theLasmigonaspecies were congruent, although the level of divergence in the COI region was up to three times greater. The genusLasmigona, as represented by the four species surveyed in this study, may not be monophyletic.
Phylogeography of the California mountain kingsnake,Lampropeltis zonata(Colubridae)
Authors: Rodríguez‐Robles Javier A. , DeNardo Dale F. , Staub Richard E. 
Published: March 2003

AbstractThe phylogeography of the California mountain kingsnake,Lampropeltis zonata, was studied using mitochondrial DNA sequences from specimens belonging to the seven recognized subspecies and collected throughout the range of the species. Maximum parsimony and maximum likelihood methods identified a basal split withinL. zonatathat corresponds to southern and northern segments of its distribution. The southern clade is composed of populations from southern California (USA) and northern Baja California, Mexico. The northern clade is divided into two subclades, a ‘coastal’ subclade, consisting of populations from the central coast of California and the southern Sierra Nevada Mountains of eastern California, and a ‘northeastern’ subclade, mainly comprised of populations north of the San Francisco Bay and from the majority of the Sierra Nevada. We suggest that past inland seaways in southwestern California and the embayment of central California constituted barriers to gene flow that resulted in the two deepest divergences withinL. zonata. Throughout its evolutionary history, the northern clade apparently has undergone instances of range contraction, isolation, differentiation, and then expansion and secondary contact. Examination of colour pattern variation in 321 living and preserved specimens indicated that the two main colour pattern characters used to define the subspecies ofL. zonataare so variable that they cannot be reliably used to differentiate taxonomic units within this complex, which calls into question the recognition of seven geographical races of this snake.
Species relationships and population structure ofLittorina saxatilisOlivi andL. tenebrosaMontagu in Ireland using single‐strand conformational polymorphisms (SSCPs) of cytochromebfragments
Authors: Small M. P. , Gosling E. M. 
Published: March 2003

AbstractLittorina saxatilisis a ubiquitous snail of intertidal habitats in the North Atlantic. Shell type in littorinids is extremely polymorphic and defined by habitat. Taxonomy based upon shell type has been revised in the light of anatomic and genetic information, but uncertainties remain. In this study, the population structure ofL. saxatilisandL. tenebrosawas studied at 11 sites in Ireland using single‐strand conformational polymorphisms of a 375‐bp portion of the cytochromebgene, and the status ofL. tenebrosa, the small, fragile‐shelled, brackish water type, was considered. The genetic patterns amongL. saxatilis andL. tenebrosapopulations were examined over varying distances andL. tenebrosawas compared with adjacentL. saxatilispopulations at four sites on the west coast of Ireland and one site on the east coast. Haplotype diversity was high with 32 haplotypes present among 995 individuals. Pairwise tests suggest gene flow over small scales among and between habitat types and may reflect the stochastic legacy of postglacial recolonization over larger scales. Inamovatests, geography explained nearly twice as much of the variance (30%) as habitat type (18%), indicating that gene flow is more restricted by distance than by habitat type, and supporting the status ofL. tenebrosaas an ecotype ofL. saxatilisrather than a separate species.
Mitochondrial DNA (mtDNA) reveals that female Bechstein’s bats live in closed societies
Authors: Kerth Gerald , Mayer Frieder , König Barbara 
Published: March 2003

AbstractWe present a microgeographic analysis of mitochondrial DNA (mtDNA) in Bechstein’s bats using three sources of control region sequence variability, including a novel mtDNA microsatellite, to assess individual relatedness both within and among 10 maternity colonies. Comparison of marker variability among 268 adult females revealed little genetic variability within each colony. However, most colonies were clearly distinguished by colony‐specific mitochondrial haplotypes (total n = 28). Low intracolony variability and strong haplotype segregation among colonies, was reflected by an extraordinary high FST of 0.68, indicating a very low intercolony dispersal rate of approximately one female in five generations. Haplotype distribution among 18 solitary males showed that males frequently disperse between colony locations, indicating the absence of dispersal barriers. Bechstein’s bat maternity colonies are thus closed groups that comprise 20–40 females probably belonging to only one or, at most, two matrilines. The genetic population structure of Bechstein’s bats is in agreement with the hypothesis that females seek familiar and, at least, partially related cooperation partners for raising their young. Alternatively strong philopatry might reflect the importance of profound roost or habitat knowledge for successful reproduction in female Bechstein’s bats.
Population structure of long‐finned pilot whales in the North Atlantic: a correlation with sea surface temperature?
Authors: Fullard K. J. , Early G. , Heide‐Jørgensen M. P. , Bloch D. , Rosing‐Asvid A. , Amos W. 
Published: March 2003

AbstractThe long‐finned pilot whale,Globicephala melas, is a social, pelagic odontocete distributed widely in the cold temperate waters of the North Atlantic. Despite genetic, morphometric, physiological and observational studies, it remains unclear whether any population substructure exists. We have used eight highly polymorphic microsatellite loci to analyse samples from four disparate sampling sites: USA East Coast (Cape Cod), West Greenland, the Faeroe Islands and the UK. Our results indicate that substructure does exist, and is particularly pronounced between West Greenland and other sites. The magnitudes of the various pairwise comparisons do not support a simple isolation‐by‐distance model. Instead, the patterns of genetic differentiation suggest that population isolation occurs between areas of the ocean which differ in sea surface temperature. Such a mechanism is supported by the observation that temperature is a primary factor determining the relative distributions of two short‐finned pilot whale (G. macrorhynchus) populations off the Pacific coast of Japan.
Examination of species boundaries in theAcropora cervicornisgroup (Scleractinia, Cnidaria) using nuclear DNA sequence analyses
Authors: Oppen M. J. H. Van , Willis B. L. , Vugt H. W. J. A. Van , Miller D. J. 
Published: March 2003

AbstractAlthoughAcroporais the most species‐rich genus of the scleractinian (stony) corals, only three species occur in the Caribbean:A. cervicornis,A. palmataandA. prolifera. Based on overall coral morphology, abundance and distribution patterns, it has been suggested thatA. proliferamay be a hybrid betweenA. cervicornisandA. palmata. The species boundaries among these three morphospecies were examined using DNA sequence analyses of the nuclearPax‐C46/47 intron and the ribosomal DNA Internal Transcribed Spacer (ITS1 and ITS2) and 5.8S regions. Moderate levels of sequence variability were observed in the ITS and 5.8S sequences (up to 5.2% overall sequence difference), but variability within species was as large as between species and all three species carried similar sequences. Since this is unlikely to represent a shared ancestral polymorphism, the data suggest that introgressive hybridization occurs among the three species. For thePax‐Cintron,A. cervicornisandA. palmatahad very distinct allele frequencies andA. cervicorniscarried a unique allele at a frequency of 0.769 (although sequence differences between alleles were small). AllA. proliferacolonies examined were heterozygous for thePax‐Cintron, whereas heterozygosity was only 0.286 and 0.333 forA. cervicornisandA. palmata, respectively. These data support the hypothesis thatA. proliferais the product of hybridization between two species that have a different allelic composition for thePax‐Cintron, i.e.A. cervicornisandA. palmata. We therefore suggest thatA. proliferais a hybrid betweenA. cervicornisandA. palmata, which backcrosses with the parental species at low frequency.
The comparative phylogeography of Neotropical mammals: patterns of intraspecific mitochondrial DNA variation among bats contrasted to nonvolant small mammals
Authors: Ditchfield A. D. 
Published: March 2003

AbstractThe major aim of this study was to compare the phylogeographic patterns of codistributed bats and small nonvolant Neotropical mammals. Cytochrome b sequences (mitochondrial DNA) were obtained for a total of 275 bats representing 17 species. The tissue samples were collected in coastal Brazil, and were available from Mexico and the Guyana. The study concentrates on four species (Artibeus lituratus, Carollia perspicillata, Sturnira lilium and Glossophaga soricina) which were well represented. The other 13 species were sequenced to test the generality of the patterns observed. In general, sequence divergence values within species were low, with most bat species presenting less than 4% average sequence divergence, and usually between 1 and 2.5%. Clades of highly similar haplotypes enjoyed broad distribution on a continental scale. These clades were not usually geographically structured, and at a given locality the number of haplotypes was high (8–10). As distance increased, some moderately divergent clades were found, although the levels of divergence were low. This suggests a geographical effect that varied depending on species and scale. Small nonvolant mammals almost invariably have high levels of sequence divergence (> 10%) for cytochrome b over much shorter distances (< 1000 km). The grain of intraspecific variation found in small nonvolant mammals is much finer than in bats. Low levels of geographical structuring cannot be attributed to a slower evolutionary rate of bat DNA in relation to other mammalian taxa. The phylogeographic pattern of bats contrasts sharply with the pattern found for Neotropical rodents and marsupials.
Mitochondrial DNA phylogeography of Acrossocheilus paradoxus (Cyprinidae) in Taiwan
Authors: Wang J. P. , Hsu K. C. , Chiang T. Y. 
Published: March 2003

AbstractNucleotide sequences of 3′ end of the cytochrome b gene, tRNA genes, D‐loop control region, and the 5′ end of the 12S rRNA of mitochondrial DNA (mtDNA) were used to assess the genetic and phylogeographic structure of Acrossocheilus paradoxus populations, a Cyprinidae fish of Taiwan. A hierarchical examination of populations in 12 major streams from three geographical regions using an analysis of molecular variance (
amova) indicates high genetic differentiation both among populations (ΦST = 0.511, P < 0.001) and among regions (ΦCT = 0.368, P < 0.001). Limited migration largely contributed to the genetic differentiation. High nucleotide diversity (1.13%) and haplotype diversity (0.80%) were detected among populations. The degree of genetic differentiation was correlated with geographical distance between populations, a result consistent with the one‐dimensional stepping stone models. A neighbour‐joining tree recovered by (
dambe) supports the pattern of isolation by distance and reveals a closer relationship between populations of the central and southern regions. A minimum spanning network based on nucleotide substitutions reflected migration routes from populations of the central region to the northern and southern regions, respectively. Postglacial colonization and expansion can explain the phylogeographical pattern. Single and ancient migration events may have allowed the northern region to attain the monophyly of mtDNA alleles. In contrast, most populations within geographical regions are either paraphyletic or polyphyletic due to the relatively shorter time period for coalescence. Both low haplotype number and genetic variability suggest a bottleneck event in the Chingmei population of northern Taiwan. Based on coalescence theory, the monophyly of the Tungkang population of the southern region may be associated with a founder event.