bluuebunny/crossref_metadata_2025_split huggingface dataset:
INVITED REVIEW: Local adaptation and species segregation in two mussel (Mytilus edulis × Mytilus trossulus) hybrid zones
Authors: RIGINOS C. , CUNNINGHAM C. W. 
Published: January 2005

AbstractFew marine hybrid zones have been studied extensively, the major exception being the hybrid zone between the mussels Mytilus edulis and Mytilus galloprovincialis in southwestern Europe. Here, we focus on two less studied hybrid zones that also involve Mytilus spp.; Mytilus edulis and Mytilus trossulus are sympatric and hybridize on both western and eastern coasts of the Atlantic Ocean. We review the dynamics of hybridization in these two hybrid zones and evaluate the role of local adaptation for maintaining species boundaries. In Scandinavia, hybridization and gene introgression is so extensive that no individuals with pure M. trossulus genotypes have been found. However, M. trossulus alleles are maintained at high frequencies in the extremely low salinity Baltic Sea for some allozyme genes. A synthesis of reciprocal transplantation experiments between different salinity regimes shows that unlinked Gpi and Pgm alleles change frequency following transplantation, such that post‐transplantation allelic composition resembles native populations found in the same salinity. These experiments provide strong evidence for salinity adaptation at Gpi and Pgm (or genes linked to them). In the Canadian Maritimes, pure M. edulis and M. trossulus individuals are abundant, and limited data suggest that M. edulis predominates in low salinity and sheltered conditions, whereas M. trossulus are more abundant on the wave‐exposed open coasts. We suggest that these conflicting patterns of species segregation are, in part, caused by local adaptation of Scandinavian M. trossulus to the extremely low salinity Baltic Sea environment.
FAST‐TRACK: Integrating QTL mapping and genome scans towards the characterization of candidate loci under parallel selection in the lake whitefish (Coregonus clupeaformis)
Authors: ROGERS S. M. , BERNATCHEZ L. 
Published: January 2005

AbstractAs natural selection must act on underlying genetic variation, discovering the number and location of loci under the influence of selection is imperative towards understanding adaptive divergence in evolving populations. Studies employing genome scans have hypothesized that the action of divergent selection should reduce gene flow at the genomic locations implicated in adaptation and speciation among natural populations, yet once ‘outlier’ patterns of variation have been identified the function and role of such loci needs to be confirmed. We integrated adaptive QTL mapping and genomic scans among diverging sympatric pairs of the lake whitefish (Coregonus clupeaformis) species complex in order to test the hypothesis that differentiation between dwarf and normal ecotypes at growth‐associated QTL was maintained by directional selection. We found evidence of significantly high levels of molecular divergence among eight growth QTL where two of the strongest candidate loci under the influence of directional selection exhibited parallel reductions of gene flow over multiple populations.
Nonshivering thermogenesis capacity associated to mitochondrial DNA haplotypes and gender in the greater white‐toothed shrew, Crocidura russula
Authors: FONTANILLAS PIERRE , DÉPRAZ ALINE , GIORGI MAUD S. , PERRIN NICOLAS 
Published: January 2005

AbstractA selection gradient was recently suggested as one possible cause for a clinal distribution of mitochondrial DNA (mtDNA) haplotypes along an altitudinal transect in the greater white‐toothed shrew, Crocidura russula (Ehinger et al. 2002). One mtDNA haplotype (H1) rare in lowland, became widespread when approaching the altitudinal margin of the distribution. As H1 differs from the main lowland haplotype by several nonsynonymous mutations (including on ATP6), and as mitochondria play a crucial role in metabolism and thermogenesis, distribution patterns might stem from differences in the thermogenic capacity of different mtDNA haplotypes. In order to test this hypothesis, we measured the nonshivering thermogenesis (NST) associated with different mtDNA haplotypes. Sixty‐two shrews, half of which had the H1 haplotype, were acclimated in November at semioutdoor conditions and measured for NST throughout winter. Our results showed the crucial role of NST for winter survival in C. russula. The individuals that survived winter displayed a higher significant increase in NST during acclimation, associated with a significant gain in body mass, presumably from brown fat accumulation. The NST capacity (ratio of NST to basal metabolic rate) was exceptionally high for such a small species. NST was significantly affected by a gender × haplotype interaction after winter‐acclimation: females bearing the H1 haplotype displayed a better thermogenesis at the onset of the breeding season, while the reverse was true for males. Altogether, our results suggest a sexually antagonistic cyto‐nuclear selection on thermogenesis.
Population structure in African Drosophila melanogaster revealed by microsatellite analysis
Authors: DIERINGER DANIEL , NOLTE VIOLA , SCHLÖTTERER CHRISTIAN 
Published: January 2005

AbstractTropical sub‐Saharan regions are considered to be the geographical origin of Drosophila melanogaster. Starting from there, the species colonized the rest of the world after the last glaciation about 10 000 years ago. Consistent with this demographic scenario, African populations have been shown to harbour higher levels of microsatellite and sequence variation than cosmopolitan populations. Nevertheless, limited information is available on the genetic structure of African populations. We used X chromosomal microsatellite variation to study the population structure of D. melanogaster populations using 13 sampling sites in North, West and East Africa. These populations were compared to six European and one North American population. Significant population structure was found among African D. melanogaster populations. Using a Bayesian method for inferring population structure we detected two distinct groups of populations among African D. melanogaster. Interestingly, the comparison to cosmopolitan D. melanogaster populations indicated that one of the divergent African groups is closely related to cosmopolitan flies. Low, but significant levels of differentiation were observed for sub‐Saharan D. melanogaster populations from West and East Africa.
Chloroplast DNA variation of Quercus rubra L. in North America and comparison with other Fagaceae
Authors: MAGNI C. R. , DUCOUSSO A. , CARON H. , PETIT R. J. , KREMER A. 
Published: January 2005

Abstract Quercus rubra is one of the most important timber and ornamental tree species from eastern North America. It is a widespread species growing under variable ecological conditions. Chloroplast DNA variation was studied by PCR‐RFLP (polymerase chain reaction‐restriction fragment length polymorphism) in 290 individuals from 66 populations sampled throughout the natural range. A total of 12 haplotypes were detected, with one found in 75% of the trees. Population differentiation is relatively low (GST = 0.46), even when similarities between haplotypes are taken into account (NST = 0.50), pointing to a weak phylogeographical structure. Furthermore, no spatial structure of genetic diversity could be detected. The genetic differentiation increased northwards, reflecting the postglacial history of Q. rubra. The unusual aspect of this study was the low level of chloroplast DNA genetic differentiation in Q. rubra compared to that typically observed in other oak species. Palynological evidence indicates that during the last glacial maximum, Q. rubra had one major distribution range with populations located relatively far to the north, resulting in only modest movement northwards when climate improved, whereas European white oaks were largely restricted to the southern European peninsulas and experienced extensive movements during the postglacial period. The contrasted geographical features and levels of tree species richness of both continents might further explain why congeneric species sharing similar life history traits have genetic structures that are so different.
Similarity coefficients for molecular markers in studies of genetic relationships between individuals for haploid, diploid, and polyploid species
Authors: KOSMAN E. , LEONARD K. J. 
Published: January 2005

AbstractDetermining true genetic dissimilarity between individuals is an important and decisive point for clustering and analysing diversity within and among populations, because different dissimilarity indices may yield conflicting outcomes. We show that there are no acceptable universal approaches to assessing the dissimilarity between individuals with molecular markers. Different measures are relevant to dominant and codominant DNA markers depending on the ploidy of organisms. The Dice coefficient is the suitable measure for haploids with codominant markers and it can be applied directly to (0,1)‐vectors representing banding profiles of individuals. None of the common measures, Dice, Jaccard, simple mismatch coefficient (or the squared Euclidean distance), is appropriate for diploids with codominant markers. By transforming multiallelic banding patterns at each locus into the corresponding homozygous or heterozygous states, a new measure of dissimilarity within locus was developed and expanded to assess dissimilarity between multilocus states of two individuals by averaging across all codominant loci tested. There is no rigorous well‐founded solution in the case of dominant markers. The simple mismatch coefficient is the most suitable measure of dissimilarity between banding patterns of closely related haploid forms. For distantly related haploid individuals, the Jaccard dissimilarity is recommended. In general, no suitable method for measuring genetic dissimilarity between diploids with dominant markers can be proposed. Banding patterns of diploids with dominant markers and polyploids with codominant markers represent individuals’ phenotypes rather than genotypes. All dissimilarity measures proposed and developed herein are metrics.
Genetic variation and phylogeographic analyses of two species of Carpobrotus and their hybrids in California
Authors: SCHIERENBECK KRISTINA A. , SYMONDS V. VAUGHAN , GALLAGHER KELLY G. , BELL JEFFREY 
Published: January 2005

AbstractDespite the commonality and study of hybridization in plants, there are few studies between invasive and noninvasive species that examine the genetic variability and gene flow of cytoplasmic DNA. We describe the phylogeographical structure of chloroplast DNA (cpDNA) variation within and among several interspecific populations of the putative native, Carpobrotus chilensis and the introduced, Carpobrotus edulis (Aizoaceae). These species co‐occur throughout much of coastal California and form several ‘geographical hybrid populations’. Two hundred and thirty‐seven individuals were analysed for variation in an approximate 7.0 kb region of the chloroplast genome using PCR‐RFLP (polymerase chain reaction – restriction fragment length polymorphism) data. Phylogenetic analyses and cpDNA population differentiation were conducted for all morphotypes. Historic geographical dispersion and the coefficient of ancestry of the haplotypes were determined using nested clade analyses. Two haplotypic groupings (I and II) were represented in C. chilensis and C. edulis, respectively. The variation in cpDNA data is in agreement with the previously reported allozyme and morphological data; this supports relatively limited variation and high population differentiation among C. chilensis and hybrids and more wide‐ranging variation in C. edulis and C. edulis populations backcrossed with C. chilensis. C. chilensis disproportionately contributes to the creation of hybrids with the direction of gene flow from C. chilensis into C. edulis. The cpDNA data support C. chilensis as the maternal contributor to the hybrid populations.
Intriguing asexual life in marginal populations of the brown seaweed Fucus vesiculosus
Authors: TATARENKOV A. , BERGSTRÖM L. , JÖNSSON R. B. , SERRÃO E. A. , KAUTSKY L. , JOHANNESSON K. 
Published: January 2005

AbstractReproduction of attached large brown algae is known to occur only by sexual zygotes. Using microsatellites we show evolution of asexual reproduction in the bladder wrack promoting population persistence in the brackish water Baltic Sea (< 6 psu). Here a dwarf morph of Fucus vesiculosus is dominated by a single clone but clonal reproduction is also present in the common form of the species. We describe a possible mechanism for vegetative reproduction of attached algae, and conclude that clonality plays an important role in persistence and dispersal of these marginal populations, in which sexual reproduction is impaired by low salinity.
Phylogeography of the Italian wall lizard, Podarcis sicula, as revealed by mitochondrial DNA sequences
Authors: PODNAR MARTINA , MAYER WERNER , TVRTKOVIĆ NIKOLA 
Published: January 2005

AbstractIn a phylogeographical survey of the Italian wall lizard, Podarcis sicula, DNA sequence variation along an 887‐bp segment of the cytochrome b gene was examined in 96 specimens from 86 localities covering the distribution range of the species. In addition, parts of the 12S rRNA and 16S rRNA genes from 12 selected specimens as representatives of more divergent cytochrome b haploclades were sequenced (together about 950 bp). Six phylogeographical main groups were found, three representing samples of the nominate subspecies Podarcis sicula sicula and closely related subspecies and the other three comprising Podarcis sicula campestris as well as all subspecies described from northern and eastern Adriatic islands. In southern Italy a population group with morphological characters of P. s. sicula but with the mitochondrial DNA features of P. s. campestris was detected indicating a probably recent hybridization zone. The present distribution patterns were interpreted as the consequence of natural events like retreats to glacial refuges and postglacial area expansions, but also as the results of multiple introductions by man.
Super‐infections ofWolbachiain byturid beetles and evidence for genetic transfer between A and B super‐groups ofWolbachia
Authors: MALLOCH G. , FENTON B. 
Published: January 2005

AbstractWolbachiaare maternally inherited bacteria responsible for altering host reproduction. The two main groups found in insects, A and B, are based on molecular characterization using ribosomal,ftsZ,wsp(Wolbachiasurface protein) orgroE genes. We have used thewspandftsZ genes to studyWolbachiain byturid beetles.Byturus affiniscontained a single copy of theftsZ gene which grouped with AftsZ sequences and a single copy of thewspgene which grouped with Bwspsequences. This suggests that genetic exchange between A and B groups has occurred in theWolbachiaof this beetle.FtsZ andwspsequences that were identical or nearly identical to those ofB. affiniswere found inB. tomentosus, suggesting that it also contains the same recombinantWolbachiagenotype. Most other byturids had more than onewspsequence with at least one from the A and B groups, suggesting multiple copies of bacterial genes or multiple infections.B. ochraceusandB. unicolorboth had four distinctwspgene sequences. All the byturids had a closely related Awspsequence and most a closely related Bwspsequence. Therefore, there appears to be an association between specific A and Bwsptypes.
Multilevel genetic analyses of two European supercolonies of the Argentine ant, Linepithema humile
Authors: JAQUIÉRY J. , VOGEL V. , KELLER L. 
Published: January 2005

AbstractSome ants have an extraordinary unicolonial social organization, whereby individuals mix freely among physically separated nests. Recently, it was shown that the European population of Linepithema humile consisted of two enormous unicolonial supercolonies. Workers of the same supercolony are never aggressive to each other. In contrast, aggressiveness is invariably high between workers from different supercolonies. Here we investigated whether gene flow occurs between two supercolonies. We identified a contact zone in which we sampled 46 nests. For each nest, aggression tests were conducted against workers from reference nests from both supercolonies. Workers were always very aggressive towards workers of one of the supercolonies but not to workers of the other. Thus, all nests could be clearly assigned to one of the two supercolonies. For 22 of the 46 nests, we genotyped 15–16 workers at five microsatellite loci. A four‐level hierarchical analysis of variance revealed very strong genetic differentiation between the two supercolonies (FSUPERCOLONY‐TOTAL = 0.541) and low differentiation between sectors (i.e. group of nests connected together with trails) within supercolonies (FSECTOR‐SUPERCOLONY = 0.064). The very high differentiation between the two supercolonies indicates a lack of ongoing gene flow, a conclusion further bolstered by the finding that the two supercolonies share no common alleles at two of the five microsatellite loci. A Bayesian clustering method also revealed the occurrence of two distinct clusters. These clusters exactly match the grouping obtained by aggression tests. None of the 332 genotyped individuals were admixed despite the fact that some nests of the two supercolonies were separated by less than 30 m. These results demonstrate that the two supercolonies have completely separate gene pools.
SNPs in ecological and conservation studies: a test in the Scandinavian wolf population
Authors: SEDDON J. M. , PARKER H. G. , OSTRANDER E. A. , ELLEGREN H. 
Published: January 2005

AbstractSingle nucleotide polymorphisms (SNPs) have the potential to become the genetic marker of choice in studies of the ecology and conservation of natural populations because of their capacity to access variability across the genome. In this study, we provide one of the first demonstrations of SNP discovery in a wild population in order to address typical issues of importance in ecology and conservation in the recolonized Scandinavian and neighbouring Finnish wolfCanis lupuspopulations. Using end sequence from BAC (bacterial artificial chromosome) clones specific for dogs, we designed assays for 24 SNP loci, 20 sites of which had previously been shown to be polymorphic in domestic dogs and four sites were newly identified as polymorphic in wolves. Of the 24 assayed loci, 22 SNPs were found to be variable within the Scandinavian population and, importantly, these were able to distinguish individual wolves from one another (unbiased probability of identity of 4.33 × 10−8), providing equivalent results to that derived from 12 variable microsatellites genotyped in the same population. An assignment test shows differentiation between the Scandinavian and neighbouring Finnish wolf populations, although not all known immigrants are accurately identified. An exploration of the misclassification rates in the identification of relationships shows that neither 22 SNP nor 20 microsatellite loci are able to discriminate across single order relationships. Despite the remaining obstacle of SNP discovery in nonmodel organisms, the use of SNPs in ecological and conservation studies is encouraged by the advent of large scale screening methods. Furthermore, the ability to amplify extremely small fragments makes SNPs of particular use for population monitoring, where faecal and other noninvasive samples are routinely used.
Brood size modifications affect plumage bacterial assemblages of European starlings
Authors: LUCAS FRANÇOISE S. , MOUREAU BENOIT , JOURDIE VIOLAINE , HEEB PHILIPP 
Published: January 2005

AbstractDuring reproduction, birds face trade‐offs between time and energy devoted to parental effort and traits associated with self‐maintenance. We manipulated brood sizes to investigate the effects of such trade‐offs on feather bacterial densities and the structure of bacterial assemblages on feathers in adult European starlings,Sturnus vulgaris, andin vitrofeather degradation. As predicted by a trade‐off between parental effort and self‐maintenance, we found that birds with enlarged broods had more free‐living bacteria on their feathers than birds with reduced broods. Furthermore, we found a significant interaction between brood manipulation and original brood size on free‐living bacterial densities suggesting that the trade‐off is mediated by the adults’ initial reproductive investment. In contrast, brood size manipulations had no significant effect on densities of attached bacteria. Using ribosomal intergenic spacer analysis (RISA), we demonstrated that brood manipulations significantly modified the structure (band pattern) of feather‐degrading bacterial assemblages, but had no significant effect on their richness (number of bands) or thein vitrofeather degradation.In vitrofeather degradation varied in relation to the premanipulation brood size and positively with the richness of the feather degrading bacterial community. Besides brood manipulation effect, we found that ecological factors and individual traits, such as the age, the nest location or the capture date, shaped bacterial assemblages and feather degradation capacities.
Male nest site fidelity and female serial polyandry in lingcod (Ophiodon elongatus, Hexagrammidae)
Authors: KING JACQUELYNNE R. , WITHLER RUTH E. 
Published: January 2005

AbstractNest site fidelity and serial polyandry were examined in lingcod, Ophiodon elongatus, a teleost fish in which the nest‐guarding male parent invests more heavily in parental care than the elusive female parent. Lingcod parental and progeny genotypes were established for fish spawning on a 200 m2 section of Snake Island reef, British Columbia in two successive years to evaluate male and female mate choice (monogamy or polygamy) and nest site reuse by the same parents (nest site fidelity) and/or different parents (nest site affinity). Thirteen nests (egg masses) guarded by nine males and 14 nests guarded by seven males were observed in 2002 and 2003, respectively. No female laid more than one nest per season or spawned in the study area in both years. In contrast, at least six (86%) and possibly all seven (100%) of the 2003 guardian males had been guardian or auxiliary males in 2002. Both nest site affinity and extreme male nest site fidelity were observed, with at least four males reusing the exact same nest site. Serial polyandry resulting from the high male and low female nest site fidelity is consistent with predictions based on a low female parental investment and high rate of progeny loss to predation and cannibalism. Male polygyny, achieved primarily by cuckoldry within seasons, was enhanced by the lack of female fidelity between seasons. Polygamy in both sexes of nest‐tending marine fish may minimize reproductive skew and maximize genetic diversity within populations.