bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inbreeding and population structure in two pairs of cryptic fig wasp species
Authors: Molbo Drude , Machado Carlos A. , Herre Edward Allen , Keller Laurent 
Published: May 2004

AbstractWe used recently developed microsatellites to directly estimate inbreeding levels in two pairs of coexisting cryptic fig wasp species (‘Pegoscapus hoffmeyeri sp. A and sp. B’, ‘P. gemellus sp. A and sp. B’). Previous tests of Hamilton's local mate competition (LMC) theory in fig wasps have used the number of dead foundresses in a fig fruit to indirectly estimate the relative contribution of each to the common brood and thereby the level of local mate competition. Further, the population level of inbreeding has been indirectly estimated using the distribution of foundress numbers across broods. Our direct genetic estimates confirmed previous assumptions that the species characterized by lower foundress numbers showed higher relative levels of inbreeding. However, there were quantitative differences between the observed level of inbreeding and the expectation based on the distribution of foundress numbers in both pollinator species associated with Ficus obtusifolia. Here, genotype compositions of broods revealed that only 23% of fruits with multiple foundresses actually contained brood from more than one foundress, thus explaining at least part of the underestimate of actual sibmating. Within the four wasp species there was no evidence for genetic differentiation among the wasp populations sampled from different trees across 20 km and from different points in time. Further, no genotypic disequilibrium was detected within any of the species. Although F1 hybrids were observed between the two species pollinating F. obtusifolia, there was no evidence of genetic introgression. Finally, we found that 11% of the sons of allospecifically mated mothers were diploid hybrids suggesting a break down of the sex determination system in hybrids.
Single nucleotide polymorphism (SNP) discovery in mammals: a targeted‐gene approach
Authors: Aitken Nicola , Smith Steven , Schwarz Carsten , Morin Phillip A. 
Published: May 2004

AbstractSingle nucleotide polymorphisms (SNPs) have rarely been exploited in nonhuman and nonmodel organism genetic studies. This is due partly to difficulties in finding SNPs in species where little DNA sequence data exist, as well as to a lack of robust and inexpensive genotyping methods. We have explored one SNP discovery method for molecular ecology, evolution, and conservation studies to evaluate the method and its limitations for population genetics in mammals. We made use of ‘CATS’ (or ‘EPIC’) primers to screen for novel SNPs in mammals. Most of these primer sets were designed from primates and/or rodents, for amplifying intron regions from conserved genes. We have screened 202 loci in 16 representatives of the major mammalian clades. Polymerase chain reaction (PCR) success correlated with phylogenetic distance from the human and mouse sequences used to design most primers; for example, specific PCR products from primates and the mouse amplified the most consistently and the marsupial and armadillo amplifications were least successful. Approximately 24% (opossum) to 65% (chimpanzee) of primers produced usable PCR product(s) in the mammals tested. Products produced generally high but variable levels of readable sequence and similarity to the expected genes. In a preliminary screen of chimpanzee DNA, 12 SNPs were identified from six (of 11) sequenced regions, yielding a SNP on average every 400 base pairs (bp). Given the progress in genome sequencing, and the large numbers of CATS‐like primers published to date, this approach may yield sufficient SNPs per species for population and conservation genetic studies in nonmodel mammals and other organisms.
Adaptive radiation within New Zealand endemic species of the cockroach genus Celatoblatta Johns (Blattidae): a response to Plio‐Pleistocene mountain building and climate change
Authors: Chinn Warren G. , Gemmell Neil J. 
Published: May 2004

AbstractThe South Island of New Zealand offers unique opportunities to study insect evolution due to long‐term physical isolation, recent alpine habitats and high levels of biotic endemism. Using DNA sequence data from cytochrome oxidase subunit 1, we investigated the phylogeographical pattern among 10 endemic cockroach species within the genus Celatoblatta Johns (Blattidae). We tested the hypothesis that an ancestral cockroach species underwent rapid speciation in response to major climatic differentiation induced by mountain building. Results suggest that speciation was a twofold process, with an interspecific radiation of Pliocene/Pleistocene age followed by intraspecific diversification during the mid Pleistocene. Average genetic distance (maximum likelihood GTR + I + Γ) was 9.17%, with a maximum of 14.5%. Data revealed eight deep well‐supported branches, each with terminal clades. Six clades were differentiated according to morphological species, while the seventh was composed of three sympatric species. We consider the latter to be a phylogenetic species, possibly as a result of hybridization within a defined geographical area. This finding seriously challenges species distinctions for these three cockroach species. Correlation between genetic distances and a Climate Similarity Index (CSI) was negative, suggesting that species found in similar habitats are also genetically closely related. A Mantel test on within‐clade genetic distances vs. linear geographical distance was positive, suggesting allopatric isolation for those haplotypes. We present a model of speciation for South Island Celatoblatta.
Stocking impact and migration pattern in an anadromous brown trout (Salmo trutta) complex: where have all the stocked spawning sea trout gone?
Authors: Ruzzante Daniel E. , Hansen Michael M. , Meldrup Dorte , Ebert Kaare M. 
Published: May 2004

AbstractWe examined polymorphism at seven microsatellite loci among sea trout (Salmo trutta) (n = 846) collected from three areas in the Limfjord (Denmark). We then assessed their potential population source by comparing, using a mixed stock analysis (MSA) Bayesian framework, their genetic composition to that of brown trout collected from 32 tributaries pooled into nine geographical regions (n = 3801) and two hatcheries (n = 222) used for stocking. For each of the three regional sea trout groups (western, central and eastern Limfjord, n = 91, n = 426, n = 329, respectively), MSA was conducted with (i) all individuals in the group, (ii) with the subset of spawning sea trout only and (iii) with the subset of foraging, nonspawning individuals only, a subset that consisted primarily of sea trout caught during their first year at sea. For all three regional sea trout groups, a higher proportion of individuals (regardless of whether they were foraging or spawning) appear to have originated from the rivers that drain locally, than from the rivers that drain in other parts of the Limfjord. This suggests (1) that sea trout, at least during their first year at sea, undertake limited migrations within the Limfjord system and (2) that sea trout on their spawning run were caught close to their natal rivers. The proportion of sea trout of hatchery origin varied widely among all three Limfjord areas and broadly reflected regional stocking histories, with high proportions of sea trout of domestic origin in the east (39.3%), where stocking with domestic trout was practised intensely at the time of sampling, and in the west (57.2%), where a programme of coastal stocking of post smolts took place over several years in the early 1990s. In contrast, in the central Limfjord, where stocking with domestic trout was largely abandoned in the early 1990s, the proportion of sea trout of domestic origin was only 8.5%. Interestingly, for all three regional sea trout groups, virtually no sea trout of hatchery origin were found among the spawning individuals, which were on average larger than the nonspawning sea trout. These results suggest that stocked domestic brown trout that become anadromous experience high mortality at sea and are therefore largely absent among the larger, spawning individuals. We conclude that sea trout of domestic origin exhibit much reduced ability to reproduce and are unlikely to contribute significantly to the local gene pool largely because of a relatively high mortality at sea before the onset of maturity.
High similarity between flanking regions of different microsatellites detected within each of two species of Lepidoptera:Parnassius apolloandEuphydryas aurinia
Authors: Meglecz Emese , Petenian Frederic , Danchin Etienne , D’Acier Armelle Coeur , Rasplus Jean‐Yves , Faure Eric 
Published: May 2004

AbstractMicrosatellite flanking regions have been compared in two butterfly species. Several microsatellite flanking regions showed high similarity to one another among different microsatellites within a same species, but very few similarities were found between species. This can be the consequence of either duplication/multiplication events involving large regions containing microsatellites or of microsatellites imbedded in minisatellite regions. The multiplication of microsatellites might also be linked to mobile elements. Furthermore, crossing over between nonhomologous microsatellites can lead to the exchange of the flanking regions between microsatellites. The same phenomenon was observed in both studied butterfly species but not inAphis fabae(Hemiptera), which was screened at the same time using the same protocol. These findings might explain, at least partially, why microsatellite isolation in Lepidoptera has been relatively unsuccessful so far.
How species evolve collectively: implications of gene flow and selection for the spread of advantageous alleles
Authors: Morjan Carrie L. , Rieseberg Loren H. 
Published: May 2004

AbstractThe traditional view that species are held together through gene flow has been challenged by observations that migration is too restricted among populations of many species to prevent local divergence. However, only very low levels of gene flow are necessary to permit the spread of highly advantageous alleles, providing an alternative means by which low‐migration species might be held together. We re‐evaluate these arguments given the recent and wide availability of indirect estimates of gene flow. Our literature review ofFSTvalues for a broad range of taxa suggests that gene flow in many taxa is considerably greater than suspected from earlier studies and often is sufficiently high to homogenize even neutral alleles. However, there are numerous species from essentially all organismal groups that lack sufficient gene flow to prevent divergence. Crude estimates on the strength of selection on phenotypic traits and effect sizes of quantitative trait loci (QTL) suggest that selection coefficients for leading QTL underlying phenotypic traits may be high enough to permit their rapid spread across populations. Thus, species may evolve collectively at major loci through the spread of favourable alleles, while simultaneously differentiating at other loci due to drift and local selection.
Mitochondrial DNA variation in Northeast Atlantic and Mediterranean populations of Norway lobster, Nephrops norvegicus
Authors: Stamatis C. , Triantafyllidis A. , Moutou K. A. , Mamuris Z. 
Published: May 2004

AbstractAnalysis of the genetic structure of the Norway lobster (Nephrops norvegicus), a marine crustacean with high commercial value, was undertaken to gain information regarding the differentiation of Atlantic from Mediterranean populations of marine invertebrates. Restriction fragment length polymorphism analysis of two mitochondrial DNA segments, 3.6 kilobases in total, was performed. Twelve populations from the North Sea, Irish Sea, Portuguese coast and Aegean Sea were analysed. Low levels of differentiation were found among them (FST = 0.018, P < 0.001) and there were no signs of an Atlantic–Mediterranean divide or of an isolation‐by‐distance scheme of differentiation. Possible reasons for these low levels of differentiation can be found in the recent expansion of N. norvegicus populations. This is supported by the mismatch distribution of pairwise haplotype differences, as well as by the high mean haplotype diversity (h = 0.93) combined with medium nucleotide diversity (π = 0.0057) (in comparison to values for marine crustaceans or teleosts) found in this study. This combination of high levels of haplotype diversity with moderate to low levels of nucleotide diversity has also been frequently attributed to a recent time of divergence for various marine species. No evidence was found for a Mediterranean refugium during glaciation periods, separate from the Atlantic, as has been reported for some marine species. The Irish Sea population was the most differentiated as a result of reduced levels of diversity. Results are also discussed in the light of future management of N. norvegicus stocks.
Past and current gene flow in the selfing, wind‐dispersed species Mycelis muralis in western Europe
Authors: Chauvet S. , Van Der Velde M. , Imbert E. , Guillemin M. L. , Mayol M. , Riba M. , Smulders M. J. M. , Vosman B. , Ericson L. , Bijlsma R. , Giles B. E. 
Published: May 2004

AbstractThe distribution of genetic diversity in Mycelis muralis, or wall lettuce, was investigated at a European scale using 12 microsatellite markers to infer historical and contemporary forces from genetic patterns. Mycelis muralis has the potential for long‐distance seed dispersal by wind, is mainly self‐pollinated, and has patchily distributed populations, some of which may show metapopulation dynamics. A total of 359 individuals were sampled from 17 populations located in three regions, designated southern Europe (Spain and France), the Netherlands, and Sweden. At this within‐region scale, contemporary evolutionary forces (selfing and metapopulation dynamics) are responsible for high differentiation between populations (0.34 < FST < 0.60) but, contrary to expectation, levels of within‐population diversity, estimated by Nei's unbiased expected heterozygosity (HE) (0.24 < HE < 0.68) or analyses of molecular variance (50% of the variation found within‐populations), were not low. We suggest that the latter results, which are unusual in selfing species, arise from efficient seed dispersal that counteracts population turnover and thus maintains genetic diversity within populations. At the European scale, northern regions showed lower allelic richness (A = 2.38) than populations from southern Europe (A = 3.34). In light of postglacial colonization hypotheses, these results suggest that rare alleles may have been lost during recolonization northwards. Our results further suggest that mutation has contributed to genetic differentiation between southern and northern Europe, and that Sweden may have been colonized by dispersers originating from at least two different refugia.
Molecular evidence for the hybrid origin of species in the soft coral genusAlcyonium(Cnidaria: Anthozoa: Octocorallia)
Authors: Mcfadden Catherine S. , Hutchinson M. Breton 
Published: May 2004

AbstractSeveral recent studies have suggested that hybridization may play a previously unrecognized and important role in the evolution of corals. Our observations of polymorphic and recombinant sequences in the multicopy ribosomal internal transcribed spacer (ITS) region suggested the possible hybrid origin of two European soft coral species,Alcyonium hibernicumandBellonella bocagei. To examine this possibility further we cloned and sequencedITS‐1from multiple individuals and populations of these two species as well as two sympatric congeners,A. coralloidesandA.sp.M2. Phylogenetic analyses separated the observed sequence variants into two distinct clades. AllA. coralloidessequences belonged to clade A, whileA.sp.M2 had only clade B sequences. A majority ofA. hibernicumindividuals, however, contained both clade A and B sequences that were identical to the predominant sequence variants found inA. coralloidesandA.sp.M2, respectively. This pattern of additivity suggests thatA. hibernicumoriginated from a hybrid cross betweenA. coralloidesandA.sp.M2, a hypothesis that is supported by its unusual mode of reproduction (meiotic parthenogenesis). The predominant sequence variant found inB. bocageiwas a unique, derived clade B sequence; in addition, however, most individuals of this species also had copies of a sequence identified as a recombinant between clade A and clade B sequence types. The presence of this recombinant sequence in theB. bocageigenome suggests that this species may also be the product of past hybridization events within the clade. Reticulate evolution may explain the failure of several previous studies to resolve the phylogeny of these four species.
Mitochondrial DNA and microsatellite variation in the eider duck (Somateria mollissima) indicate stepwise postglacial colonization of Europe and limited current long‐distance dispersal
Authors: Tiedemann R. , Paulus K. B. , Scheer M. , Von Kistowski K. G. , Skírnisson K. , Bloch D. , Dam M. 
Published: May 2004

AbstractTo unravel the postglacial colonization history and the current intercolony dispersal in the common eider, Somateria mollissima, we analysed genetic variation at a part of the mitochondrial control region and five unlinked autosomal microsatellite loci in 175 eiders from 11 breeding colonies, covering the entire European distribution range of this species. As a result of extreme female philopatry, mitochondrial DNA differentiation is substantial both among local colonies and among distant geographical regions. Our study further corroborates the previous hypothesis of a single Pleistocene refugium for European eiders. A nested clade analysis on mitochondrial haplotypes suggests that (i) the Baltic Sea eider population is genetically closest to a presumably ancestral population and that (ii) the postglacial recolonization progressed in a stepwise fashion via the North Sea region and the Faroe Islands to Iceland. Current long‐distance dispersal is limited. Differentiation among colonies is much less pronounced at microsatellite loci. The geographical pattern of this nuclear genetic variation is to a large extent explained by isolation by distance. As female dispersal is very limited, the geographical pattern of nuclear variation is probably explained by male‐mediated gene flow among breeding colonies. Our study provides genetic evidence for the assumed prominent postglacial colonization route shaping the present terrestrial fauna of the North Atlantic islands Iceland and the Faroes. It suggests that this colonization had been a stepwise process originating in continental Europe. It is the first molecular study on eider duck populations covering their entire European distribution range.
Contrasting population genetic patterns and evolutionary histories among sympatric Sonoran Desert cactophilic Drosophila
Authors: Hurtado L. A. , Erez T. , Castrezana S. , Markow T. A. 
Published: May 2004

AbstractWe studied population genetic differentiation in the sympatric Sonoran Desert cactophilic flies Drosophila pachea, D. mettleri and D. nigrospiracula across their continental and peninsular ranges. These flies show marked differences in ecology and behaviour including dispersal distances and host cactus specialization. Examination of a fragment of the mitochondrial cytochrome oxidase subunit I gene (mtCOI) reveals that the Sea of Cortez has constituted an effective dispersal barrier for D. pachea, leading to significant genetic differentiation between the continental and peninsular ranges of this species. No genetic differentiation was detected, however, within its continental and peninsular ranges. In contrast, our mtCOI‐based results for D. mettleri and D. nigrospiracula are consistent with a previous allozyme‐based study that showed no significant genetic differentiation between continental and peninsular ranges of these two species. For D. mettleri, we also found that the insular population from Santa Catalina Island, California, is genetically differentiated with respect to continental and peninsular localities. We discuss how differences in the genetic structure patterns of D. pachea, D. mettleri and D. nigrospiracula may correspond to differences in their dispersal abilities, host preferences and behaviour.
Phylogeography of subterranean and surface populations of water lice Asellus aquaticus (Crustacea: Isopoda)
Authors: Verovnik R. , Sket B. , Trontelj P. 
Published: May 2004

AbstractThe water louse Asellus aquaticus is a widespread, euryoecious species, mostly uniform throughout its range. However, six subspecies are known from the Dinaric karst in the northwestern Balkans. They include some specialized subterranean populations. The pattern of genetic variation among subterranean and surface populations in this hydrographically highly fragmented karst region was investigated using a 653 bp fragment of the mitochondrial gene (COI). Sequencing of 168 individuals from 25 localities revealed 72 haplotypes. amova and methods of phylogenetic reconstruction all uncovered hydrographic structuring of genetic variation of the populations. Nested clade analysis pointed out several fragmentation events, along with some range expansions within hydrographical systems. By superimposing the subterranean mode of life on the phylogeographical pattern, three independent cave colonizations could be inferred within a distance of < 100 km. Caves were invaded after the ancestral surface populations became isolated through vicariant fragmentation. A possible scenario of hydrographic history of the region was constructed combining the molecular data with palaeogeographical information.
Extra‐pair paternity does not result in differential sexual selection in the mutually ornamented black swan (Cygnus atratus)
Authors: Kraaijeveld K. , Carew P. J. , Billing T. , Adcock Greg J. , Mulder Raoul A. 
Published: May 2004

AbstractWe studied patterns of parentage in 85 broods (332 cygnets) of black swans during three breeding seasons, using a set of eight polymorphic microsatellite markers. We detected both intraspecific brood parasitism (IBP; < 5% of cygnets per year) and extra‐pair paternity (EPP). In these years, 10–17% (mean = 15.1%) of cygnets resulted from EPP, and 27–40% (mean 37.6%) of broods contained at least one extra‐pair cygnet. Compared with levels of EPP in closely related species with similar life histories, these values are unexpectedly high. EPP in black swans appears unrelated to ecological factors (breeding density and synchrony) or genetic factors (genetic similarity between pair members or genetic quality of the offspring). We found no evidence that a mutual sexual feather ornament known to play a role in social mate choice in black swans (curled wing feathers) is involved in extra‐pair mate choice. EPP does not lead to greater variance in reproductive success in males, relative to females in this species. We therefore suggest that EPP does not result in differential sexual selection on males and females, explaining why they are ornamented to the same degree.