bluuebunny/crossref_metadata_2025 huggingface dataset:
Population genetic structure in the dioecious pioneer plant species Hippophae rhamnoides investigated by random amplified polymorphic DNA (RAPD) markers
Authors: Bartish  , Jeppsson  , Nybom
Published: March 2003

Hippophae rhamnoides is an outcrossing pioneer plant species with a severely fragmented distribution. Random amplified polymorphic DNA (RAPD) marker variation was analysed in 10 populations of ssp. rhamnoides and in one population of ssp. mongolica to estimate the amount and distribution of genetic variability. No less than 89.7% of the scorable markers were polymorphic, but few of these were fixed and populations consequently differed mainly by frequency variation of individual markers. Within‐population gene diversity was somewhat low for an outcrossing plant species: 0.192 or 0.159 for ssp. rhamnoides, depending on whether it was based on all 156 polymorphic RAPDs or on only those 63 RAPDs that fulfilled the 3/N criterion. Analysis of molecular variance applied to the ssp. rhamnoides showed only 15% between‐population variability, indicating a relatively restricted population differentiation as expected in outcrossing species and shown in several other AMOVA studies. The tendency for island populations to be somewhat more differentiated, and to have less within‐population diversity than mainland populations, may indicate an effect of population fragmentation. Genetic distance estimates among populations, obtained with and without pruning of RAPD loci on the basis of the 3/N criterion, were generally in very good agreement. Cluster analyses and principal coordinate analyses showed populations of ssp. rhamnoides to be rather close, but quite isolated from the single ssp. mongolica population. Genetic and geographical distances between the ssp. rhamnoides populations were not associated, indicating that large‐scale geographical and ecotypic differentiation was not reflected in the RAPD profiles.
Isozyme uniformity in a wild extinct insular plant,Lysimachia minoricensisJ.J. Rodr. (Primulaceae)
Authors: Ibáñez  , Calero  , Mayol  , Rosselló
Published: March 2003

Isozyme analyses were conducted to evaluate the genetic diversity of seed accessions ofLysimachia minoricensis(a Balearic endemic plant that became extinct in the wild) provided by 10 European botanical gardens. No isozyme variation was detected after examination of the electrophoretic patterns of 22 putative loci in more than 150 plants. The lack of genetic variation inL. minoricensisis probably due to the shortage of sample propagules originally recovered in the field before its extinction. Extant plants ofL. minoricensisare believed to have originated from a single source, therefore limiting their use as seed stocks for restoration projects.
Phylogeographic differentiation in the mitochondrial control region in the koala,Phascolarctos cinereus(Goldfuss 1817)
Authors: Houlden Bronwyn A. , Costello Brian H. , Sharkey Deirdre , Fowler Elizabeth V. , Melzer Alistair , Ellis William , Carrick Frank , Baverstock Peter R. , Elphinstone Martin S.
Published: March 2003

The koala,Phascolarctos cinereus, is a geographically widespread species endemic to Australia, with three currently recognized subspecies:P.c. adustus,P.c. cinereus, andP.c. victor. Intraspecific variation in the mitochondrial DNA (mtDNA) control region was examined in over 200 animals from 16 representative populations throughout the species’ range. Eighteen different haplotypes were defined in the ≈ 860 bp mtDNA control region, as determined by heteroduplex analysis/temperature gradient gel electrophoresis (HDA/TGGE). Any single population typically possessed only one or two haplotypes yielding an average within‐population haplotypic diversity of 0.180 ± 0.003, and nucleotide diversity of 0.16%. Overall, mtDNA control region sequence diversity between populations averaged 0.67%, and ranged from 0% to 1.56%. Nucleotide divergence between populations averaged 0.51%, and ranged from 0% to 1.53%. Neighbour‐joining methods revealed limited phylogenetic distinction between geographically distant populations of koalas, and tentative support for a single evolutionarily significant unit (ESU). This is consistent with previous suggestions that the morphological differences formalized by subspecific taxonomy may be interpreted as clinal variation. Significant differentiation in mtDNA‐haplotype frequencies between localities suggested that little gene flow currently exists among populations. When combined with microsatellite analysis, which has revealed substantial differentiation among koala populations, we conclude that the appropriate short‐term management unit (MU) for koalas is the local population.
Allelic and haplotype variation of major histocompatibility complex class IIDRB1andDQBloci in the St Lawrence beluga (Delphinapterus leucas)
Authors: Murray Brent W. , Michaud Robert , White Bradley N.
Published: March 2003

In order to assess levels of major histocompatibility complex (Mhc) variation within the St Lawrence beluga (Delphinapterus leucas) the variation at the belugaMhc DRB1class II locus was assessed by single‐strand conformation polymorphism (SSCP) analysis of the peptide‐binding region for 313 whales collected from 13 sampling locations across North America. In addition, samples from west Greenland and the St Lawrence were also typed at theDQBlocus, allowing comparison to a previous study and assessment of linkage disequilibrium of alleles at the two loci. Comparisons ofDRB1andDQBallele frequencies among all sampling locations indicated genetic structure (α < 0.005). Most of this structure resulted from differences between the different wintering groups. Significant genetic structure (α = 0.05) exists among each pair of the following groups at both theDRB1andDQBloci; St Lawrence, Hudson Strait, Bering Sea, Cunningham Inlet, and Davis Strait (minus Cunningham Inlet), except the St Lawrence and Hudson Strait for theDQBlocus. In the St Lawrence population, six of the eightDRB1alleles are present representing all five known allelic lineages. Evidence of linkage disequilibrium between theDRB1andDQBis present in two sampling locations, the St Lawrence and Nuussuaq (α = 0.05). Analysis of probableDRB1–DQBhaplotypes among groups of beluga suggests a haplotype reduction in the St Lawrence.
Genetic differentiation in the striped dolphin Stenella coeruleoalba from European waters according to mitochondrial DNA (mtDNA) restriction analysis
Authors: García‐martínez J. , Moya A. , Raga J. A. , Latorre A.
Published: March 2003

We used mitochondrial DNA (mtDNA) restriction analysis to study genetic variation in 98 striped dolphins (Stenella coeruleoalba) stranded on coasts from different European countries and from animals caught by fisheries. A total of 63 different restriction sites was mapped after digestion of mtDNA with 15 restriction endonucleases that yielded a total of 27 haplotypes. No haplotype was shared between Mediterranean and Atlantic areas. All the analyses indicate the existence of two different populations with a very limited gene flow across the Strait of Gibraltar.
Population genetic structure and the effect of founder events on the genetic variability of moose, Alces alces, in Canada
Authors: Broders H. G , Mahoney S. P , Montevecchi W. A , Davidson W. S
Published: March 2003

Moose, Alces alces, occur naturally throughout most of Canada but successful introductions of known numbers of animals have been made to the islands of Newfoundland and Cape Breton. Five microsatellite loci were used to investigate the population genetic structure and any change in genetic variability due to founder events of moose in Canada. Comparisons of allele frequencies for moose from 11 regions of the country suggested that there are at least seven genetically distinct populations (P < 0.05) in North America, namely Alberta, eastern Ontario, New Brunswick, Cape Breton, Labrador, western Newfoundland, and the Avalon Peninsula of Newfoundland. The average population heterozygosity was approximately 33% (range from 22 to 41%). upgma analysis of Nei’s genetic distances produced phenograms similar to what would be expected when geographical location and population history are considered. The loss of heterozygosity due to a single founder event (n = 3; two introductions and a natural colonization) ranged from 14 to 30%, and the cumulative loss of heterozygosity due to two successive founder events (an introduction followed by a natural colonization) was 46%. In these examples loss of genetic variability has not been associated with any known phenotypic deviances, suggesting that populations may be established from a small number of founders. However, the viability of these founded populations over evolutionary timescales cannot be determined and is highly dependent upon chance.
Mitochondrial DNA sequence variation within the remnant populations of the endangered numbat (Marsupialia: Myrmecobiidae: Myrmecobius fasciatus)
Authors: Fumagalli L. , Moritz C. , Taberlet P. , Friend J. A.
Published: March 2003

The numbat has been reduced to two populations in Western Australia. To better understand the effects of range reduction on gene flow and genetic variation, and to address questions crucial for the species’ management, we analysed mitochondrial DNA (mtDNA) sequences of free‐ranging individuals and museum specimens. The results suggest recent connectivity between the remnant populations, although one of those may have lost significant amounts of genetic diversity during the recent population size reduction. We propose that for management purposes the remnant populations should be treated as a single historical lineage and that, subject to certain caveats, consideration should be given to population augmentation by translocation.
Genetic relationship and distribution of the Japanese wild boar (Sus scrofa leucomystax) and Ryukyu wild boar (Sus scrofa riukiuanus) analysed by mitochondrial DNA
Authors: Watanobe T. , Okumura N. , Ishiguro N. , Nakano M. , Matsui A. , Sahara M. , Komatsu M.
Published: March 2003

Mitochondrial genetic variations were used to investigate the relationships between two Japanese wild boars, Japanese wild boar (Sus scrofa leucomystax) and Ryukyu wild boar (S.s. riukiuanus). Nucleotide sequences of the control (27 haplotypes) and cytochrome b (cyt‐b) regions (19 haplotypes) were determined from 59 Japanese wild boars, 13 Ryukyu wild boars and 22 other boars and pigs. From phylogenetic analyses, the mtDNA of Ryukyu wild boar has a distinct lineage from that of Japanese wild boar, which was classified into the Asian pig lineage. This result suggests that the Ryukyu wild boar has a separate origin from the Japanese wild boar.
A phylogeographical analysis of the Bemisia tabaci species complex based on mitochondrial DNA markers
Authors: Frohlich D. R. , Torres‐Jerez I. , Bedford I. D. , Markham P. G. , Brown J. K.
Published: March 2003

Mitochondrial 16S (~550 bp) and cytochrome oxidase I (COI) (~700 bp) sequences were utilized as markers to reconstruct a phylogeography for representative populations or biotypes of Bemisia tabaci. 16S sequences exhibited less divergence than COI sequences. Of the 429 characters examined for COI sequences, 185 sites were invariant, 244 were variable and 108 were informative. COI sequence identities yielded distances ranging from less than 1% to greater than 17%. Whitefly 16S sequences of 456 characters were analysed which consisted of 298 invariant sites, 158 variable sites and 53 informative sites. Phylogenetic analyses conducted by maximum parsimony, maximum‐likelihood and neighbour‐joining methods yielded almost identical phylogenetic reconstructions of trees that separated whiteflies based on geographical origin. The 16S and COI sequence data indicate that the B‐biotype originated in the Old World (Europe, Asia and Africa) and is most closely related to B‐like variants from Israel and Yemen, with the next closest relative being a biotype from Sudan. These data confirm the biochemical, genetic and behavioural polymorphisms described previously for B. tabaci. The consideration of all global variants of B. tabaci as a highly cryptic group of sibling species is argued.
Potential of microsatellites for individual assignment: the North Atlantic redfish (genusSebastes) species complex as a case study
Authors: Roques Severine , Duchesne Pierre , Bernatchez Louis
Published: March 2003

We used the four redfish taxa (genusSebastes) from the North Atlantic to evaluate the potential of multilocus genotype information obtained from microsatellites in assigning individuals at two different levels of group divergence. We first tested the hypothesis that microsatellites can diagnostically discriminate individual redfish from different groups. Second, we compared two different methods to quantify the effect of number of loci and likelihood stringency levels on the power of microsatellites for redfish group membership. The potential of microsatellites to discriminate individuals from different taxa was illustrated by a shared allele distance tree in which four major clusters corresponding to each taxa were defined. Concomitant with this strong discrimination, microsatellites also proved to be powerful in reclassifying specimens to the taxon of origin, using either an empirical or simulated method of estimating assignment success. By testing for the effect of both the number of loci and the level of stringency on the assignment success, we found that 95% of all specimens were still correctly reclassified with only four loci at the most commonly used criterion of log0. In contrast, the results obtained at the population level within taxa highlighted several problems of assignment that may occur at low levels of divergence. Namely, a drastic decrease of success with increasing stringency illustrated the lack of power of our set of loci. Strong discrepancy was observed between results obtained from the empirical and simulated methods. Finally, the highest assignment success was obtained when reducing the number of loci used, an observation previously reported in studies of human populations.
Macrogeographical population differentiation in oceanic environments: a case study of European hake (Merluccius merluccius), a commercially important fish
Authors: Lundy Caroline J. , Moran Paloma , Rico Ciro , Milner Richard S. , Hewitt Godfrey M.
Published: March 2003

Polymorphism at six microsatellite loci was used to study genetic variability and population structure in six geographically distant natural populations of European hake (Merluccius merluccius L.). Four hundred and eighty‐three individuals were sampled from Trondheimsfjord in Norway, the Celtic Sea, the southern Bay of Biscay, Faro off Portugal, the Mediterranean Sea north of the coast of Tunisia and the Adriatic Sea. Population subdivision was found between Mediterranean and Atlantic samples, θ = 0.029 (P < 0.001). No substructuring was found between samples within the Mediterranean Sea, θ = 0.003 and RST = 0.007 (P > 0.05). The Atlantic population structure appears to be more complex than previously suggested by the placement of stock boundaries by the International Council for the Exploration of the Seas (ICES). Analyses based on various models of microsatellite evolution all suggest that differentiation exists between Bay of Biscay and Portugese samples, θ = 0.013 (P < 0.001), RST = 0.036 (P < 0.001) which are currently managed as one stock. By contrast, fixation indices indicated no differentiation between southern Bay of Biscay samples and Celtic Sea samples, θ = 0.003 (P = 0.02), φST = 0.007 (P = 0.10) which are managed as separate stocks. These results suggest that if the observed trends are stable through time, current management policy of European hake may need revision.
Mitochondrial sequence analysis of Salamandra taxa suggests old splits of major lineages and postglacial recolonizations of Central Europe from distinct source populations of Salamandra salamandra
Authors: Steinfartz Sebastian , Veith Michael , Tautz Diethard
Published: March 2003

Representatives of the genus Salamandra occur in Europe, Northern Africa and the Near East. Many local variants are known but species and subspecies status of these is still a matter of dispute. We have analysed samples from locations covering the whole expansion range of Salamandra by sequence analysis of mitochondrial D‐loop regions. In addition, we have calibrated the rate of divergence of the D‐loop on the basis of geologically dated splits of the closely related genus Euproctus. Phylogenetic analysis of the sequences suggests that six major monophyletic groups exist (S. salamandra, S. algira, S. infraimmaculata, S. corsica, S. atra and S. lanzai) which have split between 5 and 13 million years ago (Ma). We find that each of the Salamandra species occupies a distinct geographical area, with the exception of S. salamandra. This species occurs all over Europe from Spain to Greece, suggesting that it was the only species that has recolonized Central Europe after the last glaciation. The occurrence of specific east and west European haplotypes, as well as allozyme alleles in the S. salamandra populations suggests that this recolonization has started from at least two source populations, possibly originating in the Iberian peninsula and the Balkans. Two subpopulations of S. salamandra were found that are genetically very distinct from the other populations. One lives in northern Spain (S. s. bernardezi) and one in southern Italy (S. s. gigliolii). Surprisingly, the mitochondrial lineages of these subpopulations group closer together than the remainder S. salamandra lineages. We suggest that these populations are remnants of a large homogeneous population that had colonized Central Europe in a previous interglacial period, approximately 500 000 years ago. Animals from these populations were apparently not successful in later recolonizations. Still, they have maintained their separate genetic identity in their areas, although they are not separated by geographical barriers from very closely related neighbouring populations.
Mitochondrial haplotype diversity among Portuguese brown trout Salmo trutta L. populations: relevance to the post‐Pleistocene recolonization of northern Europe
Authors: Weiss S. , Antunes A. , Schlötterer C. , Alexandrino P.
Published: March 2003

Mitochondrial haplotype diversity in seven Portuguese populations of brown trout, Salmo trutta L., was investigated by sequencing the 5′ end of the mitochondrial DNA (mtDNA) control region. Five new haplotypes were described for this species, each two to three mutational steps distant from the common north Atlantic haplotype. Significant population subdivision of mtDNA haplotypes was also apparent. Based on these results, as well as on published data describing the distribution of both mtDNA haplotypes and allozyme alleles throughout Europe, the postglacial recolonization of northern Europe was re‐evaluated. It is argued that the available data do not support the contribution of two major glacial refugia (southwest Atlantic and Ponto‐Caspian Basin) to this postglacial recolonization, as proposed in a recently published model. The unique genetic architecture of Portuguese brown trout within the Atlantic‐basin clade of this species represents a highly valuable genetic resource that should be protected from introgression with nonendemic strains of hatchery fish.
The colonization history of Olea europaea L. in Macaronesia based on internal transcribed spacer 1 (ITS‐1) sequences, randomly amplified polymorphic DNAs (RAPD), and intersimple sequence repeats (ISSR)
Authors: Hess J. , Kadereit J. W. , Vargas P.
Published: March 2003

Phylogenetic relationships in the Olea europaea complex and the phylogeography of 24 populations of the Macaronesian olive (O. europaea ssp. cerasiformis) were assessed by using three molecular markers: nuclear ribosomal internal transcribed spacer 1 (ITS‐1) sequences, randomly amplified polymorphic DNAs (RAPD), and intersimple sequence repeats (ISSR). Parsimony analysis of the ITS‐1 sequences and Neighbour‐joining (NJ) analyses of RAPD and ISSR banding variation revealed four major lineages in the O. europaea complex: (1) ssp. cuspidata; (2) ssp. cerasiformis from Madeira; (3) ssp. laperrinei; and (4) ssp. cerasiformis from the Canary Islands plus ssp. europaea. These results provide unequivocal support for two independent dispersal events of Olea to the Madeira and Canary Islands. Molecular and morphological evidence led to recognition of two separate olive taxa in Macaronesia, to date included in ssp. cerasiformis. NJ analyses of the combined RAPD and ISSR data suggest that the colonization of the Canaries by O. europaea may have followed an east to west stepping‐stone model. An interisland dispersal sequence can be recognized, starting from the continent to Fuerteventura, Gran Canaria, Tenerife, La Gomera, and finally La Palma. High dispersal activity of the lipid‐rich Olea fruits by birds in the Mediterranean region is congruent with multiple dispersal of olives to Macaronesia and successive colonization of the archipelagos. The observation of strong genetic isolation between populations of different islands of the Canary Islands suggests, however, that subsequent interisland dispersal and establishment has been very rare or may not have occurred at all.
Do earthworms help to sustain the slug predatorPterostichus melanarius(Coleoptera: Carabidae) within crops? Investigations using monoclonal antibodies
Authors: Symondson W. O. C. , Glen D. M. , Erickson M. L. , Liddell J. E. , Langdon C. J.
Published: March 2003

Earthworms provide a major potential source of alternative food for polyphagous predators, such as carabid beetles, that are natural enemies of slugs, aphids and other agricultural pests. Non‐pest prey may foster larger numbers of natural enemies, which then help to control pests, or alternatively may help to divert the predators away from pest control. An earthworm‐specific monoclonal antibody was developed to study carabid–earthworm interactions in the field and assess the role of earthworms as alternative prey. The antibody could identify as little at 7 ng of earthworm protein in an ELISA, and could detect earthworm remains in the foregut of the carabid beetlePterostichus melanariusfor 64 h after consumption. Thirty‐six per cent of field‐collected beetles contained earthworm remains. Quantities of earthworm proteins in the beetle foreguts were negatively related to total foregut biomass, suggesting that earthworm consumption increased as total prey availability declined. There was also a negative relationship between foregut biomass and beetle numbers, but both quantities and concentrations of earthworm proteins in beetle foreguts were positively related to beetle numbers. This suggests that as beetle activity–density increased, total prey availability declined, or, as prey availability declined, beetles spent more time searching. In these circumstances, beetles fed to a greater extent on earthworms, an acceptable but nonpreferred food item. Earthworms may, therefore, provide an ideal alternative prey forP. melanarius, helping to sustain it when pest numbers are low but allowing it to perform a ‘lying‐in‐wait’ strategy, ready to switch back to feeding on pests when they become available.
Genetic diversity and heavy metal tolerance in populations ofSilene paradoxaL. (Caryophyllaceae): a random amplified polymorphic DNA analysis
Authors: Mengoni A. , Gonnelli C. , Galardi F. , Gabbrielli R. , Bazzicalupo M.
Published: March 2003

Metal‐contaminated sites can occur naturally in serpentine outcrops or as consequence of anthropogenic activities, such as mining deposits, aerial fallout from smelters and industrial processes. Serpentine outcrops are characterized by high levels of nickel, cobalt and chromium and present a typical vegetation which includes endemisms and plants which also live in uncontaminated soils. These latter metal‐tolerant populations provide the opportunity to investigate the first steps in the differentiation of plant populations under severe selection pressure and to select plants to be used in the phytoremediation of industrially contaminated soils. In this report eight populations ofSilene paradoxaL. (Caryophyllaceae) growing in copper mine deposits, in serpentine outcrops or in noncontaminated soil in central Italy, were analysed using random amplified polymorphic DNA (RAPD) markers to investigate the pattern of genetic variation. The genetic diversity observed in populations at copper mine deposits was found to be at least as high as that of the neighbouring serpentine populations. Analysis of molecular variance (amova) of the RAPD markers gave high statistical significance to the groupings of populations according: (i) with their geographical location; and (ii) with the metals present in the soil of origin (copper vs. nickel), indicating that RAPD markers detected a polymorphism related to the soil contamination by copper. Finally, two RAPD bands exclusive to copper‐tolerant populations were identified.
Genetic structure of avian populations — allozymes revisited
Authors: Crochet P.‐A.
Published: March 2003

Selection on allozymes has sometimes been advanced as one explanation for the low levels of population differentiation detected in avian populations by the use of enzymatic markers. Comparisons of the amount of population subdivision (estimated by FST values or analogous indices) measured by enzymatic and mitochondrial DNA (mtDNA) markers in birds were seen as evidence for this because mtDNA typically produces a more structured picture of population subdivisions. In fact, when taking into account the smaller effective population size of mtDNA, nuclear and mitochondrial markers give concordant results. Some discrepancies still exist, but I suggest that some might originate from different amounts of nuclear vs. mitochondrial gene flow due to partial reproductive isolation. Variable number of tandem repeat (VNTR) loci do not provide a dramatically different picture of population structures in birds compared to allozymes. Although more tests are needed, such as comparing the amount of genetic structure detected in the same populations with allozymes and microsatellites, the low levels of population subdivision measured with allozymes in birds seem to reflect historical and demographic processes and would not appear to result from any peculiarities of bird enzymatic loci.
Fragmented forests, evolving flies: molecular variation in African populations of Drosophila teissieri
Authors: Cobb Matthew , Huet Michèle , Lachaise Daniel , Veuille Michel
Published: March 2003

Microsatellite variation from eight loci was studied in five populations of Drosophila teissieri, a fruit‐fly found only in the rain forests of sub‐Saharan Africa. Five noncontiguous rain forest sites (from Tanzania, Gabon and Ivory Coast) were sampled to measure the effects of historical forest fragmentation on population structure in an obligatory forest‐dwelling species. The Ivory Coast and Gabon populations showed a wider range of alleles, different modal alleles and had a higher genetic diversity than the three East African populations. As could be expected, genetic differentiation (FST) was significantly correlated with physical distance, but the westernmost population (Ivory Coast) showed values that were intermediate between the central (Gabon) and Eastern (Tanzania) populations. A migration‐drift equilibrium in a stable continuum of populations did not appear adequate to describe the observed distribution. It seems probable that the species has undergone abrupt changes involving isolation, merging and migration of populations, as a consequence of repeated waves of forest fragmentation and coalescence.
Large sequence divergence of mitochondrial DNA genotypes of the control region within populations of the African antelope, kob (Kobus kob)
Authors: Birungi J. , Arctander P.
Published: March 2003

The genetic differentiation among kob populations (Kobus kob) representing two recognized subspecies was examined using mitochondrial control region sequences. Two distinct lineages (estimated sequence divergence of 9.8%) exhibited different geographical distributions and do not coincide with previously recognized ranges of subspecies. The presence of the two lineages was further supported with sequences of mitochondrial cytochrome b gene. One lineage was predominant in the west and southern ranges of the populations studied and the other was commonly found in a more northern distribution (Murchison populations) in Uganda. Murchison and the geographically intermediate Toro populations (Uganda) represented the area of overlap. The existence of the two lineages in the area of overlap is hypothesized to have resulted from a range expansion and secondary contact of the two lineages of kob that evolved in allopatry. The existence of the kob during the Pleistocene offers a plausible explanation for the observed biogeographic pattern. Our mitochondrial data reveal two examples of discordance between a gene tree and presumed species tree as: (i) the two lineages co‐occur in the kob subspecies, Kobus kob thomasi (Uganda kob); and (ii) the puku, which was included in the analysis because of its controversial taxonomic status (currently recognized as a distinct species from the kob), is paraphyletic with respect to the kob. Significant degrees of heterogeneity were detected between populations. Relatively high genetic variation was observed in the populations, however, the inclusion of distinct lineages influences the population structure and nucleotide diversity of the kob populations.
Mating behaviour ofRhytidoponerasp. 12 ants inferred from microsatellite analysis
Authors: Tay W. T. , Crozier R. H.
Published: March 2003

In the queenless ponerine antRhytidoponerasp. 12, all workers have a spermatheca and functional ovaries and are potentially able to mate and reproduce. Within a colony gamergates may either be full sisters to each other (Type 1 colony), or they may not be full sisters but still be significantly related to each other (Type 2 colony) due to daughter gamergates reproducing in their natal colonies after mating. Despite many studies the mating behaviour ofR. sp. 12 has been poorly understood. In this study, we used microsatellite markers to investigate intracolony relatednesses of male mates to the gamergates (bmq) and between male mates (bmm), and mating frequencies and mating patterns, using gamergate DNA and sperm DNA isolated from the spermathecae of gamergates from five colonies. Averagebmmandbmqestimates for all five colonies studied were not significantly different from zero, suggesting that on average, within colonies, mating males were unrelated both to each other and to the gamergates. A low frequency (3%) of multiple mating by gamergates was detected. Multiple mating by individual males with sister gamergates within Type 1 colonies was also detected at 3% and could give rise to half‐sister nestmate workers. Polygamy inR. sp. 12 might indicate local female‐biased operational sex ratios despite the expectation of overall male biases. Our results concur with previous reports that gamergates mate within the colony or nearby, but indicate more diversity in mating patterns than previously indicated for this polygynous ponerine ant species.
Tandem repeats in plant mitochondrial genomes: application to the analysis of population differentiation in the conifer Norway spruce
Authors: Sperisen C. , Büchler U. , Gugerli F. , Mátyás G. , Geburek T. , Vendramin G. G.
Published: March 2003

Mitochondrial DNA, widely applied in studies of population differentiation in animals, is rarely used in plants because of its slow rate of sequence evolution and its complex genomic organization. We demonstrate the utility of two polymorphic mitochondrial tandem repeats located in the second intron of the nad1 gene of Norway spruce. Most of the size variants showed pronounced population differentiation and a distinct geographical distribution. A GenBank search revealed that mitochondrial tandem repeats occur in a broad range of plant species and may serve as a novel molecular marker for unravelling population processes in plants.
Population genetic structure of the lemon shark (Negaprion brevirostris) in the western Atlantic: DNA microsatellite variation
Authors: Feldheim K. A. , Gruber S. H. , Ashley M. V.
Published: March 2003

DNA microsatellite markers were used to characterize the population genetic structure of the lemon shark, Negaprion brevirostris, in the western Atlantic. This study demonstrates for the first time the usefulness of microsatellites to study population genetic structure and mating systems in the Chondricthyes. Lemon sharks (mostly juveniles) were sampled non‐destructively from four locations, Gullivan Bay and Marquesas Key in Florida, Bimini, Bahamas, and Atol das Rocas, Brazil. At least 545 individuals were genotyped at each of four dinucleotide loci. The number of alleles per locus ranged from 19 to 43, and expected heterozygosities ranged from 0.69 to 0.90. Relatively little genetic structure was found in the western Atlantic, with small but significant values for estimators of FST and RST among populations, θ (0.016) and ρ (0.026), respectively. No sharp discontinuities were found between the Caribbean sites and Brazil, and most alleles were found at all four sites, indicating that gene flow occurs throughout the western Atlantic with no evidence for distinct stocks.
Surprising similarity of sneaking rates and genetic mating patterns in two populations of sand goby experiencing disparate sexual selection regimes
Authors: Jones Adam G. , Walker Deette , Lindström Kai , Kvarnemo Charlotta , Avise John C.
Published: March 2003

Molecular markers have proved extremely useful in resolving mating patterns within individual populations of a number of species, but little is known about how genetic mating systems might vary geographically within a species. Here we use microsatellite markers to compare patterns of sneaked fertilization and mating success in two populations of sand goby (Pomatoschistus minutus) that differ dramatically with respect to nest‐site density and the documented nature and intensity of sexual selection. At the Tvärminne site in the Baltic Sea, the microsatellite genotypes of 17 nest‐tending males and mean samples of more than 50 progeny per nest indicated that approximately 35% of the nests contained eggs that had been fertilized by sneaker males. Successful nest holders mated with an average of 3.0 females, and the distribution of mate numbers for these males did not differ significantly from the Poisson expectation. These genetically deduced mating‐system parameters in the Tvärminne population are remarkably similar to those in sand gobies at a distant site adjoining the North Sea. Thus, pronounced differences in the ecological setting and sexual selection regimes in these two populations have not translated into evident differences in cuckoldry rates or other monitored patterns of male mating success. In this case, the ecological setting appears not to be predictive of alternative male mating strategies, a finding of relevance to sexual selection theory.
Sustaining genetic variation in a small population: evidence from the Mauritius kestrel
Authors: Nichols Richard A. , Bruford Michael W. , Groombridge Jim J.
Published: March 2003

We obtained measures of genetic diversity in 10 kestrel species at a suite of 12 microsatellite loci. We estimated the relative effective size (Ne) of the species using a Markov chain Monte Carlo (MCMC) approach, which jointly estimated the locus specific mutation rates as nuisance parameters. There was surprisingly high genetic diversity found in museum specimens of the Mauritius kestrel. Being an endemic species on a small island, it is known to have a long history of small population size. Conversely, kestrels with a continental distribution hadNeestimates that were only one order of magnitude larger and similar to each other, despite having current population sizes that were between one and three orders of magnitude larger than the Mauritius kestrel. We show how many of the theoretical results describing the effective size of a subdivided population can be captured in terms of three rates which describe the branching pattern of the gene genealogy, and that they are useful in estimating the time to migration‐drift and mutation‐drift equilibrium. We use this approach to argue that population subdivision has helped retain genetic diversity in the Mauritius kestrel, and that the continental species’ genetic diversity has yet to reach equilibrium after the range changes following the last ice age. We draw parallels with Hewitt’s observation that genetic variation seems to survive species’ range compression and is rather vulnerable to range expansion.
The role of hybridization in evolution
Authors: Barton N. H.
Published: March 2003

Hybridization may influence evolution in a variety of ways. If hybrids are less fit, the geographical range of ecologically divergent populations may be limited, and prezygotic reproductive isolation may be reinforced. If some hybrid genotypes are fitter than one or both parents, at least in some environments, then hybridization could make a positive contribution. Single alleles that are at an advantage in the alternative environment and genetic background will introgress readily, although such introgression may be hard to detect. ‘Hybrid speciation’, in which fit combinations of alleles are established, is more problematic; its likelihood depends on how divergent populations meet, and on the structure of epistasis. These issues are illustrated using Fisher’s model of stabilizing selection on multiple traits, under which reproductive isolation evolves as a side‐effect of adaptation in allopatry. This confirms a priori arguments that while recombinant hybrids are less fit on average, some gene combinations may be fitter than the parents, even in the parental environment. Fisher’s model does predict heterosis in diploid F1s, asymmetric incompatibility in reciprocal backcrosses, and (when dominance is included) Haldane’s Rule. However, heterosis arises only when traits are additive, whereas the latter two patterns require dominance. Moreover, because adaptation isviasubstitutions of small effect, Fisher’s model does not generate the strong effects of single chromosome regions often observed in species crosses.
Spatial structure of lemming populations (Dicrostonyx groenlandicus) fluctuating in density
Authors: Ehrich D. , Jorde P. E. , Krebs C. J. , Kenney A. J. , Stacy J. E. , Stenseth N. C.
Published: March 2003

The pattern and scale of the genetic structure of populations provides valuable information for the understanding of the spatial ecology of populations, including the spatial aspects of density fluctuations. In the present paper, the genetic structure of periodically fluctuating lemmings (Dicrostonyx groenlandicus) in the Canadian Arctic was analysed using mitochondrial DNA (mtDNA) control region sequences and four nuclear microsatellite loci. Low genetic variability was found in mtDNA, while microsatellite loci were highly variable in all localities, including localities on isolated small islands. For both genetic markers the genetic differentiation was clear among geographical regions but weaker among localities within regions. Such a pattern implies gene flow within regions. Based on theoretical calculations and population census data from a snap‐trapping survey, we argue that the observed genetic variability on small islands and the low level of differentiation among these islands cannot be explained without invoking long distance dispersal of lemmings over the sea ice. Such dispersal is unlikely to occur only during population density peaks.
Genetic and ecological divergence of a monophyletic cichlid species pair under fully sympatric conditions in Lake Ejagham, Cameroon
Authors: Schliewen Ulrich , Rassmann Kornelia , Markmann Melanie , Markert Jeff , Kocher Thomas , Tautz Diethard
Published: March 2003

Although there is mounting evidence that speciation can occur under sympatric conditions, unambiguous examples from nature are rare and it is almost always possible to propose alternative allopatric or parapatric scenarios. To identify an unequivocal case of sympatric speciation it is, therefore, necessary to analyse natural settings where recent monophyletic species flocks have evolved within a small and confined spatial range. We have studied such a case with a cichlid species flock that comprises five Tilapia forms endemic to a tiny lake (Lake Ejagham with a surface area of approximately 0.49 km2) in Western Cameroon. Analysis of mitochondrial D‐Loop sequences shows that the flock is very young (approximately 104 years) and has originated from an adjacent riverine founder population. We have focused our study on a particular pair of forms within the lake that currently appears to be in the process of speciation. This pair is characterized by an unique breeding colouration and specific morphological aspects, which can serve as synapomorphic characters to prove monophyly. It has differentiated into a large inshore and a small pelagic form, apparently as a response to differential utilization of food resources. Still, breeding and brood care occurs in overlapping areas, both in time and space. Analysis of nuclear gene flow on the basis of microsatellite polymorphisms shows a highly restricted gene flow between the forms, suggesting reproductive isolation between them. This reproductive isolation is apparently achieved by size assortative mating, although occasional mixed pairs can be observed. Our findings are congruent with recent theoretical models for sympatric speciation, which show that differential ecological adaptations in combination with assortative mating could easily lead to speciation in sympatry.
Shared parentage and incest avoidance in the cooperatively breeding acorn woodpecker
Authors: Haydock J. , Koenig W. D. , Stanback M. T.
Published: March 2003

Social groups of acorn woodpeckers (Melanerpesformicivorus) range in size from unaided pairs to 15 adults. Behavioural indicators of mate guarding, assumed incest avoidance and observations of egg‐laying indicate that social organization ranges from monogamous pairs to groups with up to seven male and three female putative cobreeders plus up to 10 nonbreeding helpers. In addition, groups occasionally lack a putative breeder throughout the breeding season. Here we report results from multilocus DNA fingerprinting of 372 nestlings from 123 nests in groups with putative cobreeders of one or both sexes. No extra‐group fertilizations were found. Putative cobreeding males within social groups shared paternity. However, the most reproductively successful male was, on average, almost three times as successful as the next most successful and additional males only occasionally sired offspring. In contrast, cobreeding females shared parentage equally. Helpers never bred incestuously when their opposite‐sex parent (or another relative, such as their uncle) held breeding status in the group. However, during breeding male vacancies, 14 nestlings were produced when helper males bred incestuously with their mother. Both male and female helpers usually became successful cobreeders with their same‐sex parent following replacement of the opposite‐sex breeder(s) by unrelated individuals.
Spatial patterns of genetic diversity in Posidonia oceanica, an endemic Mediterranean seagrass
Authors: Procaccini G. , Orsini L. , Ruggiero M. V. , Scardi M.
Published: March 2003

Posidonia oceanica is an endemic seagrass species in the Mediterranean Sea. In order to assess levels of genetic structure in this species, the microsatellite polymorphism was analysed from meadows collected in several localities, along the coasts of the Tyrrhenian Sea (Mediterranean Sea). The existence of single population units and the recruitment of seedlings collected in some localities were investigated. Moreover, genetic structure at different spatial scales and biogeographic relationships among populations were also assessed. Our analysis showed the existence of clear patterns of genetic structure in P. oceanica in the area considered in the analysis. P. oceanica, in fact, is present in separate meadows that represent discrete populations, characterized by low genetic diversity. Comparable levels of genetic variability between mature meadows and seedlings were found. Patterns of genetic relatedness among populations seem to be in accord with direction of dominant current flux in the whole area, separating South Tyrrhenian from North Tyrrhenian populations. Moderate levels of gene flow between populations and genetic substructure within populations, together with the finding of the limited role of sexual reproduction in increasing genetic variability, should be a cause for concern for the persistence of this essential resource in the Mediterranean basin.
Genetic structure of populations of the human hookworm, Necator americanus, in China
Authors: Hawdon J. M. , Li T. , Zhan B. , Blouin M. S.
Published: March 2003

Twenty‐one to 58 individual Necator americanus were sampled from each of four villages in south‐western China. Each nematode was sequenced for 588 bp of the mitochondrial cytochrome oxidase I gene. Allelic and nucleotide diversity varied two‐fold among villages. Overall FST among populations was ≈ 0.28, but this large value resulted from one low‐diversity population that had a large genetic distance to the other three populations (FST = 0.10 without that population). There was no correlation between geographical and genetic distance among sites. Thus, the genetic structure of this species in China may be characterized by variable effective sizes and uneven movement among sites. We discuss the implications of this genetic structure for vaccine development and the spread of drug resistance in human hookworms, and compare the genetic structure of hookworms with that of other nematodes.
Allozyme and microsatellite loci provide discordant estimates of population differentiation in the endangered dusky grouper (Epinephelus marginatus) within the Mediterranean Sea
Authors: De Innocentiis S. , Sola L. , Cataudella S. , Bentzen P.
Published: March 2003

The dusky grouper, Epinephelus marginatus, inhabits coastal reefs in the Mediterranean Sea and Atlantic Ocean. A decline in the abundance of this long‐lived protogynous hermaphrodite has led to its listing as an endangered species in the Mediterranean, and heightened management concerns regarding its genetic variability and population substructure. To address these concerns, we analysed genetic variation at seven microsatellite and 28 allozyme loci in dusky groupers sampled from seven areas (for microsatellites) and three areas (for allozymes) in the west‐central Mediterranean. Levels of genetic variability were higher for microsatellites than for allozymes (mean HE = 0.78 and 0.07, respectively), but similar to those observed in other marine fishes with comparable markers. Both microsatellites and allozymes revealed significant genetic differentiation among all areas analysed with each class of marker, but the magnitude of differentiation revealed by allozymes over three locales (FST = 0.214) was greater than that detected with microsatellites over seven areas, or over the three areas shared with the allozyme analysis (FST = 0.018 and ~0, respectively). A large proportion of the allozyme differentiation was due to a single locus (ADA*) possibly influenced by selection, but allozyme differentiation over the three areas was still highly significant (FST = 0.06, P < 0.0001), and the 95% confidence intervals for allozyme and microsatellite FST did not overlap when this locus was excluded. There was no evidence of isolation by distance with either class of markers. Our results lead us to conclude that dusky groupers are not panmictic in the Mediterranean Sea and suggest that they should be managed on a local basis. However, more work is needed to elucidate genetic relationships among populations.