bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantifying effects of phytoplankton on the heat budgets of two large limnetic enclosures
Authors: JONES IAN , GEORGE GLEN , REYNOLDS COLIN 
Published: June 2005

Summary1. The aestival heat budgets of two large limnetic enclosures within a small lake in the English Lake District were studied. During summer, these enclosures had different nutrient supplies and consequently different phytoplankton populations.2. As initial temperature profiles were similar and the incoming surface heat and momentum fluxes for the two enclosures were identical, subsequent changes in the heat budget were assumed to be induced by the biological differences between the enclosures. The proposed mechanism is an increased surface absorption of solar radiation leading to extra surface warming and a consequent excess loss of heat to the atmosphere through long‐wave emittance and sensible and latent heat fluxes, conservatively estimated to be of the order of 10–30 W m−2.3. Theoretical calculations show that potential effects on a heat budget could be considerably larger than those observed here. The inherent non‐linearity of the heat fluxes implies that such effects will be more important in warmer lakes than in colder ones.4. Thermocline depth and strength were also altered by the response to differences in phytoplankton.5. Any changes in climate or in nutrient loading from the catchment which substantially affect abundance or timing of phytoplankton populations in a lake will consequently also change the thermal structure of the lake.
Patterns of vegetative growth and gene flow in Rhizopogon vinicolor and R. vesiculosus (Boletales, Basidiomycota)
Authors: KRETZER ANNETTE M. , DUNHAM SUSIE , MOLINA RANDY , SPATAFORA JOSEPH W. 
Published: June 2005

AbstractWe have collected sporocarps and tuberculate ectomycorrhizae of both Rhizopogon vinicolor and Rhizopogon vesiculosus from three 50 × 100 m plots located at Mary's Peak in the Oregon Coast Range (USA); linear map distances between plots ranged from c. 1 km to c. 5.5 km. Six and seven previously developed microsatellite markers were used to map the approximate size and distribution of R. vinicolor and R. vesiculosus genets, respectively. Genetic structure within plots was analysed using spatial autocorrelation analyses. No significant clustering of similar genotypes was detected in either species when redundant samples from the same genets were culled from the data sets. In contrast, strong clustering was detected in R. vesiculosus when all samples were analysed, but not in R. vinicolor. These results demonstrate that isolation by distance does not occur in either species at the intraplot sampling scale and that clonal propagation (vegetative growth) is significantly more prevalent in R. vesiculosus than in R. vinicolor. Significant genetic differentiation was detected between some of the plots and appeared greater in the more clonal species R. vesiculosus with ΦST values ranging from 0.010 to 0.078*** than in R. vinicolor with ΦST values ranging from −0.002 to 0.022** (*P < 0.05, **P < 0.01, ***P < 0.001). When tested against the null hypothesis of no relationship between individuals, parentage analysis detected seven likely parent/offspring pairs in R. vinicolor and four in R. vesiculosus (α = 0.001). Of these 11 possible parent/offspring pairs, only two R. vinicolor pairs were still supported as parent/offspring when tested against the alternative hypothesis of being full siblings (α = 0.05). In the latter two cases, parent and offspring were located at approximately 45 m and 28 m from each other. Challenges to parentage analysis in ectomycorrhizal fungi are discussed.
Genetic structure in a solitary rodent (Ctenomys talarum): implications for kinship and dispersal
Authors: CUTRERA A. P. , LACEY E. A. , BUSCH C. 
Published: June 2005

AbstractThe genetic structure of a population provides critical insights into patterns of kinship and dispersal. Although genetic evidence of kin structure has been obtained for multiple species of social vertebrates, this aspect of population biology has received considerably less attention among solitary taxa in which spatial and social relationships are unlikely to be influenced by kin selection. Nevertheless, significant kin structure may occur in solitary species, particularly if ecological or life history traits limit individual vagility. To explore relationships between genetic structure, kinship, and dispersal in a solitary vertebrate, we compared patterns of genetic variation in two demographically distinct populations of the talar tuco‐tuco (Ctenomys talarum), a solitary species of subterranean rodent from Buenos Aires Province, Argentina. Based on previous field studies of C. talarum at Mar de Cobo (MC) and Necochea (NC), we predicted that natal dispersal in these populations is male biased, with dispersal distances for males and females being greater at NC. Analyses of 12 microsatellite loci revealed that in both populations, kin structure was more apparent among females than among males. Between populations, kinship and genetic substructure were more pronounced at MC. Thus, our findings were consistent with predicted patterns of dispersal for these animals. Collectively, these results indicate that populations of this solitary species are characterized by significant kin structure, suggesting that, even in the absence of sociality and kin selection, the spatial distributions and movements of individuals may significantly impact patterns of genetic diversity among conspecifics.
Detecting the number of clusters of individuals using the software structure: a simulation study
Authors: EVANNO G. , REGNAUT S. , GOUDET J. 
Published: June 2005

AbstractThe identification of genetically homogeneous groups of individuals is a long standing issue in population genetics. A recent Bayesian algorithm implemented in the software structure allows the identification of such groups. However, the ability of this algorithm to detect the true number of clusters (K) in a sample of individuals when patterns of dispersal among populations are not homogeneous has not been tested. The goal of this study is to carry out such tests, using various dispersal scenarios from data generated with an individual‐based model. We found that in most cases the estimated ‘log probability of data’ does not provide a correct estimation of the number of clusters, K. However, using an ad hoc statistic ΔK based on the rate of change in the log probability of data between successive K values, we found that structure accurately detects the uppermost hierarchical level of structure for the scenarios we tested. As might be expected, the results are sensitive to the type of genetic marker used (AFLP vs. microsatellite), the number of loci scored, the number of populations sampled, and the number of individuals typed in each sample.
High diversity of oilseed rape pollen clouds over an agro‐ecosystem indicates long‐distance dispersal
Authors: DEVAUX C. , LAVIGNE C. , FALENTIN‐GUYOMARC'H H. , VAUTRIN S. , LECOMTE J. , KLEIN E. K. 
Published: June 2005

AbstractEstimating the frequency of long‐distance pollination is important in cultivated species, particularly to assess the risk of gene transfer following the release of genetically modified crops. For this purpose, we estimated the diversity and origin of fertilizing pollen in a 10 × 10 km French oilseed rape production area. First, the cultivar grown in each field was identified through surveys to farmers and using microsatellite markers. Examination of the seed set in fields indicated high rates of seed contamination (8.7%) and pollination from other sources (5%). Then, male‐sterile plants were scattered over the study area and their seed genotyped using the same markers. Most pollination was local: 65% of the seeds had a compatible sire in the closest field, i.e. at 50 or 300 m depending on site, but the nearest compatible field was found more than 1000 m away for 13% of the seeds. To assess the diversity of fertilizing pollen, each seed was assigned to the nearest putative siring cultivar. The observed diversity of pollen was then compared to that predicted by simulations using three empirical dispersal models with increasing proportion of long‐distance pollination. The diversity was sensitive to the dispersal kernel used in the simulations, fatter‐tailed functions predicting higher diversities. The dispersal kernel that was more consistent with our data predicted more long‐distance dispersal than the exponential function.
Landscape genetics of the blotched tiger salamander (Ambystoma tigrinum melanostictum)
Authors: SPEAR STEPHEN F. , PETERSON CHARLES R. , MATOCQ MARJORIE D. , STORFER ANDREW 
Published: June 2005

AbstractThe field of landscape genetics has great potential to identify habitat features that influence population genetic structure. To identify landscape correlates of genetic differentiation in a quantitative fashion, we developed a novel approach using geographical information systems analysis. We present data on blotched tiger salamanders (Ambystoma tigrinum melanostictum) from 10 sites across the northern range of Yellowstone National Park in Montana and Wyoming, USA. We used eight microsatellite loci to analyse population genetic structure. We tested whether landscape variables, including topographical distance, elevation, wetland likelihood, cover type and number of river and stream crossings, were correlated with genetic subdivision (FST). We then compared five hypothetical dispersal routes with a straight‐line distance model using two approaches: (i) partial Mantel tests using Akaike's information criterion scores to evaluate model robustness and (ii) the BIOENV procedure, which uses a Spearman rank correlation to determine the combination of environmental variables that best fits the genetic data. Overall, gene flow appears highly restricted among sites, with a global FST of 0.24. While there is a significant isolation‐by‐distance pattern, incorporating landscape variables substantially improved the fit of the model (from an r2 of 0.3 to 0.8) explaining genetic differentiation. It appears that gene flow follows a straight‐line topographic route, with river crossings and open shrub habitat correlated with lower FST and thus, decreased differentiation, while distance and elevation difference appear to increase differentiation. This study demonstrates a general approach that can be used to determine the influence of landscape variables on population genetic structure.
Age, phylogeography and population structure of the microendemic banded spring snail,Mexipyrgus churinceanus
Authors: JOHNSON STEVEN G. 
Published: June 2005

AbstractRecent theoretical and empirical studies of phylogeography and population structure indicate that many processes influence intraspecific evolutionary history. The present study represents the first examination of various forces influencing the spatial and temporal patterns of sequence variation in the freshwater Mexican banded spring snail,Mexipyrgus churinceanus. This snail occurs in one of the most critically endangered centres of freshwater endemism, the desert ecosystem of Cuatro Ciénegas. From cytochromebmtDNA sequence variation, there is strong evidence of long‐term isolation of three regions, suggesting that these regions represent evolutionarily distinct lineages. Molecular clock estimates of clade age indicate a time to most recent common ancestor of approximately 2.5 million years ago (Ma). The three regions differ considerably in the historical and demographic forces affecting population structure. The western populations have extremely low mtDNA diversity consistent with a severe bottleneck dating to 50 000 years before present (bp). The nearby Rio Mesquites drainage is characterized by fragmentation events, restricted gene flow with isolation by distance, and higher levels of mtDNA polymorphism. These patterns are consistent with the long‐term stability of this drainage along with habitat heterogeneity and brooding contributing to population isolation and restricted gene flow. Southeastern populations show evidence of range expansion and a strong influence of genetic drift. Migration rates between drainages indicate very little gene flow between drainages except for asymmetric migration from the Rio Mesquites into both western and southeastern drainages.
Half‐sib family structure of Fagus crenata saplings in an old‐growth beech–dwarf bamboo forest
Authors: ASUKA Y. , TOMARU N. , MUNEHARA Y. , TANI N. , TSUMURA Y. , YAMAMOTO S. 
Published: June 2005

AbstractHalf‐sib family structure of Fagus crenata saplings was examined in an old‐growth beech–dwarf bamboo (Sasa spp.) forest using microsatellite genotypes in parentage analysis to identify the half‐sib families in two 50 × 50 m plots: one with 36 adults, 641 saplings and no Sasa cover, the other with 21 adults, 61 saplings and Sasa cover. For large proportions of the saplings (44.6% and 75.4%, respectively) both of their parents were found within the same plot, indicating that pollination events frequently involved short‐range pollen dispersal, probably because of the high density of adults in the study population. Although almost all of the adults had half‐sib families, the number of offspring in the families was highly variable. In the plot with no Sasa cover, the variation in the number of offspring was significantly explained by the size of parents, i.e. the reproductive success is higher for large adults than for small adults. The half‐sibs were aggregately distributed around their parents and the distribution overlapped among different half‐sib families, which may be due to the limited seed dispersal and overlapping seed shadows of this species. As expected, there was weak genetic structure in the plot. By contrast, in the plot with Sasa cover, the half‐sibs were distributed sparsely with a low density, and the degree of genetic structure was very weak. The difference in the half‐sib family structure and genetic structure among saplings presumably reflects the difference in density that should be affected by regeneration dynamics associated with environmental conditions.
Invasion of Lepidium draba (Brassicaceae) in the western United States: distributions and origins of chloroplast DNA haplotypes
Authors: GASKIN JOHN F. , ZHANG DAO‐YUAN , BON MARIE‐CLAUDE 
Published: June 2005

AbstractAdvances in phylogeography are of great value for understanding the population structure and origins of invasive genotypes. Such insights provide constructive information for current or future biological control research efforts. In this study, we investigated a highly variable chloroplast DNA (cpDNA) marker for populations of the weed Lepidium draba (Brassicaceae) in its native Eurasian and invasive US ranges. We sequenced DNA from 684 individuals from Eurasia and the US and found 41 different haplotypes. Our comparative study between the native and invasive ranges showed a 33% reduction in allelic richness (A) and a 7% reduction in haplotype diversity (h) since introduction into the US. Most genetic variation in the native range was observed within geographical regions and populations, not between regions, and this result was similar for the invasive range. Assignment tests indicated the most likely origins of many invasive haplotypes. Some of these occurred in western Europe, supporting an expanded native range that had been proposed for the species. Exact locations were identified for a diverse set of invasive haplotypes which can be used in ongoing host‐specificity tests of potential biological control agents.
A mitogenic view on the evolutionary history of the Holarctic freshwater gadoid, burbot (Lota lota)
Authors: VAN HOUDT J. K. J. , DE CLEYN L. , PERRETTI A. , VOLCKAERT F. A. M. 
Published: June 2005

AbstractClimatic oscillations during the Pleistocene epoch had a dramatic impact on the distribution of biota in the northern hemisphere. In order to trace glacial refugia and postglacial colonization routes on a global scale, we studied mitochondrial DNA sequence variation in a freshwater fish (burbot,Lota lota; Teleostei, Gadidae) with a circumpolar distribution. The subdivision of burbot in the subspeciesLota lota lota(Eurasia and Alaska) andLota lota maculosa(North America, south of the Great Slave Lake) was reflected in two distinct mitochondrial lineages (average genetic distance is 2.08%). Thelotaform was characterized by 30 closely related haplotypes and a large part of its range (from Central Europe to Beringia) was characterized by two widespread ancestral haplotypes, implying that transcontinental exchange/migration was possible for cold‐adapted freshwater taxa in recent evolutionary time. However, the derived mitochondrial variants observed in peripheral populations point to a recent separation from the core group and postglacial recolonization from distinct refugia. Beringia served as refuge from whereL. l. lotadispersed southward into North America after the last glacial maximum. Genetic variation in themaculosaform consisted of three mitochondrial clades, which were linked to at least three southern refugia in North America. Two mitochondrial clades east of the Continental Divide (Mississippian and Missourian clades) had a distinct geographical distribution in the southern refuge zones but intergraded in the previously glaciated area. The third clade (Pacific) was exclusively found west of the Continental Divide.
Parentage versus two‐generation analyses for estimating pollen‐mediated gene flow in plant populations
Authors: BURCZYK JAROSLAW , KORALEWSKI TOMASZ E. 
Published: June 2005

AbstractAssessment of contemporary pollen‐mediated gene flow in plants is important for various aspects of plant population biology, genetic conservation and breeding. Here, through simulations we compare the two alternative approaches for measuring pollen‐mediated gene flow: (i) theneighborhoodmodel — a representative of parentage analyses, and (ii) the recently developedtwogeneranalysis of pollen pool structure. We investigate their properties in estimating the effective number of pollen parents (Nep) and the mean pollen dispersal distance (δ). We demonstrate that both methods provide very congruent estimates ofNepand δ, when the methods’ assumptions considering the shape of pollen dispersal curve and the mating system follow those used in data simulations, although theneighborhoodmodel exhibits generally lower variances of the estimates. The violations of the assumptions, especially increased selfing or long‐distance pollen dispersal, affect the two methods to a different degree; however, they are still capable to provide comparable estimates ofNep. Theneighborhoodmodel inherently allows to estimate both self‐fertilization and outcrossing due to the long‐distance pollen dispersal; however, thetwogenermethod is particularly sensitive to inflated selfing levels, which in turn may confound and suppress the effects of distant pollen movement. As a solution we demonstrate that in case oftwogenerit is possible to extract the fraction of intraclass correlation that results from outcrossing only, which seems to be very relevant for measuring pollen‐mediated gene flow. The two approaches differ in estimation precision and experimental efforts but they seem to be complementary depending on the main research focus and type of a population studied.
Genetic structure and environmental heterogeneity in the European hake (Merluccius merluccius)
Authors: CIMMARUTA R. , BONDANELLI P. , NASCETTI G. 
Published: June 2005

AbstractThis study aimed at assessing the genetic structure and the state of the stocks of the European hake (Merluccius merluccius). To this end, 15 samples were taken from the whole range of the species and analysed using allozymes. Since 11 samples were taken from the poorly studied Mediterranean Sea, the results obtained provided a complete picture of the hake's genetic structure and an initial insight into its relationships with environmental features. Atlantic and Mediterranean hake populations are separated by the Almeria‐Oran front. This area has been proved to be the boundary between Atlantic and Mediterranean stocks of many marine organisms, but some doubt exists concerning the efficaciousness of the local gyres as barriers to the gene flow. Our data have evidenced a latitudinal cline at loci Gapdh and Gpi‐2 within the Mediterranean Sea, with a further steep change across the Almeria‐Oran front. The genetic pattern showed a strong correlation with the values of the salinity both at the surface and at −320 m and of the salinity + temperature at the surface, suggesting a role for these parameters in maintaining the genetic differentiation among the two population groups through selective processes. Finally, the levels of genetic variability were found to be slightly lower in the depleted Atlantic stock than in the Mediterranean one.
Microsatellite analyses reveal fine‐scale genetic structure in grey mouse lemurs (Microcebus murinus)
Authors: FREDSTED T. , PERTOLDI C. , SCHIERUP M. H. , KAPPELER P. M. 
Published: June 2005

AbstractInformation on genetic structure can be used to complement direct inferences on social systems and behaviour. We studied the genetic structure of the solitary grey mouse lemur (Microcebus murinus), a small, nocturnal primate endemic to western Madagascar, with the aim of getting further insight on its breeding structure. Tissue samples from 167 grey mouse lemurs in an area covering 12.3 km2in Kirindy Forest were obtained from trapping. The capture data indicated a noncontinuous distribution of individuals in the study area. Using 10 microsatellite markers, significant genetic differentiation in the study area was demonstrated and dispersal was found to be significantly male biased. Furthermore, we observed an overall excess of homozygotes in the total population (FIT = 0.131), which we interpret as caused by fine‐scale structure with breeding occurring in small units. Evidence for a clumped distribution of identical homozygotes was found, supporting the notion that dispersal distance for breeding was shorter than that for foraging, i.e. the breeding neighbourhood size is smaller than the foraging neighbourhood size. In conclusion, we found a more complex population structure than what has been previously reported in studies performed on smaller spatial scales. The noncontinuous distribution of individuals and the effects of social variables on the genetic structure have implications for the interpretation of social organization and the planning of conservation activities that may apply to other solitary and endangered mammals as well.