bluuebunny/crossref_metadata_2025_split huggingface dataset:
Patterns of diversity of the north‐eastern Atlantic blenniid fish fauna (Pisces: Blenniidae)
Authors: Almada Vítor C. , Oliveira Rui F. , Gonçalves Emanuel J. , Almeida Armando J. , Santos Ricardo S. , Wirtz Peter 
Published: March 2003

AbstractThis paper presents an analysis of the distributional patterns of blenniids (Pisces: Blenniidae) in the north‐eastern Atlantic. Two peaks of species diversity were found, both in terms of number of species and number of endemics: one in the tropical African coast and another in the Mediterranean Sea. A cluster analysis of similarity values (Jaccard coefficient) among the eastern Atlantic zoogeographical areas, revealed the following groups: a north temperate group, a tropical group formed by the tropical African coast and Mauritania, another group formed by the islands of Cape Verde, a south temperate group (South Africa), and a southern Atlantic group formed by the islands of Ascension and St Helena. Within the north temperate group, the subgroups with higher similarities were: Azores and Madeira, Canary Islands and Morocco, and the Mediterranean and the Atlantic coast of the Iberian Peninsula. Based on affinity indices, the probable directions of faunal flows were inferred. The tropical coast of Africa and the Mediterranean emerged from this analysis as probable speciation centres of the north‐eastern Atlantic blenniid fauna. The Mediterranean may have also acted as a refuge during glacial periods.
Historical biogeography of Iberobathynella (Crustacea, Syncarida, Bathynellacea), an aquatic subterranean genus of Parabathynellids, endemic to the Iberian Peninsula
Authors: Guil Noemí , Camacho Ana I. 
Published: March 2003

Abstract

The origin and distribution of the species of freshwater interstitial (stygobiont) syncarids of the Iberobathynella genus (Crustacea, Parabathynellidae), endemic to the Iberian Peninsula, are considered in the context of evolutionary biogeography.
We established the most likely phylogenetic relationships between the 14 known species of the Iberobathynella genus on the basis of morphological characters. We assumed a common marine ancestor and estimated the possible phylogenetic ages of the 14 inland species from the number of cladogram nodes.
The land ages at the sites where the species are found help to tell us when the landmasses emerged definitively: most species are found in areas that have undergone one or more marine transgressions/regressions since the Triassic and which could therefore have been colonized by the common ancestors.
We assessed the Boutin–Coineau two‐step model of colonization and evolution in an attempt to elucidate the evolutionary history of Iberobathynella and to offer a plausible palaeogeographical scenario. We looked for concordance between the possible chronology of Iberobathynella taxa colonization and their phylogenetic relationships, but found none of significance. Hence, we cannot reject the possibility that evolutionary clade divergence within the genus was independent of sea‐level changes in the Senonian (88.5–65 mya) and Eocene (56.5–35.4 mya) epochs. We can therefore neither confirm nor rule out a correlation.
Biodiversity hotspots: hot for what?
Authors: Jepson Paul , Canney Susan 
Published: March 2003

AbstractIn complex areas of international policy, such as biodiversity conservation, there is a risk that well‐promoted strategies will be received by decision makers as a cure‐all. The U.S.‐based Conservation International is promoting biodiversity hotspots as a ‘silver bullet’ strategy for conserving most species for least cost. We assess the degree to which this goal is compatible with four social values that characterize the conservation movement. We find that biodiversity hotspots provide only a partial response because conservation does not treat all species as equal. We argue that explicit recognition of such values is fundamental to a structured debate contributing to the development of a common strategy for biodiversity conservation.
Equal diversity in disparate species assemblages: a comparison of native and exotic woodlands in California
Authors: Sax Dov F. 
Published: March 2003

AbstractThe species richness of ecosystems can remain stable over time, despite changes in species composition and changes in the dominant plant species. While this pattern of stability is known to occur temporally, it has been examined poorly in a spatial context. To examine this spatially, the species richness, diversity and composition of native woodlands (of oak and bay trees) and exotic woodlands (of eucalypt trees) were compared in California. Species richness was nearly identical for understorey plants, leaf‐litter invertebrates, amphibians and birds; only rodents had significantly fewer species in eucalypt sites. Species diversity patterns (using the Shannon–Wiener Index) were qualitatively identical to those for species richness, except for leaf‐litter invertebrates, which were significantly more diverse in eucalypt sites during the spring. Species composition was different between sites, as evidenced by a principal components analysis, coefficients of similarity, and the relatively few species shared between native and eucalypt sites. Thus, the consistency in richness and diversity observed for most groups, in most seasons, occurred despite significant differences in species composition. These results are consistent with previous demonstrations of temporal stability, suggesting that species richness may often be stable, both temporally and spatially, despite changes in composition and regardless of the dominant vegetation.
Responses of vegetation structure and primary production of a forest transect in eastern China to global change
Authors: Yu Mei , Gao Qiong , Liu Yinghui , Xu Hongmei , Shi Peijun 
Published: March 2003

AbstractAim A regional model of vegetation dynamics was enhanced to include biogeochemical cycling of nitrogen and was then applied to a forest transect in east China (FTEC) in order to investigate the responses of the transect to possible global change.Location Eastern China.Methods Biomass and nitrogen concentration of green and nongreen portions of vegetation, moisture contents of three soil layers, and total and available soil nitrogen are included as state variables in the enhanced model. The model was parameterized and validated against field observations of biomass, productivity, plant and soil nitrogen concentration, nitrogen uptake, a vegetation index derived from satellite remote sensing and digital maps of vegetation and soil distributions along a forest transect in eastern China (FTEC). The model was applied to FTEC in order to investigate the responsive characteristics of the ecosystems to global climatic change. Scenarios of climate change under doubled CO2 produced by seven general circulation models (GCM) were used to drive the model.Results The simulations indicated that the model is capable of simulating accurately potential vegetation distribution and net primary productivity under contemporary climatic conditions. The simulations for GCM‐projected future climate scenarios with doubled atmospheric CO2 concentration predicted that broadleaf forests would increase, but conifer forests, shrubs and grasses would decrease; and that deciduous forests would have the largest relative increase, but evergreen shrubs would have the largest decrease.Conclusions The overall effects of doubling CO2 and climatic changes on FTEC were to produce an increased net primary productivity (NPP) at equilibrium for all seven GCM scenarios. The inclusion of nitrogen dynamics in the model imposes more constraint on the responses of FTEC to climatic change than the previous version of the model without nitrogen dynamics. Temperature exerts a stronger control on NPP than precipitation, as indicated by the negative correlations between NPP and temperature. The southern portion of FTEC, at latitudes less than 33 °N, show much larger increases in annual NPP than in the north. However, the predicted range of NPP increases is much larger in the north than in the south.
On the determinants of census area: implications for mammalian macroecological patterns
Authors: Prince Mary Ellen , Silva Marina 
Published: March 2003

AbstractThe aim of this study was to examine the effects of various biological factors such as body mass, trophic level, climate and geography on census area in terrestrial mammals. We also examine the effects of census area on the population density–body mass relationship. The geographic areas covered in this study include most major terrestrial biomes including taïga, desert, savanna, grassland, tropical dry forest, temperate dry forest, tropical rain forest and temperate rain forest. An extensive literature search was conducted and we compiled data on census area and body mass from 377 mammalian populations and 59 communities. Statistical analyses include linear regression, Kruskal–Wallis analysis of variance, LOWESS, and multiple regression. Overall, the regression between log census area (A) and log body mass (M) yielded a slope of 0.710, which did not differ significantly from 0.75, but it was significantly different from 1.0. The analyses also showed that the log A–log M relationship is constrained within a well‐defined space in a similar fashion to the home range–body mass relationship. When mammals were separated into trophic groups, regression lines differed significantly in their intercepts, but not in slopes. At the community level, the census area was particularly affected by the population with the largest body mass within the community. Both the number of species and number of taxa encompassed by the community were found to be correlated positively with log A (r = 0.26, P = 0.0464 and r = 0.27, P = 0.0398, respectively). Sampling of mammalian species is not usually random. Not only is census area significantly associated with the technique used to sample a given species, but it is also influenced by biological factors that have been shown previously to influence population density. Striking similarities were found between the census area–body mass relationship and the home range–body mass relationship, suggesting that investigators may sample mammalian populations over areas that actually reflect the use of space of their focal species.
The relationships between local and regional species richness and spatial turnover
Authors: Koleff Patricia , Gaston Kevin J. 
Published: March 2003

AbstractAim To determine the empirical relationships between species richness and spatial turnover in species composition across spatial scales. These have remained little explored despite the fact that such relationships are fundamental to understanding spatial diversity patterns.Location South‐east Scotland.Methods Defining local species richness simply as the total number of species at a finer resolution than regional species richness and spatial turnover as turnover in species identity between any two or more areas, we determined the empirical relationships between all three, and the influence of spatial scale upon them, using data on breeding bird distributions. We estimated spatial turnover using a measure independent of species richness gradients, a fundamental feature which has been neglected in theoretical studies.Results Local species richness and spatial turnover exhibited a negative relationship, which became stronger as larger neighbourhood sizes were considered in estimating the latter. Spatial turnover and regional species richness did not show any significant relationship, suggesting that spatial species replacement occurs independently of the size of the regional species pool. Local and regional species richness only showed the expected positive relationship when the size of the local scale was relatively large in relation to the regional scale.Conclusions Explanations for the relationships between spatial turnover and local and regional species richness can be found in the spatial patterns of species commonality, gain and loss between areas.
Sib‐TDT analysis of human TGF‐β1 gene single nucleotide polymorphisms in female twins: evidence for linkage and association with blood pressure at the codon 263 polymorphism
Authors: Snieder H. , Van Den Oord Ejcg , Chiano M. , MacGregor Aj , Spector Td 
Published: March 2003

AbstractWe illustrate the use of a quantitative trait locus (QTL) association test with data on blood pressure and six single nucleotide polymorphisms (SNPs) within the transforming growth factor‐β1(TGF‐β1) gene in a large sample of dizygotic (DZ) twins. The test was specified within the framework of structural equation modelling and allows for population stratification and easily incorporates confounders. Results showed linkage in the presence of association between the TGF‐β1 263 polymorphism and blood pressure levels, with carriers showing a clinically significant increase of 6 and 4 mm Hg in systolic and diastolic blood pressure, respectively. The described association test offers an easy and flexible way to analyse QTL data in sib or DZ twin pairs while controlling for population stratification by making use of within‐family controls.
Regression models for association studies of quantitative trait loci in humans
Authors: Cardon Lon R. , Abecasis Gonçalo R. 
Published: March 2003

AbstractRegression analysis is a simple, computationally efficient and often robust method for assessment of genotype–phenotype relationships in quantitative traits. It has long been used in studies of familiality and selection, and recently has been further extended for linkage and association analysis, linkage disequilibrium mapping and population substructure assessment. We review and compare some of the most commonly used regression models and highlight some useful properties of one model via analysis of angiotensin‐converting enzyme phenotype and marker data.
Adding power to Haseman and Elston’s (1972) method
Authors: Elston Robert C. , Shete Sanjay S. 
Published: March 2003

AbstractHaseman and Elston1 proposed a model‐free method for testing linkage between a polymorphic marker and a quantitative trait locus from data on a sample of independent sib pairs. In that method the squared sib‐pair trait difference is regressed on the estimated proportion of alleles shared by the sibs at a marker locus, a negative regression coefficient suggesting linkage. It is possible to obtain more power by modelling the sib covariance, as in the variance component method of linkage analysis, and yet retain a method that is computationally fast, involving only linear regression. To do this it is only necessary to change the dependent variable from the squared trait difference to the difference between the squared mean‐corrected sum and the squared trait difference. The method can accommodate sibships of arbitrary size by using generalized least squares and can be made more powerful by weighting the two components. The method is robust in large samples in the presence of any trait distribution, and, in the case of ascertained samples, the mean can be chosen to maximize power.
Distinct differences in a cyclin D1 single nucleotide polymorphism between ethnic groups
Authors: McKay Judith A. , Githang’a Jessie , Indalo Anne , Li Tao , Liu Xiehe , Ameyaw Margaret‐Mary , Ofori‐Adjei David , McLeod Howard L. 
Published: March 2003

AbstractIntroduction  Cyclin D1, encoded by the CCND1 gene, is a key regulator of the cell cycle at the G1/S phase checkpoint. A common A/G single nucleotide polymorphism (SNP) at nt870 of the CCND1 gene has been associated with outcome in patients with lung tumours and head and neck cancer. The aim of this study was to ascertain the genotype and allele frequency of the CCND1 polymorphism in five distinct ethnic populations.Methods Polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) analysis was carried out on genomic DNA from 505 subjects from five distinct ethnic populations (i.e. Caucasian, South‐west Asian, Ghanaian, Kenyan and Chinese subjects).Results Marked differences in genotype were apparent between the ethnic populations, with homozygosity for the G allele ranging from 13.6% in the Chinese subjects to 62.4% amongst Kenyan individuals (P < 0.001). Whereas the East and West African populations demonstrated almost identical allele frequencies, both populations differed significantly from each of the remaining populations. the allele frequencies for the South‐west Asian population fell between that of the Caucasian and Chinese populations but did not differ significantly from either, while the Caucasian and Chinese subjects displayed significant differences in CCND1 alleles (P = 0.003).Discussion These marked variations in SNP frequencies between ethnic groups may have a significant impact on prognosis of cancer in these populations, because the CCND1 genotype appears to influence prognosis in each tumour type examined to date.
The implications of solar UV radiation exposure for fish and fisheries
Authors: Zagarese Horacio E , Williamson Craig E 
Published: March 2003

AbstractUltraviolet radiation (UVR) possesses three important properties that combine to make it a potent environmental force. These include the potential to induce damage: UVR carries more energy per photon than any other wavelength reaching the Earth’s surface. Such highly energetic photons are known to damage many biological molecules, such as DNA and proteins. In addition, they can initiate a series of redox reactions to form reactive oxygen species (ROS), which cause oxidative stress to cells and tissues. The second property is ubiquity: owing to their dependence on light, primary producers and most visual predators, such as fish, are also necessarily exposed to damaging levels of UVR. Thirdly, the combined effect of UVR and additional environmental factors may result in synergistic effects, such as the photoactivation of organic pollutants and photosensitisation. In natural environments, the concentration of dissolved organic matter (DOM) and habitat depth are the two main factors controlling the degree of UVR exposure experienced by fish. Additional factors include vegetation coverage, particulate materials in suspension, pH and hydrological characteristics, and site location (latitude, elevation). The range of potential effects on fish includes direct DNA damage resulting in embryo and larval mortality, and adult and juvenile sunburn, as well as indirect oxidative stress, phototoxicity and photosensitisation.
Compensatory density dependence in fish populations: importance, controversy, understanding and prognosis
Authors: Rose Kenneth A , Cowan James H , Winemiller Kirk O , Myers Ransom A , Hilborn Ray 
Published: March 2003

AbstractDensity‐dependent processes such as growth, survival, reproduction and movement are compensatory if their rates change in response to variation in population density (or numbers) such that they result in a slowed population growth rate at high densities and promote a numerical increase of the population at low densities. Compensatory density dependence is important to fisheries management because it operates to offset the losses of individuals. While the concept of compensation is straightforward, it remains one of the most controversial issues in population dynamics. The difficulties arise when going from general concepts to specific populations. Compensation is usually quantified using some combination of spawner–recruit analysis, long‐term field monitoring or manipulative studies, and computer modelling. Problems arise because there are limitations to each of these approaches, and these limitations generally originate from the high uncertainty associated with field measurements. We offer a hierarchical approach to predicting and understanding compensation that ranges from the very general, using basic life‐history theory, to the highly site‐specific, using detailed population models. We analyse a spawner–recruit database to test the predictions about compensation and compensatory reserve that derive from a three‐endpoint life‐history framework designed for fish. We then summarise field examples of density dependence in specific processes. Selected long‐term field monitoring studies, manipulative studies and computer modelling examples are then highlighted that illustrate how density‐dependent processes led to compensatory responses at the population level. Some theoretical and empirical advances that offer hope for progress in the future on the compensation issue are discussed. We advocate an approach to compensation that involves process‐level understanding of the underlying mechanisms, life‐history theory, careful analysis of field data, and matrix and individual‐based modelling. There will always be debate if the quantification of compensation does not include some degree of understanding of the underlying mechanisms.
Ecoepidemiology of the effects of pollution on reproduction and survival of early life stages in teleosts
Authors: Murl Rolland Rosalind 
Published: March 2003

AbstractEvidence from the field and laboratory has shown that reproduction and early life‐stage survival of several species of teleost fishes have been adversely affected following the release of several classes of synthetic, organic chemicals into the environment. Field studies from many geographic areas over several decades have found associations between exposure to synthetic chemicals in the environment and effects on hatchability, embryological success and larval survival. In more recent research, exposure to sewage treatment and bleached kraft mill effluents has been correlated with changes in reproductive system development and alterations in the endocrine physiology of wild teleost fishes. Loss of fecundity and damage during various stages of development and reproduction have been associated with exposure to endocrine disruptors, including many currently used chemicals. The supporting laboratory studies have confirmed that various wild fish species are sensitive to certain synthetic chemicals at levels of exposure of parts per billion and parts per trillion, concentrations that are biochemically, physiologically, and environmentally relevant. This paper reviews the relevant field and laboratory research, and organizes the studies using the ecoepidemiological criteria of time‐order, strength of association, specificity, consistency on replication, coherence and predictive performance. There is sufficient evidence to conclude that ambient concentrations of synthetic chemicals in some regions are at or above concentrations at which certain species could be affected. The viability of fishery resources must be linked not only to the quantity of habitat but also to the quality of habitat.