bluuebunny/crossref_metadata_2025_split huggingface dataset:
Elevational diversity patterns of small mammals on Mount Kinabalu, Sabah, Malaysia
Authors: Nor Shukor MD. 
Published: March 2003

Abstract1 Diversity patterns of small mammals were studied along an elevational transect on Mount Kinabalu, the highest mountain in South‐east Asia, utilizing data from previously existing sources and a new field study. A mark‐and‐release study (conducted during wet and dry seasons between November 1994 and April 1995) resulted in captures of 12 small mammal species, including two species of squirrels, two tree shrews, seven murid rodents and one gymnure.2 Based on data compiled from this survey, museum specimens, and published and unpublished literature (analysed by locally weighted sums of squares and quadratic polynomial regressions), species richness of small mammals formed a middle elevation bulge, highest at about 1200–1400 m and declining at lower and higher elevations. Trapping during two seasons did not change the assessment of the pattern.3 A cluster analysis of these data indicated that there are two elevationally associated faunas, one in the highlands and another in the lowlands. The transition between these two assemblages is at 1700–1800 m elevation. The lowland faunal assemblage has the highest number of species, with maximum species richness at about 1300 m for total small mammal species, about 1200 m for arboreal species and about 1400 m for terrestrial species.4 The areas where much overlapping of species occurs are the elevations where climate and vegetation change rapidly from lowland to montane types. Tree species, gymnosperms, orchids and ferns showed a similar curvilinear pattern along the same elevational gradient, with maximum species richness at about 1400–1500 m. Temperature declined progressively with increasing elevation, but rainfall and humidity reached their highest levels at about 1700 m.5 Maximum diversity of small mammals thus occurred at the elevation where a highland and a lowland assemblage overlapped, where several types of plants reached their maximum diversity, and where rainfall and humidity reached their maxima. Similar patterns have been documented for small mammals, plants, and climate at sites scattered in Indo‐Australia from Taiwan to New Guinea.
Estimating mixtures of leaf functional types using continental‐scale satellite and climatic data
Authors: Berry Sandra L. , Roderick Michael L. 
Published: March 2003

AbstractAim Recent research has shown that much of the variability in leaf gas exchange and leaf longevity can be related to variations in the surface : volume ratio of leaves. The aim of this paper was to develop a theoretical framework and a practical method to extend that result to the vegetation at the continental scale.Location The study was conducted in Australia.Methods We propose that vegetation is composed of a mixture of three basic leaf types, ‘turgor’ (T), ‘mesic’ (M) and ‘sclerophyll’ (S) leaves. Changes in the relative proportions of T, M and S leaves within a vegetation type are visualized using a ternary diagram and differences in vegetation structure are shown to be easily mapped onto the ternary diagram. We estimate the proportions of T, M and S leaves using readily available data. The total amount of PAR absorbed by the vegetation (fPAR) is estimated using continental‐scale satellite observations. The total fPAR is then decomposed into that absorbed by T, M and S leaves. The relative absorption of PAR by T leaves is estimated from the temporal dynamics in the satellite signal, while the relative proportions of M and S leaves are estimated using climatic (solar radiation, rainfall) data.Results When the availability of light, nutrients and water were near‐optimal, the vegetation was composed of predominantly M leaves. In low nutrient environments S leaves predominated. T leaves were dominant in disturbed environments.Conclusions The theoretical framework is used to predict that elevated atmospheric CO2 would tend to increase the proportion of M and S leaves in an ecosystem and the resulting change means that the proportion of T leaves would decrease. In terms of the TMS scheme, this implies that elevated CO2 has the same net effect on the vegetation as a decrease in disturbance.
Does body size predict dates of species description among North American and Australian reptiles and amphibians?
Authors: Reed Robert N. , Boback Scott M. 
Published: March 2003

AbstractWhich factors determine whether a species is obvious to collectors? For some taxa, species of small body size tend to be described later than large‐bodied species, perhaps because large animals are more obvious or easily captured. Thus it has been proposed that current estimates of species numbers within taxa may be biased, as they may not include small species. However, the trend for recently described species to be small‐bodied has only been observed in a few higher taxa, and may not be general. Herein, we examine the relationships between body size and date of description for the entire herpetofaunas of North America and Australia (snakes, lizards, turtles, frogs and salamanders). We found that body size is generally a poor predictor of description date in herpetofaunal taxa. Even for most taxa that did exhibit a negative relationship between these variables, recently described species could not be distinguished from a random draw from overall species pools. We interpret our results in the light of the history of exploration of these continents and the biology of reptiles and amphibians.
The endemic headwater stream amphibians of the American Northwest: associations with environmental gradients in a large forested preserve
Authors: Adams Michael J. , Bury R. Bruce 
Published: March 2003

AbstractWe used a large forested preserve (Olympic National Park, USA) to examine the habitat associations of a unique and environmentally sensitive stream amphibian fauna: Ascaphus truei Stegneger, Rhyacotriton olympicus (Gaige) and Dicamptodon copei Nussbaum. We quantified the relative abundance of stream amphibians and compared them to physical, topographic, climatic and landscape variables. All three species were associated with the south‐west to north‐east climate gradient, tending to be most abundant in the south‐west. Although a habitat generalist relative to the other two species, Dicamptodon copei was absent from the north‐eastern portion of the park. Ascaphus truei and Rhyacotriton olympicus were both associated with coarse substrates and steep gradients. Unlike studies in harvested forests, all stream amphibians were common in waters with unconsolidated surface geology (e.g. marine sediments that erode easily). Studies of ecological preserves can provide an important baseline for evaluating species associations with environmental gradients and can reveal patterns not evident in more disturbed landscapes.
Modelling the species richness distribution of French dung beetles (Coleoptera, Scarabaeidae) and delimiting the predictive capacity of different groups of explanatory variables
Authors: Jorge M. Lobo  , Lumaret Jean‐Pierre , Jay‐Robert Pierre 
Published: March 2003

AbstractAim To predict French Scarabaeidae dung beetle species richness distribution, and to determine the possible underlying causal factors.Location The entire French territory has been studied by dividing it into 301 grid cells of 0.72 × 0.36 degrees.Method Species richness distribution was predicted using generalized linear models to relate the number of species with spatial, topographic and climate variables in grid squares previously identified as well sampled (n = 66). The predictive function includes the curvilinear relationship between variables, interaction terms and the significant third‐degree polynomial terms of latitude and longitude. The final model was validated by a jack‐knife procedure. The underlying causal factors were investigated by partial regression analysis, decomposing the variation in species richness among spatial, topographic and climate type variables.Results The final model accounts for 86.2% of total deviance, with a mean jack‐knife predictive error of 17.7%. The species richness map obtained highlights the Mediterranean as the region richest in species, and the less well‐explored south‐western region as also being species‐rich. The largest fraction of variability (38%) in the number of species is accounted for by the combined effect of the three groups of explanatory variables. The spatially structured climate component explains 21% of variation, while the pure climate and pure spatial components explain 14% and 11%, respectively. The effect of topography was negligible.Conclusions Delimiting the adequately inventoried areas and elaborating forecasting models using simple environmental variables can rapidly produce an estimate of the species richness distribution. Scarabaeidae species richness distribution seems to be mainly influenced by temperature. Minimum mean temperature is the most influential variable on a local scale, while maximum and mean temperature are the most important spatially structured variables. We suggest that species richness variation is mainly conditioned by the failure of many species to go beyond determined temperature range limits.
The mid‐domain effect cannot explain the diversity gradient of Nearctic birds
Authors: Hawkins Bradford A. , Diniz‐Filho José Alexandre Felizola 
Published: March 2003

AbstractA recent explanation for diversity gradients proposes a ‘null model’ based on how species ranges are constrained by the geometry of bounded domains. We conduct a test of this hypothesis by comparing patterns predicted by two two‐dimensional geometric models against observed diversity patterns for terrestrially feeding Nearctic birds. Consistent with previous tests in two‐dimensional space, we find empirical support for the hypothesis to be very weak. We also point out a fundamental conceptual flaw in the hypothesis with respect to the key assumption that ranges can exist independently of the environment in which they are embedded that undermines its theoretical basis as well. We conclude that the mid‐domain effect has little empirical support and no theoretical support for its existence, and recommend that it be eliminated as a potential explanation for diversity gradients.
Ecological characterization of bat species distributions in Michoacán, México, using a geographic information system
Authors: Wang H. George , Owen Robert D. , Sánchez‐Hernández Cornelio , De Lourdes Romero‐Almaraz María 
Published: March 2003

ABSTRACTAim To investigate the relationship between chiropteran species distributions and four fundamental environmental factors — temperature, precipitation, soil and vegetation — and to construct a species richness prediction map based on the environmental factors.Location The state of Michoacán, México.Methods Bat specimens collected during a 2‐year project were combined with museum specimens to form a dataset of over 3200 entries pertaining to 71 species of bats. Coordinates of the collection localities were recorded with GPS receivers or determined from maps. ArcView GIS was used to characterize the distribution of the species relative to the four environmental factors by projecting coordinates of the collection sites onto digitized maps of those factors. Correspondence analysis (CA) was used to evaluate the relationship between species distributions and the environmental factors.Results The CA results indicated that the order of importance of these factors is (from highest to lowest): temperature, vegetation, precipitation and soil. A predicted distribution map was constructed for each species of bat, based on the result of the CA analysis, using correspondences of each species to climate, vegetation and precipitation. Soil types were excluded from the prediction model because soil type does not appear to carry high predictive value for bat species in Michoacán. Distribution maps of the 71 bat species were then overlaid to generate a map of bat species richness for the state of Michoacán.Main conclusions  Neither family membership nor feeding guild affiliation appear to play important roles in chiropteran species distributions in Michoacán. The bat species richness prediction map will be a useful tool for conservation works in the region.
Some principles for modelling genotype–environment correlations and interactions with quantitative trait loci
Authors: Van Den Oord Edwin J. C. G. 
Published: March 2003

AbstractGenotype measurements will increasingly be used in scientific disciplines to study genotype–environment correlations and interactions, and strengthen research designs. This report summarizes some principles for using quantitative trait loci in statistical models. Special attention is paid to the importance of choosing a suitable parameterization, the use of parents and/or siblings to control for population stratification, and the modelling of heterogeneous and correlated error variances.
Estimating uncertainty in fish stock assessment and forecasting
Authors: Patterson Kenneth , Cook Robin , Darby Chris , Gavaris Stratis , Kell Laurence , Lewy Peter , Mesnil Benoît , Punt André , Restrepo Victor , Skagen Dankert W. , Stefánsson Gunnar 
Published: March 2003

AbstractA variety of tools are available to quantify uncertainty in age‐structured fish stock assessments and in management forecasts. These tools are based on particular choices for the underlying population dynamics model, the aspects of the assessment considered uncertain, and the approach for assessing uncertainty (Bayes, frequentist or likelihood). The current state of the art is advancing rapidly as a consequence of the availability of increased computational power, but there remains little consistency in the choices made for assessments and forecasts. This can be explained by several factors including the specifics of the species under consideration, the purpose for which the analysis is conducted and the institutional framework within which the methods are developed and used, including the availability and customary usage of software tools. Little testing of either the methods or their assumptions has yet been done. Thus, it is not possible to argue either that the methods perform well or perform poorly or that any particular conditioning choices are more appropriate in general terms than others. Despite much recent progress, fisheries science has yet to identify a means for identifying appropriate conditioning choices such that the probability distributions which are calculated for management purposes do adequately represent the probabilities of eventual real outcomes. Therefore, we conclude that increased focus should be placed on testing and carefully examining the choices made when conducting these analyses, and that more attention must be given to examining the sensitivity to alternative assumptions and model structures. Provision of advice concerning uncertainty in stock assessments should include consideration of such sensitivities, and should use model‐averaging methods, decision tables or management procedure simulations in cases where advice is strongly sensitive to model assumptions.
Trap mesh selectivity and the management of reef fishes
Authors: Mahon Robin , Hunte Wayne 
Published: March 2003

AbstractThe regulation of mesh size has frequently been proposed as a management measure for fish traps, the predominant gear used by the reef fish fisheries in the Caribbean. Studies on trap mesh selectivity show that mesh size is a determinant of catch rates and the size at which fish recruit to fish traps. Mesh size also affects the species composition in fish traps, probably through size selectivity. Other factors also affect catch rates, and the fish size and species composition in traps, for example, soak time, trap design, trap size, species body shape. Given the variety of growth rates and maturity schedules of reef fish commonly taken in fish traps in the Caribbean, no single mesh size will optimise the yield or protect against recruitment overfishing for the entire range of exploited species. Preliminary data suggest that the fishing power of traps may decrease with increased mesh size. This would reduce the effective fishing effort and thus mortality on fully recruited size classes. Studies indicate that the mesh sizes currently in use in most Caribbean countries are too small, and that a minimum mesh size of at least 3.8–5.1 cm would be required to optimise yields for local consumption. Comparative fishing experiments indicate that an increase in mesh size in areas of high fishing mortality typically results in a reduction in catch per trap. Thus increasing trap mesh size can be expected to result in short‐term loss in revenue for fishers. However, no studies have examined the times that would be required for catches to return to the levels prevailing before the increase of mesh size, and thereafter, for fishers to recover the losses incurred during the transition period. To provide managers with an estimate of the impacts that mesh‐size regulation could have on fishers, the recovery time of catches and the financial recovery times for fishers should be modelled for a hypothetical assemblage of 10–15 reef fishes using available information. These studies would enable managers to plan for the implementation of mesh‐size increases and to communicate the potential benefits to fishers in quantitative terms.
Is there a genetic basis to growth in Atlantic cod?
Authors: Imsland Albert K , Jónsdóttir Ólöf Dóra Bartels 
Published: March 2003

AbstractThere is still much disagreement and debate about whether or not genetically based growth differences occur in Atlantic cod, and there is evidence on both sides. In this review, data on genetically based growth differences in cod will be presented to shed light on this hypothesis.Motivated by the hypothesis that growth patterns may reflect specific genotype adaptations, we review stock‐specific responses on growth. An example of genetically based differences between the population units at two spawning localities off south Iceland is discussed. Here, significant differences in growth performance of the different Syp‐I genotypes were found. Also, the cod sampled at Loftstaðahraun displayed higher mean weight and length compared to the cod from Kantur indicating that these population units may display different life histories. Other studies have shown conflicting results depending on which side of the Atlantic the problem has been investigated. We propose that a common‐garden meta‐analysis with several cod stocks from both sides of the Atlantic is needed to give any reasonable answer to the question of genetically based growth differences. Until such studies have been conducted, it is premature to conclude one way or the other.In this review, we have not tried to quantify how large the environmental part of growth regulation versus the genetic part is, as this information is not available in the published literature on cod. Based on recent research on two flatfish species (turbot and Atlantic halibut), approximately 30% of growth variation is caused by genetical factors, but it remains to be seen if this is similar in cod. A fruitful way to continue this research might be to conduct controlled experiments, where performance (growth, food intake, feed conversion efficiency, feeding behaviour, etc.) and environmental factors (e.g. temperature, oxygen, photoperiod, predation risk, food availability) are studied simultaneously for different genotypes and different stocks.
Factors influencing the scope and quality of science and management decisions
Authors: Alverson Dayton L 
Published: March 2003

AbstractThe lecture traces the historical path to overfishing of the world's fish and shellfish stocks, and provides an assessment of marine fish resources in the later half of the 1990s. The basis of overfishing as noted by various fishery scientists is reviewed. Four factors, including institutional paralysis, the rapidity of technological developments, uncertainty of science, and the inability to monitor and enforce regulations are identified as the major problems leading to overfishing. The failure of the world community to deal with extensive overfishing, appears to have motivated managers and scientists to promote a new fishery management paradigm that focuses on a broader set of problems resulting from fishing, and establishes a more conservative decision‐making process founded on precautionary principle and uncertainty. The author feels that the evolving paradigm will result in the rebuilding of a number of stocks in the United States, but is less certain of its adoption on a global scale, and whether or not science will play a more useful role in fisheries management. It is noted that the support for fisheries science and the status of fisheries have followed opposite courses. Over the past half century marine science has boomed, diversified and become intellectually and materially enriched, while the number of overfished stocks and ecological disasters has increased. Looking ahead it is expected that fisheries management will move into a more conservative era. The focus of fisheries has moved from full use of ocean resources to establishing yields that take into account the impacts of fisheries on target and non‐target species and the ecosystem in general. Although there has been wide‐spread abuse in the use of the world's fishery resources and condemnation of the fishing industries, the author feels that the government institutions must bear the primary responsibility for the historical course of fishery management and its failure.
Correlation between sympotom fatigue and muscular fatigue in multiple sclerosis
Authors: Iriarte Jorge , de Castro Purificación 
Published: March 2003

The symptom of fatigue is a frequent complaint in multiple sclerosis (MS) patients. Signs of fatigability have been documented in these patients as well. However, correlation with signs of objective fatigue had not been clariffied in MS. The aim of this study was to assertain the existence of muscular fatigue in multiple seclerosis patients. and to find out if there is a correlation between the subjective symptom of fatigue and muscular fatigue.Fifty MS patients and 50 age and sex matched volunteers were studied using isometric and isotonic tests using the dominant hand. Strength was studied in the baseline condition and also after recovery of either an isotonic (experimentA) or isometric effort (experiment B). Maximum strength, strength in relationship to weight, slope of fatigability in 11 consecutive contraction, and strength and duration of a maximum effort were calculated. Fatigue as a symptom was measured using the Fatigue Severity Scale (FSS) and the Fatigue Descriptive Scale (FDS). Non‐parametric techniques were used for the statistical analysis.Patient with MS had less isometric and isotonic strength, but the recovery was the same as recovery in the control group. There was a negative linear correlation between the symptom of fatigue and the baseline strength.In conclusion, this study supports the existence of signs of muscular fatigue in MS patients. However, the recovery after exercise is normal. The corelation between the baseline scores in strength and the symptom of fatigue sugest that the same cause (probably pyramid deficits) may be involved in both of them.