bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determinants of bird species richness: role of climate and vegetation structure at a regional scale
Authors: Cueto Victor R. , de Casenave Javier Lopez 
Published: March 2003

SummaryWe examined the respective roles of climate and vegetation structure on geographical variation in bird species richness. The Province of Buenos Aires (central‐eastern Argentina) was divided into 146 squares of 50 km on a side. For each square we evaluated the number of bird species, the value of thirteen climatic variables, and the value of a vegetation strata index. The climatic matrix was analyzed by Principal Component Analysis (PCA), and the first factors resulting from PCA were considered as multifactorial climatic gradients. Simple and Partial Correlation Analysis among bird species richness, vegetation strata, and the first two factors derived from PCA (65% of total variation) indicated that bird richness distribution was determined by the availability of vegetation strata, associated with different vegetation types that, at the same time, were influenced by the climatic conditions summarized in the first climatic factor (a gradient of precipitation, relative humidity, annual termical amplitude, and frost occurrence). This relationships reflect the complexity of factors that can act directly as well as indirectly on the geographical patterns in species richness. Also, we evaluated the importance of study scale comparing our results with previous studies at macrogeographic and local scales, found out that the vegetation structure was the principal determinant of bird species richness at this three geographical scales.
GIS analysis of the biogeography of beetles of the subgenus Anisodactylus (Insecta: Coleoptera: Carabidae: genus Anisodactylus)
Authors: Noonan Gerald R. 
Published: March 2003

SummaryThe advent of GIS technology and the World Wide Web, respectively, facilitate analysing geographical relationships and electronically storing and exchanging biogeographic data. This paper illustrates GIS technology with a study of the subgenus Anisodactylus Dejean (Insecta: Coleoptera: Carabidae: genus Anisodactylus). Species are concentrated in three centres of biodiversity in North America and in four in lands near the western Mediterranean. These centres largely correspond to current areas of wetlands. Eurasia has fewer species than expected based on its area, probably because large portions have habitats unfavourable for the subgenus and/or are poorly collected for Carabidae.Members of the subgenus are primarily adapted to areas with January temperatures between −10 and 10 °C, July temperatures from 10 to 30 °C and mean annual precipitation from 20 to 200 mm. Cold is apparently a major limiting factor because it typically occurs during several consecutive months of winter and is difficult to escape except by hibernation. Heat is less of a stress when moisture is sufficient.The size of geographical ranges is often larger in the North than in the South and correlates with the latitude of the centre of ranges at r =0.42 (level of significance=0.05). Geographic ranges are often smaller in western North America and in the western Mediterranean than elsewhere in the Northern Hemisphere. Explanations for the smaller sizes include portions of western North America having unfavourable desert or montane habitats, the Rocky Mountains and deserts barring eastward dispersal of species, and the smaller size and more patchy distribution of climatic zones and habitats. In North America geographical ranges west of the Rocky Mountains are north–south elongated because they track primarily north–south orientated climatic zones and because mountains and deserts bar eastward extension. Ranges in north‐eastern and north‐central North America tend to extend east–west along temperature isotherms. In Eurasia many ranges are stretched east–west because of the shape of the continent and because many northern and southern areas lack suitable habitats. Species with relatively high numbers of apomorphic character states cluster in western Eurasia and to a lesser extent in western North America.The North American centres of biodiversity are post‐Wisconsin phenomena while those near the western Mediterranean probably date from the Oligocene or Miocene.
Structural and floristic characteristics of some monodominant and adjacent mixed rainforests in New Caledonia
Authors: Read J. , Jaffré T. , Godrie E. , Hope G. S. , Veillon J.‐M. 
Published: March 2003

Abstract Nothofagus spp. dominate the upper canopy of some rainforests on ultramafic soils in New Caledonia. These monodominant forests typically occur within, or contiguous with, larger areas of mixed‐canopy rainforest. In this study the structure, diversity and composition of six Nothofagus‐dominated plots were investigated, and comparisons were made with three adjacent mixed rainforest plots. Stand density and basal area (all stems ≥ 1.3 m high) in the Nothofagus plots were in the range 16,056–27,550 stems/ha and 43.1–69.9 m2/ha, respectively. There was no significant difference (P ≥ 0.05) in total stand density or basal area between the paired Nothofagus and mixed rainforests, but there were consistently fewer trees and less basal area of trees ≥ 40 cm d.b.h. in the Nothofagus forests. Species richness, species diversity (Shannon‐Wiener, based on basal area) and equitability (based on basal area) of trees ≥ 20 cm d.b.h. on 0.1 ha Nothofagus plots were in the range 4–17, 0.96–3.76 and 0.45–0.87, respectively. No significant differences (P ≥ 0.05) were recorded in these three parameters between the paired Nothofagus and mixed rainforests, although species diversity was consistently lower in the paired Nothofagus forests. Comparison of dominance by density and basal area indicated that although the uppermost canopy of the Nothofagus forests was dominated by Nothofagus (70–95%), the basal area and density contribution was ≤ 55% except at Col de Yaté (≈ 85%). Analysis of similarity indicated no significant difference in stand composition of trees ≥ 20 cm d.b.h. (following removal of Nothofagus from the data set) between Nothofagus and mixed rainforests using basal area, density or presence‐absence data. It is concluded that the Nothofagus‐dominated forests differ from the adjacent mixed rainforests mainly by (1) dominance of the uppermost canopy, without necessarily dominance of the stand by basal area or density, and (2) the smaller basal area contributed by large trees (all species).
The diversity and abundance of North American butterflies vary with habitat disturbance and geography
Authors: Kocher Scott D. , Williams Ernest H. 
Published: March 2003

AbstractAimWe used data from the annual Fourth of July Butterfly Count for the years 1989–97 to examine patterns of species richness and total butterfly abundance across North America and within topographically diverse and disturbed landscapes.LocationWe analysed counts from 514 different locations in North America. The counts represent all areas of the USA and southern Canada, with a few Mexican sites as well, although most counts were in the eastern USA.MethodsFirst, we standardized published count data according to the effort expended per count (total party‐hours). Using regression analysis and analysis of variance, we then examined the impact of latitude, longitude, topographical relief, habitat disturbance and different climatic measures on the species richness and total abundance of butterflies per count. We also examined the abundance of exotic species in disturbed landscapes.ResultsOur analyses suggest that: (1) species richness is highest at low latitudes and near Rocky Mountain longitudes; (2) the total abundance of individuals is highest in northern US latitudes and Great Plains longitudes; (3) species richness but not total abundance increases with greater topographical relief; (4) species richness and diversity indices are lower in more disturbed habitats; and (5) the abundance of the introduced Pieris rapae (L.) is greater in more disturbed habitats.Main conclusionsDifferent factors control the abundance and species richness of North American butterflies. Along with geographical location, habitat disturbance and topographical variability affect species richness. Our analysis also shows the value of broad‐based monitoring regimes, such as the North American Fourth of July Butterfly Count.
Biodiversity assessment: a case study in predicting richness from the potential distributions of plant species in the forests of south‐western Australia
Authors: Gioia Paul , Pigott J. Patrick 
Published: March 2003

AbstractDistributions were predicted for 1430 native plant species as part of a biodiversity assessment in the forests of south‐west Western Australia. From these predicted distributions, an index of plant species richness was generated for the forest area. The most common predictors for distribution were found to be climatic surfaces incorporating some aspect of seasonality in temperature and precipitation. Although coarse, the index confirmed existing knowledge of areas of high biodiversity within the study area and introduced a new area, the Blackwood Plateau, for consideration as a conservation reserve with high species richness. An additional survey was conducted to sample actual species richness in 11 test sites. When actual richness was regressed against predicted richness, a significant correlation was obtained if both annuals and geophytes were excluded from the analysis. With refinement of the model and further data collection targeted at areas of low effort, the species richness index is proposed as a useful tool for conservation planning.
Late Pleistocene beetle faunas of Beringia: where east met west
Authors: Elias Scott A. , Berman Daniil , Alfimov Arkady 
Published: March 2003

AbstractAim  To examine the issue of Beringian steppe‐tundra from an entomological standpoint, using fossil beetle data collected from late Pleistocene sites.Location  North‐eastern Siberia (Western Beringia), the Bering Land Bridge (Central Beringia), and Alaska and the Yukon Territory (Eastern Beringia).Methods  Analysis of habitat preferences of beetle species found in fossil assemblages, leading to classification of major habitat types characterized by the faunal assemblages.Results  Fossil beetle assemblages indicative of steppe‐tundra are found mainly in the interior regions of Eastern Beringia, whereas these assemblages dominate nearly all late Pleistocene fossil sites in Western Beringia. Eastern Beringian faunas contain a much larger proportion of mesic to hygrophilous species and very few arid‐habitat species. In contrast to this, the habitat requirements of the Western Beringian faunas are more evenly spread across the moisture spectrum.Main conclusions  The taxonomic patterns of the two sets of fossil assemblages are remarkably different. Eastern Beringian faunal assemblages contain substantial numbers of mesic tundra and riparian rove beetles (Staphylinidae); this element is almost entirely lacking in the Western Beringian fossil assemblages. Taphonomic bias tends to overemphasize moisture‐loving species at the expense of dry, upland species in the fossil record. Both Western and Eastern Beringian landscapes undoubtedly contained mosaics of habitats ranging from dry uplands (steppe‐tundra) through mesic tundra to bogs and riparian corridors.
Endemism, species selection and the origin and distribution of the vascular plant flora of New Zealand
Authors: McGlone M.S. , Duncan R. P. , Heenan P. B. 
Published: March 2003

AimTo evaluate competing views on the origin and distribution of the New Zealand flora by testing the hypothesis that the geographical distribution of species is unrelated to ecological traits such as habitat requirements and dispersal capabilities.LocationThe New Zealand archipelago.MethodsAn analysis of the factors correlated with distribution and endemism for alpine plants within New Zealand, and for the New Zealand biota as a whole.ResultsWoody plants are highly endemic; nonendemic plants tend to be herbaceous and are concentrated among the highly dispersible ferns and fern allies, orchids and wetland plants. These groups make up 32% of the total flora but contribute 78% of nonendemics. Alpine plants with wide spatial distribution tend to have greater altitudinal ranges, a broader habitat preference and better dispersal ability.Main conclusionsMost vascular plants reached New Zealand by long‐distance transoceanic dispersal, probably during the Late Miocene to early Pleistocene period. During the Miocene and Pliocene, similar climates and landscapes to those of Australia and northern island groups, and highly invasible terrain, permitted dispersal of woody plants. Cooling climates and formation of a more mountainous, more compact landscape after that time reduced dispersal of woody plants and favoured herbaceous, wetland and highly dispersible plant groups. The prominence of dispersal has led to intense selective immigration, and is responsible for many characteristic features of the flora. Species selection by glacial–interglacial cycles has restricted acquisition or retention of cool or arid climate adaptations, particularly in the lowland flora. Endemic and range disjunction patterns in the New Zealand mainland are not, in general, directly caused by Pliocene inundations or the faulting and associated horizontal displacement of terrain that has continued since the Miocene. They have arisen mainly through Pleistocene extinctions, speciation and dispersal, and some patterns are strongly linked to repeated glaciation. Endemic centres are associated with differentiated terrain and climates providing isolation, distinctive environments, and habitat continuity conducive to speciation.
Invasion history ofOenotheracongeners in Europe: a comparative study of spreading rates in the last 200 years
Authors: Mihulka Stanislav , Pyšek Petr 
Published: March 2003

AimThe dynamics of spread of some representatives ofOenothera, a genus of New World origin and alien to Europe, was analysed.LocationDistribution data from six European countries., i.e. Austria, Czech Republic, Hungary, Portugal, Serbia and UK were used.MethodsFloristic records covering the last 200 years were collated and the cumulative number of localities was plotted against time. A correction of the number of localities, taking into account the intensity of floristic research in particular countries, was applied based on the total number of available herbarium specimens to make comparisons of the rate of spread in particular countries possible.ResultsIn total, 35 alien taxa of the genus have been reported from the countries considered, the majority of which has only a limited distribution. So far 1800 records ofOenotheraspecies have been reported from the six countries analysed since 1780, withO. biennis,O. erythrosepala, O. salicifolia, O. stricta, O. cambrica, O. rubricaulis,andO. chicaginensishaving more than 50 localities. There is a highly significant negative correlation between the total number of localities in Europe and the year of the first introduction. Marked differences were found in the taxonomical pattern of invasion in particular countries.Main conclusionsMultivariate analyses have shown that in Europe, there are two distinct groups of species of North and South American origin, respectively, whose invasion is determined by climatic conditions, namely temperature and precipitation. The South American group is represented by perennial and annual species preferring oceanic climate (e.g.O. rosea, O. stricta), while the North American group consists of biennial representatives (O. biennisand others) better adapted to inland conditions with lower mean temperature and more balanced monthly precipitations. In addition, there is a transitional group of species, including namelyO. erythrosepalaandO. fallax,preferring regions with sufficient rainfall and higher temperatures. The relatively hot climate of Balkan Peninsula seems to prevent invasion byOenotherarepresentatives. Pattern of invasion of particular taxa corresponds well to the climatic conditions in the regions of their natural distribution.
Reconciling fossils and molecules: Cenozoic divergence of cichlid fishes and the biogeography of Madagascar
Authors: Vences M. , Freyhof J. , Sonnenberg R. , Kosuch J. , Veith M. 
Published: March 2003

AimThe biogeographical origins of the extant vertebrates endemic to Madagascar are largely unsolved, but have often been related to vicariance in the context of fragmentation of the supercontinent Gondwana in the Mesozoic. Such hypotheses are especially appealing in the case of cichlid fishes, which show phylogenetic relationships reflecting the temporal successions of the breakup of Gondwana. We used molecular clock data to test this assumption.LocationFragments of the 16S rRNA gene and of the nuclear Tmo‐4C4 locus, partly obtained from Genbank from South American, African, Malagasy and Indian cichlids were analysed.MethodsBased on monophyletic cichlid radiations in African lakes, we calibrated a molecular clock. The obtained rates were used to estimate the age of divergence of the major cichlid clades.ResultsThe results agreed better with a Cenozoic than with a Mesozoic divergence, and were in accordance with the fossil record. Sequence divergences of the 16S and 12S rRNA genes of most lineages of Malagasy terrestrial and freshwater vertebrates from their non‐Malagasy sister groups were below saturation and many were relatively similar to those of cichlids.Main conclusionsA Cenozoic dispersal from continental landmasses may explain the origin of most extant Malagasy vertebrate groups better than a Jurassic/Cretaceous vicariance.
Biogeography of Arabidopsis thaliana (L.) Heynh. (Brassicaceae)
Authors: Hoffmann Matthias H. 
Published: March 2003

AimThe biogeography of the genetic model plant, Arabidopsis thaliana (L.) Heynh., is studied using a climatic model of its distribution range. The climatic tolerance or amplitude of A. thaliana, as can be inferred from the general distribution range of the species, is compared with results of experimental studies addressing the species' responses to environmental stress. This is used for corroboration of the model and to reveal particular climatic conditions, whose influences on the plant species are not sufficiently known. Furthermore, this investigation shows climatic range boundaries and, thus, limits for exploiting natural variability of this species for plant physiological studies, plant genetics, and genetic engineering of crop plants. The growth conditions of A. thaliana in the greenhouse are compared with the climatic conditions of its natural range.Location Arabidopsis thaliana is native to Western Eurasia. Its natural and synanthropous northern hemispheric range is considered in the model.MethodsFrequency distributions of the species' occurrence along climatic gradients are calculated and used recurrently for modelling the range. The frequency diagrams, maps of the distribution of suitable monthly climatic conditions, and the climatic range model are used for the assessment of range limiting climatic factors. The greenhouse conditions are simulated using mean monthly temperatures above 22 °C. Water resources cannot be easily assessed because abundant supplies of water in the greenhouse can hardly be translated into terms of monthly precipitation.ResultsThe frequency diagrams show the climatic amplitude of the species in natural conditions. The archeophytic western Eurasian range is well represented in the climatic model. Differences between model and range are to be found in America where, apparently, different climatic conditions are to be found compared with Eurasia. The major range limiting climatic conditions extracted from the model and the experimental data, obtained from the literature are congruent. However, at high precipitation no range limiting conditions could be observed. Laboratory conditions (rather high temperatures and ever sufficient moisture) have been shown to be highly artificial, and were only found in the species' synanthropous North American range.Main conclusionsThe study of the climatic amplitude of A. thaliana revealed the potentials and limits of this species as a model plant for studying ecological and ecophysiological traits. Congruencies between model and experimental data may allow us to draw conclusions from the general distribution range of species as to their ecogeographical amplitude.
Accumulating evidence for a dispersal biogeography of southern cool temperate freshwater fishes
Authors: McDowall R. M. 
Published: March 2003

AimThis paper seeks to understand the biogeography of southern cool temperate freshwater fishes in the context of diverse aspects of their natural history.LocationThe fish families discussed are found widely in southern cool temperate lands: in Australia, New Zealand, Patagonian South America and southern Africa, as well as some of the smaller, remote southern oceanic islands.MethodsThe review is based on literature and primarily examines the association between distribution patterns and diadromous (sea‐migratory) life histories.ResultsThe broad distribution of freshwater fishes of the lamprey families Geotriidae and Mordaciidae and the salmoniform Galaxiidae and Retropinnidae in the southern cool temperate zone, has caused prolonged perplexity and debate. Arguments in favour of both a dispersal biogeography and a Gondwana‐based vicariance biogeography have been presented. These are not necessarily alternatives.Main conclusionsEvidence from:1 Distribution patterns in relation to life‐history strategies;2 Genetics and morphology;3 Different elements in the New Zealand fauna and their relationships;4 Recent dispersal events;5 Geological history of the Falkland Islands and the relationships of its freshwater fishes; and6 Parasitology;all support, or are consistent with, a dispersal biogeography of this southern cool temperate fauna. The groups involved are sufficiently ancient to have formerly inhabited Gondwana, but no compelling evidence indicates that present distributions reflect a former broad Gondwana‐based range. A role for dispersal in these fishes is consistent with increasingly common claims for dispersal in other taxa. This does not mean that there was no ancient influence from Gondwanan vicariance.
Trees, birds and bees in Mauritius: exploitative competition between introduced honey bees and endemic nectarivorous birds?
Authors: Hansen Dennis M. , Olesen Jens M. , Jones Carl G. 
Published: March 2003

AimsTo investigate effects of introduced honey bees, Apis mellifera L., on the nectar‐feeding activity of two species of endemic nectarivorous birds, the Grey White‐eye, Zosterops borbonicus mauritianus Gmelin, and the Olive White‐eye, Z. chloronothos Viellot, on two endemic flowering trees, Sideroxylon cinereum Lam. and S. puberulum DC. (Sapotaceae), and to examine pollination efficiency of birds and honey bees.LocationAn upland heath area on the island of Mauritius, Indian Ocean.MethodsWe quantified visitation rates of endemic birds and introduced honey bees at two endemic species of flowering trees. Diurnal variation in nectar standing crop and nectar production was measured. Pollination efficiency of flower visitors was examined using bagging and caging experiments.ResultsWhite‐eyes were only nectar‐feeding at the two Sideroxylon species early in the morning, stopping when honey bee foraging activity rapidly lowered nectar standing crops. White‐eyes continued nectar‐feeding at other flowering plant species, exploited less by honey bees, throughout the day. Honey bees were less efficient pollinators of the two Sideroxylon species than white‐eyes.Main conclusionsOur results indicate that introduced honey bees could be interfering with endemic interactions between the two Sideroxylon species and the two white‐eye species. However, because of lack of a neutral control site without honey bees, we cannot exclude other explanations. We do recommend, although, that honey bees need to be taken into consideration in the future conservation management of Mauritian ecosystems. We suggest that island ecosystems are especially vulnerable to introduced honey bees.