Showing papers in "Journal of Biogeography in 2003"

On the validity of Bergmann's rule

Abstract: Aim We reviewed the occurrence of Bergmann’s rule in birds (ninety-four species) and mammals (149 species), using only studies where statistical significance of the results was tested. We also tested whether studies using different characters as surrogates of body size have a different tendency to conform to Bergmann’s rule, whether body size and nest type (in birds) have an influence on the tendency to conform to the rule, and whether sedentary birds conform to the rule more than migratory birds. Location Worldwide. Methods We reviewed published data on geographic and temporal variation in body size, using only studies where the statistical significance of the results was tested. We asked how many species conform to the rule out of all species studied in each order and family. Results Over 72% of the birds and 65% of the mammal species follow Bergmann’s rule. An overall tendency to follow the rule occurs also within orders and families. Studies using body mass in mammals show the greatest tendency to adhere to Bergmann’s rule (linear measurements and dental measurements show a weaker tendency); while in birds, studies using body mass and other surrogates (linear measurements and egg size) show a similar tendency. Birds of different body mass categories exhibit a similar tendency to follow Bergmann’s rule, while in mammals the lower body size categories (4–50 and 50– 500 g) show a significantly lower tendency to conform to the rule. Sedentary birds tend to conform to Bergmann’s rule more than migratory species. Nest type does not affect the tendency to conform to Bergmann’s rule. Main conclusions Bergmann’s rule is a valid ecological generalization for birds and mammals.

The historical bridge between the Amazon and the Atlantic Forest of Brazil: a study of molecular phylogeography with small mammals

Abstract: Aim To examine how the genetic diversity of selected taxa of forest-dwelling small mammals is distributed between and within the major rain forest domains of Amazonia and Atlantic Forest and the intervening interior forests of Brazil, as inferred by the relationships between gene genealogies and geography. I also addressed the historical importance of the central Brazilian forests in connecting Amazon and Atlantic Forest populations of rodents and marsupials. Methods I evaluated variation in the mitochondrial cytochrome b gene to estimate the levels of sequence divergence between those taxa occurring throughout the Amazon, Atlantic Forest, and forests in the Cerrado and Caatinga regions. I inferred the hierarchical relationships between haplotypes, populations and formal taxa using the cladistic approach of maximum parsimony. I compared areas and the clades identified by superimposing cladograms on the geographical distribution of samples. The degree of concordance both in phylogeny and the depth of the nodes in these phylogenies, in addition to patterns of geographical distribution of clades, permitted me to make inferences on how, when and where the taxa differentiated. Results Sequence similarity is often greater between samples from the Atlantic Forest and either Amazon or central Brazilian forests than it is within each of the two rain forest domains. The Atlantic Forest clades are either not reciprocally monophyletic or are the sister group to all the other clades. There is some indication of northern and southern components in the Atlantic Forest. Given the geographical distribution of clades and the relatively deep levels of divergence, the central Brazilian area does not behave as a separate region but is complementary to either Amazon or Atlantic Forest. Patterns of area relationships differ across taxa, suggesting that different processes and ⁄ or historic events affected the diversification within each lineage. Main conclusions The Amazon and the Atlantic forests are not exclusive in terms of their small mammal faunas; both overlap broadly with taxa occurring in gallery forests and dry forests in central Brazil. Central Brazilian forests are an integral part of the evolutionary scenario of lowland small mammals, playing an important role as present and past habitats for rain forest species. Therefore, representatives from this area should always be included in analyses of the evolutionary history of lowland rain forest faunas. The incongruence of branching patterns among areas is in agreement with recent results presented for Neotropical passerine birds and indicates that a single hypothesis of Neotropical area relationships is unlikely. These findings reinforce the idea that speciation in the Neotropics will not be explained by any single model of vicariance or climatic changes.

Shapes and functions of species–area curves: a review of possible models

Abstract: Aim This paper reviews possible candidate models that may be used in theoretical modelling and empirical studies of species–area relationships (SARs). The SAR is an important and well-proven tool in ecology. The power and the exponential functions are by far the models that are best known and most frequently applied to species–area data, but they might not be the most appropriate. Recent work indicates that the shape of species–area curves in arithmetic space is often not convex but sigmoid and also has an upper asymptote. Methods Characteristics of six convex and eight sigmoid models are discussed and interpretations of different parameters summarized. The convex models include the power, exponential, Monod, negative exponential, asymptotic regression and rational functions, and the sigmoid models include the logistic, Gompertz, extreme value, Morgan–Mercer–Flodin, Hill, Michaelis–Menten, Lomolino and Chapman–Richards functions plus the cumulative Weibull and beta-P distributions. Conclusions There are two main types of species–area curves: sample curves that are inherently convex and isolate curves, which are sigmoid. Both types may have an upper asymptote. A few have attempted to fit convex asymptotic and/or sigmoid models to species–area data instead of the power or exponential models. Some of these or other models reviewed in this paper should be useful, especially if species–area models are to be based more on biological processes and patterns in nature than mere curve fitting. The negative exponential function is an example of a convex model and the cumulative Weibull distribution an example of a sigmoid model that should prove useful. A location parameter may be added to these two and some of the other models to simulate absolute minimum area requirements.

A regional impact assessment of climate and land‐use change on alpine vegetation

Abstract: Aim Assessing potential response of alpine plant species distribution to different future climatic and land-use scenarios. Location Four mountain ranges totalling 150 km2 in the north-eastern Calcareous Alps of Austria. Methods Ordinal regression models of eighty-five alpine plant species based on environmental constraints and land use determining their abundance. Site conditions are simulated spatially using a GIS, a Digital Terrain Model, meteorological station data and existing maps. Additionally, historical records were investigated to derive data on time spans since pastures were abandoned. This was then used to assess land-use impacts on vegetation patterns in combination with climatic changes. Results A regionalized GCM scenario for 2050 (+ 0.65 °C, −30 mm August precipitation) will only lead to local loss of potential habitat for alpine plant species. More profound changes (+ 2 °C, −30 mm August precipitation; + 2 °C, −60 mm August precipitation) however, will bring about a severe contraction of the alpine, non-forest zone, because of range expansion of the treeline conifer Pinus mugo Turra and many alpine species will loose major parts of their habitat. Precipitation change significantly influences predicted future habitat patterns, mostly by enhancing the general trend. Maintenance of summer pastures facilitates the persistence of alpine plant species by providing refuges, but existing pastures are too small in the area to effectively prevent the regional extinction risk of alpine plant species. Main conclusions The results support earlier hypotheses that alpine plant species on mountain ranges with restricted habitat availability above the treeline will experience severe fragmentation and habitat loss, but only if the mean annual temperature increases by 2 °C or more. Even in temperate alpine regions it is important to consider precipitation in addition to temperature when climate impacts are to be assessed. The maintenance of large summer farms may contribute to preventing the expected loss of non-forest habitats for alpine plant species. Conceptual and technical shortcomings of static equilibrium modelling limit the mechanistic understanding of the processes involved.

Geographical sampling bias and its implications for conservation priorities in Africa

Abstract: Aim To design and apply statistical tests for measuring sampling bias in the raw data used to the determine priority areas for conservation, and to discuss their impact on conservation analyses for the region. LocationSub-Saharan Africa. Methods An extensive data set comprising 78,083 vouchered locality records for 1068 passerine birds in sub-Saharan Africa has been assembled. Using geographical information systems, we designed and applied two tests to determine if sampling of these taxa was biased. First, we detected possible biases because of accessibility by measuring the proximity of each record to cities, rivers and roads. Second, we quantified the intensity of sampling of each species inside and surrounding proposed conservation priority areas and compared it with sampling intensity in non-priority areas. We applied statistical tests to determine if the distribution of these sampling records deviated significantly from random distributions. Results The analyses show that the location and intensity of collecting have historically been heavily influenced by accessibility. Sampling localities show dense, significant aggregation around city limits, and along rivers and roads. When examining the collecting sites of each individual species, the pattern of sampling has been significantly concentrated within and immediately surrounding areas now designated as conservation priorities. Main conclusions Assessment of patterns of species richness and endemicity at the scale useful for establishing conservation priorities, below the continental level, undoubtedly reflects biases in taxonomic sampling. This is especially problematic for priorities established using the criterion of complementarity because the estimated spatial costs of this approach are highly sensitive to sampling artefacts. Hence such conservation priorities should be interpreted with caution proportional to the bias found. We argue that conservation priority setting analyses require (1) statistical tests to detect these biases, and (2) data treatment to reflect species distribution rather than patterns of collecting effort.

Conundrums in mixed woody-herbaceous plant systems

Abstract: Aims To identify approaches to improve our understanding of, and predictive capability for, mixed tree-grass systems. Elucidation of the interactions, dynamics and determinants, and identification of robust generalizations that can be broadly applied to tree-grass systems would benefit ecological theory, modelling and land management. Methods A series of workshops brought together scientific expertise to review theory, data availability, modelling approaches and key questions. Location Ecosystems characterized by mixtures of herbaceous and woody plant life-forms, often termed 'savannas', range from open grasslands with few woody plants, to woodlands or forests with a grass layer. These ecosystems represent a substantial portion of the terrestrial biosphere, an important wildlife habitat, and a major resource for provision of livestock, fuel wood and other products. Results Although many concepts and principles developed for grassland and forest systems are relevant to these dual life-form communities, the novel, complex, nonlinear behaviour of mixed tree-grass systems cannot be accounted for by simply studying or modelling woody and herbaceous components independently. A more robust understanding requires addressing three fundamental conundrums: (1) The 'treeness' conundrum. What controls the relative abundance of woody and herbaceous plants for a given set of conditions at given site? (2) The coexistence conundrum. How do the life-forms interact with each other? Is a given woody-herbaceous ratio dynamically stable and persistent under a particular set of conditions? (3) The net primary productivity (NPP) conundrum. How does NPP of the woody vegetation, the herbaceous vegetation, and the total ecosystem (woody + herbaceous) change with changes in the tree-grass ratio? Tests of the theory and conceptual models of determinants of mixed woody-herbaceous systems have been largely site- or region-specific and have seldom been broadly or quantitatively evaluated. Cross-site syntheses based on data and modelling are required to address the conundrums and identify emerging patterns, yet, there are very few data sets for which either biomass or NPP have been quantified for both the woody and the herbaceous components of tree-grass systems. Furthermore, there are few cross-site comparisons spanning the diverse array of woody-herbaceous mixtures. Hence, initial synthesis studies should focus on compiling and standardizing a global data base which could be (1) explored to ascertain if robust generalizations and consistent patterns exist; and (2) used to evaluate the performance of savanna simulation models over a range of woody-herbaceous mixtures. Savanna structure and productivity are the result of complex and dynamic interactions between climate, soils and disturbances, notably fire and herbivory. Such factors are difficult to isolate or experimentally manipulate in order to evaluate their impacts at spatial and temporal scales appropriate for assessing ecosystem dynamics. These factors can, however, be evaluated with simulation models. Existing savanna models vary markedly with respect to their conceptual approach, their data requirements and the extent to which they incorporate mechanistic processes. Model intercomparisons can elucidate those approaches most suitable for various research questions and management applications. Conclusion Theoretical and conceptual advances could be achieved by considering a broad continuum of grass-shrub-tree combinations using data meta-analysis techniques and modelling.

How does landscape context contribute to effects of habitat fragmentation on diversity and population density of butterflies

Abstract: Aim Studies on habitat fragmentation of insect communities mostly ignore the impact of the surrounding landscape matrix and treat all species equally. In our study, on habitat fragmentation and the importance of landscape context, we expected that habitat specialists are more affected by area and isolation, and habitat generalists more by landscape context. Location and methods The study was conducted in the vicinity of the city of Gottingen in Germany in the year 2000. We analysed butterfly communities by transect counts on thirty-two calcareous grasslands differing in size (0.03-5.14 ha), isolation index (2100- 86,000/edge-to-edge distance 55-1894 m), and landscape diversity (Shannon-Wiener: 0.09-1.56), which is correlated to percentage grassland in the landscape. Results A total of 15,185 butterfly specimens belonging to fifty-four species are re- corded. In multiple regression analysis, the number of habitat specialist (n ¼ 20) and habitat generalist (n ¼ 34) butterfly species increased with habitat area, but z-values (slopes) of the species-area relationships for specialists (z ¼ 0.399) were significantly steeper compared with generalists (z ¼ 0.096). Generalists, but not specialists, showed a marginally significant increase with landscape diversity. Effects of landscape diversity were scale-dependent and significant only at the smallest scale (landscape context within a 250 m radius around the habitat). Habitat isolation was not related to specialist and generalist species numbers. In multiple regression analysis the density of specialists increased significantly with habitat area, whereas generalist density in- creased only marginally. Habitat isolation and landscape diversity did not show any effects. Main conclusions Habitat area was the most important predictor of butterfly com- munity structure and influenced habitat specialists more than habitat generalists. In contrast to our expectations, habitat isolation had no effect as most butterflies could cope with the degree of isolation in our study region. Landscape diversity appeared to be important for generalist butterflies only.

Episodic global dispersal in shallow water marine organisms: the case history of the European shore crabs Carcinus maenas and C. aestuarii

Abstract: Aim This paper evaluates global collection records, evidence of anthropogenic transport methods, and experimental and distributional data relative to temperature requirements to understand the historical and potential dispersal of a well-known genus of estuarine crab. Location The records analysed are from temperate and tropical coastal ocean areas. Methods The study is based primarily on literature analysis and examination of museum specimens. Results The human-mediated successful global dispersal of the European shore crabs Carcinus maenas (Linnaeus, 1758) and C. aestuarii (Nardo, 1847) occurred in three major episodes: around 1800, in the 1850s–70s, and in the 1980s–90s. The nineteenth century introductions occurred through transport by ships (probably in hull fouling or in solid ballast), while the introductions in the 1980s could have occurred through a greater variety of dispersal mechanisms (ships hull fouling and seawater system fouling; fouling on semisubmersible drilling platforms; ballast water; transport with fisheries products intended for food or bait; scientific research; releases from aquaria maintained for educational or scientific purposes; or intentional non-governmental releases for human food production). These introductions have resulted in Carcinus establishment in five temperate regions outside of its native Europe in Atlantic North America, Australia, South Africa, Japan and Pacific North America, while releases into tropical regions have not established populations. C. maenas range in both its native and introduced regions appears to be regulated by similar temperature parameters, enabling an assessment of its potential distribution. Main conclusions The second episode of Carcinus global dispersal, the period from the 1850s to 1870s, may be part of a broader surge of world-wide invasions caused by an increase in shipping.

The biogeographic and tectonic history of India

Abstract: Aim To present an up to date account of the Mesozoic history of India and its rela-tionship to the other Gondwana continents and to Eurasia.Location Continents surrounding the Western Indian Ocean.Methods Utilization of recent evidence of continental relationships based upon researchin stratigraphy, palaeomagnetism, palaeontology, and contemporary biotas.Results The physical data revealed a sequence of events as India moved northward: (1)India–Madagascar rifted from east Africa 158–160 Ma (million years ago), (2) India–Madagascar from Antarctica c. 130 Ma, (3) India–Seychelles from Madagascar84–96 Ma, (4) India from Seychelles 65 Ma, (5) India began collision with Eurasia 55–65 Ma and (6) final suturing took place c. 42–55 Ma. However, data from fossil andcontemporary faunas indicate that, throughout the late Cretaceous, India maintainedexchanges with adjacent lands. There is an absence in the fossil record of peculiaranimals and plants that should have evolved, had India undergone an extended period ofisolation just before its contact with Eurasia.Main conclusions The depiction of India in late Cretaceous as an isolated continent is inerror. Most global palaeomaps, including the most recent one, show India, as it movesnorthward, following a track far out in the Indian Ocean. But the evidence now indicatesthat India’s journey into northern latitudes cannot have taken place under such isolatedcircumstances. Although real breaks among the lands were indicated by the physicaldata, faunal links were maintained by vagile animals that were able to surmount minormarine barriers. India, during its northward journey, remained close to Africa andMadagascar even as it began to contact Eurasia.KeywordsIndia, biogeography, Gondwana, late Cretaceous, palaeontology, tectonics.INTRODUCTIONIt has now been more than 40 years since the theory of platetectonics has found general acceptance and more than30 years since Dietz & Holden (1970) published their mapsillustrating the breakup of Pangea and the dispersal of con-tinents through time. Although many palaeomaps by variousauthors have been published since 1970, the predominantmodern series is that produced by the Palaeomap Project atthe University of Texas (Arlington). The latest edition enti-tled ‘Atlas of Earth History’ (Scotese, 2001) is a beautiful,colour rendition with artistic representations of sea floor,shorelines, and mountains.The Palaeomap Project produces a variety of educationalmaterials including a CD ROM map series with computeranimations and Palaeo-Globe kits for constructing physicalmodels of the earth at different periods of time. The Projecthas a web site advertising its products (http://www.scote-se.com) and offers special discounts to primary and secon-dary schools. On one hand, there is no doubt that thisproject performs an important educational service providingan attractive introduction to plate tectonics for a broadaudience; on the other hand, it must be asked if the maps andvirtual reality simulations are accurate representations ofcurrent scientific knowledge. The information is presented ina factual manner with no indication that some of it may notbe on firm ground.In the case of India, the Project supplies a virtual realitysequence in which that continent is shown as separatingfrom Madagascar 90 Ma, moving through the middle of the

Area shape and isolation of tropical forest fragments: Effects on tree species diversity and implications for conservation,

Abstract: Aim To quantify the influences of forest area, shape and isolation on tree species diversity in Ghana and to compare their significance with the influences of climate (average annual rainfall) and disturbance (fire burn, logging, agriculture). Location The forest zone of southern Ghana, West Africa (between 5 and 8� N). Methods For twenty-two forest fragments (1) bivariate regression analyses of tree species diversity (number and composition) were employed with forest spatial geometry, climate and disturbance variables. (2) Multivariate regression analyses of tree species number and all seven environmental variables were used to determine the variability in tree species number that could be accounted for by these environmental variables. Results Forest area, shape and isolation accounted for sharply decreasing proportions of variability in tree species diversity. Large forest fragments contained the greatest numbers of tree species and the highest proportions of rare tree species; irregular fragments had high proportions of regenerating, light-demanding pioneers and mature, animal-dispersed species and isolated fragments were floristically similar to less isolated fragments. Fire burn and average annual rainfall accounted for small, but nevertheless significant, proportions of variability in tree species diversity. Logging and agriculture were non-significant variables. Main conclusions (1) Forest area is the most important consideration when planning tropical forest reserves. (2) Management of disturbance should take priority over management of forest shape if higher levels of tree diversity and species quality are to be maintained. (3) If new reserves are to be designated, they should be located within different climatic zones in order to capture a large fraction of the regional biota. (4) Biogeographers have an important role to play in formulating and testing hypotheses at a broad spatial scale and ultimately, informing conservation management within the tropical biome.

Patterns of distribution and processes of speciation in Brazilian reef fishes

Abstract: Aim To evaluate the state of knowledge about the biogeography of Brazilian reef fishes and propose processes that lead to the observed distribution patterns. Location The tropical western Atlantic. Methods The geological history of the Amazon barrier was obtained from the literature, and its potential influence on speciation of reef fishes was analysed. Species distributions were analysed based on literature records and material deposited at Brazilian and American collections. Results Recent estimates indicate that about 12% of the Brazilian reef fish species are endemic, and most ichthyologists agree that this endemism is generated by the barrier formed by the freshwater and sediment discharge of large rivers in north-eastern South America, mainly the Amazon, Orinoco and their tributaries. However, little is known about the dynamics of this barrier, and recent studies have demonstrated that it can be crossed through deep sponge bottoms on the outer continental shelf off north-eastern South America. Moreover, the recent discovery of species regarded as Brazilian endemics in the extreme southern Caribbean is showing that the Amazon barrier is weaker than previously thought. Main conclusions The Amazon freshwater and sediment outflow is a strong barrier to shallow water reef fish and other organisms, and it is probably responsible for most of the endemism found in Brazilian coastal habitats. However, sea-level fluctuations influence the effectiveness of such barrier and may play a large role in the generation of diversity in the western tropical Atlantic. Alternatively, larval exchange between Brazil and the Caribbean is small but constant, and contrasting selection pressures in divergent environments (continental Brazil vs. insular Caribbean) may be the central force driving speciation.

Neogene marine transgressions, palaeogeography and biogeographic transitions on the Thai-Malay Peninsula

Abstract: Aim The aim of this review is to contribute to our understanding of the origination of the Sundaic and Indochinese biotas in Southeast Asia. Numerous unsolved problems surround the origination of the differences between these biotas and the determinants of the breadth and current position of the transition between them. Location Literature reviews show that phytogeographical and zoogeographical transitions between the Sundaic and Indochinese subregions lie on the Thai–Malay peninsula just north of the Isthmus of Kra. A second, more widely recognized botanical transition lies 500 km further south at the Kangar–Pattani line near the Thai–Malay border. Results The phytogeographical transition involves 575 genera of plants, and a change from wet seasonal evergreen dipterocarp rain forest to moist mixed deciduous forest. The zoogeographical transition is best characterized for forest birds, and more than half the species present in this region have species boundaries north of the Isthmus of Kra, at 11–13� N latitude. Although the phytogeographical transition is climate-related today, and the avifaunal transition is viewed as being associated with the vegetation change, there is no obvious present day geological, physiographical or environmental feature to account for the origination of the provincial biotas. Similarly, known Neogene palaeoenvironmental changes on the tectonically stable peninsula, including those associated with periods of lower sea levels and the emergence of Sundaland, fail to account for either the origination of the provincial differences or the current position of the transition. Main conclusions Contrary to earlier palaeogeographical reconstructions, it is suggested that Neogene marine transgressions flooded the peninsula in two areas and created circumstances leading to the biogeographical patterns of the present day. The Vail global eustatic curve, supported by the oxygen isotope record, indicates that sea levels were c. 100 m above the present-day level during the early/middle Miocene (24–13 Ma) and again during the early Pliocene (5.5–4.5 Ma). Present topography suggests such high sea stands would have created 30–100-km wide seaways north and south of the Nakhon si Thammarat Range in the central peninsula (southern Thailand). Geological, palaeontological and phylogenetic evidence for such hypothetical seaways is scant (there have been no focussed searches) but does not preclude their occurrence. The role of such Neogene highstands in explaining present day biogeographical patterns in Southeast Asia and elsewhere requires assessment.

A model for the species–area–habitat relationship

Abstract: Aim To propose a model (the choros model) for species diversity, which embodies number of species, area and habitat diversity and mathematically unifies area per se and habitat hypotheses. Location Species richness patterns from a broad scale of insular biotas, both from island and mainland ecosystems are analysed. Methods Twenty-two different data sets from seventeen studies were examined in this work. The r2 values and the Akaike's Information Criterion (AIC) were used in order to compare the quality of fit of the choros model with the Arrhenius species–area model. The classic method of log-log transformation was applied. Results In twenty of the twenty-two cases studied, the proposed model gave a better fit than the classic species–area model. The values of z parameter derived from choros model are generally lower than those derived from the classic species–area equation. Main conclusions The choros model can express the effects of area and habitat diversity on species richness, unifying area per se and the habitat hypothesis, which as many authors have noticed are not mutually exclusive but mutually supplementary. The use of habitat diversity depends on the specific determination of the ‘habitat’ term, which has to be defined based on the natural history of the taxon studied. Although the values of the z parameter are reduced, they maintain their biological significance as described by many authors in the last decades. The proposed model can also be considered as a stepping-stone in our understanding of the small island effect.

Latitude, seed predation and seed mass

Abstract: Aim We set out to test the hypothesis that rates of pre- and post-dispersal seed predation would be higher towards the tropics, across a broad range of species from around the world. We also aimed to quantify the slope and predictive power of the relationship between seed mass and latitude both within and across species. Methods Seed mass, pre-dispersal seed predation and post-dispersal seed removal data were compiled from the literature. Wherever possible, these data were combined with information regarding the latitude at which the data were collected. Analyses were performed using both cross-species and phylogenetic regressions. Results Contrary to expectations, we found no significant relationship between seed predation and latitude (log10 proportion of seeds surviving predispersal seed predation vs. latitude, P = 0.63; R2 = 0.02; n = 122 species: log10 proportion of seeds remaining after postdispersal seed removal vs. latitude, P = 0.54; R2 = 0.02; n = 205 species). These relationships remained non-significant after variation because of seed mass was accounted for. We also found a very substantial (R2 = 0.21) relationship between seed mass and latitude across 2706 species, with seed mass being significantly higher towards the tropics. Within-species seed mass decline with latitude was significant, but only about two-sevenths, as rapid as the cross-species decline with latitude. Results of phylogenetic analyses were very similar to cross-species analyses. We also demonstrated a positive relationship between seed mass and development time across ten species from dry sclerophyll woodland in Sydney (P < 0.001; R2 = 0.77; Standardized Major Axis slope = 0.14). These data lend support to the hypothesis that growing period might affect the maximum attainable seed mass in a given environment. Main conclusions There was no evidence that seed predation is higher towards the tropics. The strong relationship between seed mass and latitude shown here had been observed in previous studies, but had not previously been quantified at a global scale. There was a tenfold reduction in mean seed mass for every c. 23° moved towards the poles, despite a wide range of seed mass within each latitude.

The decay of similarity with geographical distance in parasite communities of vertebrate hosts

Abstract: Aim The rate at which similarity in species composition decays with increasing distance was investigated among communities of parasitic helminths in different populations of the same host species. Rates of distance decay in similarity of parasite communities were compared between populations of fish and mammal hosts, which differ with respect to their vagility and potential to disperse parasite species over large distances. Location Data on helminth communities were compiled for several populations of three mammalian host species (Ondatra zibethicus, Procyon lotor and Canis latrans) and three fish host species (Perca flavescens, Catostomus commersoni and Esox lucius) from continental North America. Methods Distances between localities and similarity in the composition of helminth communities, the latter computed using the Jaccard index, were calculated for all possible pairs of host populations within each host species. Similarity values were then regressed against distance to see if they decayed at exponential rates, as reported for plant communities; the significance of the regressions was assessed using randomization tests. Results The number of hosts examined per population did not correlate with the number of helminth species found per population, and thus sampling effort is unlikely to have confounded the results. In four (two mammals and two fish) of the six host species, similarity in helminth communities decayed exponentially with distance. When the log of similarity is plotted against untransformed distance, the slopes obtained for the two fish species are lower than those obtained for the two mammalian host species. Main conclusions Similarity in the composition of parasite communities appears to decay exponentially with increasing distance in some host species, but not in all host species. The rate of decay is not necessarily associated with the vagility of the host. Although distance decay of similarity is generally occurring, it seems that other ecological processes, related either to the host or its habitat, can obscure it.

Marine nematode deep‐sea biodiversity – hyperdiverse or hype?

Abstract: Nematodes have been identified as a potentially hyperdiverse group and the deep sea as a potentially hyperdiverse environment (i.e. > 1 million species). A large-scale data set from the equatorial central Pacific is used to estimate regional diversity with results that challenge this view; regional diversity is higher in some coastal waters despite lower sample diversity in coastal waters than in the deep sea. The data suggests a paradigm where the deep sea has modest regional diversity, despite high local diversity through patch dynamics, because similar patches in a similar habitat are repeated for considerable distances. Disturbance in shallow water dominates over patch-dynamic mechanisms reducing local diversity but regional diversity is high because of the close packing of multiple habitats within a single region. The Pacific data are also used to demonstrate the pitfalls of extrapolating from local to global diversity. There is no reason to conclude that nematodes are less diverse than other benthic groups, indeed where direct comparison is possible the Nematoda appear to be as diverse as the Polychaeta, the most diverse macrofaunal taxon. This analysis is not consistent with the hypothesis that either marine nematodes or the deep-sea benthos are hyperdiverse raising the question whether any environment or metazoan taxon has more than a million species.

Reconstructing the spread of invasive plants: taking into account biases associated with herbarium specimens

Abstract: Aim To reconstruct the spread of invasive wetland species using herbarium specimens and to develop a method that accounts for the biases associated with this type of historical record.

Australian biogeographical connections and the phylogeny of large genera in the plant family Myrtaceae

Abstract: Aim To compare the phylogeny of the eucalypt and melaleuca groups with geological events and ages of fossils to discover the time frame of clade divergences. Location Australia, New Caledonia, New Guinea, Indonesian Archipelago. Methods We compare published molecular phylogenies of the eucalypt and melaleuca groups of the plant family Myrtaceae with geological history and known fossil records from the Cretaceous and Cenozoic. Results The Australasian eucalypt group includes seven genera, of which some are relictual rain forest taxa of restricted distribution and others are species-rich and widespread in drier environments. Based on molecular and morphological data, phylogenetic analyses of the eucalypt group have identified two major clades. The monotypic Arillastrum endemic to New Caledonia is related in one clade to the more species-rich Angophora, Corymbia and Eucalyptus that dominate the sclerophyll vegetation of Australia. Based on the time of rifting of New Caledonia from eastern Gondwana and the age of fossil eucalypt pollen, we argue that this clade extends back to the Late Cretaceous. The second clade includes three relictual rain forest taxa, with Allosyncarpia from Arnhem Land the sister taxon to Eucalyptopsis of New Guinea and the eastern Indonesian archipelago, and Stockwellia from the Atherton Tableland in north-east Queensland. As monsoonal, drier conditions evolved in northern Australia, Arnhem Land was isolated from the wet tropics to the east and north during the Oligocene, segregating ancestral rain forest biota. It is argued also that the distribution of species in Eucalyptopsis and Eucalyptus subgenus Symphyomyrtus endemic in areas north of the stable edge of the Australian continent, as far as Sulawesi and the southern Philippines, is related to the geological history of south-east Asia-Australasia. Colonization (dispersal) may have been aided by rafting on micro-continental fragments, by accretion of arc terranes onto New Guinea and by land brought into closer proximity during periods of low sea-level, from the Late Miocene and Pliocene. The phylogenetic position of the few northern, non-Australian species of Eucalyptus subgenus Symphyomyrtus suggests rapid radiation in the large Australian sister group(s) during this time frame. A similar pattern, connecting Australia and New Caledonia, is emerging from phylogenetic analysis of the Melaleuca group (Beaufortia suballiance) within Myrtaceae, with Melaleuca being polyphyletic. Main conclusion The eucalypt group is an old lineage extending back to the Late Cretaceous. Differentiation of clades is related to major geological and climatic events, including rifting of New Caledonia from eastern Gondwana, development of monsoonal and drier climates, collision of the northern edge of the Australian craton with island arcs and periods of low sea level. Vicariance events involve dispersal of biota.

Predicting reptile distributions at the mesoscale: relation to climate and topography

Abstract: Aim To explore the respective power of climate and topography to predict the distribution of reptiles in Switzerland, hence at a mesoscale level. A more detailed knowledge of these relationships, in combination with maps of the potential distribution derived from the models, is a valuable contribution to the design of conservation strategies. Location All of Switzerland. Methods Generalized linear models are used to derive predictive habitat distribution models from eco-geographical predictors in a geographical information system, using species data from a field survey conducted between 1980 and 1999. Results The maximum amount of deviance explained by climatic models is 65%, and 50% by topographical models. Low values were obtained with both sets of predictors for three species that are widely distributed in all parts of the country (Anguis fragilis, Coronella austriaca, and Natrix natrix), a result that suggests that including other important predictors, such as resources, should improve the models in further studies. With respect to topographical predictors, low values were also obtained for two species where we anticipated a strong response to aspect and slope, Podarcis muralis and Vipera aspis. Main conclusions Overall, both models and maps derived from climatic predictors more closely match the actual reptile distributions than those based on topography. These results suggest that the distributional limits of reptile species with a restricted range in Switzerland are largely set by climatic, predominantly temperature-related, factors.

Dispersal vs. vicariance in the Mediterranean: historical biogeography of the Palearctic Pachydeminae (Coleoptera, Scarabaeoidea)

Abstract: Aim The geological evolution of the Mediterranean region is largely the result of the Tertiary collision of the African and Eurasian Plates, but also a mosaic of migrating island arcs, fragmenting tectonic belts, and extending back-arc basins. Such complex paleogeography has resulted in a ‘reticulate’ biogeographical history, in which Mediterranean biotas repeatedly fragmented and merged as dispersal barriers appeared and disappeared through time. In this study, dispersal-vicariance analysis (DIVA) is used to assess the relative role played by dispersal and vicariance in shaping distribution patterns in the beetle subfamily Pachydeminae Reitter, 1902 (Scarabaeoidea), an example of east–west Mediterranean disjunction. Location The Mediterranean region, including North Africa, the western Mediterranean, Balkans–Anatolia, Middle East, Caucasus, the Iranian Plateau, and Central Asia. Methods A phylogenetic hypothesis of the Palearctic genera of Pachydeminae in conjunction with distributional data was analysed using DIVA. This method reconstructs the ancestral distribution in a given phylogeny based on the vicariance model, while allowing dispersal and extinction to occur. Unlike other methods, DIVA does not enforce area relationships to conform to a hierarchical ‘area cladogram’, so it can be used to reconstruct ‘reticulate’ biogeographical scenarios. Results Optimal reconstructions, requiring 23 dispersal events, suggest that the ancestor of Pachydeminae was originally present in the south-east Mediterranean region. Basal splitting within the subfamily was caused by vicariance events related to the late Tertiary collision of the African microplates Apulia and Arabia with Eurasia, and the resultant arise of successive dispersal barriers (e.g. the Red Sea, the Zagros Mountains). Subsequent diversification in Pachydeminae involved multiple speciation events within the Middle East and Iran–Afghanistan regions, which gave rise to the least speciose genera of Pachydeminae (e.g. Otoclinius Brenske, 1896). Finally, the presence of Pachydeminae in the western Mediterranean region seems to be the result of a recent dispersal event. The ancestor of the Iberian genera Ceramida Baraud, 1987 and Elaphocera Gene, 1836 probably dispersed from the Middle East to the Iberian Peninsula across North Africa and the Gibraltar Strait during the ‘Messinian salinity crisis’ at the end of the Miocene. Main conclusions Although the basal diversification of Pachydeminae around the Mediterranean appears to be related to vicariance events linked to the geological formation of the Mediterranean Basin, dispersal has also played a very important role. Nearly 38% of the speciation events in the phylogeny resulted from dispersal to a new area followed by allopatric speciation between lineages. Relationships between western and eastern Mediterranean disjuncts are usually explained by dispersal through Central Europe. The biogeographical history of the Pachydeminae corroborates other biogeographical studies that consider North Africa to be an alternative dispersal route by which Mediterranean taxa could have achieved circum-Mediterranean distributions.

The limits to biogeographical distributions: insights from the northward range extension of the marine snail, Kelletia kelletii (Forbes, 1852)

Abstract: Aim The development of accurate models predicting species range shifts in response to climate change requires studies on the population biology of species whose distributional limits are in the process of shifting. We examine the population biology of an example system using the recent northward range expansion of the marine neogastropod Kelletia kelletii (Forbes, 1852). Location This is a marine coastal shelf neogastropod species whose range extends from Isla Asuncion (Baja California, Mexico) to Monterey (CA, USA). Research sites spanned the extent of the range. Methods We examine abundance distributions and size frequency distributions of K. kelletii for evidence of factors determining historic and contemporary distributional patterns. Population studies were supplemented by historic and contemporary hydrographic data, including seawater temperature data from California Cooperative Oceanic Fisheries Investigations (CalCOFI ) and National Data Buoy Center (NDBC), and seawater circulation data. Results The structure of recently established populations varied dramatically from that of historic populations. Markedly low densities and irregular size frequency distributions characterized recently established populations and suggested only occasionally successful recruitment. The point of transition between historic and recently established populations also corresponded to the location of a gradient in seawater temperature and the confluence of two major oceanic currents. The accumulated data suggest that temperature and/or barriers to dispersal could have set both contemporary patterns in population structure as well as the former northern range limit. Main conclusions Early life stages play a critical role in determining distributional patterns of K. kelletii. Dispersal barriers and temperature limitation are two plausible mechanisms that could determine both contemporary and historic distributional patterns. Future studies on this species should attempt to tease apart the relative importance of these factors in maintaining the populations at the northern edge of the range.

Prediction of species geographical ranges

Abstract: The use of climate matching to improve the success rate of introductions of biological control agents into new environments is well-established (DeBach, 1964). Similarly, there have been robust examples where the risk of establishment of invasive species has been successfully defined a priori using climatic modelling. These include: Leptinotarsa decemlineata (Say) in Europe (Sutherst et al., 1991), Amblyomma variegatum (Fabricius) and A. hebraeum (Koch) in Zimbabwe (Bruce & Wilson, 1998); Chrysomya bezziana (Villeneuve) in Ethiopia (Hall & Wall, 1995) and Boophilus microplus (Canestrini) in east and southern Africa (Sutherst, 2001). Samways et al. (1999) claim to have tested ‘how accurate predictions of range change might be before entertaining global climatic change’. They attempted to do this by using climate matching to predict the success of establishment of fifteen species of ladybirds (Coccinellidae, Chilocorus spp.), which had been the subject of efforts to spread them beyond their native ranges to enhance biological control. The ‘percent correct predictions of establishment’ was the criterion used to test their hypothesis, expressed also as ‘predicting species climatic tolerances’. After achieving an apparently low success rate, they concluded that ‘even in the absence of climate change, range cannot always be determined, which means that most predictions of range change with climate change are likely to be wrong’. I discuss here how such a statement demonstrates weak scientific inference. Samways et al. used the CLIMEX model (Sutherst & Maywald, 1985; Sutherst et al., 1995, 1999) and its associated ‘Match Climates’, climate-matching algorithm to make their predictions. The CLIMEX model is a simulation model of moderate complexity for inferring the responses of a species to climate from its geographical distribution. Once response functions have been fitted, the model can be run with meteorological data from other parts of the world to estimate the species response to new climatic environments. The potential range, as determined by climate, can then be estimated. The model parameter values constitute the hypotheses on the climatic factors that determine the species population growth, and survival during adverse seasonal conditions, and so limit the geographical distribution. Alternatively, the meteorological data base can be manipulated to create scenarios of climate change. Samways et al. attempted to explain the success or otherwise of particular introductions of Chilocorus species to new environments based on their estimated potential climatic range. This assumes that both the claims of the predictive success of climate matching, in this case using CLIMEX, and the base rates for establishment of exotic introductions are both 100%. However, Smith et al. (1999) showed that low base rates for establishment of exotic species influence the reliability of predictive tools. In the field of biological control, using arthropods, the base rates are in fact quite high, at around 65% (Julien et al., 1984; Waterhouse & Sands, 2001). Nevertheless such a suboptimal base rate caps the maximum success rate for predictions below the accuracy that is estimated on the assumption that all introductions into suitable climates will be successful. Sutherst & Maywald (1985) stated a caveat that users of CLIMEX need to exclude non-climatic factors limiting the distribution before assuming that climate is the only factor. The CLIMEX model, or other climate-matching tools, do not pretend to predict the outcome of particular introduction events. They define the role of climate as a factor in determining the potential for establishment when all other factors are not included. In addition, the CLIMEX software includes a facility for comparing meteorological data from different places (Match Climates). Samways et al. also used this algorithm in their efforts to explain the outcomes of introductions. A comprehensive response to correct errors in Samways et al. would have required many weeks of literature reviews and re-calculations of their analysis of each species, which was not practical. Rather, I point out examples of the main types of factual and methodological errors, inappropriate assumptions and omissions in the paper and show why the results of their analyses are invalid and their conclusions are not logical. I then investigate re-fitting of the parameter values of the CLIMEX model for one species – C. cacti (Linnaeus 1767) – to illustrate how the modelling is recommended to be carried out. GUEST EDITORIAL Journal of Biogeography, 30, 805–816

Mammals of south‐east Asian islands and their Late Pleistocene environments

Abstract: Aim The environments that existed in south-east Asian islands during the last glacial are poorly known, limiting our understanding of mammalian biogeography in the region. The objective of this research is to investigate the ecological characteristics of mammal faunas on small islands, and to see whether the habitat requirements of the species in those faunas can be used to deduct the vegetation types that existed on islands before becoming isolated by rising sea levels. Location The maps presented here cover the small islands of tropical south-east Asia, including the Burmese, Thai and Cambodian islands in the north, the islands off the coast of west Sumatra in the west, the islands around Java in the south, and the islands off the east coast of Borneo in the east, including the Philippine islands of Palawan and those in the Sulu Archipelago. Methods The presence records of mammal species on 215 small islands in the region were compiled, and the habitat requirements for each of these species was assessed (species that had probably been introduced by humans were excluded from the analysis). For each island location (longitude and latitude), maximum altitude of the island, total area, depth to nearest land, distance to nearest island, and distance to nearest mainland were assessed. Geographical and statistical analyses were used to investigate patterns of mammalian habitat requirements. Results The geographical analysis showed that forest-dependent species, i.e. species that are only found in primary forest (lowland and mountainous), appear to be concentrated on islands off west Sumatra, in the Lingga and Riau Archipelagos, around Palawan, and around Bunguran Island; they are absent mostly from the islands of the Java Sea, those off the east coast of eastern Borneo, from most islands in the Sunda Strait, several islands in the northern South China Sea, and from all islands off the west coast of the Malay/ Thai Peninsula and in the Gulf of Thailand. Species that generally occur outside primary forest, that is those in secondary forest, gardens, plantations and open areas mostly occurred on islands where the forest-dependent species were absent. The statistical analysis showed that latitude and size of islands were important factors that determined the absence and presence of forest-dependent species on small islands. Main conclusions The data suggest that during the last glacial there were several areas in the Sundaic region that remained forest covered: west of Sumatra, north-west of Borneo, the Malacca Straits and around Palawan. Other areas may have been covered by more open vegetation types like tree savanna, or open deciduous forest: on and to the east of the Malay/Thai Peninsula, the Java Sea area, including the Sunda Strait, and eastern Borneo.

The Indochinese–Sundaic faunal transition at the Isthmus of Kra: an analysis of resident forest bird species distributions

Abstract: Aim To establish the geographical position of the biogeographical transition between Indochinese and Sundaic faunas using distributional data for the best-documented taxon, the birds Methods Distributional data of 544 resident forest and forest edge bird species of Thailand and the Thai–Malay peninsula were examined at 45 sites spanning 15� of latitude from northern-most Thailand to the southern peninsular Malaysia Sites were grouped into 23 degree or half-degree latitudinal zones and avifaunal similarity coefficients were calculated between each zone Results A Mantel test revealed a significant transition between northern Indochinese and southern Sundaic (Indomalay) avifauna assemblages just north of the Isthmus of Kra (10� 30¢ N) Northern and southern range limits of 152 species (> 269 species and subspecies combined) lie between 11� and 13� N Main conclusions This transition between zoogeographical subregions is not coincident with the widely recognized transition between floristic provinces which is traditionally placed 400–500 km further south at the Kangar–Pattani line, but is associated with a change from wet seasonal evergreen dipterocarp rain forest to mixed moist deciduous forest north of the Isthmus of Kra in the northern Thai–Malay peninsula Climatological and ecological factors associated with the distribution of forest types today are reviewed and it is hypothesized that the avian transition tracks the northern phytogeographical boundary Palaeogeographical factors, including hypothetical Neogene seaways, which may account for the historical development of both phytogeographical and avifaunal transitions are also described

Trophic diversity of the otter (Lutra lutra L.) in temperate and Mediterranean freshwater habitats

Abstract: Aim To analyse the geographical patterns in the composition and diversity of otter’s (Lutra lutra L.) diet and their relationship with climatic characteristics. Location European freshwater habitats under Mediterranean and temperate climatic regimes. Methods Thirty-seven otter diet studies were reviewed, twenty-one from temperate and sixteen from Mediterranean areas. All studies were based on spraint analysis and their results expressed as relative frequency of occurrence of seven main prey categories. Principal Component Analysis was performed to extract the main gradients of diet composition. Pearson’s correlation and t-tests were used to assess the relationship between diet characteristics (composition, diversity and taxonomic richness) and geographical and climatic variables. Results A clear latitudinal gradient in diet composition was observed. Otter diet was more diverse and featured more prey classes in southern localities, while the species was more piscivorous towards the north, where it predated upon a higher number of fish families. This pattern was similar when temperate and Mediterranean localities of Europe were compared. Mediterranean otters behaved as more generalist predators than temperate ones, relying less on fish, and more on aquatic invertebrates and reptiles. Main conclusions Geographical differences in otter feeding ecology in Europe seem to be related with the two contrasted climatic conditions affecting prey populations. The otter can act as a highly specialized piscivorous predator in temperate freshwater ecosystems, which do not suffer a dry season and have a comparatively stable water regime compared to Mediterranean ones. However, the unpredictable prey availability in Mediterranean areas, affected by strong spatial and temporal water shortages, favours a diversification of the otter’s diet.

The pristine rain forest? Remnants of historical human impacts on current tree species composition and diversity

Abstract: Aim Tropical rain forests are often regarded as pristine and undisturbed by humans. In Central Africa, community-wide disturbances by natural causes are rare and therefore current theory predicts that natural gap phase dynamics structure tree species composition and diversity. However, the dominant tree species in many African forests recruit poorly, despite the presence of gaps. To explain this, we studied the disturbance history of a species-rich and structurally complex rain forest. Location Lowland rain forest in Southern Cameroon. Methods We identified the recruitment conditions of trees in different diameter classes in 16 ha of species-rich and structurally complex old growth rain forest. For the identification of recruitment preference we used independent data on the species composition along a disturbance gradient, ranging from shifting cultivation fields (representing large-scale disturbance), to canopy gaps and old growth forest. Results In nine of sixteen 1-ha forest plots the older trees preferred shifting cultivation fields for recruitment while younger trees preferred gaps and closed forest conditions. This indicates that these nine sites once experienced large-scale disturbances. Three lines of evidence suggest that historical agricultural use is the most likely disturbance factor: (1) size of disturbed and undisturbed patches, (2) distribution of charcoal and (3) historical accounts of human population densities. Main conclusions Present-day tree species composition of a structurally complex and species-rich Central African rain forest still echoes historical disturbances, most probably caused by human land use between three to four centuries ago. Human impact on African rain forest is therefore, contrary to common belief, an issue not of the last decades only. Insights in historical use will help to get a more balanced view of the pristine rain forest, acknowledging that the dualism between old growth and secondary forest may be less clear than previously thought.

Assessing endemism at multiple spatial scales, with an example from the Australian vascular flora

Abstract: Aim To develop an approach for assessing the spatial scale of centres of endemism among species level data. Location Australia. Methods Endemism is inherently scale dependent. Therefore, the Corrected Weighted Endemism (CWE) index used by Crisp et al. [J. Biogeogr. (2001)28:183] is extended to account for species samples in local neighbourhoods as a Spatial CWE index. This then allows an analysis of how the degree of endemism of a location (cell) changes with spatial scale. The quality of the Spatial CWE index results are assessed using three spatial randomizations at the species level with and without preserving species richness and distributional patterns. We show that CWE is equivalent to beta diversity and predict that it should show high rates of change around centres of endemism. Results Similar patterns to those found by Crisp et al. using a data set of vascular flora from Australia are retrieved, but the extent to which they are scale dependent is more easily identified. For example, the Central Australian centre discounted by Crisp et al. is identified when a three-cell radius neighbourhood is used. However, the level of endemism in this centre is no greater than in the margins of many of the coastal centres of endemism. Most of the identified centres of endemism are better than random at all scales and are increasingly so as the spatial scale increases. As predicted, the highest rate of change in Spatial CWE (beta diversity) is most often between zero- and one-cell radius neighbours in most centres of endemism. Main conclusions The explicit incorporation of geographical space in analyses allows for a greater understanding of the scale-dependence of phenomena, in this case endemism and beta diversity.

Patterns in species richness and distribution of vascular epiphytes in Chiapas, Mexico

Abstract: Aim We aim to assess regional patterns in the distribution and species richness of vascular epiphytes with an emphasis on forests that differ in altitude and the amount of rainfall. Location Tropical America, in particularly the 75000 km2 large state of Chiapas in southern Mexico at 14.5-18.0o N. Chiapas is diverse in habitats with forests from sea-level to the tree-line at approximately 3800 m altitude and with annual amounts of rainfall ranging from 800 to over 5000 mm. It is also one of the botanical best-explored regions in the tropics. Methods First we give an overview of epiphyte inventories to date. Such epiphyte surveys were mostly carried out on the basis of surface area or individual trees and we discuss their problematic comparison. Applying a different methodological approach, next we used 12276 unique vascular epiphyte plant collections from Chiapas that are deposited in various botanical collections. The locality data were georeferenced and compiled in a relational database that was analysed using a Geographic Information System. To compare the number of species between inventories that differed in the numbers of records, we estimated the total richness, SChao, at each. Results We recorded 1173 vascular epiphyte species in 39 families (23 angiosperms), comprising c. 14% of all confirmed plant species in the state. About half of all species were orchids (568). Ferns and bromeliads were the next species rich groups with 244 and 101 species, respectively. Most species were found in the Montane Rain Forest and in the Central Plateau. Trees of different forest formations, rainfall regimes, altitudes and physiographic regions supported a characteristic epiphyte flora. Main conclusions We were able to confirm the presumed presence of a belt of high diversity at mid-elevations (500 - 2000 m) in neotropical mountains. In contrast to predictions, however, we observed a decrease in diversity when the annual amount of rainfall exceeded 2500 mm. The decrease is attributed to wind-dispersed orchids, bromeliads and Pteridophyta that may find establishment problematical under frequent downpours. In the wet but seasonal forests in Chiapas, this decrease is not compensated by plants in the animal-dispersed Araceae that are abundant elsewhere. We presume that in addition to the annual amount of rainfall, its distribution in time determines the composition of the epiphyte community.

A floristic analysis of the lowland dipterocarp forests of Borneo

Abstract: Aim To (1) identify floristic regions in the lowland (below 500 m a.s.l.) tropical dipterocarp rain forest of Borneo based on tree genera, (2) determine the characteristic taxa of these regions, (3) study tree diversity patterns within Borneo, and (4) relate the floristic and diversity patterns to abiotic factors such as mean annual rainfall and geographical distance between plots. Location Lowland tropical dipterocarp rain forest of Borneo. Methods We used tree (diameter at breast height ‡ 9.8 cm) inventory data from 28 lowland dipterocarp rain forest locations throughout Borneo. From each location six samples of 640 individuals were drawn randomly. With these data we calculated a Sorensen and Steinhaus similarity matrix for the locations. These matrices were then used in an UPGMA clustering algorithm to determine the floristic relations between the locations (dendrogram). Principal coordinate analysis was used to ordinate the locations. Characteristic taxa for the identified floristic clusters were determined with the use of the INDVAL method of Dufrene & Legendre (1997). Finally, Mantel analysis was applied to determine the influence of mean annual rainfall and geographical distance between plots on floristic composition.