Diversity patterns of the terrestrial snail fauna of Nyungwe Forest National Park (Rwanda), a Pleistocene refugium in the heart of Africa

We investigated the land snail fauna of Nyungwe Forest National Park in south‐western Rwanda. Fifty plots at altitudes between 1718 and 2573 m were studied. In total, 3461 specimens were collected and were assigned to 102 land snail species. With respect to land snail species, Nyungwe Forest is the richest forest known in Africa. A comparison with other forests in the northern Albertine Rift indicates that land snail species richness in this region is significantly correlated with distance from Pleistocene forest refugia. The high beta diversity in Nyungwe is the result of a high species turnover between sites, which has biogeographical and ecological origins. Nyungwe Forest is situated on the Congo–Nile divide where species of different geographical origin may meet. Moreover, Nyungwe Forest offers a high diversity of habitats because it extends across a wide range of altitudinal zones. Species richness decreased with increasing altitude. It was also correlated with the presence of bare rocks that offer additional microhabitats and shelter. Although the occurrences of different land snail species in Nyungwe Forest were significantly clustered, only a minority of the species could be assigned to a group of species with similar occurrences. The majority of the species respond individualistically to environmental variables. The significant nestedness of the occurrences of the land snail species in Nyungwe was mainly correlated with altitude. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 363–375.     

Does vicariance shape biotas? Biogeographical tests of the vicariance model in the north‐west European land snail fauna

Aim To investigate the importance of vicariance in shaping the north‐west European land snail fauna. Location North‐west Europe. Methods We tested whether there is a non‐random congruence, i.e. a clustering of species ranges, using a Monte Carlo procedure with a null model that generates range data sets such that their range size distribution, the species richness distribution of the geographic cells and the spatial autocorrelation of the occurrences of a taxon approach the parameters in the real data set. Biotic elements, groups of species with similar ranges, were delimited with Model based Gaussian clustering. The prediction that closely related species belong to different biotic elements, has been tested with a chi‐square test. Results The distribution areas of the north‐west European land snail species are significantly clustered as predicted by the vicariance model. One widespread and seven regional biotic elements were identified. Contrary to the predictions of the vicariance model, closely related north‐west European land snail species belong significantly more often to the same biotic element than should be expected by chance. Main conclusions The clustering of closely related north‐west European land snail species within the same biotic element indicates that speciation modes other than vicariance were frequent or that the imprint of vicariance on the ranges was obscured by extensive post‐speciational dispersal. Extensive dispersal may have been caused by Pleistocene climatic fluctuations. The core areas of the regionally restricted biotic elements might indicate the positions of glacial refugia of land snails.     

Native and introduced land snail species as ecological indicators in different land use types in Java

We investigated the effects of different land use types and environmental parameters on the number and abundance of native and introduced land snail species in East Java. 2919 specimens were sampled and assigned to 55 species of which 8 are introduced. Whereas species richness was highest in primary forest, the highest number of introduced species was found in agroforest. The snail assemblages in different habitat types differ much clearer in composition than in total species richness. Plantations and agroforest are dominated by introduced pulmonates with regard to number of individuals, while primary forest is dominated by native prosobranchs. The habitat requirements of the introduced pulmonates differ from those of the native species. In the study area, the abundance of native as well as introduced pulmonate species increased with increasing human impact. However, the abundance of introduced pulmonate species decreased with increasing density of the canopy cover, whereas the abundance of native pulmonate species increased with increasing canopy cover. The abundance of native prosobranch land snails also tends to increase with increasing canopy cover and with the availability of deadwood, but decreased with increasing human impact. Improving the canopy cover and retaining deadwood in plantations and agroforests might help to control the populations of introduced species or even prevent their establishment in these habitats. Land snails are good indicators for the long-term stability of natural habitats, because several species are restricted to undisturbed natural habitats and because of their low dispersal abilities. However, complete inventories of land snail species are costly. Therefore we propose two indices that can be scored with much less effort, namely the percentage of prosobranch individuals and the percentage of individuals of introduced species. Both indices are significantly correlated with the number of native species. Dense plantations and agroforests bordering primary forests may protect the latter from introduced species and help to conserve the native fauna by reducing desiccation and buffering the human impact on the primary forests.     

The biogeographical assignment of a west Kenyan rain forest remnant: further evidence from analysis of its reptile fauna

Aim The Kakamega Forest, western Kenya, has been biogeographically assigned to both lowland and montane forest biomes, or has even been considered to be unique. Most frequently it has been linked with the Guineo‐Congolian rain forest block. The present paper aims to test six alternative hypotheses of the zoogeographical relationships between this forest remnant and other African forests using reptiles as a model group. Reptiles are relatively slow dispersers, compared with flying organisms (Aves and Odonata) on which former hypotheses have been based, and may thus result in a more conservative biogeographical analysis. Location Kakamega Forest, Kenya, Sub‐Saharan Africa. Methods The reptile diversity of Kakamega Forest was evaluated by field surveys and data from literature resources. Faunal comparisons of Kakamega Forest with 16 other African forests were conducted by the use of the ‘coefficient of biogeographic resemblance’ using the reptile communities as zoogeographic indicators. Parsimony Analysis of Endemism and Neighbour Joining Analysis of Endemism were used to generate relationship trees based on an occurrence matrix with paup *. Results The analysis clearly supports the hypothesis that the Kakamega Forest is the easternmost fragment of the Guineo‐Congolian rain forest belt, and thus more closely related to the forests of that Central–West African complex than to any forest further east, such as the Kenyan coastal forests. Many Kenyan reptile species occur exclusively in the Kakamega Forest and its associated forest fragments. Main conclusions The Kakamega Forest is the only remnant of the Guineo‐Congolian rain forest in the general area. We assume that the low degree of resemblance identified for the Guineo‐Congolian forest and the East African coastal forest reflect the long history of isolation of the two forest types from each other. Kenyan coastal forests may have been historically connected through forest ‘bridges’ of the southern highlands with the Congo forest belt, allowing reptile species to migrate between them. The probability of a second ‘bridge’ located in the region of southern Tanzanian inselbergs is discussed. Although not particularly rich in reptile species, the area should be considered of high national priority for conservation measures.     

Biogeographical tests of the vicariance model in Mediterranean land snails

Aim To investigate the importance of vicariance in shaping land snail faunas. Location Three data sets of Mediterranean land snails were analysed: Helicoidea of the Iberian Peninsula and the complete land snail faunas of the central and eastern Aegean Islands and of Israel and Palestine. Methods The vicariance model predicts a clustering of species ranges. We tested for clustering of species ranges with a Monte Carlo simulation. For this simulation we used a null model that generates range data sets in such a way that their range size distribution, their species richness distribution and the spatial autocorrelation of the ranges approximate the parameters in the real data set. Biotic elements (clusters of species ranges) were delimited with model‐based Gaussian clustering. A second prediction of the vicariance model is that closely related species belong to different biotic elements. This was tested with a chi‐squared test. Results The distribution areas of the Iberian Helicoidea and the Israeli/Palestinian land snails are significantly clustered. The same is true for Israeli/Palestinian land snail species belonging to groups with geographically restricted species. However, the clustering is not significant in the complete central and eastern Aegean land snail data set, the Iberian Helicoidea species, and the central and eastern Aegean land snails belonging to groups with geographically restricted species. Contrary to the prediction of the vicariance model, closely related Iberian Helicoidea species and Israeli/Palestinian land snails belong significantly more often to the same biotic element than expected by chance. The null hypothesis that closely related species are homogeneously distributed across biotic elements cannot be rejected only for the data set that includes the Israeli/Palestinian land snails belonging to groups with geographically restricted species. Main conclusions The patterns found in the central and eastern Aegean land snail and the Iberian Helicoidea data sets do not correspond with the predictions of the vicariance model. This indicates that speciation modes other than vicariance were frequent, or that the distribution areas of many species in these faunas were largely modified by extensive post‐speciation dispersal and/or regional extinction. Hardly any possible vicariance events that might have contributed to the origin of the observed biotic elements in the Israeli/Palestinian land snail fauna could be identified. On the contrary, the biotic elements of the Israeli/Palestinian land snail fauna correspond with ecological factors. Vicariance has had only a limited influence on current biogeographical patterns in Mediterranean land snails.     

Estimating and conserving patterns of invertebrate diversity: a test case of New Zealand land snails

Aim Using New Zealand land snails as a case study, we evaluated recent spatial modelling approaches for the analysis of diversity in species‐rich invertebrate groups. Applications and prospects for improved conservation assessment were investigated. Location New Zealand. Methods The study used a spatially extensive and taxonomically comprehensive, plot‐based dataset on community structure in New Zealand land snails. Generalized regression analysis and spatial prediction (GRASP) was used to model and predict species richness as a function of environmental variables (including aspects of climate, soils and vegetation). Generalized dissimilarity modelling (GDM) was used to model turnover in species composition in relation to environmental and geographical distances, and to assess community similarity and the representativeness of the reserve network. Results Observed land snail richness in 20 × 20 m plots ranged from 1 to 74 (mean 17.5). The GRASP model explained a modest 27% of the variation in richness. The GDM model explained 57% of the variation in species turnover and indicated approximately equal amounts related to environmental (Cody’s beta diversity) and geographical distance (Cody’s gamma diversity). Temperature and moisture were the most important environmental variables. Results indicate that snail distributions are not only sorted by environment but are also strongly influenced by historical effects consistent with those expected of poorly dispersing taxa that have persisted in refugia during past climatic change. The GDM model enabled spatial classifications of snail communities, highlighting diverse communities in heterogeneous regions, such as the South Island mountains, and also enabled continuous depictions of community similarity and adequacy of New Zealand’s protected natural areas network. Main conclusions The GRASP and GDM analyses allowed us to model and depict spatial patterns of diversity in land snail communities involving 845 species, and produce community classifications and estimates of community similarity. These tools advance conservation assessment in species‐rich groups, but require further conceptual and methodological development.     

Biogeography of Great Basin butterflies: revisiting patterns, paradigms, and climate change scenarios

We used comprehensive data on butterfly distributions from six mountain ranges in the Great Basin to explore three connected biogeographic issues. First, we examined species richness and occurrence patterns both within and among mountain ranges. Only one range had a significant relationship between species richness and area. Relationships between species richness and elevation varied among mountain ranges. Species richness decreased as elevation increased in one range, increased as elevation increased in three ranges, and was not correlated in two ranges. In each range, distributional patterns were nested, but less vagile species did not always exhibit greater nestedness. Second, we compared our work with similar studies of montane mammals. Results from both taxonomic groups suggest that it may be appropriate to modify existing general paradigms of the biogeography of montane faunas in the Great Basin. Third, we revisited and refined previous predictions of how butterfly assemblages in the Great Basin may respond to climate change. The effects of climate change on species richness of montane butterflies may vary considerably among mountain ranges. In several ranges, few if any species apparently would be lost. Neither local species composition nor the potential order of species extirpations appears to be generalizable among ranges.     

Distinct subspecies or phenotypic plasticity? Genetic and morphological differentiation of mountain honey bees in East Africa

Identifying the forces shaping intraspecific phenotypic and genotypic divergence are of key importance in evolutionary biology. Phenotypic divergence may result from local adaptation or, especially in species with strong gene flow, from pronounced phenotypic plasticity. Here, we examine morphological and genetic divergence among populations of the western honey bee Apis mellifera in the topographically heterogeneous East African region. The currently accepted “mountain refugia hypothesis” states that populations living in disjunct montane forests belong to a different lineage than those in savanna habitats surrounding these forests. We obtained microsatellite data, mitochondrial sequences, and morphometric data from worker honey bees collected from feral colonies in three montane forests and corresponding neighboring savanna regions in Kenya. Honey bee colonies from montane forests showed distinct worker morphology compared with colonies in savanna areas. Mitochondrial sequence data did not support the existence of the two currently accepted subspecies. Furthermore, analyses of the microsatellite data with a Bayesian clustering method did not support the existence of two source populations as it would be expected under the mountain refugia scenario. Our findings suggest that phenotypic plasticity rather than distinct ancestry is the leading cause behind the phenotypic divergence observed between montane forest and savanna honey bees. Our study thus corroborates the idea that high gene flow may select for increased plasticity.     

Nestedness of north-west European land snail ranges as a consequence of differential immigration from Pleistocene glacial refuges

We investigated whether ranges in continental biota are nested. We propose a test for nested subset structure which can detect nestedness even if there are several sets of nested subsets as expected on a larger geographical scale. The test is based on a Monte Carlo simulation with a null model that considers spatial autocorrelation of the occurrences of a taxon. The number of cases in which the occurrences of a species form a subset of the occurrences of another species is used as test statistic. In a case study we show that the ranges of north-west European land snail species are significantly nested. The geographic centres of the sets of nested subsets correlate with glacial refuges. The differential immigration of taxa restricted to southern refuges during the glacials was probably an important mechanism resulting in the observed nestedness of the ranges of the north-west European land snail species. Some species which were more widespread during Pleistocene glacials contribute little to the nested subset pattern and are not nested among themselves. A comparison between groups of species differing in their dispersal abilities indicates that differences in the degree of nestedness are primarily due to differences in the variance of range sizes and not in dispersal abilities. We found a very weak correlation between dispersal ability and the rank of ranges in the sets of nested subsets indicating that nestedness might in part be caused by differential dispersal abilities. We assume that the graded variation of environmental parameters might be more important in generating the nestedness of ranges of north-west European land snail species than their differential dispersal abilities.     

History, island area and habitat availability determine land snail species richness of Aegean islands

Aim We examined the species-area relation of Aegean land snails, comparing different models to describe the relation. By examining those factors other than area that may also affect species richness, we tested whether the Aegean land snail fauna was more influenced by equilibrial migration and colonization processes, or rather is conservative and relictual. Location The Aegean archipelago (Greece). Methods Sixty-five islands were examined. Data were taken from own collections and from literature sources. Multiple regression analysis was used to test the null hypothesis of no relationship between species richness and island area, elevation, distance to the next larger island, and the presence and extent of calcareous substrate. Results The single most important factor determining land snail species number was area. While colonization-extinction dynamics have frequently been cited to explain this result, this conclusion was not tenable in this study as it was contradicted by species number not being related to the islands’ distances to neighbouring larger islands, after accounting for other factors affecting species number. We also found that habitat diversity affected species richness even after accounting for the effects of area: both increased elevation and greater extent of calcareous substrate on islands resulted in higher species number. This effect was most likely due to the fact that particular ecological conditions increased the probability that particular species could survive on an island. We compared the utility of the power and extreme-value function models of the species-area relation and found that both gave substantially the same results. However, fitting the power function model using nonlinear regression was of questionable utility. Main conclusions We conclude that the snail fauna of the Aegean is relictual, not equilibrial. The unusually high number of land snail species found on Crete is consistent with this conclusion. Crete is a currently united island which was separated into at least six smaller islands for 7–9 million years during the Neogene. Our results are consistent with the hypothesis that Crete still hosts a large number of endemic species of these paleoislands, resulting in a total number of species in excess of what would be expected based on area alone.     

The distribution of forest passerine birds and Quaternary climatic change in tropical Africa

A cluster analysis of the distribution patterns of forest passerine birds in tropical Africa showed that they could be divided into three main distribution types: those of restricted distribution (144 species), those of disjunct distributions across West, Central and rarely to East Africa (65 species) and those of very wide distribution (81 species). Centres of species richness, endemism and disjunction coincide spatially, and are identified as forest refugia, where forest persisted throughout Quaternary climatic vicissitudes. These distribution patterns agree with modern interpretations of Quaternary palaeoclimatic changes, which show that glacial periods were arid and interglacials humid. Glacial periods were therefore too dry for montane forest to have spread into areas at present occupied by lowland forest, as advocated by Moreau and other supporters of ihe "pluvial" theory; montane forest is probably as extensive now as at any time during the Quaternary and there is no evidence of past connections between currently isolated montane forests. Bird distribution can be explained largely by slow dispersal outwards from refugia as climatic conditions allowed forest to spread, combined with a relaxing of the distinction between "montane" and "lowland" species under conditions of reduced interspecific competition.     

High resilience of Mediterranean land snail communities to wildfires

In the Mediterranean region, wildfires have devastating effects on animals with limited mobility. With their poor dispersal abilities, their habitats on vegetation and in litter, and their sensitivity to humidity and shade, we expected land snails to be an interesting model to assess short, medium and long-term impact of fires on fauna biodiversity and their resilience. Stratified sampling was carried out on 12 sampling sites in garrigues and forests of Provence (southeastern France), according to fire regime (number of fires, fire intervals and age of the last fire) over the past 30 years. Data were investigated using diversity indexes, Kruskal–Wallis test, dendrogram of affinities and Correspondence Analysis (CA). We found, however, that Mediterranean land snail communities are particularly resilient to fires. Although abundance is drastically reduced in the short-term, species richness and community diversity are preserved provided that the time lapse between two successive fires is longer than the time required for recovery (i.e. around 5 years). This high community resilience in the short-term may be partly due to ecological and ethological aptitudes of land snails. However, these astonishing results, which have implications for conservation biology, are mainly due to the presence, within burned areas, of cryptic refuges that allow initial land snail survival, malacofauna persistence after successive fires and consistent biogeographical patterns in the long-term.     

Biogeographic patterns of the East African coastal forest vertebrate fauna

The archipelago-like coastal forest of East Africa is one of the highest priority ecosystems for biodiversity conservation worldwide. Here we investigate patterns of species richness and biogeographic distribution among birds, mammals and reptiles of these forests, using distribution data obtained from recently published reviews and information collated by the WWF Eastern Africa Coastal Forest Ecoregion Programme. Birds and mammals species were divided into forest specialists and generalists, and forest specialist reptiles into ‘coastal’ and ‘forest’ endemics. The species richness of birds and generalist mammals increased with area, and is probably a result of area-dependent extinction. Only in birds, however, species richness increased with decreasing isolation, suggesting possible isolation-dependent colonization. Forest diversity, associated to altitudinal range, is important for specialist birds and mammals, whose species richness increased with wider altitudinal range. The number of relict coastal endemic and forest endemic reptiles was higher in forests with wider altitudinal ranges and on relatively higher altitude, respectively. Such forests have probably provided a suitable (and perhaps stable) environment for these species through time, thus increasing their persistence. Parsimony analysis of distributions (PAD) and cluster analyses showed geographical distance and general ecological similarity among forests as a determinant factor in bird distribution patterns, with compositional similarity decreasing with increasing inter-forest distance. Compositional similarity patterns of mammals among the forests did not show a strong geographical correspondence or a significant correlation with inter-forest distance, and those of reptiles were not resolved, with very low similarity levels among forest faunas. Our results suggest that the relative importance (and causal relationship) of forest attributes affecting the distribution of the East African coastal forest vertebrate fauna varies depending on life history traits such as dispersal ability and forest specialization. The groupings in PAD are partly congruent with some of the previous classifications of areas of endemism for this region, supporting the ‘naturalness’ of these regions.     

Deficiency in African plant distribution data – missing pieces of the puzzle

Biodiversity is spatially unevenly distributed and so is the information on its spatial patterns. This uneven distribution of information on species occurrences is an important impediment to the conservation of biodiversity. Based on 185 427 collection records of 5873 plant species in sub-Saharan Africa, we analyse the availability of distribution data suitable for the GIS-based mapping of plant diversity patterns at a one-degree resolution. Using the bioclimatic model GARP, distribution ranges for each species were modelled. In order to identify data-deficient areas, the documented and modelled diversity patterns were compared. Only for a few, well-known centres of plant diversity are there comparatively many data collection records available. For several of the areas with very few collection records, such as the Guinean montane forests, the north-western Congolian lowland forests, and the southern Albertine Rift montane forests, the model predicts a species richness much higher than currently documented. In many of the data deficient areas, difficult conditions for scientific research appear to have limited collection activities for decades. Only strategic field collections can fill these gaps. Another cause of data deficiency is that data collected and digitized do not match the quality requirements for GIS-based work at the super-regional scale. In particular, regional databases documenting partial ranges of species are rarely connected. One challenge for the Global Strategy for Plant Conservation is therefore to establish international collaborative structures and technical standards that will allow analysis of biogeographical patterns across political boundaries.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 150 , 355–368.     

Multi-scale altitudinal patterns in species richness of land snail communities in south-eastern France

Aim Species richness is an important feature of communities that varies along elevational gradients. Different patterns of distribution have been described in the literature for various taxonomic groups. This study aims to distinguish between species density and species richness and to describe, for land snails in south‐eastern France, the altitudinal patterns of both at different spatial scales. Location The study was conducted on five calcareous mountains in south‐eastern France (Etoile, Sainte Baume, Sainte Victoire, Ventoux and Queyras). Methods Stratified sampling according to vegetation and altitude was undertaken on five mountains, forming a composite altitudinal gradient ranging from 100 to 3100 m. Visual searching and analysis of turf samples were undertaken to collect land snail species. Species density is defined as the number of species found within quadrats of 25 m². Species richness is defined as the number of species found within an elevation zone. Different methods involving accumulation curves are used to describe the patterns in species richness. Elevation zones of different sizes are studied. Results Eighty‐seven species of land snails were recovered from 209 samples analysed during this study. Land snail species density, which can vary between 29 and 1 species per 25 m², decreases logarithmically with increasing altitude along the full gradient. However, on each mountain separately, only a linear decrease is observable. The climatic altitudinal gradient can explain a large part of this pattern, but the great variability suggests that other factors, such as heterogeneity of ground cover, also exert an influence on species density. The altitudinal pattern of species richness varies depending on the spatial resolution of the study. At fine resolution (altitudinal zones of 100 m) land snail species richness forms a plateau at altitudes below 1000 m, before decreasing with increasing altitude. At coarse resolution (altitudinal zones of 500 and 1000 m) the relationship becomes linear. Main conclusions This study reveals that land snail species density and land snail species richness form two different altitudinal patterns. Species density exhibits strong variability between sites of comparable altitude. A large number of samples seem necessary to study altitudinal patterns of species density. Species density decreases logarithmically with increasing altitude. Above a critical altitudinal threshold, this decrease lessens below the rate seen in the first 1500 m. Different methods exist to scale‐up species density to species richness but these often produce different patterns. In this study, the use of accumulation curves has yielded a pattern of species richness showing a plateau at low altitude, whereas simple plotting of known altitudinal ranges from single mountains would have produced stronger mid‐altitudinal peaks. This study shows that not only factors such as temperatures and habitat heterogeneity, but also an ecotone effect, are responsible for the observed patterns.     

Species Composition,Physiognomy and Plant Diversity of the Tropical Montane Evergreen Broad-leaved Forest in Southern Yunnan

Species composition, physiognomy and plant diversity of the less known tropical montane forests in southern Yunnan were studied based on the data from 15 sampling plots in three sites. These forests are mainly dominated by the families Theaceae, Fagaceae, Lauraceae and Euphorbiaceae in floristic composition, and dominated by evergreen phanerophytes with mesophyllous leaves. These forests are similar to lower montane rain forests in equatorial southeastern Asia in floristic composition and altitudinal distributions, but differ in physiognomy by having few epiphytes, but more lianas and more plants with compound leaves. These differences could be due to strongly seasonal climate and so-called mass elevation effect in southern Yunnan. They also differ from the tropical seasonal rain forests at lower altitudes in southern Yunnan by having conspicuously lower species richness, few epiphytes, fewer mega-mesophanerophytes, more abundant micro-nanophanerophytes and hemicryptophytes and more plants with microphyllous leaves. It is suggested that these forests could be termed tropical montane evergreen broad-leaved forests, and be a vegetation type from the northern margin of mainland southeastern Asia controlled by a strongly seasonal climate.     

Mitochondrial differentiation in a polymorphic land snail: evidence for Pleistocene survival within the boundaries of permafrost

The genetic differentiation of populations having colonized formerly unsuitable habitats after the Pleistocene glaciations depends to a great extent on the speed of expansion. Slow dispersers maintain their refugial diversity whereas fast dispersal leads to a reduction of diversity in the newly colonized areas. During the Pleistocene, almost the entire current range of the land snail Arianta arbustorum has repeatedly been covered with ice or been subjected to permafrost. Owing to the low potential for dispersal of land snails, slow (re)colonization of the wide range from southern refugia can be excluded. Alternatively, fast, passive dispersal from southern refugia or survival in and expansion from multiple refugia within the area subjected to permafrost may account for the current distribution. To distinguish between these scenarios we reconstructed a phylogeography based on the sequences of a fragment of the cytochrome oxidase I from 133 individuals collected at 45 localities and analysed the molecular variance. Seventy-five haplotypes were found that diverged on average at 7.52% of positions. This high degree of diversity suggests that A. arbustorum is an old species in which the population structure, isolation and the hermaphroditic nature have reduced the probability of lineage extinction. The genetic structure was highly significant with the highest variance partition found among regions. Geographic distance and mitochondrial differentiation were not congruent. Lineages had overlapping ranges. The clear genetic differentiation and the patchy pattern of haplotype distribution suggest that colonization of formerly unsuitable habitats was mainly achieved from multiple populations from within the permafrost area.     

Insect taxonomic diversity in the Russian Far East

The insect fauna of the Russian Far East comprises 634 families from 31 orders. The estimated species number is 31500. The largest orders are Hymenoptera (76 families, 9000 estimated species), Diptera (120 families, 8000 estimated species), Coleoptera (114 families, 5500 estimated species), and Lepidoptera (81 families, 5000 estimated species). The fractions of the main insect orders in the fauna of the Russian Far East correspond to those in the Holarctic temperate zone. The high biodiversity of insects in the Russian Far East results from the position of this region extending across several climatic zones. There are four levels of diversity both for the families and for the species, corresponding to the tundra, taiga, the transitional area between taiga and broadleaved forests, and the broadleaved forest zone. The number of insect families increases by 3 times while that of species increases by 20 times from the tundra to the broadleaved forests. Differentiation of the insect fauna of the Russian Far East results from the recent climatic situation (the influence of the Pacific monsoon) and the geologic history (broadleaved forest refugia resulting from the absence of complete ice cover during Pleistocenic glaciation in the south of the Russian Far East); it reflects deep faunistic connections of the eastern Palaearctic with the Nearctic and Oriental Regions. The mountain areas in the North Pacific are the refugia of the Mesozoic and Tertiary insect faunas. The Pacific may have substantially reduced the Cenozoic aridization in the northern hemisphere, which was one of the important factors of formation of the recent biota in the Palaearctic and Nearctic regions.     

Assessing fern diversity: relative species richness and its environmental correlates in Uganda

Techniques for the rapid quantification of tropical biodiversity are of critical importance in deciding where to invest scarce conservation resources. Here we describe a simple survey method for assessing species-level richness of a poorly known plant group, the pteridophytes. We then illustrate the use of a powerful, rarefaction- based technique of controlling for inevitable differences in sampling effort to calculate the relative species richness of our study sites. Lastly, we explore how closely observed patterns of relative species richness of Ugandan forests are correlated with a suite of simple environmental variables. We find that fully 75% of the variance in our estimate of fern diversity can be predicted from just two measures: soil fertility (scored as C/N ratio, itself related to rainfall); and distance from the nearest putative Pleistocene refugium.