Although many studies have shown that species richness decreases from low to high latitudes (the Latitudinal Diversity Gradient), little is known about the relationship between latitude and phylogenetic diversity. Here we examine global latitudinal patterns of phylogenetic diversity using a dataset of 459 woody and 589 herbaceous plant communities. We analysed the relationships between community phylogenetic diversity, latitude, biogeographic realm and vegetation type. Using the most recent global megaphylogeny for seed plants and the standardised effect sizes of the phylogenetic diversity metrics 'mean pairwise distance' (SESmpd) and 'mean nearest taxon distance' (SESmntd), we found that species were more closely-related at low latitudes in woody communities. In herbaceous communities, species were more closely-related at high latitudes than at intermediate latitudes, and the strength of this effect depended on biogeographic realm and vegetation type. Possible causes of this difference are contrasting patterns of speciation and dispersal. Most woody lineages evolved in the tropics, with many gymnosperms but few angiosperms adapting to high latitudes. In contrast, the recent evolution of herbaceous lineages such as grasses in young habitat types may drive coexistence of closely-related species at high latitudes. Our results show that high species richness commonly observed at low latitudes is not associated with high phylogenetic diversity.
Macroecologists seek to identify drivers of community turnover (β-diversity) through broad spatial scales. However, the influence of local habitat features in driving broad-scale β-diversity patterns remains largely untested, owing to the objective challenges of associating local-scale variables to continental-framed datasets. We examined the relative contribution of local- versus broad-scale drivers of continental β-diversity patterns, using a uniquely suited dataset of cave-dwelling spider communities across Europe (35-70° latitude). Generalized dissimilarity modelling showed that geographical distance, mean annual temperature and size of the karst area in which caves occurred drove most of β-diversity, with differential contributions of each factor according to the level of subterranean specialization. Highly specialized communities were mostly influenced by geographical distance, while less specialized communities were mostly driven by mean annual temperature. Conversely, local-scale habitat features turned out to be meaningless predictors of community change, which emphasizes the idea of caves as the human accessible fraction of the extended network of fissures that more properly represents the elective habitat of the subterranean fauna. To the extent that the effect of local features turned to be inconspicuous, caves emerge as experimental model systems in which to study broad biological patterns without the confounding effect of local habitat features.
- MeSH
- Biodiversity MeSH
- Species Specificity MeSH
- Ecosystem MeSH
- Spiders physiology MeSH
- Temperature MeSH
- Geography MeSH
- Environment * MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Geographicals
- Europe MeSH
We examined the presence of possible Recent refugia of Pleistocene mammalian faunas in Eurasia by analysing regional differences in the mammalian species composition, occurrence and extinction rates between Recent and Last Glacial faunas. Our analyses revealed that most of the widespread Last Glacial species have survived in the central Palearctic continental regions, most prominently in Altai-Sayan (followed by Kazakhstan and East European Plain). The Recent Altai-Sayan and Kazakhstan regions show species compositions very similar to their Pleistocene counterparts. The Palearctic regions have lost 12% of their mammalian species during the last 109,000 years. The major patterns of the postglacial changes in Palearctic mammalian diversity were not extinctions but rather radical shifts of species distribution ranges. Most of the Pleistocene mammalian fauna retreated eastwards, to the central Eurasian steppes, instead of northwards to the Arctic regions, considered Holocene refugia of Pleistocene megafauna. The central Eurasian Altai and Sayan mountains could thus be considered a present-day refugium of the Last Glacial biota, including mammals.
- MeSH
- Biodiversity * MeSH
- Grassland * MeSH
- Mammals * MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Geographicals
- Kazakhstan MeSH
- Siberia MeSH
During the last two centuries, thousands of insect species have been transported (largely inadvertently) and established outside of their native ranges worldwide, some with catastrophic ecological and economic impacts. Global variation in numbers of invading species depends on geographic variation in propagule pressure and heterogeneity of environmental resistance to invasions. Elton's diversity-invasibility hypothesis, proposed over sixty years ago, has been widely explored for plants but little is known on how biodiversity affects insect invasions. Here we use species inventories from 44 land areas, ranging from small oceanic islands to entire continents in various world regions, to show that numbers of established insect species are primarily driven by diversity of plants, with both native and non-native plant species richness being the strongest predictor of insect invasions. We find that at large spatial scales, plant diversity directly explains variation in non-native insect species richness among world regions, while geographic factors such as land area, climate and insularity largely affect insect invasions indirectly via their effects on local plant richness.
- MeSH
- Models, Biological * MeSH
- Datasets as Topic MeSH
- Insecta physiology MeSH
- Population Dynamics statistics & numerical data MeSH
- Plants * MeSH
- Animal Distribution * MeSH
- Introduced Species statistics & numerical data MeSH
- Geography MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
BACKGROUND AND AIMS: Genome duplication is widely acknowledged as a major force in the evolution of angiosperms, although the incidence of polyploidy in different floras may differ dramatically. The Greater Cape Floristic Region of southern Africa is one of the world's biodiversity hotspots and is considered depauperate in polyploids. To test this assumption, ploidy variation was assessed in a widespread member of the largest geophytic genus in the Cape flora: Oxalis obtusa. METHODS: DNA flow cytometry complemented by confirmatory chromosome counts was used to determine ploidy levels in 355 populations of O. obtusa (1014 individuals) across its entire distribution range. Ecological differentiation among cytotypes was tested by comparing sets of vegetation and climatic variables extracted for each locality. KEY RESULTS: Three majority (2x, 4x, 6x) and three minority (3x, 5x, 8x) cytotypes were detected in situ, in addition to a heptaploid individual originating from a botanical garden. While single-cytotype populations predominate, 12 mixed-ploidy populations were also found. The overall pattern of ploidy level distribution is quite complex, but some ecological segregation was observed. Hexaploids are the most common cytotype and prevail in the Fynbos biome. In contrast, tetraploids dominate in the Succulent Karoo biome. Precipitation parameters were identified as the most important climatic variables associated with cytotype distribution. CONCLUSIONS: Although it would be premature to make generalizations regarding the role of genome duplication in the genesis of hyperdiversity of the Cape flora, the substantial and unexpected ploidy diversity in Oxalis obtusa is unparalleled in comparison with any other cytologically known native Cape plant species. The results suggest that ploidy variation in the Greater Cape Floristic Region may be much greater than currently assumed, which, given the documented role of polyploidy in speciation, has direct implications for radiation hypotheses in this biodiversity hotspot.
- MeSH
- Biodiversity MeSH
- Chromosomes, Plant MeSH
- Genetic Variation * MeSH
- Magnoliopsida cytology genetics MeSH
- Ploidies * MeSH
- Genetics, Population MeSH
- Flow Cytometry methods MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Geographicals
- Africa, Southern MeSH
Polyploidization is a rare yet sometimes successful way for animals to rapidly create geno- and phenotypes that may colonize new habitats and quickly adapt to environmental changes. In this study, we use water frogs of the Pelophylax esculentus complex, comprising two species (Pelophylax lessonae, genotype LL; Pelophylax ridibundus, RR) and various diploid (LR) and triploid (LLR, LRR) hybrid forms, summarized as P. esculentus, as a model for studying recent hybridization and polyploidization in the context of speciation. Specifically, we compared the geographic distribution and genetic diversity of diploid and triploid hybrids across Europe to understand their origin, maintenance and potential role in hybrid speciation. We found that different hybrid and parental genotypes are not evenly distributed across Europe. Rather, their genetic diversity is structured by latitude and longitude and the presence/absence of parental species but not of triploids. Highest genetic diversity was observed in central and eastern Europe, the lowest in the northwestern parts of Europe. This gradient can be explained by the decrease in genetic diversity during postglacial expansion from southeastern glacial refuge areas. Genealogical relationships calculated on the basis of microsatellite data clearly indicate that hybrids are of multiple origin and include a huge variety of parental genomes. Water frogs in mixed-ploidy populations without any parental species (i.e. all-hybrid populations) can be viewed as evolutionary units that may be on their way towards hybrid speciation. Maintenance of such all-hybrid populations requires a continuous exchange of genomes between diploids and triploids, but scenarios for alternative evolutionary trajectories are discussed.
- MeSH
- Bayes Theorem MeSH
- Diploidy MeSH
- Genetic Variation * MeSH
- Genotype MeSH
- Hybridization, Genetic * MeSH
- Microsatellite Repeats MeSH
- DNA, Mitochondrial genetics MeSH
- Evolution, Molecular MeSH
- Molecular Sequence Data MeSH
- Polyploidy * MeSH
- Genetics, Population MeSH
- Ranidae genetics MeSH
- Genetic Speciation MeSH
- Geography MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Geographicals
- Europe MeSH
The causes of biodiversity patterns are controversial and elusive due to complex environmental variation, covarying changes in communities, and lack of baseline and null theories to differentiate straightforward causes from more complex mechanisms. To address these limitations, we developed general diversity theory integrating metabolic principles with niche-based community assembly. We evaluated this theory by investigating patterns in the diversity and distribution of soil bacteria taxa across four orders of magnitude variation in spatial scale on an Antarctic mountainside in low complexity, highly oligotrophic soils. Our theory predicts that lower temperatures should reduce taxon niche widths along environmental gradients due to decreasing growth rates, and the changing niche widths should lead to contrasting α- and β-diversity patterns. In accord with the predictions, α-diversity, niche widths and occupancies decreased while β-diversity increased with increasing elevation and decreasing temperature. The theory also successfully predicts a hump-shaped relationship between α-diversity and pH and a negative relationship between α-diversity and salinity. Thus, a few simple principles explained systematic microbial diversity variation along multiple gradients. Such general theory can be used to disentangle baseline effects from more complex effects of temperature and other variables on biodiversity patterns in a variety of ecosystems and organisms.
- MeSH
- Bacteria metabolism MeSH
- Ecosystem MeSH
- Microbiota * MeSH
- Soil Microbiology * MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
- Geographicals
- Antarctic Regions MeSH
In this study, we characterized a collection of clinical samples obtained from Syrian and Turkish patients with cutaneous leishmaniasis using internal transcribed spacer 1 (ITS1) sequences. All obtained sequences belonged to Leishmania tropica. Combining them with those available from GenBank allowed us performing a broad-scale analysis of genetic diversity for this species. We demonstrated that L. tropica has a complex phylogeographic pattern with some haplotypes being widespread across endemic countries and others restricted to particular regions. We hypothesize that at least some of them may be associated with alternative vectors or animal reservoirs.
- MeSH
- Phylogeography MeSH
- Genetic Variation * MeSH
- Haplotypes MeSH
- Disease Vectors MeSH
- Leishmania tropica genetics MeSH
- Leishmaniasis, Cutaneous epidemiology transmission MeSH
- Humans MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Male MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
Most of earth's biodiversity is comprised of interactions among species, yet it is unclear what causes variation in interaction diversity across space and time. We define interaction diversity as the richness and relative abundance of interactions linking species together at scales from localized, measurable webs to entire ecosystems. Large-scale patterns suggest that two basic components of interaction diversity differ substantially and predictably between different ecosystems: overall taxonomic diversity and host specificity of consumers. Understanding how these factors influence interaction diversity, and quantifying the causes and effects of variation in interaction diversity are important goals for community ecology. While previous studies have examined the effects of sampling bias and consumer specialization on determining patterns of ecological networks, these studies were restricted to two trophic levels and did not incorporate realistic variation in species diversity and consumer diet breadth. Here, we developed a food web model to generate tri-trophic ecological networks, and evaluated specific hypotheses about how the diversity of trophic interactions and species diversity are related under different scenarios of species richness, taxonomic abundance, and consumer diet breadth. We investigated the accumulation of species and interactions and found that interactions accumulate more quickly; thus, the accumulation of novel interactions may require less sampling effort than sampling species in order to get reliable estimates of either type of diversity. Mean consumer diet breadth influenced the correlation between species and interaction diversity significantly more than variation in both species richness and taxonomic abundance. However, this effect of diet breadth on interaction diversity is conditional on the number of observed interactions included in the models. The results presented here will help develop realistic predictions of the relationships between consumer diet breadth, interaction diversity, and species diversity within multi-trophic communities, which is critical for the conservation of biodiversity in this period of accelerated global change.
- MeSH
- Bayes Theorem MeSH
- Biodiversity * MeSH
- Models, Biological * MeSH
- Herbivory MeSH
- Linear Models MeSH
- Computer Simulation MeSH
- Food Chain * MeSH
- Plants MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Formation of all metazoan bodies is controlled by a group of selector genes including homeobox genes, highly conserved across the entire animal kingdom. The homeobox genes from Pou and Six classes are key members of the regulation cascades determining development of sensory organs, nervous system, gonads and muscles. Besides using common bilaterian models, more attention has recently been targeted at the identification and characterization of these genes within the basal metazoan phyla. Cnidaria as a diploblastic sister group to bilateria with simple and yet specialized organs are suitable models for studies on the sensory organ origin and the associated role of homeobox genes. In this work, Pou and Six homeobox genes, together with a broad range of other sensory-specific transcription factors, were identified in the transcriptome of hydrozoan jellyfish Craspedacusta sowerbyi. Phylogenetic analyses of Pou and Six proteins revealed cnidarian-specific sequence motifs and contributed to the classification of individual factors. The majority of the Craspedacusta sowerbyi Pou and Six homeobox genes are predominantly expressed in statocysts, manubrium and nerve ring, the tissues with sensory and nervous activities. The described diversity and expression patterns of Pou and Six factors in hydrozoan jellyfish highlight their evolutionarily conserved functions. This study extends the knowledge of the cnidarian genome complexity and shows that the transcriptome of hydrozoan jellyfish is generally rich in homeodomain transcription factors employed in the regulation of sensory and nervous functions.
- MeSH
- POU Domain Factors chemistry genetics metabolism MeSH
- Phylogeny MeSH
- Genetic Variation MeSH
- Hydrozoa genetics MeSH
- Evolution, Molecular MeSH
- Organ Specificity MeSH
- Protein Structure, Tertiary MeSH
- Transcriptome MeSH
- Animals MeSH
- Check Tag
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
