Global Diversity Patterns Research Articles

Genomic landscape of the global oak phylogeny.

The tree of life is highly reticulate, with the history of population divergence emerging from populations of gene phylogenies that reflect histories of introgression, lineage sorting and divergence. In this study, we investigate global patterns of oak diversity and test the hypothesis that there are regions of the oak genome that are broadly informative about phylogeny. We utilize fossil data and restriction-site associated DNA sequencing (RAD-seq) for 632 individuals representing nearly 250 Quercus species to infer a time-calibrated phylogeny of the world's oaks. We use a reversible-jump Markov chain Monte Carlo method to reconstruct shifts in lineage diversification rates, accounting for among-clade sampling biases. We then map the >20000 RAD-seq loci back to an annotated oak genome and investigate genomic distribution of introgression and phylogenetic support across the phylogeny. Oak lineages have diversified among geographic regions, followed by ecological divergence within regions, in the Americas and Eurasia. Roughly 60% of oak diversity traces back to four clades that experienced increases in net diversification, probably in response to climatic transitions or ecological opportunity. The strong support for the phylogeny contrasts with high genomic heterogeneity in phylogenetic signal and introgression. Oaks are phylogenomic mosaics, and their diversity may in fact depend on the gene flow that shapes the oak genome.

Relationship between area size and elevational distribution pattern of cryptic pheasant species in Mts. Gaoligong, China

The size of a geographic area is believed to be one of the most important factors that drive patterns of species richness. Studies have shown that mountains have a diverse range of patterns (area, species distribution, etc.) along an elevation gradient. Therefore, an understanding of the relationship between the distribution patterns of mountainous species and the area of altitudinal bands is of great importance to accurately determine and monitor global patterns of species diversity. However, the effects of area size on the distribution of species depends on taxon-specific idiosyncrasies. Few studies have assessed such effects on the secretive terrestrial pheasant species. In this study, we conducted three-dimensional map-based interview survey (3DIS) with local human communities that inhabit the same environments as the pheasants in Mts. Gaoligong, Western China. We obtained distributional information for 15 pheasant species, which enabled further analyses to be conducted. The area sizes of the different elevation bands were determined using a Digital Elevation Model database, and the altitudinal range of each species was calculated via interpolation. The area sizes at different altitudes showed a unimodal hump-shaped pattern that matched the diversity distribution of the pheasants. This study confirmed that the pattern of biodiversity of cryptic pheasants in the mountainous areas of Southwest China was hump-shaped, which is a very typical biodiversity pattern for most biotaxa. Regression analysis also revealed that area size was a key factor that affects the diversity and distribution of pheasant species, and may act concurrently with other factors, such as climate, energy, geometric constraints, and human disturbance.

Global diversity patterns are modulated by temporal fluctuations in primary productivity

AbstractAimTo evaluate the role of seasonal and non‐seasonal productivity fluctuations in global patterns of species richness.LocationWorldwide.Time period2000–2017.Major taxa studiedAmphibians, birds, mammals.MethodsWe analysed time series of monthly variation of the Normalized Difference Vegetation Index (NDVI), a surrogate of primary productivity, within c. 100 km × 100 km cells across all continents, estimating the mean, periodic seasonal variation and aperiodic unpredictable fluctuations of the NDVI in these cells. We then explored the relationships between mean NDVI and the components of its temporal variation and evaluated the independent effects of the above‐mentioned variables on species richness in the three vertebrate groups by means of variation partitioning.ResultsThere is a hump‐shaped relationship between mean productivity and variation in productivity, so that temporal variation in productivity is lowest in regions with minimum and maximum values of mean productivity. Although mean productivity is a strong determinant of species richness, both seasonal and non‐seasonal productivity variation significantly affect the species richness of all studied taxa when accounting for mean productivity. However, the direction of these effects differs between regions differing in the mean productivity level. High variation in productivity has a negative effect on species richness in regions with moderate to high productivity levels, whereas species richness is higher in arid regions with high variation in productivity.Main conclusionsSpecies richness is affected by temporal variation in productivity, but these effects differ regionally. In productive areas, high environmental stochasticity may increase population extinction rates, whereas arid regions probably benefit from resource fluctuations that promote species coexistence. Our results indicate that contemporary changes in patterns of temporal resource fluctuations may affect future global patterns of biological diversity on Earth.

Soil niche of rain forest plant lineages: Implications for dominance on a global scale

AbstractAimWhy some lineages are species‐rich and widespread, while others are species‐poor and localized, is a fundamental question in evolutionary biology and ecology. Diversification and range expansion relate to lineage‐specific niche characters, but this link has seldom been quantified across multiple lineages and environments. This study explored the link between local dominance and soil niche in rain forest plants, and tested the hypothesis that local soil niche patterns can be used to predict the global diversity and occupancy of equal‐aged plant lineages.LocationThe study was carried out in Brunei Darussalam (Borneo) and projected worldwide.MethodsOur approach involved the subdivision of vascular plants into the lineages found 120 Mya, a time preceding the explosive radiation of the eudicots. We quantified the representation of the 120 Mya lineages in different forest types associated with dramatically different soils, but sharing the same climatic conditions. The forest types included primary and secondary lowland rain forest, flooded and nutrient‐impoverished inland forests, and mangroves. Niche breadth and position, estimated from the soil types that a lineage occupied, were used to predict global diversity and occupancy patterns, after accounting for relatedness to the dominant eudicots.ResultsDespite marked differences in soil characteristics among the forest types, three eudicot lineages (Malvidae, Fabidae, Asteridae) were consistently dominant over the other 28 lineages present. A broad, intermediate soil niche, relatedness to eudicots, and the interaction between these factors were found to be strong predictors of global diversity and occupancy.Main conclusionsWe show that vegetation plot data from one of the world's most diverse regions (in terms of plant species richness and ancient lineage representation) can be used to successfully predict lineage diversity and occupancy on a global scale. However, because lineage dominance likely depends on the interaction between soil niche and above‐ground factors, including above‐ground niche features should improve the accuracy of predicting global distribution and diversity—particularly when explaining eudicot dominance.

Geography best explains global patterns of genetic diversity and postglacial co-expansion in marine turtles.

For many species, climate oscillations drove cycles of population contraction during cool glacial periods followed by expansion during interglacials. Some groups, however, show evidence of uniform and synchronous expansion, while others display differences in the timing and extent of demographic change. We compared demographic histories inferred from genetic data across marine turtle species to identify responses to postglacial warming shared across taxa and to examine drivers of past demographic change at the global scale. Using coalescent simulations and approximate Bayesian computation (ABC), we estimated demographic parameters, including the likelihood of past population expansion, from a mitochondrial data set encompassing 23 previously identified lineages from all seven marine turtle species. For lineages with a high posterior probability of expansion, we conducted a hierarchical ABC analysis to estimate the proportion of lineages expanding synchronously and the timing of synchronous expansion. We used Bayesian model averaging to identify variables associated with expansion and genetic diversity. Approximately 60% of extant marine turtle lineages showed evidence of expansion, with the rest mainly exhibiting patterns of genetic diversity most consistent with population stability. For lineages showing expansion, there was a strong signal of synchronous expansion after the Last Glacial Maximum. Expansion and genetic diversity were best explained by ocean basin and the degree of endemism for a given lineage. Geographic differences in sensitivity to climate change have implications for prioritizing conservation actions in marine turtles as well as for identifying areas of past demographic stability and potential resilience to future climate change for broadly distributed taxa.

World distribution, diversity and endemism of aquatic macrophytes

To test the hitherto generally-accepted hypothesis that most aquatic macrophytes have broad world distributions, we investigated the global distribution, diversity and endemism patterns of 3457 macrophyte species that occur in permanent, temporary or ephemeral inland freshwater and brackish waterbodies worldwide. At a resolution of 10 × 10° latitude x longitude, most macrophyte species were found to have narrow global distributions: 78% have ranges (measured using an approach broadly following the IUCN-defined concept “extent of occurrence”) that individually occupy <10% of the world area present within the six global ecozones which primarily provide habitat for macrophytes. We found evidence of non-linear relationships between latitude and macrophyte α- and γ-diversity, with diversity highest in sub-tropical to low tropical latitudes, declining slightly towards the Equator, and also declining strongly towards higher latitudes. Landscape aridity and, to a lesser extent, altitude and land area present per gridcell also influence macrophyte diversity and species assemblage worldwide. The Neotropics and Orient have the richest ecozone species-pools for macrophytes, depending on γ-diversity metric used. The region around Brasilia/Goiás (Brazil: gridcell 10–20 °S; 40–50 °W) is the richest global hotspot for macrophyte α-diversity (total species α-diversity, ST: 625 species/gridcell, 350 of them Neotropical endemics). In contrast, the Sahara/Arabian Deserts, and some Arctic areas, have the lowest macrophyte α-diversity (ST <20 species/gridcell). At ecozone scale, macrophyte species endemism is pronounced, though with a>5-fold difference between the most species-rich (Neotropics) and species-poor (Palaearctic) ecozones. Our findings strongly support the assertion that small-ranged species constitute most of Earth’s species diversity.

High species diversity and turnover in granite inselberg floras highlight the need for a conservation strategy protecting many outcrops.

Determining patterns of plant diversity on granite inselbergs is an important task for conservation biogeography due to mounting threats. However, beyond the tropics there are relatively few quantitative studies of floristic diversity, or consideration of these patterns and their environmental, biogeographic, and historical correlates for conservation. We sought to contribute broader understanding of global patterns of species diversity on granite inselbergs and inform biodiversity conservation in the globally significant Southwest Australian Floristic Region (SWAFR). We surveyed floristics from 16 inselbergs (478 plots) across the climate gradient of the SWAFR stratified into three major habitats on each outcrop. We recorded 1,060 species from 92 families. At the plot level, local soil and topographic variables affecting aridity were correlated with species richness in herbaceous (HO) and woody vegetation (WO) of soil‐filled depressions, but not in woody vegetation on deeper soils at the base of outcrops (WOB). At the outcrop level, bioclimatic variables affecting aridity were correlated with species richness in two habitats (WO and WOB) but, contrary to predictions from island biogeography, were not correlated with inselberg area and isolation in any of the three habitats. Species turnover in each of the three habitats was also influenced by aridity, being correlated with bioclimatic variables and with interplot geographic distance, and for HO and WO habitats with local site variables. At the outcrop level, species replacement was the dominant component of species turnover in each of the three habitats, consistent with expectations for long‐term stable landscapes. Our results therefore highlight high species diversity and turnover associated with granite outcrop flora. Hence, effective conservation strategies will need to focus on protecting multiple inselbergs across the entire climate gradient of the region.

Global geographic patterns of heterospecific pollen receipt help uncover potential ecological and evolutionary impacts across plant communities worldwide

Species interactions are known to be key in driving patterns of biodiversity across the globe. Plant-plant interactions through heterospecific pollen (HP) transfer by their shared pollinators is common and has consequences for plant reproductive success and floral evolution, and thus has the potential to influence global patterns of biodiversity and plant community assembly. The literature on HP transfer is growing and it is therefore timely to review patterns and causes of among-species variation in HP receipt at a global scale, thus uncovering its potential contribution to global patterns of biodiversity. Here we analyzed published data on 245 species distributed across five continents to evaluate latitudinal and altitudinal patterns of HP receipt. We further analyzed the role of floral symmetry and evolutionary history in mediating patterns of HP receipt. Latitude and elevation affected the likelihood and intensity of HP receipt indicating that HP transfer increases in species-rich communities and in areas with high abundance of vertebrate pollinators. Floral symmetry and evolutionary history determined HP load size across plant communities worldwide. Overall, our results suggest that HP receipt may have the potential to contribute to global geographic patterns of plant diversity by imposing strong selective pressures in species-rich areas across the globe.

Contrasting latitudinal patterns in phylogenetic diversity between woody and herbaceous communities

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.

SPlot – A new tool for global vegetation analyses

AbstractAimsVegetation‐plot records provide information on the presence and cover or abundance of plants co‐occurring in the same community. Vegetation‐plot data are spread across research groups, environmental agencies and biodiversity research centers and, thus, are rarely accessible at continental or global scales. Here we present the sPlot database, which collates vegetation plots worldwide to allow for the exploration of global patterns in taxonomic, functional and phylogenetic diversity at the plant community level.ResultssPlot version 2.1 contains records from 1,121,244 vegetation plots, which comprise 23,586,216 records of plant species and their relative cover or abundance in plots collected worldwide between 1885 and 2015. We complemented the information for each plot by retrieving climate and soil conditions and the biogeographic context (e.g., biomes) from external sources, and by calculating community‐weighted means and variances of traits using gap‐filled data from the global plant trait database TRY. Moreover, we created a phylogenetic tree for 50,167 out of the 54,519 species identified in the plots. We present the first maps of global patterns of community richness and community‐weighted means of key traits.ConclusionsThe availability of vegetation plot data in sPlot offers new avenues for vegetation analysis at the global scale.

Biodiversity of leaf litter fungi in streams along a latitudinal gradient

Global patterns of biodiversity have emerged for soil microorganisms, plants and animals, and the extraordinary significance of microbial functions in ecosystems is also well established. Virtually unknown, however, are large-scale patterns of microbial diversity in freshwaters, although these aquatic ecosystems are hotspots of biodiversity and biogeochemical processes. Here we report on the first large-scale study of biodiversity of leaf-litter fungi in streams along a latitudinal gradient unravelled by Illumina sequencing. The study is based on fungal communities colonizing standardized plant litter in 19 globally distributed stream locations between 69°N and 44°S. Fungal richness suggests a hump-shaped distribution along the latitudinal gradient. Strikingly, community composition of fungi was more clearly related to thermal preferences than to biogeography. Our results suggest that identifying differences in key environmental drivers, such as temperature, among taxa and ecosystem types is critical to unravel the global patterns of aquatic fungal diversity.

Niche conservatism and elevated diversification shape species diversity in drylands: evidence from Zygophyllaceae.

The integrated contributions of climate and macroevolutionary processes to global patterns of species diversity are still controversial in spite of a long history of studies. The niche conservatism hypothesis and the net diversification rate hypothesis have gained wide attention in recent literature. Many studies have tested these two hypotheses for woody species in humid forests; however, the determinants of species diversity patterns for arid-adapted plants remain largely ignored. Here, using a molecular phylogeny and the global distributions of Zygophyllaceae, a typical arid-adapted plant family, we assessed the effects of contemporary climate and net diversification rates on species diversity patterns in drylands. We found the variables representing water availability to be the best predictors for Zygophyllaceae diversity. Specifically, Zygophyllaceae species diversity significantly decreased with the increase in water availability, probably owing to phylogenetic conservatism of water-related niches. The net diversification rates of Zygophyllaceae accelerated sharply in the recent 10 Myr, coinciding roughly with the period of global aridification. The species diversity of Zygophyllaceae significantly increased with the increase in mean net diversification rates per geographical unit, especially in the Old World, supporting the net diversification rate hypothesis. Our study provides a case exploring climatic and evolutionary mechanisms of dryland species diversity patterns, and suggests that the conservatism in water-related niches and elevated net diversification rates in drylands may have jointly determined the global patterns of dryland species diversity.

Explaining the ocean's richest biodiversity hotspot and global patterns of fish diversity.

For most marine organisms, species richness peaks in the Central Indo-Pacific region and declines longitudinally, a striking pattern that remains poorly understood. Here, we used phylogenetic approaches to address the causes of richness patterns among global marine regions, comparing the relative importance of colonization time, number of colonization events, and diversification rates (speciation minus extinction). We estimated regional richness using distributional data for almost all percomorph fishes (17 435 species total, including approximately 72% of all marine fishes and approximately 33% of all freshwater fishes). The high diversity of the Central Indo-Pacific was explained by its colonization by many lineages 5.3-34 million years ago. These relatively old colonizations allowed more time for richness to build up through in situ diversification compared to other warm-marine regions. Surprisingly, diversification rates were decoupled from marine richness patterns, with clades in low-richness cold-marine habitats having the highest rates. Unlike marine richness, freshwater diversity was largely derived from a few ancient colonizations, coupled with high diversification rates. Our results are congruent with the geological history of the marine tropics, and thus may apply to many other organisms. Beyond marine biogeography, we add to the growing number of cases where colonization and time-for-speciation explain large-scale richness patterns instead of diversification rates.

Evolution within a language: environmental differences contribute to divergence of dialect groups

BackgroundThe processes leading to the diversity of over 7000 present-day languages have been the subject of scholarly interest for centuries. Several factors have been suggested to contribute to the spatial segregation of speaker populations and the subsequent linguistic divergence. However, their formal testing and the quantification of their relative roles is still missing. We focussed here on the early stages of the linguistic divergence process, that is, the divergence of dialects, with a special focus on the ecological settings of the speaker populations. We adopted conceptual and statistical approaches from biological microevolution and parallelled intra-lingual variation with genetic variation within a species. We modelled the roles of geographical distance, differences in environmental and cultural conditions and in administrative history on linguistic divergence at two different levels: between municipal dialects (cf. in biology, between individuals) and between dialect groups (cf. in biology, between populations).ResultsWe found that geographical distance and administrative history were important in separating municipal dialects. However, environmental and cultural differences contributed markedly to the divergence of dialect groups. In biology, increase in genetic differences between populations together with environmental differences may suggest genetic differentiation of populations through adaptation to the local environment. However, our interpretation of this result is not that language itself adapts to the environment. Instead, it is based on Homo sapiens being affected by its environment, and its capability to adapt culturally to various environmental conditions. The differences in cultural adaptations arising from environmental heterogeneity could have acted as nonphysical barriers and limited the contacts and communication between groups. As a result, linguistic differentiation may emerge over time in those speaker populations which are, at least partially, separated.ConclusionsGiven that the dialects of isolated speaker populations may eventually evolve into different languages, our result suggests that cultural adaptation to local environment and the associated isolation of speaker populations have contributed to the emergence of the global patterns of linguistic diversity.

Global patterns of Rhododendron diversity: The role of evolutionary time and diversification rates

AbstractAimUnderstanding the evolution of the latitudinal diversity gradient (i.e. increase in species diversity towards the tropics) is a prominent issue in ecology and biogeography. Disentangling the relative contributions of environment and evolutionary history in shaping this gradient remains a major challenge because their relative importance has been found to vary across regions and taxa. Here, using the global distributions and a molecular phylogeny of Rhododendron, one of the largest genera of flowering plants, we aim to compare the relative contributions of contemporary environment, evolutionary time and diversification rates in generating extant species diversity patterns.LocationGlobal.Time periodUndefined.Major taxa studiedRhododendron.MethodsWe compiled the global distributions of all Rhododendron species, and constructed a dated molecular phylogeny using nine chloroplast genes and seven nuclear regions. By integrating these two datasets, we estimated the temporal trends of Rhododendron diversification, and explored the global patterns of its species diversity, net diversification rates, and species ages. Next, we reconstructed the geographical ancestral area of the clade. Finally, we compared the relative contribution of contemporary environment, time‐for‐speciation, and diversification rates on the species diversity pattern of Rhododendron.ResultsIn contrast to the predictions of the time‐for‐speciation hypothesis, we found that although Rhododendron originated at a temperate latitude, its contemporary species diversity is highest in the tropics/subtropics, suggesting an into‐the‐tropics colonization for this genus. We found that the elevated diversification induced by heterogeneous environmental conditions in the tropics/subtropics shapes the global pattern of Rhododendron diversity.Main conclusionsOur findings support tropical and subtropical mountains as not only biodiversity and endemism hotspots, but also as cradles for the diversification of Rhododendron. Our study emphasizes the need of unifying ecological and evolutionary approaches in order to gain comprehensive understanding of the mechanisms underlying the global patterns of plant diversity.

Trophic interactions among vertebrate guilds and plants shape global patterns in species diversity.

Trophic interactions play critical roles in structuring biotic communities. Understanding variation in trophic interactions among systems provides important insights into biodiversity maintenance and conservation. However, the relative importance of bottom-up versus top-down trophic processes for broad-scale patterns in biodiversity is poorly understood. Here, we used global datasets on species richness of vascular plants, mammals and breeding birds to evaluate the role of trophic interactions in shaping large-scale diversity patterns. Specifically, we used non-recursive structural equation models to test for top-down and bottom-up forcing of global species diversity patterns among plants and trophic guilds of mammals and birds (carnivores, invertivores and herbivores), while accounting for extrinsic environmental drivers. The results show that trophic linkages emerged as being more important to explaining species richness than extrinsic environmental drivers. In particular, there were strong, positive top-down interactions between mammal herbivores and plants, and moderate to strong bottom-up and/or top-down interactions between herbivores/invertivores and carnivores. Estimated trophic interactions for separate biogeographical regions were consistent with global patterns. Our findings demonstrate that, after accounting for environmental drivers, large-scale species richness patterns in plant and vertebrate taxa consistently support trophic interactions playing a major role in shaping global patterns in biodiversity. Furthermore, these results suggest that top-down forces often play strong complementary roles relative to bottom-up drivers in structuring biodiversity patterns across trophic levels. These findings underscore the importance of integrating trophic forcing mechanisms into studies of biodiversity patterns.

Phylogeography and genetics of the globally invasive snail Physa acuta Draparnaud 1805, and its potential to serve as an intermediate host to larval digenetic trematodes

BackgroundPhysa acuta is a globally invasive freshwater snail native to North America. Prior studies have led to conflicting views of how P. acuta populations are connected and genetic diversity is partitioned globally. This study aims to characterize phylogeographic and population genetic structure within the native range of P. acuta, elucidate its invasion history and assess global patterns of genetic diversity. Further, using meta-analytic methods, we test the ‘Enemy-Release hypothesis’ within the P. acuta – digenetic trematode system. The ‘Enemy-Release hypothesis’ refers to the loss of native parasites following establishment of their host within an invasive range. Population genetic data is combined with surveys of trematode infections to map range-wide trematode species richness associated with P. acuta, and to identify relevant host-population parameters important in modeling host-parasite invasion.ResultsPhylogenetic analyses using mtDNA uncovered two major clades (A & B). Clade A occurs globally while clade B was only recovered from the Western USA. All invasive populations sampled grouped within Clade A, where multiple independent source populations were identified from across North America. Significant population genetic structure was found within the native range of P. acuta, with some evidence for contemporary geographic barriers between western and eastern populations. Mito-nuclear discordance was found suggesting historical isolation with secondary contact between the two mitochondrial clades. Trematode species richness was found to differ significantly between native and invasive populations, in concordance with the ‘Enemy-Release hypothesis’. Further, our data suggests a positive relationship between nucleotide diversity of invasive populations and trematode prevalence and richness.ConclusionsThis study includes a wider geographic sampling of P. acuta within its native range that provides insight into phylogeographic and population genetic structure, range-wide genetic diversity and estimation of the invasion history. Meta-analysis of P. acuta – trematode surveys globally is consistent with the ‘Enemy-Release hypothesis’. Additionally, results from this study suggest that host demographic parameters, namely genetic diversity as a proxy for population size, may play an essential role in how parasite communities assemble within invasive host populations. This knowledge can be used to begin to construct a framework to model host-parasite invasion dynamics over time.

Diversity and distribution of Archaea in global estuarine ecosystems

Estuarine ecosystem is a unique geographical transitional zone between freshwater and seawater, harboring a wide range of microbial communities including Archaea. Although a large number of Archaea have been detected in such ecosystem, the global patterns in archaeal diversity and distribution are extremely scarce. To bridge this gap, we carried out a comprehensive survey of archaeal communities using ca. 4000 publicly available archaeal 16S rRNA gene sequences (>300 bp) collected from 24 estuaries in different latitude regions. These sequences were divided into 1450 operational taxonomic units (OTUs) at 97% identity, suggesting a high biodiversity that increased gradually from the high- to low-latitude estuaries. Phylogenetic analysis showed that estuarine ecosystem was a large biodiversity pool of Archaea that was mainly composed of 12 phyla. Among them, the predominant groups were Bathyarchaeota, Euryarchaeota and Thaumarchaeota. Interestingly, archaeal distribution demonstrated a geographical differentiation in that Thaumarchaeota was dominated in the low-latitude estuaries, Bathyarchaeota in the mid-latitude estuaries, and Euryarchaeota in the high-latitude estuaries, respectively. Furthermore, the majority of the most abundant 20 OTUs demonstrated an overrepresented or underrepresented distribution pattern in some specific estuaries or latitude regions while a few were evenly distributed throughout the estuaries. This pattern indicates a potential selectivity of geographical distribution. In addition, the analysis of environmental parameters suggested that latitude would be one of the major factors driving the distribution of archaeal communities in estuarine ecosystem. This study profiles a clear framework on the diversity and distribution of Archaea in the global estuarine ecosystem and explores the general environmental factors that influence these patterns. Our findings constitute an important part of the exploration of the global ecology of Archaea.

Phylogenetic uniqueness, not latitude, explains the diversity of avian blood parasite communities worldwide

AbstractAimCharacterizing macroecological patterns in biodiversity is key to improve our understanding of community assembly. Global biodiversity for many taxa follows a latitudinal gradient, with increased diversity in tropical latitudes. Less is known about global parasite biodiversity, inhibiting our ability to predict how global change will impact parasitic disease emergence. Using distribution and phylogenetic data for 2,386 avian haemosporidian blood parasites (genera Plasmodium, Haemoproteus and Leucocytozoon), I assessed how contemporary and historical drivers influence the composition of parasite communities worldwide.LocationGlobal.Time periodCurrent.Major taxa studiedHaemosporidian blood parasites.MethodsParasite distribution and cytochrome b sequence data were accessed from an open‐source database. Bayesian phylogenetic tree distributions were constructed for each parasite genus using two substitution models to capture uncertainty. Hierarchical regressions assessed effects of environmental variation, latitude and phylogenetic β‐diversity (βdiv; a proxy for phylogenetic uniqueness) on the diversity and asymmetry of parasite communities around the globe.ResultsI uncovered biodiversity hotspots and identified broad variation in global diversity patterns among parasite genera. Community diversity increased with increasing phylogenetic uniqueness for all three parasite genera; however, these diverse and unique regions did not consistently occur in the tropics. I found no evidence of a latitudinal diversity gradient, and support for a latitudinal gradient in community phylogenetic asymmetry was weak.Main conclusionsGlobal variation in avian haemosporidian phylogenetic diversity does not reflect a latitudinal gradient. Instead, parasite biogeography may reflect fundamental differences in host‐switching tendencies or the timing of avian evolutionary radiations. Examining the interplay between shared evolutionary history and phylogenetic diversity can provide important insights into the drivers of parasite biodiversity at global scales.

Angiosperm leaves and cuticles from the uppermost Cretaceous of Patagonia, biogeographic implications and atmospheric paleo-CO2 estimates

The study of plant material from localities of Late Cretaceous age from southern latitudes is fundamental to improve our understanding of global patterns of angiosperm evolution, diversity, paleoecology, and biogeography. Herein, angiosperm leaf fossils of the recently discovered Cañadón del Loro locality, from the Maastrichtian portion of the Lefipán Formation, Patagonia, Argentina are studied. Leaf architecture was used to differentiate morphotypes, to describe them, and to make comparisons with other southern latitudes floras of similar age. Six angiosperm leaf morphotypes were described from 132 collected specimens; one of them, with exceptional preservation, was named Lefipania padillae gen. et sp. nov. and its cuticle anatomy and insect damage were also described. The Cañadón del Loro fossils represent a local assemblage of low diversity deposited in an upper delta plain. Biogeographically, L. padillae was widespread throughout the southern hemisphere during the Late Cretaceous, possibly favored by a warm climate and the geographical proximity of these southern landmasses. The morphotype with well-preserved cuticles clearly shows four insect damage types attributed to feeding. This morphotype was also used for estimating paleo-atmospheric CO2 concentration (pCO2), using a stomatal-proxy gas exchange model, which resulted in approximately 464 ppm. The estimated pCO2 is in agreement with previous estimations for this time interval and supports the hypothesis of a decrease of pCO2 towards end of the Cretaceous.