Biogeographic Structure Research Articles

Microsatellite markers for the prized matsutake mushroom (Tricholoma matsutake, Tricholomataceae).

Premise of the StudyNovel and cost‐effective microsatellite markers were developed to explore the population genetics, biogeographic structure, and evolutionary history of the prized Euro‐Asian wild edible ectomycorrhizal fungus Tricholoma matsutake (Tricholomataceae).Methods and resultsEighteen new polymorphic simple sequence repeat loci, detected from a microsatellite‐enriched genomic library, were used to characterize 131 individuals from eight T. matsutake populations. The number of alleles ranged from two to 10, with averages of 1.42 to 3.22. Levels of observed and expected heterozygosity ranged from 0.00–1.00 and from 0.00–0.83, with mean values of 0.21 and 0.26, respectively. In total, 50% of the loci showed interspecific transferability and polymorphism in the related species T. equestre.ConclusionsThese newly developed markers will aid research into the genetic diversity and population structure of T. matsutake. They can also be used in other species of Tricholoma.

Immigration and extirpation selectivity patterns of brachiopods and bivalves across a Carboniferous glacial to non-glacial transition (Pennsylvanian, central western Argentina) and their influence in building the biotic bathymetric gradient

The growth and demise of glaciers during the Late Paleozoic ice age had profound consequences on the marine biota. In central western Argentina the transition from glacial to non-glacial interval during the Pennsylvanian, caused a major regional turnover which remodeled the bathymetric diversity gradient. In order to understand the nature of the environmental changes related to such turnover event, we compared selectivity patterns in extirpation and immigration of bivalves and brachiopods using logistic regression. We tested for a wide range of potential drivers of extirpation and immigration, namely body size, geographic range size, environmental breadth, preferred depth, metabolic rates, infaunalism and taxonomic identity. While extirpation preferentially hit brachiopods and genera having smaller geographic ranges and smaller body sizes, immigration was related to genera with preference for deeper environment and small geographic ranges.Extirpation selectivity was not uniform along the bathymetric gradient. Both geographic range and body size selectivity are stronger towards deeper environments. Each clade, on the other hand, showed idiosyncratic responses to climate change. While brachiopods show extirpation selectivity for smaller geographic ranges, small sized bivalves were preferentially extirpated. These contrasting selectivity regimes, however, could be reflecting different faunal responses to the same environmental changing factor, namely higher thermal amplitude. Immigration in both brachiopods and bivalves was related to preference to deep environments, confirming previous results. However, brachiopods also showed preferential immigration of small geographic range genera, which is puzzling given the extinction selectivity related to the glacial non-glacial transition. Possible explanations point to a brief time span in which an increase in thermal amplitude occurred. The rapid climate changes, particularly related to a rise in maximum temperatures, lead the ecological response of the benthic faunas. Differences in extinction and immigration selectivity along the bathymetric gradient, suggest that the turnover event also remodeled the bathymetric gradient in body size and biogeographic structure and brachiopod:bivalve proportions. Such changes were driven by extirpation, contrasting with the remodeling of the bathymetric diversity gradient that was driven by immigration. Our results, therefore, highlight that immigration and extirpation can shape different aspects of the bathymetric biotic gradient.

Selection, drift, and introgression shape MHC polymorphism in lizards.

The major histocompatibility complex (MHC) has long served as a model for the evolution of adaptive genetic diversity in wild populations. Pathogen-mediated selection is thought to be a main driver of MHC diversity, but it remains elusive to what degree selection shapes MHC diversity in complex biogeographical scenarios where other evolutionary processes (e.g. genetic drift and introgression) may also be acting. Here we focus on two closely related green lizard species, Lacerta trilineata and L. viridis, to address the evolutionary forces acting on MHC diversity in populations with different biogeographic structure. We characterized MHC class I exon 2 and exon 3, and neutral diversity (microsatellites), to study the relative importance of selection, drift, and introgression in shaping MHC diversity. As expected, positive selection was a significant force shaping the high diversity of MHC genes in both species. Moreover, introgression significantly increased MHC diversity in mainland populations, with a primary direction of gene flow from L. viridis to L. trilineata. Finally, we found significantly fewer MHC alleles in island populations, but maintained MHC sequence and functional diversity, suggesting that positive selection counteracted the effect of drift. Overall, our data support that different evolutionary processes govern MHC diversity in different biogeographical scenarios: positive selection occurs broadly while introgression acts in sympatry and drift when the population sizes decrease.

The stability of coastal benthic biogeography over the last 10 million years

AbstractAimWe demarcate marine benthic global bioregions based on fossil and recent occurrence data. Our main goal is to compare past and present biogeography and to extract major abiotic drivers of biogeographical patterns. We specifically test the hypothesis that global biogeography has changed markedly after the climatic fluctuations of the past 10 Myr.LocationWorldwide.Time periodRecent; late Miocene–Pleistocene interval.Major taxa studiedBenthic taxa with a rich fossil record: Bivalvia, Brachiopoda, Bryozoa, Gastropoda, Echinodermata, Decapoda and reef corals.MethodsWe use occurrence data from the Ocean Biogeographic Information System (OBIS) and the Paleobiology Database to construct compositional networks and outline objective marine bioregions of benthic marine invertebrates using the “infomap” community detection algorithm. We assess the association of modern bioregions with a variety of environmental parameters by applying multivariate statistical analyses, such as principal components analysis, random forests and multiple logistic regressions.ResultsRecent first‐order bioregions for the coastal ocean are, in general, consistent across all taxa. Seawater temperature surpasses nutrients, primary production and salinity as a predictor of modern bioregion distributions. Despite substantial climatic variations, late Cenozoic biogeographical patterns recorded in fossils are very similar to modern ones.Main conclusionsBiogeographical boundaries within oceans are strongly controlled by temperature gradients, but open oceanic and continental barriers determine the global biogeographical structure. The joint structure of a landmass distribution, deep ocean basins and the latitudinal temperature gradient defines bioregionalization of the benthic marine habitat, which did not change substantially over the past 10 Myr.

Genetic Diversity and Cooccurrence Patterns of Marine Cyanopodoviruses and Picocyanobacteria.

Picocyanobacteria Prochlorococcus and Synechococcus are abundant in the global oceans and subject to active viral infection. In this study, the genetic diversity of picocyanobacteria and the genetic diversity of cyanopodoviruses were synchronously investigated along water columns in the equatorial Indian Ocean and over a seasonal time course in the coastal Sanya Bay, South China Sea. Using the 16S-23S rRNA internal transcribed spacer (ITS)-based clone library and quantitative PCR (qPCR) analyses, the picocyanobacterial community composition and abundance were determined. Sanya Bay was dominated by clade II Synechococcus during all the seasons, and a typical population shift from high-light-adapted Prochlorococcus to low-light-adapted Prochlorococcus was found along the vertical profiles. Strikingly, the DNA polymerase gene sequences of cyanopodoviruses revealed a much greater genetic diversity than we expected. Nearly one-third of the phylogenetic groups were newly described here. No apparent seasonal pattern was observed for the Sanya Bay picocyanobacterial or cyanopodoviral communities. Different dominant cyanopodovirus lineages were identified for the coastal area, upper euphotic zone, and middle-to-lower euphotic zone of the open ocean. Diversity indices of both picocyanobacteria and cyanopodoviruses were highest in the middle euphotic zone and both were lower in the upper euphotic zone, reflecting a host-virus interaction. Cyanopodoviral communities differed significantly between the upper euphotic zone and the middle-to-lower euphotic zone, showing a vertical pattern similar to that of picocyanobacteria. However, in the surface waters of the open ocean, cyanopodoviruses exhibited no apparent biogeographic pattern, differing from picocyanobacteria. This study demonstrates correlated distribution patterns of picocyanobacteria and cyanopodoviruses, as well as the complex biogeography of cyanopodoviruses.IMPORTANCE Picocyanobacteria are highly diverse and abundant in the ocean and display remarkable global biogeography and a vertical distribution pattern. However, how the diversity and distribution of picocyanobacteria affect those of the viruses that infect them remains largely unknown. Here we synchronously analyzed the community structures of cyanopodoviruses and picocyanobacteria at spatial and temporal scales. Both spatial and temporal variations of cyanopodoviral communities can be linked to those of picocyanobacteria. The coastal area, upper euphotic zone, and middle-to-lower euphotic zone of the open ocean have distinct cyanopodoviral communities, showing horizontal and vertical variation patterns closely related to those of picocyanobacteria. These findings emphasize the driving force of host community in shaping the biogeographic structure of viruses. Our work provides important information for future assessments of the ecological roles of viruses and hosts for each other.

Distribution of the genus Zonaria (Dictyotales: Phaeophyceae) in New Zealand, and description of Zonaria cryptica sp. nov from Stewart Island

ABSTRACTThe brown algal genus Zonaria (Dictyotales: Dictyotaceae) is widely distributed in temperate waters. Two species, Zonaria turneriana J.Agardh and Zonaria aureomarginata J.A. Phillips & W.A. Nelson have previously been recorded from mainland New Zealand, and a third species, Zonaria diesingiana, has been recorded from the Kermadec Islands. As part of an ongoing study of the order Dictyotales in New Zealand, we have identified an undescribed species of Zonaria present on Stewart Island in southern New Zealand. The new species, described here as Zonaria cryptica, is very similar in external morphology to Z. turneriana, also found on Stewart Island, but differs both genetically and anatomically from Z. turneriana and from other previously described species in the genus. We present a description of the new species based on morphological and anatomical observations, as well as on DNA sequence data from three plastid markers: psaA, psbA and rbcL. Our analysis also indicates the presence of some biogeographic structuring within Z. turneriana and Z. aureomarginata.

Palaeobiogeographical distribution of Smithian (Early Triassic) ammonoid faunas within the western USA basin and its controlling parameters

AbstractWe present the first quantitative palaeobiogeographical analysis in terms of distribution and abundance of Early Triassic ammonoids from the western USA basin during the Smithian, c. 1 myr after the Permian–Triassic boundary mass extinction. The faunal dataset consists of a taxonomically homogenized compilation of spatial and temporal occurrences and abundances from 27 sections distributed within the western USA basin. Two complementary multivariate techniques were applied to identify the main biogeographical structuring recorded in the analysed presence/absence data: additive cluster analysis using the neighbor‐joining algorithm (NJ) and non‐metric multidimensional scaling (NMDS). Regarding abundance data, a taxonomic diversity (sensu evenness) analysis was coupled with graphical comparisons of relative abundances of selected taxa. The identified relationships indicate that middle Smithian ammonoids of the western USA basin were geographically organized in terms of both distribution and abundance, with the biogeographical distinction of a southern and a northern cluster. This N–S structuring in the distribution and abundance of middle Smithian ammonoids is notably paralleled by the relative amount of siliciclastics, which suggests that clastic load of the water column was a major controlling factor. In marked contrast with the middle Smithian, the studied late Smithian ammonoid assemblages do not show any significant differences, whatever the depositional environment. This abrupt biogeographical homogenization, independent from intrabasinal facies heterogeneity, indicates a switch from regional to global drivers, associated with the well‐known late Smithian global extinction and remarkable cosmopolitan ammonoid distributions during that time.

Noninvasive genetic assessment provides evidence of extensive gene flow and possible high movement ability in the African golden wolf

The African golden wolf, Canis anthus, is a newly recognized medium-sized canid species from North Africa, which has remained poorly studied to date. We applied genetic methods for individual identification of non-invasively collected samples (n = 93) of the African golden wolf in Tunisia, assessing their genetic diversity and structure. The mitochondrial control region exhibited high haplotype diversity (Hd = 0.907 ± 0.018) with 15 haplotypes detected among 28 individuals. Similarly, a set of 15 microsatellite loci revealed high genetic diversity at the nuclear level (expected heterozygosity = 0.83 ± 0.04; average number of alleles = 8.30 ± 0.99). The Bayesian model-based clustering method implemented in STRUCTURE did not reveal population structure in African golden wolves within Tunisia. This result was corroborated by the Discriminant Analysis of Principal Components where no clear clusters were observed. Based on seven individuals that were found multiple times among samples, we estimated straight distance movements up to 230 km. Our results provide movement lengths for the species and no evidence for biogeographical structure of genetic diversity within Tunisian golden wolves, probably related to the high dispersal ability of the species, facilitating high gene flow. The evaluation of population diversity and the first information on movement ability provided in this study should be considered as baseline information in the development of a management plan for African golden wolf in Tunisia.

The biogeographical imprint of mass extinctions.

Mass extinctions are defined by extinction rates significantly above background levels and have had substantial consequences for the evolution of life. Geographically selective extinctions, subsequent originations and species redistributions may have changed global biogeographical structure, but quantification of this change is lacking. In order to assess quantitatively the biogeographical impact of mass extinctions, we outline time-traceable bioregions for benthic marine species across the Phanerozoic using a compositional network. Mass extinction events are visually recognizable in the geographical depiction of bioregions. The end-Permian extinction stands out with a severe reduction of provinciality. Time series of biogeographical turnover represent a novel aspect of the analysis of mass extinctions, confirming concentration of changes in the geographical distribution of benthic marine life.

Unmasking the complexity of species identification in Australasian flying-foxes.

Pteropus (flying-foxes) are a speciose group of non-echolocating large bats, with five extant Australian species and 24 additional species distributed amongst the Pacific Islands. In 2015, an injured flying-fox with unusual facial markings was found in Sydney, Australia, following severe and widespread storms. Based on an initial assessment, the individual belonged to Pteropus but could not be readily identified to species. As a consequence, four hypotheses for its identification/origin were posited: the specimen represented (1) an undescribed Australian species; or (2) a morphological variant of a recognised Australian species; or (3) a hybrid individual; or (4) a vagrant from the nearby Southwest Pacific Islands. We used a combination of morphological and both mitochondrial- and nuclear DNA-based identification methods to assess these hypotheses. Based on the results, we propose that this morphologically unique Pteropus most likely represents an unusual P. alecto (black flying-fox) potentially resulting from introgression from another Pteropus species. Unexpectedly, this individual, and the addition of reference sequence data from newly vouchered specimens, revealed a previously unreported P. alecto mitochondrial DNA lineage. This lineage was distinct from currently available haplotypes. It also suggests long-term hybridisation commonly occurs between P. alecto and P. conspicillatus (spectacled flying-fox). This highlights the importance of extensive reference data, and the inclusion of multiple vouchered specimens for each species to encompass both intraspecific and interspecific variation to provide accurate and robust species identification. Moreover, our additional reference data further demonstrates the complexity of Pteropus species relationships, including hybridisation, and potential intraspecific biogeographical structure that may impact on their management and conservation.

Biogeographical structure and endemism pattern in reptiles of the Western Palearctic

The analysis of biogeographical structure and patterns of endemism are central topics of biogeography, but require exhaustive distribution data. A lack of accurate broad-scale information on the distribution of reptiles has so far limited the analyses of biogeographical structure. Here we analysed the distribution of reptiles within the broad-sense Western Palearctic to assess biogeographical regionalization using phylogenetic and non-phylogenetic approaches, identified areas of endemism and evaluated the environmental factors promoting community uniqueness and endemism. We gathered distributional records from the literature and from the field, mapping the distribution of all the Western Palearctic reptiles on a 1-degree resolution grid. βsimdissimilarity and hierarchical clustering was used to identify bioregions, analysing data both at the species and at the genus level, and considering phylogenetic dissimilarity. Consensus areas of endemism were identified on the basis of the optimality criterion. We then assessed whether biogeographical structure is related to present-day climate, insularity, orography and velocity of climate change during the Late Quaternary. The genus-level analysis identified five main biogeographical regions within the Western Palearctic, in partial agreement with previous proposals, while the species-level analysis identified more bioregions, largely by dividing the ones identified by genera. Phylogenetic bioregions were generally consistent with the non-phylogenetic ones. The strongest community uniqueness was observed in subtropical warm climates with seasonal precipitation and low productivity. We found nine consensus areas of endemism, mostly in regions with limited velocity of Quaternary climate change and warm subtropical climates. The biogeographical structure of Western Palearctic reptiles is comparable to what has been observed in other vertebrates, with a clear distinction between the Saharo-Arabian-Sindian and Euro-Mediterranean herpetofaunas. Unlike other vertebrates, in reptiles the highest uniqueness and endemism is observed in dry climates, but the velocity of climate change during the Quaternary remains a major driver of endemism across all the vertebrates.

Raznolikost i strukturiranost hrvatskih kontinentalnih i alpsko-dinarskih populacija bijele johe (Alnus incana /L./ Moench subsp. incana); geografska i okolišna izolacija kao uzrok fenotipske divergencije

Bijela, odnosno siva joha, Alnus incana (L.) Moench subsp. incana, listopadna je, jednodomna i anemofilna drvenasta vrsta iz porodice Betulaceae. Prirodno je rasprostranjena u sjevernoj, srednjoj i mjestimično južnoj Europi, zapadnom Sibiru i Turskoj, od nizinskoga pojasa do preko 1800 m nadmorske visine u alpskom području. Bijela joha je mezofilna do higrofilna vrsta koja dobro podnosi oštru planinsku i kontinentalnu klimu, a raste na karbonatnim, ali i silikatnim, pjeskovitim, šljunčanim, slabo humusnim tlima. Najčešća je u planinskim dolinama, uz potoke i rijeke gdje na vlažnim staništima s mnogim higrofilnim vrstama tvori guste, fragmentarne sastojine, često obnovljene iz panja. To su povremeno plavljeni lokaliteti uz vodotoke ili okolne padine kroz koje se postrano procjeđuje voda prema glavnom vodotoku. Prisutnost bijele johe u Hrvatskoj vezana je za dva oštro ograničena područja: sjeveroistočno, u nizinskom dijelu Hrvatske (110 do 190 m nadmorske visine) uz tok rijeke Drave; i sjeverozapadno, u alpsko-dinarskom području uz rijeku Kupu i njene pritoke (220 do 550 m nadmorske visine). U sjeveroistočnom području rasprostiru se sastojine definirane kao Equiseto hyemali-Alnetum incanae Moor 1958 (Trinajstić 1964; Franjić et al. 1999), u kojima se u odnosu na sastojine bijele johe u gorskome području kao razlikovne vrste izdvajaju: Ulmus laevis Pall., U. minor Mill., Prunus padus L., Equisetum hyemale L. i druge. Ove sastojine danas su rjeđe nego nekada, manje se koriste, a zbog nekadašnjeg načina sječe vrlo su često panjače. Nekadašnje šumske površine koje je Trinajstić istraživao (1964) danas više nisu pod šumom. Poplavne i vlažne šume u blizini urbanih središta isušuju se, a na njihovim su staništima izgrađena naselja i komunalna infrastruktura tako da su danas šume sive johe uz tok rijeke Drave u velikoj regresiji. U alpsko-dinarskom području istraživane sastojine svrstane su u šumsku zajednicu Lamio orvalae-Alnetum incanae Dakskobler 2010, a opisane su kao geografska varijanta Helleborus dumetorum (Vukelić et al. 2012, 2017). Ona se ističe mnogim vrstama iz dinarske vegetacijske zone, poput Fraxinus excelsior L., Ulmus glabra Huds., Fagus sylvatica L., Acer pseudoplatanus L., Lamium orvala L., Lunaria rediviva L., Scopolia carniolica Jacq., Helleborus dumetorum Waldst. et Kit., Knautia drymeia Heuff. subsp. drymeia i druge. Siva joha ovdje raste u kanjonu Kupe i na obalnim terasama koje su uglavnom antropogenizirane, a nekoć su bile korištene u poljoprivrednoj proizvodnji. Glavni ciljevi rada bili su utvrditi morfološku raznolikost i strukturiranost populacija bijele johe u Hrvatskoj te istražiti na koji način ekološki i geografski čimbenici utječu na varijabilnost populacija. Materijal za morfometrijsku analizu sakupljen je iz sedam prirodnih populacija – tri iz kontinentalne i četiri iz alpsko-dinarske regije (slika 1). Svaka populacija predstavljena je s 20 stabala, a svako stablo s 20 zdravih i neoštećenih listova s kratkih fertilnih izbojaka iz vanjskog, osvijetljenog dijela krošnje. Listovi su sakupljeni početkom srpnja 2016. godine, odnosno sredinom vegetacijskog razdoblja, kada su s obzirom na dimenzije i oblik u potpunosti razvijeni. Listovi su skenirani i izmjereni pomoću programa WinFolia. Ukupno je izmjereno devet lisnih značajki (slika 2). Deskriptivnim statističkim metodama utvrđena je visoka varijabilnost listova bijele johe, kao i jasan trend divergencije između kontinentalnih i alpsko-dinarskih populacija (slika 3). Najvarijabilnijim su se pokazale značajke: površina plojke, širina lista mjerena na 90 % dužine plojke i dužina peteljke. Za razliku od toga, najmanji stupanj varijabilnosti zabilježen je za varijable koje opisuju osnovu lisne plojke. Iako je trend variranja pojedinih značajki po populacijama bio sličan, u populacijama alpsko-dinarske regije zabilježena je nešto viša unutar-populacijska raznolikost. Kontinentalne populacije su imale veće vrijednosti svih mjerenih značajki lista u odnosu na populacije iz alpsko-dinarske regije. Analizom varijance, utvrđene su statistički značajne razlike između istraživanih regija te između stabla unutar populacija, dok su se populacije unutar regija razlikovale samo za četiri istraživane značajke (tablica 1). Unutarpopulacijska varijabilnost veća je od međupopulacijske varijabilnosti, što je odlika mnogih vrsta drveća. Multivarijatne analize potvrđuju postojanje jasne razlike između kontinentalnih i alpsko-dinarskih populacija bijele johe (slika 1, slika 4, tablica 3), što upućuje na mogućnost da istraživane populacije predstavljaju dva različita ekotipa. Morfološka udaljenost između populacija bila je korelirana s geografskom i ekološkom udaljenošću, što potvrđuje uzorak „isolation by distance“ i „isolation by environmental distance“. Drugim riječima, utvrđeno je da geografska udaljenost i ekološka divergencija imaju važan utjecaj na oblikovanje morfološke strukture populacija te da je ona posljedica njihove moguće lokalne prilagodbe na okolišne uvjete i njihove geografske udaljenosti (tablica 2). Dobivene spoznaje o varijabilnosti populacija mogu doprinijeti razvoju učinkovitijih planova očuvanja i gospodarenja sivom johom u Hrvatskoj. Kako bi se potvrdili dobiveni zaključci o varijabilnosti populacija sive johe dobiveni morfometrijskim metodama, istraživanja je svakako potrebno proširiti i na molekularno-biološke metode.

Using collections data to infer biogeographic, environmental, and host structure in communities of endophytic fungi

ABSTRACTBiodiversity collections contain a wealth of information encapsulated both in specimens and in their metadata, providing the foundation for diverse studies in fields such as ecology. Yet biodiversity repositories can present a challenge for ecological inferences because collections rarely are structured with ecological questions in mind: collections may be opportunistic in space or time, may focus on particular taxonomic groups, may reflect different collection strategies in different places or times, or may not be exhaustive in terms of retaining every specimen or having similar metadata for each record. In addition to its primary holdings, the Robert L. Gilbertson Mycological Herbarium at the University of Arizona holds a collection of living specimens of fungi isolated from the interior of healthy plants and lichens (i.e., endophytic and endolichenic fungi). Over the past decade, more than 7000 isolates from the southwestern United States were accessioned, including strains from diverse hosts in more than 50 localities across the biotically rich state of Arizona. This collection is distinctive in that metadata and barcode sequences are available for each specimen, many localities have been sampled with consistent methods, and all isolates obtained in surveys have been retained. Here, we use this herbarium collection to examine endophyte community structure in an ecological and evolutionary context. We then artificially restructure the collection to resemble collections more typical of biodiversity repositories, providing a case study for ecological insights that can be gleaned from collections that were not structured explicitly to address ecological questions. Overall, our analyses highlight the relevance of biogeography, climate, hosts, and geographic separation in endophyte community composition. This study showcases the importance of extensive metadata in collections and highlights the utility of biodiversity collections that can yield emergent insights from many surveys to answer ecological questions in mycology, ultimately providing information for understanding and conserving fungal biodiversity.

Species limits and cryptic biogeographic structure in a widespread complex of Australian monsoon tropics trees (broad-leaf paperbarks: Melaleuca, Myrtaceae)

The Australian monsoon tropics are currently dominated by savanna and tropical woodland biomes that have arisen in response to a cooling and drying trend within the past ~3 million years. It is expected that organisms well adapted to these conditions have expanded into available habitats, leading to the differentiation of populations and species across this landscape, a process that could be magnified by the presence of several biogeographic barriers. The broad-leaved paperbark (Melaleuca leucadendra (L.) L.) complex is one such group of plants, with 14 poorly morphologically differentiated species occupying large overlapping distributions across the region, and across several recognised biogeographic barriers. Using phylogenetic and network analyses of nuclear and plastid sequences, we tested species limits among currently described species within the complex and for phylogeographic structure within species across seven of these barriers. Overall, our data suggested patterns of differentiation among species consistent with the early to middle stages of incomplete lineage sorting, and evidence for an idiosyncratic cryptic response of species to biogeographic barriers. Unexpectedly, we found a deep molecular split across all species, broadly coinciding with the northern part of the Great Dividing Range, a feature not typically considered to be a barrier to dispersal. Our study has offered one of the first insights into the dynamics within and among widespread species across the north of Australia, suggesting considerably more geographic structure than was previously recognised.

Co-occurrence Patterns of Bird Species in the World

In order to identify key nations and bird species of conservation concern we described multinational collaborations as defined using network analysis linked by birds that are found in all nations in the network. We used network analysis to assess the patterns in bird occurrence for 10,422 bird inventories from 244 countries and territories. Nations that are important in multinational collaborations for bird conservation were assessed using the centrality measures, closeness and betweenness centrality. Countries important for the multinational collaboration of bird conservation were examined based on their centrality measures, which included closeness and betweenness centralities. Comparatively, the co-occurrence network was divided into four groups that reveal different biogeographical structures. A group with higher closeness centrality included countries in southern Africa and had the potential to affect species in many other countries. Birds in countries in Asia, Australia and the South Pacific that are important to the cohesiveness of the global network had a higher score of betweenness centrality. Countries that had higher numbers of bird species and more extensively distributed bird species had higher centrality scores; in these countries, birds may act as excellent indicators of trends in the co-occurrence bird network. For effective bird conservation in the world, much stronger coordination among countries is required. Bird co-occurrence patterns can provide a suitable and powerful framework for understanding the complexity of co-occurrence patterns and consequences for multinational collaborations on bird conservation.

Preliminary comparative genomics revealed pathogenic potential and international spread of Staphylococcus argenteus

BackgroundStaphylococcus argenteus and S. schweitzeri, were recently proposed as novel species within S. aureus complex (SAC). S. argenteus has been reported in many countries and can threaten human health. S. schweitzeri has not been associated with human infections, but has been isolated from non-human primates. Questions regarding the evolution of pathogenicity of these two species will remain elusive until an exploratory evolutionary framework is established.ResultsWe present genomic comparison analysis among members of SAC based on a pan-genome definition, which included 15 S. argenteus genomes (five newly sequenced), six S. schweitzeri genomes and 30 divergent S. aureus genomes. The three species had divergent core genomes and rare interspecific recombination was observed among the core genes. However, some subtypes of staphylococcal cassette chromosome mec (SCCmec) elements and prophages were present in different species. Of 111 tested virulence genes of S. aureus, 85 and 86 homologous genes were found in S. argenteus and S. schweitzeri, respectively. There was no difference in virulence gene content among the three species, but the sequence of most core virulence genes was divergent. Analysis of the agr locus and the genes in the capsular polysaccharides biosynthetic operon revealed that they both diverged before the speciation of SAC members. Furthermore, the widespread geographic distribution of S. argenteus, sequence type 2250, showed ambiguous biogeographical structure among geographically isolated populations, demonstrating an international spread of this pathogen.ConclusionsS. argenteus has spread among several countries, and invasive infections and persistent carriage may be not limited to currently reported regions. S. argenteus probably had undergone a recent host adaption and can cause human infections with a similar pathogenic potential.

Molecular, morphological, and biogeographic perspectives on the classification of Acrobolboideae (Acrobolbaceae, Marchantiophyta)

The liverwort subfamily Acrobolboideae has historically contained the three genera: Acrobolbus, Marspidium, and Tylimanthus. Generic delimitations in this subfamily have been historically inferred from morphological characters, specifically the location of gametangia. Taxonomists have had difficulty separating the genera, with some combining Tylimanthus and Acrobolbus, whereas others merged Marsupidium and Tylimanthus. We used five chloroplast loci to reconstruct a phylogeny of the group, revealing all three genera are polyphyletic as currently described. An assessment of key morphological characters used to separate genera in the subfamily resulted in several observations: characters used to circumscribe Acrobolbus were homoplasious; characters used to circumscribe each genus (e.g., the placement of female reproductive organs) do not reflect phylogenetic relationships; and the evolutionary trajectories of some characters (i.e., the number of antheridia, male reproductive organs, per male bract) correspond directly with previous evolutionary hypotheses for the family, but do not follow historical taxonomic inferences. Irrespective of generic concepts, several well–supported clades within the phylogeny have a strong biogeographic structure. Using these lines of evidence, we recognize Acrobolbus as a single genus in Acrobolboideae.

Zooplankton structure in high latitude fjords with contrasting oceanography (Hornsund and Kongsfjorden, Spitsbergen)

Summary Zooplankton inhabiting the Hornsund and Kongsfjorden fjords on Spitsbergen (Svalbard) were investigated in summer 2013. The goal of the study was to determine how the zooplankton communities vary in environments functioning under different oceanographic regimes. Sampling was conducted with nets of different mesh size and selectivity (56 μm WP-2, 180 μm MultiNet, and 1000 μm Tucker Trawl), which permitted comparing a wide size spectrum of zooplankton components. Species composition did not differ substantially between the fjords, but the zooplankton in Hornsund was almost two times less numerous, and it had lower biomass per unit volume. The highest abundance at both sites was in the smallest zooplankton size fraction found only in samples taken with 56 μm mesh WP-2 net. These comprised as much as 71% and 58% of the total zooplankton abundance in Hornsund and Kongsfjorden, respectively. The communities in both fjords had comparable contributions of Arctic and boreo-Arctic species biomass in the year of the study. However, the comparison of zooplankton characteristics over several years showed changes in abundance and biogeographic structure that corresponded with variations in the physical environments of the fjords. The results of the study permit predicting the possible effects of the increasing influence of Atlantic waters on zooplankton communities inhabiting Arctic marine pelagic ecosystems.

Transition boundaries for protistan species turnover in hypersaline waters of different biogeographic regions.

The identification of environmental barriers which govern species distribution is a fundamental concern in ecology. Even though salt was previously identified as a major transition boundary for micro- and macroorganisms alike, the salinities causing species turnover in protistan communities are unknown. We investigated 4.5 million high-quality protistan metabarcodes (V4 region of the SSU rDNA) obtained from 24 shallow salt ponds (salinities 4%-44%) from South America and Europe. Statistical analyses of protistan community profiles identified four salinity classes, which strongly selected for different protistan communities: 4-9%, 14-24%, 27-36% and 38-44%. The proportion of organisms unknown to science is highest in the 14-24% salinity class, showing that environments within this salinity range are an unappreciated reservoir of as yet undiscovered organisms. Distinct higher-rank taxon groups dominated in the four salinity classes in terms of diversity. As increasing salinities require different cellular responses to cope with salt, our results suggest that different evolutionary lineages of protists have evolved distinct haloadaptation strategies. Salinity appears to be a stronger selection factor for the structuring of protistan communities than geography. Yet, we find a higher degree of endemism in shallow salt ponds compared with less isolated ecosystems such as the open ocean. Thus, rules for biogeographic structuring of protistan communities are not universal, but depend on the ecosystem under consideration.

Fauna of Cladocera and Copepoda from Xinjiang Uyghur Autonomous Region (China).

This study evaluates the species composition of Cladocera and Copepoda in the five lakes of the Bogda-Shan Mountain range and in the floodplain of the Tarim and Konchedarya rivers located in the Xinjiang Uygur Autonomous Region of China (Xinjiang). We collected seven species of Cladocera and six species of Copepoda. Seven species were identified as new for Xinjiang fauna, and two species (Cyclops cf. herberti Einsle, 1996, and Eucyclops roseus Ishida, 1997) were first records for China. Herein, we characterize the distribution ranges for the detected species and provide taxonomic remarks. The total species list for water bodies in Xinjiang compiled from original data and available literature includes 56 species of Cladocera and 33 species of Copepoda. We also discuss the biogeographical structure of Cladocera and Copepoda faunas in Xinjiang.