High Taxonomic Diversity Research Articles

High Taxonomic and Functional Diversity of Bacterial Communities Associated with Melon Fly, Zeugodacus cucurbitae (Diptera: Tephritidae).

The next generation sequencing (NGS) approach has facilitated the investigations of gut microbiota with high throughput and resolution. The present study was focused on the taxonomic and functional characterization of bacterial community associated with different developmental stages of melon fly, Zeugodacus cucurbitae using 16S ribosomal RNA (rRNA) gene amplicons metagenomics. Z. cucurbitae is considered an invasive and most staid polyphagous pest of cucurbitaceous and other related crops. The taxonomic analysis of highly variable V3-V4 region of bacterial 16S rRNA gene sequencing indicated that the bacterial community associated with Z. cucurbitae consists of a total of 23 bacterial phyla (including unclassified and unassigned bacteria), comprising 32 classes, 69 orders, 99 families and 130 genera. Proteobacteria, Firmicutes, Actinobacteria and Tenericutes were dominant phyla of which family, Enterobacteriaceae was the most abundant in the larval and adult female stages, whereas Mycoplasmataceae was the dominant in the pupal stage. In larval stages of Z. cucurbitae, genus Providencia and Comamonas were the most abundant. However, genus Candidatus-Bacilloplasma and Klebsiella werethe most dominant in pupae and adult females of Z. cucurbitae, respectively. PICRUSt analysis conducted for prediction of metabolic activities revealed that associated microbiota were involved in membrane transport, carbohydrate metabolism, amino acid metabolism, energy metabolism, replication and repair processes as well as cellular processes and signalling. The higher number of OTUs was annotated for phosphoglycerate mutase and transketolase in adult females followed by larval stages, which may support the digestive function of the microbiota in larvae and adult females. Our findings provide insights about the high variation in microbiota across developmental stages and basis for microbiota-based management strategies of fruit flies.

Charophyte variation in sensitivity to eutrophication affects their potential for the trophic and ecological status indication

Charophytes (stoneworts) form a group of macrophytes that are considered sensitive to eutrophication. The high indicator value of charophytes toward eutrophication results in their wide use in the bioassessment systems. I explored the variability of stonewort communities' requirements for trophic conditions in lowland temperate lakes and attempted to determine the role of individual syntaxa in assessing the ecological status of lakes in Poland. The position of charophyte communities' niches along the trophic gradient was analysed using the Outlying Mean Index approach. A few stonewort communities, i.e., Nitelletum opacae, N. mucronatae, N. flexilis and Charetum filiformis appeared to be specialised concerning water quality and may be considered indicators of habitats less eutrophic than the “mean” trophic conditions in the study domain. Most stonewort communities were relatively common in European waters. Four of them, i.e., Charetum tomentosae, C. asperae, C. contrariae and Nitellopsidetum obtusae, can be classified as ‘generalists’ with low marginality and broad ecological tolerance. Most stonewort communities appeared in a broad range of ecological status classes. In the case of 15 communities, 6 to 25% of occurrences were observed in lakes representing a less than good status, and they cannot be considered indicative of good ecological conditions. However, the high taxonomic diversity and extensive phytolittoral zone were most likely to occur when the phytocoenoses of stoneworts were present. In lowland naturally eutrophic lakes inhabited by eurytopic species, the extraordinary role of charophytes in the assessment of the ecological status can be interpreted through their significant contribution to the development of the littoral.

Morphological variation in the dentition of Uruguaysuchidae (Crocodyliformes: Notosuchia).

Uruguaysuchidae was a diverse group of crocodyliforms with widespread Gondwanan distribution. Recent phylogenies recover a clade comprising six species of Araripesuchus and one Uruguaysuchus. We reviewed the morphological variation in the dentition of uruguaysuchid specimens, including unpublished fossils from the Crato (SMNK PAL 6404) and Romualdo (MN 7061-V) formations of the Araripe Basin. Dental patterns are clearly distinct between species, with important taxonomic and possible ecological implications. Neither Araripesuchus nor Uruguaysuchus have characters suggesting exclusive herbivory, even for species in which tooth-tooth occlusion is observed. New data on A. gomesii shows differences in teeth number between the new specimen MN 7061-V and the holotype, probably due to preservation. The specimen SMNK PAL 6404 has a unique combination of dental characters, which reinforces the hypothesis that it might belong to a new Araripesuchus species. The alveoli pattern of A. rattoides is very distinctive in comparison to other araripesuchids, what also suggests different taxonomic affinities. One interpretation for the morphological variation in the dentition of Uruguaysuchidae is foraging specializations for different life habits. Niche partitioning and ecological specialization could have been an important process in explaining the high taxonomic diversity and widespread spatial distribution of these animals in the Cretaceous of Gondwana.

Root-associated community composition and co-occurrence patterns of fungi in wild grapevine

Crops’ wild relatives host a wide range of microorganisms, including some beneficial species that are not found or are under-represented in the domesticated crops. Our goal was to study the underexplored composition of root-associated fungal communities in endangered wild grapevines. We found high taxonomic diversity representing multiple trophic guilds that include beneficial symbiotrophs and endophytes. Soil factors explain a relatively small part of their overall variability. In contrast, the majority of the associated fungal taxa shows a close fit to the neutral model for prediction of their distributions. Only beneficial arbuscular mycorrhizal fungi and the pathogenic Ilyonectria depart from the neutral distribution model and form intimate interactions with the plant host. In addition, pathogenic fungi rarely occurred in samples that included ectomycorrhizal fungi, which suggested potentially applicable inter-microorganism interactions. High abundance and diversity of fungal endophytes on the wild grapevine roots highlight the need for their careful consideration in future studies. • Wild grapevine roots host high diversity of fungi from multiple trophic guilds. • Root-associated fungi fit mainly into neutral model for distribution prediction. • Arbuscular mycorrhizal fungi and Ilyonectria most intimately relate to the host. • Pathogenic fungi rarely occurred in samples that included ectomycorrhizal fung.

Microeukaryotes in the Metagenomes of Late Pleistocene Permafrost Deposits

The analysis of metagenomes from four Late Pleistocene permafrost samples allowed us to recognize nearly four hundred genera of protists and fungi, as well as nematodes, in the microeukaryotic assemblage. The sample of the ancient oxbow lake sediments is characterized by the highest taxonomic diversity. Heterotrophic protists and autotrophs dominated the deposits that formed under hydromorphic conditions. Fungi, in turn, prevailed in the Ice Complex deposits. In general, metagenomic analysis characterizes the assemblages from permafrost deposits more entirely than the standard methods of enrichment cultivation.

The Role of Microhabitat and Water Level in Regulating the Small-Scale Distribution, Seasonal Abundance and Overwintering Success of the Protected Snail Vertigo moulinsiana in a Natural Wetland

Despite the high taxonomic diversity, wide distribution and important ecosystem functions of snails, their ecology remains obscure, and this can hamper their conservation. Overwintering in the studied population of Vertigo moulinsiana is effective enough to allow the majority of it to survive. The population dynamics of V. moulinsiana is specific, where the summer boom in a suboptimal habitat covering a small area (wet patches of sweet grass) can determine the snail's range over much larger areas. Our results suggest that humidity could have been the major factor governing population increase. The summer boom is caused by juveniles appearing in very large numbers during this period, thus the peak height is mostly influenced by the considerable susceptibility of juveniles and eggs to desiccation. The limiting influence of humidity is evident in the unequal spatial distribution of individuals: the wetter the substrate, the greater the abundance of snails. As a consequence, the boom may be spatially regulated and only occurs in wet habitats, even though the snail actually occupies a much larger area. Our results indicate that this V. moulinsiana population does not follow typical models constructed for vertebrates or other animals with high dispersal abilities, like the Ideal Free Distribution (IFD) model, and requires a specific approach. Its specific spatiotemporal pattern should be taken into account during monitoring surveys and conservation actions.

Different response of the taxonomic, phylogenetic and functional diversity of birds to forest fragmentation

Habitat fragmentation is considered as major threat to biodiversity worldwide. Biodiversity can be described as taxonomic, functional and phylogenetic diversity. However, the effect of forest fragmentation on taxonomic, phylogenetic and functional diversity is barely understood. We compare the response of taxonomic (species richness), phylogenetic and functional diversity of birds to forest fragmentation. We hypothesised that with increasing forest patch isolation and/or decreasing patch size the diversity of birds decreases but only if certain thresholds of fragmentation metrics are reached. Specifically, we hypothesized that out of the three diversity components the taxonomic diversity is the most sensitive to forest fragmentation, which means that it starts declining at larger patch size and higher connectivity values than phylogenetic and functional diversity do. We compared the three biodiversity metrics of central European bird species in a large set of forest patches located in an agricultural landscape. General additive modeling and segmented regression were used in analyses. Habitat fragmentation differentially affected studied biodiversity metrics. Bird taxonomic diversity was the most responsive towards changes in fragmentation. We observed an increase in taxonomic diversity with increasing patch area, which then stabilized after reaching certain patch size. Functional diversity turned out to be the least responsive to the fragmentation metrics and forest stand characteristics. It decreased linearly with the decreasing isolation of forest patches. Apart from the habitat fragmentation, bird taxonomic diversity but not phylogenetic diversity was positively associated with forest stand age. The lower share of dominant tree species, the highest taxonomic diversity was. While preserving a whole spectrum of forests (in terms of age, fragmentation and size) is important from the biodiversity perspective, forest bird species might need large, intact, old-growth forests. Since the large and intact forest becomes scarcer, our study underscore their importance for the preservation of forest specialist species.

The crossover from microscopy to genes in marine diversity: from species to assemblages in marine pelagic copepods.

An accurate identification of species and communities is a prerequisite for analysing and recording biodiversity and community shifts. In the context of marine biodiversity conservation and management, this review outlines past, present and forward-looking perspectives on identifying and recording planktonic diversity by illustrating the transition from traditional species identification based on morphological diagnostic characters to full molecular genetic identification of marine assemblages. In this process, the article presents the methodological advancements by discussing progress and critical aspects of the crossover from traditional to novel and future molecular genetic identifications and it outlines the advantages of integrative approaches using the strengths of both morphological and molecular techniques to identify species and assemblages. We demonstrate this process of identifying and recording marine biodiversity on pelagic copepods as model taxon. Copepods are known for their high taxonomic and ecological diversity and comprise a huge variety of behaviours, forms and life histories, making them a highly interesting and well-studied group in terms of biodiversity and ecosystem functioning. Furthermore, their short life cycles and rapid responses to changing environments make them good indicators and core research components for ecosystem health and status in the light of environmental change.This article is part of the theme issue ‘Integrative research perspectives on marine conservation’.

Survival and growth of soil microbial communities under influence of sodium perchlorates

AbstractPreviously conducted space missions revealed the presence of perchlorates, which are known to have a high oxidizing potential in Martian regolith, at the level of 0.5%. Due to hygroscopic properties and crystallization features of perchlorate-containing solutions, assumptions leading to the possibility of the existence of liquid water in the form of brines, which can contribute to the vital activity of microorganisms, have been made. At the same time, high concentrations of perchlorates can inhibit the growth of microorganisms and cause their death. Previously performed studies have discovered the presence of highly diverse microbial communities in terrestrial perchlorate-containing soils and have also demonstrated the stability and activity of some prokaryotes cultured on highly concentrated perchlorates media (over 10%). Nevertheless, the limits of microbial tolerance to perchlorates and whether microbial communities are able to withstand the effects of high concentrations of perchlorates remain uncertain. The aim of this research was to study the reaction of microbial communities of hot-arid and cryo-arid soils and sedimentary rocks to the adding of a highly concentrated solution of sodium perchlorate (5%) in situ. An increase in the total number of prokaryotes, the number of metabolically active Bacteria and Archaea, and the variety of the consumed substrates were revealed. It was observed that in samples incubated with sodium perchlorate, a high taxonomic diversity of the microbial community is preserved at a level comparable to control sample. The study shows that the presence of high concentrations of sodium perchlorate (5%) in the soil does not lead to the death or significant inhibition of microbial communities.

Differences in diversity and photoprotection capability between ice algae and under-ice phytoplankton in Saroma-Ko Lagoon, Japan: a comparative taxonomic diatom analysis with microscopy and DNA barcoding

Sea ice algae, comprised mainly of diatoms, are the main primary producers in polar ecosystems, and they are generally distributed with the highest biomass at the bottom of ice. The taxonomy of ice algae has been traditionally investigated using light microscopy, but molecular techniques, including pigment analysis, have recently provided new insights into the diversity and physiology of ice algae. However, no comparative taxonomic survey has been conducted for ice algae thus far. Here, we investigated differences and similarities in (1) the diversity and (2) the photosynthetic strategies of diatom communities in sea ice and the underlying seawater of Saroma-Ko Lagoon, Hokkaido, Japan, using algal pigment signatures determined by ultra-high performance liquid chromatography, light and scanning electron microscopy and Ion Torrent next-generation sequencing techniques targeting the 18S rRNA gene (i.e., DNA barcoding). Ice algae typically possessed greater biomass (> 20-fold) and chlorophyll (Chl) a breakdown products than under-ice phytoplankton, suggesting that the ice algae formed blooms, and cell senescence and disruption could be significant mitigating factors. At the genus level, the diversity of diatoms in sea ice was higher than in under-ice seawater, although the evenness was comparable or lower in ice algae than in under-ice phytoplankton. Ice algae had a larger xanthophyll pool size and a higher ratio of photoprotective to photosynthetic pigments (11-fold and 4.5-fold higher, respectively) than under-ice phytoplankton. The results indicated that ice algae were well adapted to changes in the light regime, which could partly support their survival capability and high taxonomic diversity.

Tackling the jelly web: Trophic ecology of gelatinous zooplankton in oceanic food webs of the eastern tropical Atlantic assessed by stable isotope analysis

AbstractGelatinous zooplankton can be present in high biomass and taxonomic diversity in planktonic oceanic food webs, yet the trophic structuring and importance of this “jelly web” remain incompletely understood. To address this knowledge gap, we provide a holistic trophic characterization of a jelly web in the eastern tropical Atlantic, based on δ13C and δ15N stable isotope analysis of a unique gelatinous zooplankton sample set. The jelly web covered most of the isotopic niche space of the entire planktonic oceanic food web, spanning > 3 trophic levels, ranging from herbivores (e.g., pyrosomes) to higher predators (e.g., ctenophores), highlighting the diverse functional roles and broad possible food web relevance of gelatinous zooplankton. Among gelatinous zooplankton taxa, comparisons of isotopic niches pointed to the presence of differentiation and resource partitioning, but also highlighted the potential for competition, e.g., between hydromedusae and siphonophores. Significant differences in spatial (seamount vs. open ocean) and depth‐resolved patterns (0–400 m vs. 400–1000 m) pointed to additional complexity, and raise questions about the extent of connectivity between locations and differential patterns in vertical coupling between gelatinous zooplankton groups. Added complexity also resulted from inconsistent patterns in trophic ontogenetic shifts among groups. We conclude that the broad trophic niche covered by the jelly web, patterns in niche differentiation within this web, and substantial complexity at the spatial, depth, and taxon level call for a more careful consideration of gelatinous zooplankton in oceanic food web models. In light of climate change and fishing pressure, the data presented here also provide a valuable baseline against which to measure future trophic observations of gelatinous zooplankton communities in the eastern tropical Atlantic.

An aid to the identification of fish bones from southeast Arabia: The influence of reference collections on taxonomic diversity

AbstractIdentification of fish bones from archaeological sites in southeast Arabia is challenging because of high taxonomic diversity, comparatively few reference collections with a wide range of species, as well as access to these resources. This paper provides illustrations of bones from many common taxonomic groups of fish from the southeast Arabia including several species of fish identified in very few assemblages, probably because of the lack of comparative reference material. This is a guide to aid other analysts in the identification process. We also consider the effect of reference collection size on the taxonomic diversity of analysed fish bone assemblages and conclude that research would benefit by the publication of further identification guides. Ideally these should include differences between closely related species, as this has a significant impact on the taxonomic diversity of archaeo‐ichthyological assemblages. Although many papers are devoted to the influence of sample size, recovery method or recording protocols on the taxonomic diversity of faunal assemblages, a similar discussion on the effect of the reference collection used is often overlooked.

Effect of soil chemical fertilization on the diversity and composition of the tomato endophytic diazotrophic community at different stages of growth.

The aim of this work was to gain a more comprehensive and perspicacious view of the endophytic diazotrophic community (EDC) of tomato plant bacteria and assess the effects of chemical fertilization and the plant phenologic stage on the status of those microbes. When the EDC of stem and roots from tomato plants grown in a greenhouse with and without exogenous chemical fertilization was examined by pyrosequencing the nifH gene during the growth cycle, a high taxonomic and phylogenetic diversity was observed. The abundant taxa were related to ubiquitous endophytes such as Rhizobium or Burkholderia but also involved anaerobic members usually restricted to flooded plant tissues, such as Clostridium, Geobacter, and Desulfovibrio. The EDC composition appeared to be dynamic during the growth phase of the tomato, with the structure of the community at the early stages of growth displaying major differences from the late stages. Inorganic fertilization negatively affected the diversity and modified the profile of the predominant components of the EDC in the different growth stages. Populations such as Burkholderia and Geobacter plus the Cyanobacteria appeared particularly affected by fertilization.Our work demonstrates an extensive endophytic diazotrophic diversity, suggesting a high potential for nitrogen fixation. The effect of the phenologic stage and inorganic-chemical soil fertilization on the community structure indicated a dynamic community that responded to environmental changes. These findings contribute to a better understanding of endophytic associations that could be helpful in assisting to shape the endomicrobiome that provides essential benefits to crops.

A Widespread, Nearly Monospecific Silicified Coccoidal Microbiota from the Permian Of Brazil (AssistÊncia Formation, Irati Subgroup, Paraná Basin)

Well-preserved fossil microbiotas normally present relatively high taxonomic diversity, especially if the host-rock is distributed over a large area. Estimates of taxonomic diversity, however, require proper consideration of ontogenetic, taphonomic, and ecological influences on morphological variety. Otherwise, diversity may be overestimated. Chert in the Permian Assistencia Formation (Irati Subgroup, Parana Basin, Brazil) contains an abundant, well-preserved fossil microbiota that has been studied from seven localities distributed over about 500 km. Despite the great numbers of microfossils present, morphological analysis revealed a low apparent diversity. There is no evidence of filamentous microorganisms and the chroococcacean Gloeodiniopsis lamellosa is overwhelmingly dominant, accounting for 98.6% of counted individuals. In addition to G. lamellosa, only five taxa are recognized of which four are formally described: the chroococcaceans Cyanosarcinopsis hachiroi gen. et sp. nov. and cf. Coniunctiophycus sp. and two taxa considered incertae sedis: Myxococcoides sp. A (a probable cyanobacterium) and Myxococcoides sp. B (a possible delicate eukaryote). A unique but markedly different colony was designated as unnamed form (open nomenclature). Two hypotheses may explain the enigmatic absence of filaments: (i) environmental stress associated with hypersaline conditions that severely limited diversity or (ii) long-term optimal growth conditions for coccoidal cyanobacterial blooms due to sustained basin-wide eutrophic conditions.

Biodiversity Loss Threatens the Current Functional Similarity of Beta Diversity in Benthic Diatom Communities

The global biodiversity loss has increased the need to understand the effects of decreasing diversity, but our knowledge on how species loss will affect the functioning of communities and ecosystems is still very limited. Here, the levels of taxonomic and functional beta diversity and the effect of species loss on functional beta diversity were investigated in an estuary that provides a naturally steep environmental gradient. The study was conducted using diatoms that are among the most important microorganisms in all aquatic ecosystems and globally account for 40% of marine primary production. Along the estuary, the taxonomic beta diversity of diatom communities was high (Bray-Curtis taxonomic similarity 0.044) and strongly controlled by the environment, particularly wind exposure, salinity, and temperature. In contrast, the functional beta diversity was low (Bray-Curtis functional similarity 0.658) and much less controlled by the environment. Thus, the diatom communities stayed functionally almost similar despite large changes in species composition and environment. This may indicate that, through high taxonomic diversity and redundancy in functions, microorganisms provide an insurance effect against environmental change. However, when studying the effect of decreasing species richness on functional similarity of communities, simulated species loss to 45% of the current species richness decreased functional similarity significantly. This suggests that decreasing species richness may increase variability and reduce the stability and resilience of communities. These results highlight the importance of high taxonomic biodiversity for the stable functioning of benthic communities.

Contrasting multi-taxa functional diversity patterns along vegetation structure gradients of woody pastures

Woody pastures represent keystone habitats for biodiversity in agricultural landscapes, contributing to increased resource availability, landscape heterogeneity and structural variability. High taxonomic diversity is closely linked to vegetation structure in woody pastures, but examining functional characteristics of species assemblages can shed more light on the ecological mechanisms driving divergent responses to habitat characteristics and help guide good management practices. To this end, we use a multi-taxa approach to investigate how plant, bat and bird taxonomic and functional diversity are affected by pasture tree and shrub density, structural complexity and proximate forest cover in southern Sweden. In particular, we use a trait exclusion approach to estimate the sensitivity of diversity-environment relationships to specific traits. We found little congruence between corresponding diversity metrics across taxa. Bird species richness responded stronger to environmental variables than functional diversity metrics, whereas the functional response to the environment was stronger than the taxonomic response among plants and bats. While increasing tree densities increased the taxonomic diversity of all three taxa, a simultaneous functional response was only evident for plants. Contrasting measures of vegetation structure affected different aspects of functional diversity across taxa, driven by different traits. For plants and birds, traits linked to resource use contributed particularly to the functional response, whereas body mass had stronger influence on bat functional diversity metrics. Multi-taxa functional approaches are essential to understand the effects of woody pasture structural attributes on biodiversity, and ultimately inform management guidelines to preserve the biological values in woody pastures.

Unraveling the Spiraling Radiation: A Phylogenomic Analysis of Neotropical Costus L.

The family of pantropical spiral gingers (Costaceae Nakai; c. 125 spp.) can be used as a model to enhance our understanding of the mechanisms underlying Neotropical diversity. Costaceae has higher taxonomic diversity in South and Central America (c. 72 Neotropical species, c. 30 African, c. 23 Southeast Asian), particularly due to a radiation of Neotropical species of the genus Costus L. (c. 57 spp.). However, a well-supported phylogeny of the Neotropical spiral gingers including thorough sampling of proposed species encompassing their full morphologic and geographic variation is lacking, partly due to poor resolution recovered in previous analyses using a small sampling of loci. Here we use a phylogenomic approach to estimate the phylogeny of a sample of Neotropical Costus species using a targeted enrichment approach. Baits were designed to capture conserved elements’ variable at the species level using available genomic sequences of Costus species and relatives. We obtained 832 loci (generating 791,954 aligned base pairs and 31,142 parsimony informative sites) for samples that encompassed the geographical and/or morphological diversity of some recognized species. Higher support values that improve the results of previous studies were obtained when including all the available loci, even those producing unresolved gene trees and having a low proportion of variable sites. Concatenation and coalescent-based species trees methods converge in almost the same topology suggesting a robust estimation of the relationships, even under the high levels of gene tree conflict presented here. The bait set design here presented made inferring a robust phylogeny to test taxonomic hypotheses possible and will improve our understanding of the origins of the charismatic diversity of the Neotropical spiral gingers.

Evidence of Interspecific Chromosomal Diversification in Rainbowfishes (Melanotaeniidae, Teleostei).

Rainbowfishes (Melanotaeniidae) are the largest monophyletic group of freshwater fishes occurring in Australia and New Guinea, with 112 species currently recognised. Despite their high taxonomic diversity, rainbowfishes remain poorly studied from a cytogenetic perspective. Using conventional (Giemsa staining, C banding, chromomycin A3 staining) and molecular (fluorescence in situ hybridisation with ribosomal DNA (rDNA) and telomeric probes) cytogenetic protocols, karyotypes and associated chromosomal characteristics of five species were examined. We covered all major lineages of this group, namely, Running River rainbowfish Melanotaenia sp., red rainbowfish Glossolepis incisus, threadfin rainbowfish Iriatherina werneri, ornate rainbowfish Rhadinocentrus ornatus, and Cairns rainbowfish Cairnsichthys rhombosomoides. All species had conserved diploid chromosome numbers 2n = 48, but karyotypes differed among species; while Melanotaenia sp., G. incisus, and I. werneri possessed karyotypes composed of exclusively subtelo/acrocentric chromosomes, the karyotype of R. ornatus displayed six pairs of submetacentric and 18 pairs of subtelo/acrocentric chromosomes, while C. rhombosomoides possessed a karyotype composed of four pairs of submetacentric and 20 pairs of subtelo/acrocentric chromosomes. No heteromorphic sex chromosomes were detected using conventional cytogenetic techniques. Our data indicate a conserved 2n in Melanotaeniidae, but morphologically variable karyotypes, rDNA sites, and heterochromatin distributions. Differences were observed especially in taxonomically divergent species, suggesting interspecies chromosome rearrangements.

New occurrence of the Guanshan Lagerstätte (Cambrian Series 2, Stage 4) in the Kunming area, Yunnan, southwest China, with records of new taxa

As a classic Burgess-Shale-Type Konservat-Lagerstätte, the Guanshan biota is well known for its abundant soft-bodied fossils with high taxonomic diversity. Here, we report a new locality of the Guanshan biota in the Kunming area, Yunnan, South China with several new forms being first documented. In particular: a naraoiid euarthropod, the dorsal exoskeleton of which has characters of both naraoiids and Emucaris; and a discoidal animal, identified as a small eldonioid-like metazoan, which has a counterpart from the Emu Bay Shale Lagerstätte of South Australia, and which further strengths the biogeographic connection between the early Cambrian biotas of South China and Australia. Our new discoveries not only expand the palaeogeographic distribution of the Guanshan biota, but also reveal that its biodiversity is much higher than previously thought, and can be justifiably regarded as a community successor to the Chengjiang biota.Jun Zhao [zhaojunpaleo@126.com], Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming, Yunnan, 650091, China; Yunnan Key Laboratory of International Rivers and Transboundary Eco-Security, Yunnan University, Kunming 650091, China; MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Institute of Palaeontology, Yunnan University, Kunming, Yunnan, 650091, China; Yujing Li [yujingli@ynu.edu.cn], Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming, Yunnan, 650091, China; MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Institute of Palaeontology, Yunnan University, Kunming, Yunnan, 650091, China; Paul A. Selden [selden@ku.edu], Department of Geology, University of Kansas, 1457 Jayhawk Boulevard, Lawrence, KS 66045, USA; Natural History Museum, Cromwell Road, London SW7 5BD, UK; Peiyun Cong [cong@ynu.edu.cn], Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming, Yunnan, 650091, China; MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Institute of Palaeontology, Yunnan University, Kunming, Yunnan, 650091, China.

Evolutionary Patterns of Mandible Shape Diversification of Caviomorph Rodents

Caviomorphs are a mainly South American rodent clade with high taxonomic and ecomorphological diversity. In this study, we combine geometric morphometric, functional, ancestral reconstruction, and macroevolutionary analyses to quantify the magnitude, direction, and rates of shape diversification of the caviomorph mandible, and to explore the morpho-functional implications and potential ecological catalysts of the observed shape changes. The mandible shape was significantly related to habits and size, and had a better fit with an evolutionary model where the main clades occupy distinct adaptive peaks. The morphological evolution of octodontoids is characterized by pulses of rate acceleration, but without reaching high disparity. Such pulses are mainly linked to the acquisition of fossorial specializations, including short and robust mandibles, and the increasement of forces at incisors. Conversely, derived cavioids show slower but continuous shape changes that allowed them to reach the most divergent, grazing morphologies in which slender mandibles with more marked antero-posterior movements for grinding action are favored. Interestingly, the major morphological changes occurred mainly during the early Oligocene and lower late Miocene, two time periods that involved global climatic events and strong changes in the vegetational structure of South America. The evolution of octodontoid and cavioid mandibles seems to be related to the occupation of subterranean and epigean niches, respectively, in the progressively expanded Cenozoic open landscapes of southern South America.