Phylogenetic Structuring Research Articles

Phylogeographic structuring in a widespread southern African grass snake (Psammophiinae: Psammophylax rhombeatus)

ABSTRACT The structural and environmental heterogeneity within southern Africa has given rise to many morphological forms of Psammophylax rhombeatus distributed throughout the country, with previous studies neglecting the associated molecular significance of these forms. The species’ widespread, generalist ecology coupled with the substantial phylogenetic structuring previously acknowledged within the species, makes P. rhombeatus the ideal candidate for phylogeographic analyses. Using 103 samples, representing the full distribution of the species, phylogenetic analyses retrieved four well-supported clades: south-eastern South Africa, south-western South Africa, north-eastern South Africa and western South Africa. Although not variable enough to warrant taxonomic re-evaluation, the clades are phylogenetically distinguishable, with relatively high intraspecific genetic divergence values separating them, irrespective of the small geographic distances separating populations. This is likely a product of the taxon’s habitat-generalist lifestyle, enabling them to bypass vicariant barriers that might otherwise cause speciation in less versatile species. The clades are also geographically distinct, with little overlap, indicating previous vicariance, a finding that is supported by the split of P. rhombeatus from P. ocellatus in the mid-Pliocene, followed by the diversification of P. rhombeatus into four clades throughout the Pleistocene. The genetic structuring observed in P. rhombeatus may be a product of population expansion following ancient refugial isolation (potentially Last Glacial Maximum). The morphological groupings highlighted in previous studies are loosely attributable to the molecular clades identified in the phylogenetic reconstruction, highlighting the complex interplay of genetic and morphological characteristics in the process of speciation, and their representation in systematic accounts.

Global effects of land-use intensity and exotic plants on the structure and phylogenetic signal of plant-herbivore networks

Interactions between plants and herbivorous insects are often phylogenetically structured, with closely related insect species using similar sets of species or lineages of plants, while phylogenetically closer plants tend to share high proportions of their herbivore insect species. Notably, these phylogenetic constraints in plant-herbivore interactions tend to be more pronounced among internal plant-feeding herbivores (i.e., endophages) than among external feeders (i.e., exophages). In the context of growing human-induced habitat conversion and the global proliferation of exotic species, it is crucial to understand how ecological networks respond to land-use intensification and the increasing presence of exotic plants. In this study, we analyzed plant-herbivore network data from various locations of the World to ascertain the degree to which land-use intensity and the prevalence of exotic plants induce predictable changes in their network topology - measured by levels of nestedness and modularity - and phylogenetic structures. Additionally, we investigated whether the intimacy of plant-herbivore interactions, contrasting endophagous with exophagous networks, modulate changes in network structure. Our findings reveal that most plant-herbivore networks are characterized by significant phylogenetic and topological structures. However, neither these structures did not show consistent changes in response to increased levels of land-use intensify. On the other hand, for the networks composed of endophagous herbivores, the level of nestedness was higher in the presence of a high proportion of exotic plants. Additionally, for networks of exophagous herbivores, we observed an increase in the phylogenetic structure of interactions due to exotic host dominance. These results underscore the differential impacts of exotic species and land-use intensity on the phylogenetic and topological structures of plant-herbivore networks.

Weak phylogenetic effect on specialist plant assemblages and their persistence on habitat islands

AbstractAimThe influence of species phylogenetic relatedness on the formation of insular assemblages remains understudied in functional island biogeography, especially for terrestrial habitat islands (i.e. distinct habitat patches embedded in a matrix that differ in the prevailing environmental conditions). Here, we tested three eco‐evolutionary hypotheses: (1) functional specialization of species (i.e. specialism) is associated with phylogenetic clustering at the habitat archipelago scale, (2) such clustering increases with insularity at the habitat island scale and (3) traits indicative of effective local persistence strategies shape island specialism.LocationTerrestrial habitat islands, Europe (Fens in the Western Carpathians, Outcrops in Moravia and Mountaintops in the Cantabrian Range).TaxonAngiosperms.MethodsWe assessed the phylogenetic relatedness of habitat specialists in three different archipelagos composed of terrestrial habitat islands based on phylogenetic signals and phylogenetic diversity (PD) measures. We estimated the effect of insularity on PD using linear models and the effect of persistence traits on specialism using phylogenetic logistic regressions.ResultsOur hypotheses were largely not supported. Outcrop and mountaintop specialist assemblages did not exhibit any phylogenetic structuring, whereas fen specialists were clustered at the archipelago scale. Therefore, insularity seems not to act as a selective force for phylogenetic structure, and ecologically important persistence traits do not operate as precursors of specialism.Main ConclusionsOur results show that species phylogenetic relatedness plays a minor role in shaping habitat island specialist assemblages. Furthermore, the effects of phylogenetic relatedness on assemblages of island specialists are system and scale dependent. Finally, accounting for species' phylogenetic relatedness on persistence traits yielded results similar to previous studies, which corroborates the positive relationship between insularity and functional traits (indicative of enhanced plant persistence abilities with increasing within‐archipelago insularity).

Strong phylogenetic signal and models of trait evolution evidence phylogenetic niche conservatism for seagrasses

Abstract Phylogenetic signal (PS) is the propensity of closely related species to resemble each other. PS has been tested across clades of terrestrial plants; however, insight for seagrasses is still lacking. Signatures of PS and models of niche (trait) evolution can help to detect phylogenetic niche conservatism (PNC), that is, close relatives live in comparable niches. The initial goal of this study was to assess the pattern of PS for the world's seagrasses, by testing the non‐independence of phylogenetic relatedness and seagrass species traits. A phylogeny of 49 seagrasses was constructed, together with a matrix of nine traits covering morphological, life‐history and reproductive attributes. PS of traits was tested through complementary indices (Pagel's λ, Blomberg's K, Moran's I and Abouheif's Cmean). Three models of niche evolution (Brownian Motion, BM; Ornstein–Uhlenbeck, OU; Early Burst, EB) were then fitted to each trait and the multivariate trait matrix. Results supported the existence of strong PS for seagrasses, with a particularly large effect size for seagrass reproductive traits, which followed an EB evolution model. Local Indicators of Phylogenetic Association (local autocorrelation metrics that can help to identify areas of large autocorrelation) supported the presence of PS across seagrass lineages/clades, supported by the dominance of OU as the most parsimonious trait evolution model. The pattern of strong PS seems to be a consequence of long‐term PNC of seagrass traits after initial radiation. Synthesis: Our study highlights the relevance of evolution from common ancestors and shared history underpinning large seagrass phylogenetic structuring.

GgMOB: Elucidation of genomic conjugative features and associated cargo genes across bacterial genera using genus-genus mobilization networks.

Horizontal gene transfer mediated by conjugation is considered an important evolutionary mechanism of bacteria. It allows organisms to quickly evolve new phenotypic properties including antimicrobial resistance (AMR) and virulence. The frequency of conjugation-mediated cargo gene exchange has not yet been comprehensively studied within and between bacterial taxa. We developed a frequency-based network of genus-genus conjugation features and candidate cargo genes from whole-genome sequence data of over 180,000 bacterial genomes, representing 1,345 genera. Using our method, which we refer to as ggMOB, we revealed that over half of the bacterial genomes contained one or more known conjugation features that matched exactly to at least one other genome. Moreover, the proportion of genomes containing these conjugation features varied substantially by genus and conjugation feature. These results and the genus-level network structure can be viewed interactively in the ggMOB interface, which allows for user-defined filtering of conjugation features and candidate cargo genes. Using the network data, we observed that the ratio of AMR gene representation in conjugative versus non-conjugative genomes exceeded 5:1, confirming that conjugation is a critical force for AMR spread across genera. Finally, we demonstrated that clustering genomes by conjugation profile sometimes correlated well with classical phylogenetic structuring; but that in some cases the clustering was highly discordant, suggesting that the importance of the accessory genome in driving bacterial evolution may be highly variable across both time and taxonomy. These results can advance scientific understanding of bacterial evolution, and can be used as a starting point for probing genus-genus gene exchange within complex microbial communities that include unculturable bacteria. ggMOB is publicly available under the GNU licence at https://ruiz-hci-lab.github.io/ggMOB/.

Community-level phylogenetic diversity does not differ between rare and common lineages across tallgrass prairies in the northern Great Plains.

Niche differentiation has served as one explanation for species coexistence, and phylogenetic relatedness provides a means to approximate how ecologically similar species are to each other. To explore the contribution of rare species to community phylogenetic diversity, we sampled 21 plant communities across the Prairie Coteau ecoregion, an area of high conservation concern. We used breakpoint analysis through the iterative addition of less abundant species to the phylogenetic tree for each community to assess the contribution of rare species to community phylogenetic diversity. We also quantify the phylogenetic signal of abundance using Blomberg's K statistic and calculated the phylogenetic similarity between rare and common species using a phylogenetic beta-diversity metric (D nn). To estimate the phylogenetic structuring of these prairie communities, we calculated two common metrics that capture evolutionary relatedness at different scales (MPD and MNTD). Additionally, we examine the correlation between Faith's PD, MPD, and MNTD and species richness. We found rare species do not generally contribute higher levels of phylogenetic diversity than common species. Eight communities had significant breakpoints, with only four communities having an increasing trend for the rarest species. The phylogenetic signal for abundance was low but significant in only four communities, and communities had lower phylogenetic diversity than expected from the regional species pool. Finally, the strength of the correlation between species richness and phylogenetic diversity was mixed. Our results indicate niche differentiation does not explain the persistence of rare species in tallgrass prairies, as they were more closely related than expected from random, suggesting high functional redundancy between rare and common species. This is promising for the long-term resilience of this ecosystem, but only insofar as enough species remain in the system. With ongoing biodiversity loss, it is essential that we understand the role rare species play in their communities.

A new genus for four myobatrachid frogs from the South Western Australian Ecoregion.

The southern Australian endemic genus Geocrinia Blake 1973 (Anura: Myobatrachidae) currently contains seven species, with five restricted to Western Australia and two in the south-eastern states covering parts of New South Wales, Victoria, Tasmania and South Australia. All species have a modified life history with at least some or all of the larval stage being completed terrestrially. Four of the Western Australian species have terrestrial, non-feeding tadpoles nourished by yolk until metamorphosis. The remaining species have a biphasic development with embryos developing on land followed by an aquatic tadpole stage. The presence of species groups within the Geocrinia has been recognised since the 1970s, with all relevant subsequent studies supporting a model of two groups within the genus, recovered as reciprocally monophyletic in phylogenetic analyses. We examined character traits of the seven recognised Geocrinia species, concluding that distinction of the two monophyletic groups is supported by differences in life history strategy, larval morphology, adult morphology, call structure, breeding season and geographic distribution. The differences between the two groups correspond to phylogenetic structuring for all traits except distribution. Given reciprocal monophyly, and greater variation in traits than present within other myobatrachid genera, we conclude that the two groups should be given generic distinction. We therefore describe a new genus, Anstisia gen. nov., for four Western Australian Geocrinia species, retaining three species in Geocrinia. This increases the number of recognised myobatrachid genera to 14: five are endemic to south-western Australia.

Untangling the ecological signal in the dental morphology in the bat superfamily Noctilionoidea

Diet has been linked to the diversification of the bat superfamily Noctilionoidea, a group that underwent an impressive ecological diversification within Mammalia. For decades, studies have explored morphological adaptations and diversity of noctilionoid bats to reveal traits associated with their ecological diversity. Surprisingly, despite such interest and recent application of novel techniques, ecomorphological studies have failed to fully resolve the link between diet and a critical component of the feeding apparatus: dental morphology. Using multivariate dental topographic analysis and phylogenetic comparative methods, we examined the phylogenetic, biological and ecological signal in the dental morphology of noctilionoid bats. Analysing the lower first molars of 110 species, we explored relationships between diet and dental morphology, accounting for three different dimensions of diet (guild, composition, and breadth). Phylogenetic and size-dependent structuring of the dental topography data shows it does not correlate only to diet, highlighting the need to account for multiple sources of variation. Nectarivores showed reduced molar crown height and steepness, whereas animalivorous species had larger molars. Dietary composition suggested that the intensity of exploitation of a resource is also linked to different dimensions of dental morphology. Increasing carnivory positively correlated with molar area, whereas increasing frugivory explained the highest proportion of variation in all other variables. Based on dietary breadth, specialist herbivores and specialist animalivores represent extreme morphologies in terms of tooth steepness and crown height. Together, the results suggest that adaptations affecting different attributes of dental morphology likely facilitated the dietary diversity and specialisation found in Noctilionoidea.

Traits and phylogenies modulate the environmental responses of wood‐inhabiting fungal communities across spatial scales

Abstract Identifying the spatial scales at which community assembly processes operate is fundamental for gaining a mechanistic understanding of the drivers shaping ecological communities. In this study, we examined whether and how traits and phylogenetic relationships structure fungal community assembly across spatial scales. We applied joint species distribution modelling to a European‐scale dataset on 215 wood‐inhabiting fungal species, which includes data on traits, phylogeny and environmental variables measured at the local (log‐level) and regional (site‐level) scales. At the local scale, wood‐inhabiting fungal communities were mostly structured by deadwood decay stage, and the trait and phylogenetic patterns along this environmental gradient suggested the lack of diversifying selection. At regional scales, fungal communities and their trait distributions were influenced by climatic and connectivity‐related variables. The fungal climatic niches were not phylogenetically structured, suggesting that diversifying selection or stabilizing selection for climatic niches has played a strong role in wood‐inhabiting communities. In contrast, we found a strong phylogenetic signal in the responses to connectivity‐related variables, revealing phylogenetic homogenization in small and isolated forests. Synthesis. Altogether, our results show that species‐level traits and phylogenies modulate the responses of wood‐inhabiting fungi to environmental processes acting at different scales. This result suggests that the evolutionary histories of fungal traits diverge along different environmental axes.

Phylogeny is a stronger predictor of activity than allometry in an African mammal community

Abstract In promoting coexistence, sympatric species often partition shared resources along spatio-temporal domains. Similarly sized and phylogenetically close species, for instance, partition the times of day in which they are active to limit interference competition. Given that variation in species body mass has evolutionary underpinnings, species activity levels (time spent active in a 24-h daily cycle) within animal communities might be structured by phylogeny. However, few studies have tested this hypothesis across animal communities, and none among medium-sized to large mammals. We quantified the relative contributions of phylogeny and body mass in predicting activity levels in a community of 22 sympatric mammal species in Murchison Falls National Park, Uganda. We show that phylogeny is a stronger predictor of species activity levels than body mass. Our findings provide empirical evidence for the phylogenetic structuring of mammal activity in diverse communities. More broadly, our results suggest that evolutionary relationships mask allometry in predicting species traits in diverse animal communities.

Edaphic heterogeneity and the evolutionary trajectory of Amazonian plant communities.

We investigated how the phylogenetic structure of Amazonian plant communities varies along an edaphic gradient within the non‐inundated forests. Forty localities were sampled on three terrain types representing two kinds of soil: clayey soils of a high base cation concentration derived from the Solimões formation, and loamy soils with lower base cation concentration derived from the Içá formation and alluvial terraces. Phylogenetic community metrics were calculated for each locality for ferns and palms both with ferns as one group and for each of three fern clades with a crown group age comparable to that of palms. Palm and fern communities showed significant and contrasting phylogenetic signals along the soil gradient. Fern species richness increased but standard effect size of mean pairwise distance (SES.MPD) and variation of pairwise distances (VPD) decreased with increasing soil base cation concentration. In contrast, palm communities were more species rich on less cation‐rich soils and their SES.MPD increased with soil base cation concentration. Species turnover between the communities reflected the soil gradient slightly better when based on species occurrences than when phylogenetic distances between the species were considered. Each of the three fern subclades behaved differently from each other and from the entire fern clade. The fern clade whose phylogenetic patterns were most similar to those of palms also resembled palms in being most species‐rich on cation‐poor soils. The phylogenetic structuring of local plant communities varies along a soil base cation concentration gradient within non‐inundated Amazonian rain forests. Lineages can show either similar or different phylogenetic community structure patterns and evolutionary trajectories, and we suggest this to be linked to their environmental adaptations. Consequently, geological heterogeneity can be expected to translate into a potentially highly diverse set of evolutionarily distinct community assembly pathways in Amazonia and elsewhere.

Does anthropogenic fragmentation selectively filter avian phylogenetic diversity in a critically endangered forest system?

SummaryDocumenting phylogenetic diversity for conservation practice allows elucidation of ecosystem functioning and processes by highlighting the commonality and divergence of species’ functional traits within their evolutionary context. Conserving distinct evolutionary histories has intrinsic value, and the conservation of phylogenetically diverse communities is more likely to preserve distinct or relic evolutionary lineages. We explored the potential for anthropogenic forest fragmentation to act as a selective filter of avian phylogenetic diversity within the community of forest-dependent birds of the critically endangered Indian Ocean Coastal Belt Forest (IOCBF), South Africa. We conducted avian point count surveys during the austral breeding season, and calculated fragmentation metrics of forest structural complexity, patch size and isolation. We constructed a maximum likelihood phylogeny using the combined analysis of two mitochondrial genes and three nuclear markers and measured the influence of the fragmentation metrics on six measures of phylogenetic diversity. Our results indicated that the avian community was variously affected by anthropogenic forest fragmentation, with the different metrics of phylogenetic diversity responding with no definitive overall pattern. However, forest structural complexity emerged as an important metric explaining phylogenetic structuring. While the avian community’s phylogenetic diversity displayed resilience to anthropogenic fragmentation, previous research showed a reduction in functional diversity along the fragmentation gradient. Therefore, we recommend studies that especially aim to guide conservation management, incorporate both phylogenetic and functional diversity measures to sufficiently interrogate communities’ resilience to the threats under investigation.

Coordination between compound-specific chemistry and morphology in plant roots aligns with ancestral mycorrhizal association in woody angiosperms.

Recent studies on fine root functional traits proposed a root economics hypothesis where adaptations associated with mycorrhizal dependency strongly influence the organization of root traits, forming a dominant axis of trait covariation unique to roots. This conclusion, however, is based on tradeoffs of a few widely studied root traits. It is unknown how other functional traits fit into this mycorrhizal-collaboration gradient. Here, we provide a significant extension to the field of root ecology by examining how fine root secondary compounds coordinate with other root traits. We analyzed a dataset integrating compound-specific chemistry, morphology and anatomy of fine roots and leaves from 34 temperate tree species spanning major angiosperm lineages. Our data uncovered previously undocumented coordination where root chemistry, morphology and anatomy covary with each other. This coordination, aligned with mycorrhizal colonization, reflects tradeoffs between chemical protection and mycorrhizal dependency, and provides mechanistic support for the mycorrhizal-collaboration gradient. We also found remarkable phylogenetic structuring in root chemistry. These patterns were not mirrored by leaves. Furthermore, chemical protection was largely decoupled from the leaf economics spectrum. Our results unveil broad organization of root chemistry, demonstrate unique belowground adaptions, and suggest that root strategies and phylogeny could impact biogeochemical cycles through their links with root chemistry.

Variation in cross-sectional shape and biomechanical properties of the bat humerus under Wolff's law.

Bats use their forelimbs in different ways, but flight is the most notable example of morphological adaptation. Foraging and roosting specializations beyond flight have also been described in several bat lineages. Understanding postcranial evolution during the locomotory and foraging diversification of bats is fundamental to understanding bat evolution. We investigated whether different foraging and roosting behaviors influenced humeral cross-sectional shape and biomechanical variation, following Wolff's law of bone remodeling. The effect of body size and phylogenetic relatedness was also tested, in order to evaluate multiple sources of variation. Our results suggest strong ecological signal and no phylogenetic structuring in shape and biomechanical variation in humeral phenotypes. Decoupled modes of scaling of shape and biomechanical variation were consistently indicated across foraging and roosting behaviors, suggesting divergent allometric trajectories. Terrestrial locomoting and upstand roosting species showed unique patterns of shape and biomechanical variation across all our analyses, suggesting that these rare behaviors among bats place unique functional demands on the humerus, canalizing phenotypes. Our results suggest that complex and multiple adaptive pathways interplay in the postcranium, leading to the decoupling of different features and regions of skeletal elements optimized for different functional demands. Moreover, our results shed further light on the phenotypical diversification of the wing in bats and how adaptations besides flight could have shaped the evolution of the bat postcranium.

Relatedness and the composition of communities over time: Evaluating phylogenetic community structure in the late Cenozoic record of bivalves

AbstractUnderstanding the mechanisms that prevent or promote the coexistence of taxa at local scales is critical to understanding how biodiversity is maintained. Competitive exclusion and environmental filtering are two processes thought to limit which taxa become established in a community. However, determining the relative importance of the two processes is a complex task, especially when the critical initial stages of colonization cannot be directly observed. Here, we explore the use of phylogenetic community structure for identifying filtering mechanisms in a fossil community. We integrated a time-calibrated molecular phylogeny of bivalve genera with a spatial dataset of late Cenozoic bivalves from the Pacific coast of North America to characterize how the community that was present in the semirestricted San Joaquin Basin (SJB) embayment of present-day California was phylogenetically structured. We employed phylogenetic distance-based metrics across six time bins spanning 27–2.5 Ma and found no evidence of significant clustering or evenness in the SJB community when compared with communities randomly assembled from the regional source pool. Additionally, we found that new colonizers into the SJB were not significantly more or less closely related to native taxa than expected by chance. These findings suggest that neither competitive exclusion nor environmental filtering were overwhelmingly influential factors shaping the composition of the SJB community over time. We further discuss interpretations of these patterns in light of current understandings in community phylogenetics and reiterate the critical role historical perspectives play in how community assembly rules are assessed.

Soil bacterial and fungal community structure of a rice monoculture and rice-pasture rotation systems

Rice monoculture has been the main rice-cropping system for several years. Rice-pasture rotation system has raised in recent years as an alternative, as this practice not only increases rice yield but also adds value through the use of implanted pastures, livestock production and diversification of the system. To evaluate the impact on soil microbial diversity, we used Illumina Mi-Seq sequencing technology and phylogenetic structure analysis to study the bacterial and fungal soil communities in these two rice-cropping systems within a rice-production region of Entre Ríos province, Argentina. We detected over 11,000 and 3000 bacterial and fungal OTUs, respectively. Among them, members of the Acidobacteria, Proteobacteria, Verrucomicrobia and Ascomycota fungi phyla were the most abundant. None of the bacterial and fungal OTU differed significantly in composition between systems. In addition, microbial community diversity did not differ between rice-cropping systems, even though we found they were phylogenetically structured by a non-random pattern, mainly, due to environmental selection. In addition, the environmental variables explaining the differences between rice-cropping systems were pH, as well as the abundance of organic and inorganic elements. The results suggest that the rice-cropping system may be one of various factors influencing these observations, with a certain degree of relevance, in conjunction with other environmental variables that are not controlled but considered in this analysis.

C4 grass functional traits are correlated with biotic and abiotic gradients in an African savanna

Savanna is a species-rich biome, that includes many modern mammal lineages and C4 grass (Poaceae) species. The greater productivity and grazing pressure associated with savannas is likely attributable to the foliar traits of the grasses they support. Thus, it is important to understand the complex relationships between the abiotic environment, foliar attributes and the floristic composition of savanna grasses, and the supported grazer densities. We sampled 37 grass communities in the Kruger National Park (South Africa) across three soil types and along a rainfall gradient and found that these communities lack strong phylogenetic structure. We then measured specific leaf area and leaf tensile strength for 384 individuals representing 66 species and found that both traits were strongly phylogenetically structured and associated with both rainfall and soil type. Finally, we found that grazer densities in the Park are correlated with the foliar traits of the associated grass communities, but the resolution of our data do not allow for a thorough analysis of this association. Our results demonstrate the complex interactions between climate, soils and grazer densities relative to C4 grass functional traits.

Widespread prevalence but contrasting patterns of intragenomic rRNA polymorphisms in nematodes: Implications for phylogeny, species delimitation and life history inference.

Ribosomal RNA genes have long been a favoured locus in phylogenetic and metabarcoding studies. Within a genome, rRNA loci are organized as tandem repeated arrays and the copies are homogenized through the process of concerted evolution. However, some level of rRNA variation (intragenomic polymorphism) is known to persist and be maintained in the genomes of many species. In nematode worms, the extent of rRNA polymorphism (RP) across species and the evolutionary and life history factors that contribute to the maintenance of intragenomic RP is largely unknown. Here, we present an extensive analysis across 30 terrestrial nematode species representing a range of free-living and parasitic taxa isolated worldwide. Our results indicate that RP is common and widespread, ribosome function appears to be maintained despite mutational changes, and intragenomic variants are stable in the genome and neutrally evolving. However, levels of variation were varied widely across rRNA locus and species, with some taxa observed to lack RP entirely. Higher levels of RP were significantly correlated with shorter generation time and high reproductive rates, and population-level factors may play a role in the geographic and phylogenetic structuring of rRNA variants observed in genera such as Rotylenchulus and Pratylenchus. Although RP did not dramatically impact the clustering and recovery of taxa in mock metabarcoding analyses, the present study has significant implications for global biodiversity estimates of nematode species derived from environmental rRNA amplicon studies, as well as our understanding of the evolutionary and ecological factors shaping genetic diversity across the nematode Tree of Life.

Spatial and Trophic Structure of Anuran Assemblages in Environments with Different Seasonal Regimes in the Brazilian Northeast Region

We investigated the roles of ecological and historical factors on the phylogenetic structure and spatial and trophic niches of anurans in Caatinga and Atlantic Forest in the Brazilian Northeast Region. We sampled specimens and ecological data using both active search and pitfall traps to sample sites for 15 days during dry and wet seasons. Assemblages from Caatinga were more structured on dietary niche than those from Atlantic Forest. Ecological factors had a higher effect on the trophic niche than on the spatial niche but were lower than historical factors, thus indicating past adaptations. The onset of the dry season usually increases the dietary structure of assemblages. Water restrictions in Caatinga affected prey abundance, increasing niche segregation. Differences between environments indicated that local factors exerted greater influence in Caatinga. We did not observe spatial niche structure in most assemblages, regardless of the environment, and we found strong evidence of niche conservatism in all assemblages. Phylogenetic effects detected in spatial niches reinforce the separation between arboreal and terrestrial/semi-aquatic lineages during the Cretaceous. Lastly, no niche complementarity was detected, despite the different structure patterns. No assemblage was phylogenetically structured, and the existence of a possible “ecological filter” in Caatinga did not lead to increased “phylogenetic clustering” in this environment.

Species diversity of Marmosa subgenus Micoureus (Didelphimorphia, Didelphidae) and taxonomic evaluation of the white-bellied woolly mouse opossum, Marmosa constantiae

AbstractMarmosa subgenus Micoureus contains six currently recognized species, distributed from southern Belize to northern Argentina. Although recent studies have demonstrated the monophyly of the subgenus, the species have not been recently revised. Except for M. phaea, we evaluated the species diversity in this subgenus of mouse opossums using integrated morphological, morphometric and molecular data, with emphasis on M. constantiae. We used a total of 700 specimens for morphological and morphometric analyses. For phylogenetic, species delimitation, molecular variance and population structuring analyses (the latter two only for M. constantiae), we used the mitochondrial cytochrome b gene. Morphometric variation patterns were evaluated through Principal Component Analysis and Discriminant Function Analysis. Our results indicate that there are seven species in our samples. Among the species analysed morphologically, some can be discriminated by craniodental measurements and all can be discriminated through morphology. Marmosa constantiae is polyphyletic, composed of two lineages, one of which is correctly named M. budini. Marmosa constantiae (s.s.) has a well-known genetic structure, with no clear geographic structure and no consistent morphological patterns. Several records of M. demerarae in the literature correspond to M. constantiae. Marmosa demerarae may thus represent a complex formed of at least two species.