Investigating Carnivore Guild Structure: Spatial and Temporal Relationships amongst Threatened Felids in Myanmar

The co-occurrence of felid species in Southeast Asia provides an unusual opportunity to investigate guild structure and the factors controlling it. Using camera-trap data, we quantified the space use, temporal activity, and multi-dimensional niche overlap of the tiger, clouded leopard, Asiatic golden cat, marbled cat, and leopard cat in the Htamanthi Wildlife Sanctuary, Myanmar. We hypothesised that the spatio-temporal behaviour of smaller cats would reflect the avoidance of the larger cats, and similar-sized guild members would partition their niches in space or time to reduce resource competition. Our approach involved modelling single-species occupancy, pairwise spatial overlap using Bayesian inference, activity overlap with kernel density estimation, and multivariate analyses. The felid assembly appeared to be partitioned mainly on a spatial rather than temporal dimension, and no significant evidence of mesopredator release was observed. Nonetheless, the temporal association between the three mesopredators was inversely related to the similarity in their body sizes. The largest niche differences in the use of space and time occurred between the three smallest species. This study offers new insight into carnivore guild assembly and adds substantially to knowledge of five of the least known felids of conservation concern.

Multisubstrate DNA stable isotope probing reveals guild structure of bacteria that mediate soil carbon cycling

Soil microorganisms determine the fate of soil organic matter (SOM), and their activities compose a major component of the global carbon (C) cycle. We employed a multisubstrate, DNA-stable isotope probing experiment to track bacterial assimilation of C derived from distinct sources that varied in bioavailability. This approach allowed us to measure microbial contributions to SOM processing by measuring the C assimilation dynamics of diverse microorganisms as they interacted within soil. We identified and tracked 1,286 bacterial taxa that assimilated 13C in an agricultural soil over a period of 48 d. Overall 13C-assimilation dynamics of bacterial taxa, defined by the source and timing of the 13C they assimilated, exhibited low phylogenetic conservation. We identified bacterial guilds composed of taxa that had similar 13C assimilation dynamics. We show that C-source bioavailability explained significant variation in both C mineralization dynamics and guild structure, and that the growth dynamics of bacterial guilds differed significantly in response to C addition. We also demonstrate that the guild structure explains significant variation in the biogeographical distribution of bacteria at continental and global scales. These results suggest that an understanding of in situ growth dynamics is essential for understanding microbial contributions to soil C cycling. We interpret these findings in the context of bacterial life history strategies and their relationship to terrestrial C cycling.

Spider diversity (Arachnida; Araneae) in different plantations of Western Ghats, Wayanad region, India

The study was conducted to explore the spider diversity in different plantations of Western Ghats Wayanad, Kerala state, India. The investigation was carried out for the period from February 2019 to February 2020. A total of 100 species belonging to 74 genera under 20 families were recorded from the selected habitats. This represents 51% families recorded from the Western Ghats, Kerala. The highest species richness was found in the coffee plantation (site A) with 56 species belonging to 12 families. The tea plantation (site B) recorded 27 species belonging to 11 families. The rubber plantation (site C) showed the lowest species richness with 17 species belonging to ten families. Guild structure analyses of the collected spiders revealed nine functional groups viz.., orb-web builders, stalkers, ambushers, cob-web builders, ground runners, foliage runners, tent web builders, sheet-web builders and funnel web builders. The pattern and the architecture of webs varied among different families. During the period of study, five different web patterns were recorded- orb web, tent web, cob web, sheet web and funnel web. It is concluded that the structure of the vegetation is expected to influence the diversity of spiders in different plantations.

Theropod guild structure and the tyrannosaurid niche assimilation hypothesis: implications for predatory dinosaur macroecology and ontogeny in later Late Cretaceous Asiamerica

Well-sampled dinosaur communities from the Jurassic through the early Late Cretaceous show greater taxonomic diversity among larger (>50 kg) theropod taxa than communities of the Campano-Maastrichtian, particularly to those of eastern/central Asia and Laramidia. The large carnivore guilds in Asiamerican assemblages are monopolized by tyrannosaurids, with adult medium-sized (50–500 kg) predators rare or absent. In contrast, various clades of theropods are found to occupy these body sizes in earlier faunas, including early tyrannosauroids. Assemblages with “missing middle-sized” predators are not found to have correspondingly sparser diversity of potential prey species recorded in these same faunas. The “missing middle-sized” niches in the theropod guilds of Late Cretaceous Laramidia and Asia may have been assimilated by juvenile and subadults of tyrannosaurid species, functionally distinct from their adult ecomorphologies. It is speculated that if tyrannosaurids assimilated the niches previously occupied by mid-sized theropod predators, we would expect the evolution of distinct transitions in morphology and possibly the delay of the achievement of somatic maturity in species of this taxon.

The impact of Sosnowsky’s Hogweed on feeding guilds of birds

Plant invasions alter bird community composition worldwide, but the underlying mechanisms still require exploration. The investigation of feeding guild structure of bird communities can be informative in respect to the potential impact of invasion features on the availability of food for birds. For this purpose, we focused on determining the influence of the invasive Sosnowsky’s Hogweed Heracleum sosnowskyi on the abundance of birds from various feeding guilds. In spring and summer 2019, birds were counted three times on 52 pairs of sites (control + Heracleum) in southern Poland, at various stages of Sosnowsky’s Hogweed development (i.e. sprouting, full growth and flowering, all corresponding to respective bird counts). We have shown that the presence of invader negatively affected the abundance of birds from all feeding guilds. However, a closer examination of the invaded sites uncovered that responses of particular guilds differed in respect to development stages expressed by a set of characteristics of the invader. Ground and herb insectivores were more common on plots with a higher number of the invader, while the abundance of bush and tree insectivores was negatively correlated with hogweeds’ height. Granivores were not affected by the invader’s features, while the abundance of omnivores was negatively related to the number of flowering hogweeds. Besides showing the general negative impact of the invader on different feeding guilds, our research has shown that certain aspects of Sosnowsky’s Hogweed invasion may support or depress occurrence of different birds on invaded plots. Knowledge of these aspects may facilitate our capacity for coping with challenges the invasive plants put in front of bird conservationists.

Investigating carnivore guild structure: Spatial and temporal relationships amongst threatened felids in Myanmar

At least nine felid species can co-occur in Southeast Asia, thus providing an unusual opportunity to investigate poorly known guild structure and the factors controlling it. Using camera-trap data, we quantified space use, temporal activity, and multi-dimensional niche overlap of tiger, clouded leopard, marbled cat, leopard cat, and Asiatic golden cat in Htamanthi Wildlife Sanctuary of Myanmar. We hypothesized that the spatio-temporal behaviour of smaller cats can reflect avoidance of the larger cats, which are both potential competitors and predators, and similar-sized guild members would partition their niches in space or time to reduce competition for resources. Our approach involved single-species occupancy modelling to identify site covariates, pairwise spatial overlap using Bayesian inference, and activity overlap with Kernel density estimation and multivariate analyses to test hypotheses. We found tiger and marbled cats were primarily diurnal, clouded leopard and leopard cat were nocturnal and golden cat exhibited cathemeral activity. We observed a complex pattern of guild assembly and potential competition involving strong niche displacement between the golden cat and marbled cat, but high overlap between the relatively similarly-sized pairing of clouded leopard and golden cat, and the markedly differently-sized tiger – golden cat pairing. No significant evidence of mesopredator release was observed and the felid assembly in Northern Myanmar appeared to be partitioned mainly on a spatial, rather than temporal, dimension. Nonetheless, the temporal association between the three mesopredators was inversely related to the similarity in their body sizes. The insights into this felid guild revealed that the largest niche differences in the use of space and time occurred between the three smaller species, most evidently between the Asiatic golden cat-marbled cat pairing, followed by marbled cat - leopard cat pairing. This study offers new insight into carnivore guild assembly and, adds substantially to knowledge of five of the least known felids of conservation concern.

Assessing the bird guild patterns in heterogeneous land use types around Jammu, Jammu and Kashmir, India

Land-use sprawl in the Himalayas has caused the conversion of natural habitat into human-modified habitats, thus degrading ecosystem health. Adaptation of birds to changing physical environment can be well understood by analyzing their habitat preferences, and foraging dynamics explored to a limited extent in the Himalayan region, as yet. To achieve a comprehensive understanding of avian guild structure, we used multivariate statistical techniques to classify bird species according to their similarities in foraging patterns and habitat preferences. Observations based on habitat and diet affinities accounted for rich avian diversity with a total of 208 bird species (about 15% of country’s avifauna) recorded from six different sites during 1 year survey. Unweighted pair-group average cluster analysis performed on the families revealed ten feeding and fifteen habitat guilds among 63 bird families observed. Subtropical forests harbored more species followed by urban forests and agricultural landscapes. Insectivorous and omnivorous outnumbered other feeding guilds in the study area. Bird assemblages were richer in protected areas and semi-disturbed landscapes and did not show significant variation between the seasons. Results of the study revealed that different functional groups of birds behaved differently, primarily induced by choice of food. The site heterogeneity favored avifaunal persistence by providing favorable foraging, roosting, and nesting opportunities to birds. Composition of avian guilds indicated level of intactness and ecological integrity of ecosystems studied. This outcome thus sets the background for long-term analysis of bird-habitat relationship and their foraging dynamics. The study has the relevance for decision-makers to integrate avian guild structure as an essential ingredient in formulating conservation strategies.