Austral Ecology最新文献

Animal gut microbiomes can be very diverse, and enteric bacteria can profoundly affect the physiology of their host. The gut microbiome can be related to host health and digestion, which ultimately contribute to host body condition. However, we have a limited understanding of the co-occurrence patterns of gut bacteria in their host, and how co-occurrence and bacterial diversity change over time. This notion is especially important to animals living in groups as bacteria can transmit through social interactions. We investigated the co-occurrence patterns of gut bacteria in a lizard host. We repeatedly collected cloacal swabs from 87 sleepy lizards (Tiliqua rugosa) from two different study sites over their activity season. We determined the richness and prevalence of 82 enteric bacterial strains and used a probabilistic model to investigate their co-occurrence. At both study sites, richness and prevalence generally increased over time. We suggest that the lizards acquire strains throughout their activity season by moving through the landscape and inspecting conspecific scats. Lizards continuously tongue-flick while moving, and thereby ingest bacteria when they move through areas where other animals defaecated. Temperature, rainfall and diet change seasonally, influencing lizard activity, and may influence the observed increase in enterobacterial richness and prevalence. Further, albeit with some exceptions, most strain pairs did not occur significantly more often or less often than expected by chance. This finding shows a lack of structured co-occurrence, which may imply that most bacterial strains did not facilitate or inhibit each other. The absence of a co-occurrence pattern could also be driven by random encounters of bacteria shed by other lizards within the habitat. Our results suggest that behaviour (movement patterns, tongue-flicking), activity patterns and environmental factors collectively drive the temporal pattern of the gut bacterial community in sleepy lizards and potentially other wild reptiles.

In the current study, I report a single-site mimicry complex involving 20 arthropods from 12 families in five orders resembling the small turtle ant Cephalotes pusillus. The complex is the most species-rich single-site complex with predominately Batesian mimics that has been reported so far. Considering that small turtle ants are likely less defended than highly noxious butterflies or aculeate Hymenoptera with potent stingers, possible factors explaining the high species richness of the complex may include high model abundance, small body size and easy to develop morphological resemblance.

Altitudinal gradients can provide valuable insights into the distribution patterns of species richness at both local and regional scales. Typically, species richness peaks at intermediate elevations. This pattern can be attributed to factors such as climatic conditions, the mid-domain effect, and historical-evolutionary processes. Our research aimed to investigate the distribution patterns of vascular epiphytes along the regional elevation gradient in dwarf cloud forests of Serra da Mantiqueira (SM), Brazil. We hypothesised that species richness would peak at intermediate elevations correlating with the availability of water. To test this hypothesis, we sampled 18 plots, each measuring 20 × 20 m, in seven protected areas with varying elevation gradients. The lowest plot was at 1270 m, and the highest was at 2350 m. In each plot, we surveyed trees (phorophytes) with a circumference at breast height of 30 cm. Rarefaction analysis was conducted to compare species richness among plots, while beta diversity analysis was used to assess species composition changes along the elevation gradient and across the SM range. We employed a generalised linear model (GLM) with a Poisson distribution to examine the relationships between environmental variables and plant richness. Our findings suggest that there is no intermediate peak in species richness in any of the localities. However, regionally, the elevation range of 1500-1700 m exhibited the highest richness, particularly when compared to the higher plots, which are subject to low temperatures that act as environmental filters, limiting species richness despite higher precipitation. Furthermore, plots above 1980 m showed low turnover, indicating that these filters contribute to a more homogeneous composition. Species composition across the SM was influenced by climatic differences, and overall, geographical distance was not significant, as within the same locality exhibited low turnover. This study provides a foundation for understanding patterns of species richness and composition along altitudinal gradients in the context of global climate change.

An understanding of fine-scale movements made by animals is critical for assessing localized habitat preferences and informing the scales over which land management should be applied. However, for cryptic species such as insectivorous bats that are highly mobile and active at night, it is difficult to collect these data. Nyctophilus corbeni serves as a case study for narrow-space species as it is listed as threatened and nothing is known about its localized habitat preferences. We used miniature GPS tags to assess fine-scale movements across three sites and 2 years (autumn 2020 and 2021) in the Pilliga forests in northwest New South Wales. Each site consisted of a mosaic of forest disturbances (e.g. timber harvesting / thinning regrowth, prescribed fires and wildfires, and cleared farmland). Bats made large movements in the non-maternity season, with a maximum of ~21 km recorded as a one-way movement on a given night. On average, the maximum distance travelled by tagged bats was 6.2 ± 1.4 km per night. Short-term home (9884 ha) and core (2157 ha) ranges were extensive, but varied by sex, with ranges of females ~15 times larger than males. Bats crossed cleared land that was within close proximity (<2.3 km, but typically <~600 m) of large forest blocks (>100 ha). Based on availability of habitat types, bats selected for older regrowth and burnt forest and avoided cleared areas with scattered trees and also thinned forest, though the availability for the latter was low (<3 %). Flight speeds and the lack of clustering of GPS fixes in cleared landscapes suggest that limited foraging may occur there. Overall, our results highlight the sensitivity of the species to forest clearing and potentially to thinning, but also demonstrate the importance of maintaining large areas of forest and where possible, reforesting cleared areas that occur between smaller, more isolated forest blocks.

Understanding species distribution patterns has been a major quest in biodiversity research. Due to their secretive habits and rarity, snakes have been historically underrepresented in assessments of geographic distribution range. In this work, we employ a pipeline for predictive model-based species sampling, using Neotropical snakes as a model organism. We employ species distribution models based on verified point records for five candidate snake species of probable occurrence to Rio Grande do Sul state, Brazil: Apostolepis dimidiata (Jan 1862), Erythrolamprus aesculapii (Linnaeus 1758), Helicops leopardinus (Schlegel 1837), Lygophis meridionalis (Schenkel 1901), and Micrurus corallinus (Merrem 1820). Based on the resulting models, we conducted fieldwork on areas with higher overlap of suitable ranges and probability of new records. Our study yields a new state record of A. dimidiata to Rio Grande do Sul and highlights the usefulness of species distribution models in eliciting priority areas for faunal assessments.

Frugivorous bats in the subfamily Stenodermatinae are known to use foliage and cavities, such as tree hollows or caves, as roosting sites. Species with paler facial and dorsal markings are typically thought to prefer enclosed spaces, while those with more conspicuous markings often roost in more exposed locations. Among the genus Chiroderma, the hairy big-eyed bat (C. villosum) has the widest distribution and is the most studied ecologically, yet its roosting habits remain poorly understood. We present three observations of C. villosum using foliage as daytime roosting sites, with records from tropical rainforest areas in Belize, Brazil and Nicaragua. These findings challenge the assumption that C. villosum prefers enclosed spaces due to its less conspicuous pelage markings. The apparent scarcity of day roost reports for Chiroderma species may be due to their solitary roosting habits and the difficulty of spotting them in exposed shelters.

The threatened South-eastern Long-eared Bat (Nyctophilus corbeni, EPBC Act 1999 Vulnerable) is an insectivorous microbat that is dependent on tree hollows for roosting. Although it is sparsely distributed throughout the Murray-Darling Basin, its contemporary Victorian distribution was believed to be limited to a small population in semi-arid mallee habitats in the state's North-West. That was until a lactating female was captured in the floodplain forest in Gunbower National Park, along the Murray River in north-central Victoria, in late 2021. In light of this new record, in an ecological setting not typically occupied by the species, we sought to (a) confirm the presence of an established population of N. corbeni at Gunbower; and (b) if present, characterize the day roosts being used. Over eight nights (73 trapnights), we captured 172 microbats, including five N. corbeni. Traps set with acoustic lures (the Autobat MK2, or a generic bat chirper) appeared to capture more bats per trapnight than those set without lures. Four individual N. corbeni were successfully radiotracked to their roosts, which were a mix of small-diameter (19.5–36 cm DBH), typically multi-stemmed, live, dying and dead Black Box (Eucalyptus largiflorens) and Grey Box (Eucalyptus microcarpa) trees. While day roosts do not appear to be limiting for this species in this location, further research is needed to understand what trees are being used as maternity roosts (which may be more specialized), how far up- and down-stream along the Murray River this new population extends, and whether it is geographically and/or genetically connected to populations in the Victorian mallee or in New South Wales.

Achelous spinimanus, a species of swimming crab found along the Western Atlantic from the USA to Brazil, inhabits coastal areas up to 90 m deep across various substrates. While these crabs are known to be omnivorous, the extent of their predatory behaviour remains unclear. This note documents the first record of A. spinimanus actively preying on live fish. In the observed interaction, the fish was still alive and moving its operculum and mouth while being eaten. The observation was made during a night dive at Ilha dos Porcos, Arraial do Cabo, Brazil, where a crab was seen preying on a live Malacoctenus zaluari. The behaviour suggests that A. spinimanus may employ sit-and-wait strategy, utilizing its strong chelipeds for capturing prey. Such records are crucial for understanding the trophic dynamics and ecological roles of marine species, emphasizing the importance of both scientific and citizen science contributions to biodiversity knowledge. This finding also underscores the importance of further research on the feeding and behavioural ecology of portunids.

Floral syndromes can be a useful tool for predicting the identity of pollinators from floral morphology. However, the reliability of floral syndromes are still debated in the literature, and can often result in effective pollinators being overlooked. Pollination by moths has historically been associated with a floral syndrome comprising white tubular flowers that are heavily scented at night, but there have been few experimental tests of this association. To test whether moths preferentially land on flowers that are white and tubular, we allowed two moth species (Agrotis ipsilon (Hufnaggel, 1766) and Ichneutica mutans (Walker, 1857)) to choose freely between three plant species (Vaccinium corymbosum, Ericaceae, Pittosporum tenuifolium, Pittosporaceae, and two forms of Leptospermum scoparium, Myrtaceae) which represent four different floral morphologies. Anthers on the flowers were marked with fluorescent powder dye (pollen-tracker), with the presence of pollen-tracker on moth bodies after the experiment indicating floral visitation. We detected no floral preferences for any of the plant species by either moth species, suggesting moths will visit flowers that lack features associated with the syndrome even when in the presence of white, tubular flowers which might be predicted to be more attractive to moths. We also examined moth bodies to determine where pollen-tracker was carried most often and if this varied among the floral types. Our results indicate that some moth body parts may be more important than others for pollen transfer, depending on the morphology of the flowers visited. After visiting tubular flowers (Vaccinium and Pittosporum), pollen-tracker was most often located on the proboscis, but after visiting open-access flowers (Leptospermum) pollen-tracker was most often located on the legs. Future studies looking at the presence of pollen on moth bodies should consider this and ensure the entire moth body is examined for the presence of pollen.

Exotic vines threaten biodiversity causing damage to forest structure. We investigated the distribution of exotic vines across different patchily distributed plant communities. We surveyed patches of 12 threatened, mesic forest communities along the coastal plain in New South Wales, Australia to determine how exotic and native vine distribution and density were influenced by characteristics of forest patches and neighbouring land use. Vine density and stem widths were measured in quadrats in the edge and interior of patches. Canopy cover, number of dead trees, area to perimeter ratio and surrounding land use were recorded for each patch. Our results show that exotic vine assemblages were influenced by anthropogenic land use surrounding patches but not influenced by community type. Most exotic vine species were present across the whole region where surveys were undertaken. Exotic vines species were sometimes at high densities but had smaller stem widths than native species and there was no change in density from the edges into the interior. Araujia sericifera and Ipomoea cairica were the most prevalent exotic species and together with the fast edge growing Anredera cordifolia are of key concern. In contrast, native vine assemblages were species rich, with some individuals having large stem widths suggesting greater age and we found species composition varied with plant community type. Native vines showed continual recruitment and appeared more specialized to the attributes of each plant community. Surrounding anthropogenic land uses (residential, agricultural and industrial) were the most important factors predicting invasion of exotic vines and were more important than the length of edges. This suggests that the surrounding matrix characteristics were influencing degradation of the interior of these patches, rather than exotic vines invading along an invasion front from the edge. Exotic vines need to be controlled across the entirety of patches, rather than a focus on edge control practices.