Bat assemblages on Neotropical land-bridge islands: nested subsets and null model analyses of species co-occurrence patterns

Climatic gradients and forest composition shape bat communities in Eastern Mediterranean pine plantations

Biotic and abiotic factors can act as filters for determining the species composition of biological communities. We aimed to identify abiotic factors driving the assembly of bat communities in Eastern Mediterranean pine plantations along a north-south climatic gradient, as they are crucial forest habitats for the assessment and conservation of these communities. We expected that bat communities are predominantly shaped by environmental filtering. We conducted acoustic sampling in 35 pine plantations in Israel and analyzed recordings for species identification. We used the ESLTP analysis, an extension of the three-table ordination (RLQ analysis), to explore relationships between environmental characteristics, species occurrences, and functional traits of species while accounting for phylogenetic relationships between species and spatial distribution of the communities. Communities showed phylogenetic and trait clustering. Climatic conditions and forest vegetation composition shaped communities of bats, affecting the distribution of traits related to foraging behaviors, vegetation clutter, and the ability of bats to maneuver in it. Maneuverable species were associated with the northern Mediterranean climatic zone, with a scarce cover of drought-tolerant small shrubs and grassland. Fast flyers were associated with the center-south semi-arid area, with abundant drought-tolerant small shrubs and grassland. These forces might have a predominant role in the assembly of these communities, presumably due to the stressful climatic conditions of the study area. The ESLTP approach can be extended to other taxa and environments to predict species responses to disturbance and environmental changes and give insights into environmental management.

Scale-Dependent Habitat Nestedness and Its Implications for Anuran Conservation in the Chengdu Region: A Multi-Extent Analysis

Nestedness in community ecology predicts that species in a species-poor site should be a subset of species of a species-rich site. A variety of ecological mechanisms have been offered to explain community nestedness; however, few studies have systematically discussed the issue of scale dependence when interpreting community nestedness. This study conducted surveys of anuran species data in the vicinity of Chengdu, Sichuan, in the summers of 2019-2020, using the transect method. The study area was divided into 23 sampling sites and 8 regions to explore the relationship between environmental factors and the nested distribution pattern of anuran communities under different sampling extents (with sampling buffers set at 1 km, 2 km, and 5 km). The WNODF (weighted-nestedness metric based on overlap and decreasing fill) results indicated that anurans exhibited a strong nested pattern at both the sampling sites scale and the regional scale. The habitat matrix test results suggested that a small-scale study area requires a correspondingly small habitat-sampling extent to effectively test for habitat nestedness. As the study area expands, the habitat-sampling range can be appropriately increased. The nested pattern of anurans in the vicinity of Chengdu can only be explained by habitat nestedness, as a Spearman's correlation analysis showed that other environmental factors (area size, connectivity index, concentration index, proximity index, and distance to the city center) were not significantly correlated with the nested sequences of sampling points and regions. Therefore, regarding the conservation strategies for anurans in the vicinity of Chengdu, we recommend prioritizing the protection of areas with higher habitat diversity.

Selective extinction and habitat nestedness are the main drivers of lizard nestedness in the Zhoushan Archipelago

Nested subset pattern (nestedness) is an important part of the theoretical framework of island biogeography and community ecology. However, most previous studies often used nestedness metrics or randomization algorithms that are vulnerable to type I error. In this study, we investigated the nestedness of lizard assemblages on 37 islands in the Zhoushan Archipelago, China. We used the line-transect method to survey species occurrence, abundance, and habitat types of lizards on 37 islands during 2 breeding seasons in 2021 and 2022. We applied the nested metric WNODF and the conservative rc null model to control for type I error and quantify the significance of nestedness. Spearman rank correlations were used to evaluate the role of 4 habitat variables (island area, 2 isolation indices, and habitat diversity) and 4 ecological traits (body size, geographic range size, clutch size, and minimum area requirement) in generating nestedness. The results of WNODF analyses showed that lizard assemblages were significantly nested. The habitat-by-site matrix estimated by the program NODF was also significantly nested, supporting the habitat nestedness hypothesis. The nestedness of lizard assemblages were significantly correlated with island area, habitat diversity, clutch size, and minimum area requirement. Overall, our results suggest that selective extinction and habitat nestedness were the main drivers of lizard nestedness in our system. In contrast, the nestedness of lizard assemblages was not due to passive sampling or selective colonization. To maximize the number of species preserved, our results indicate that we should protect both large islands with diverse habitats and species with large area requirement and clutch size.

Diatom and macroinvertebrate communities dynamic: A co-occurrence pattern analysis on plastic substrates

Wetlands are habitats that provide numerous ecosystem services, but are often understudied and threatened by anthropogenic pollution, particularly plastic pollution. Macroplastics are a significant component of plastic litter that have high biological impacts but are often understudied. Previous studies have highlighted negative impacts on biota, but there is a lack of information about the communities of micro and macro organisms that settle on macroplastic litter. In this context, we investigated the colonization patterns and community structures of diatoms and macroinvertebrates on virgin substrates composed of two different plastic polymers, polystyrene and polyethylene terephthalate, located at two different depths in a protected wetland in Central Italy over a period of 10 months. The results show that diatom community is not highly structured by competitive forces and aggregation patterns emerges. In contrast, macroinvertebrate community appears to be randomly structured, without the presence of patterns following specific assembly rules. Randomness in macroinvertebrates assemblages could highlight the presence of different niches available for settlement of different taxa. Combined matrix analyses show that diatoms and macroinvertebrates co-occur, and their community assemblages are sometimes structured, while they appeared to be randomly assembled at other times. Whenever non-randomness of diatoms and macroinvertebrates co-occurrences was detected, it suggested aggregation. Moreover, the possible predatory relationship between different macroinvertebrates taxa should be investigated, as it could reveal important scenarios in the establishment of macroinvertebrate structured communities on plastic litter, including taxa that exploit different ecological niches. This could lead to an enrichment of the biological community within areas impacted by plastics.

Ecosystems Services Provided by Bats Are at Risk in Brazil

Ecosystem services (ES) are essential for human society worldwide. ES originate from ecological processes commonly occurring in well-preserved regions. Bats play an essential role in providing such services, primarily insect suppression, plant pollination, and seed dispersal. Human activities have affected Earth’s systems, compromising species and ecosystems and, consequently, the ES provision. Brazil is a country with many bat species but is also one of the world’s leaders in deforestation. Here we aimed to identify regions with high potential for bats ecosystem services provision, assuming that the predicted presence of the species represents the existence of the services. First, we used a Maximum Entropy algorithm to model the distribution of 128 bat species, which correspond to 71% of the Brazilian species. We classify all species into 10 different groups, which resulted from a combination of three body sizes and four predominant trophic guilds (i.e., frugivores, insectivores, nectarivores, and carnivores). The guilds were associated with services of seed dispersion, pest control, pollination, and animal control. Then, we created a 0.5 × 0.5-degree grid to represent an index of ES per guild, which is defined by the sum of the product of the bat’s size weight (1, 2, or 3) by the area occupied of each species in each cell. For comparison, the index was normalized and scaled from 0 to 1. Finally, we used a map of current land use to compare the effects of natural area suppression on the provision of ES in each cell. Our results indicate a substantial reduction in the provision of ES by bats in extensive parts of the central and eastern parts of Brazil, but changes in ES varies among biomes. While the loss of species is an important factor affecting the provision of ES in the Atlantic Forest and the Cerrado, the reduction of species occurrence is most important factor in Amazonia, Caatinga, or Pantanal regions. We suggest that degraded area restoration should be promoted in areas with high ES values and areas near cities and croplands and that a precautionary approach of promoting the conservation of high provider richness should be applied to protect the continuation of bat’s ES.

From island biogeography to landscape and metacommunity ecology: A macroecological perspective of bat communities

The equilibrium theory of island biogeography and its quantitative consideration of origination and extinction dynamics as they relate to island area and distance from source populations have evolved over time and enriched theory related to many disciplines in spatial ecology. Indeed, the island focus was catalytic to the emergence of landscape ecology and macroecology in the late 20th century. We integrate concepts and perspectives of island biogeography, landscape ecology, macroecology, and metacommunity ecology, and show how these disciplines have advanced the understanding of variation in abundance, biodiversity, and composition of bat communities. We leverage the well-studied bat fauna of the islands in the Caribbean to illustrate the complex interplay of ecological, biogeographical, and evolutionary processes in molding local biodiversity and system-wide structure. Thereafter, we highlight the role of habitat loss and fragmentation, which is increasing at an accelerating rate during the Anthropocene, on the structure of local bat communities and regional metacommunities across landscapes. Bat species richness increases with the amount of available habitat, often forming nested subsets along gradients of patch or island area. Similarly, the distance to and identity of sources of colonization influence the richness, composition, and metacommunity structure of islands and landscape networks.

Nestedness and underlying processes of bird assemblages in Nanjing urban parks

Nestedness is an important pattern frequently reported for species assemblages on islands or fragmented systems. However, to date, there are few studies that comprehensively investigated faunal nestedness and underlying processes in urbanized landscapes. In this study, we examined the nestedness of bird assemblages and its underlying causal mechanisms in 37 urban parks in Nanjing, China. We used the line-transect method to survey birds from April 2019 to January 2020. We used the Weighted Nestedness metric based on Overlap and Decreasing Fill (WNODF) to estimate the nestedness of bird assemblages. We applied spearman partial correlation test to examine the relationships between nestedness ranks of sites and park characteristics (area, isolation, anthropogenic noise, number of habitat types, and building index), as well as between nestedness ranks of species and their ecological traits (body size, geographic range size, clutch size, minimum area requirement, dispersal ratio, and habitat specificity). We found that bird assemblages in urban parks were significantly nested. Park area, habitat diversity, building index, habitat specificity, and minimum area requirement of birds were significantly correlated with nestedness. Therefore, the nestedness of bird assemblages was caused by selective extinction, habitat nestedness, and urbanization. However, the nestedness of bird assemblages did not result from passive sampling, selective colonization, or human disturbance. Overall, to maximize the number of species preserved in our system, conservation priority should be given to parks with large area, rich habitat diversity, and less building index. From a species perspective, we should focus on species with large area requirement and high habitat specificity for their effective conservation.

A multifaceted approach to understanding bat community response to disturbance in a seasonally dry tropical forest

Given widespread habitat degradation and loss, reliable indicators are needed that provide a comprehensive assessment of community response to anthropogenic disturbance. The family Phyllostomidae (Order Chiroptera) has frequently been the focus of research evaluating bats' response to habitat disturbance in seasonally dry tropical forests (SDTFs). However, few studies compare this family to the larger bat assemblage to assess its efficacy as a bioindicator. We compared community and species-specific attributes of understory phyllostomid and all understory bat species: (1) along a gradient of habitat disturbance within a human-modified SDTF landscape; and (2) between forest and riparian habitats within each disturbance level. We captured 290 individuals belonging to 13 species and 4 families. Phyllostomid species exhibited greater sensitivity to disturbance than the understory bat community as a whole based on richness and beta diversity. Both groups were more sensitive to disturbance in forest than riparian habitat, but phyllostomid species were more likely to be lost from highly disturbed forest habitat. The two dominant species declined in abundance with disturbance but variation in body condition was species-specific. These results suggest that Phyllostomidae are more effective indicators of human disturbance in SDTF than the understory bat community as a whole and evaluation of bats' response to disturbance is best accomplished with a multifaceted approach.

Trypanosomatid species in Didelphis albiventris from urban forest fragments

Urbanization results in loss of natural habitats and, consequently, reduction of richness and abundance of specialist to the detriment of generalist species. We hypothesized that a greater richness of trypanosomatid in Didelphis albiventris would be found in fragments of urban forests in Campo Grande, Mato Grosso do Sul, Brazil, that presented a larger richness of small mammals. We used parasitological, molecular, and serological methods to detect Trypanosoma spp. infection in D. albiventris (n = 43) from forest fragments. PCR was performed with primers specific for 18S rDNA, 24Sα rDNA, mini-chromosome satellites, and mini-exon genes. IFAT was used to detect anti-Trypanosoma cruzi IgG. All hemoculture was negative. We detected trypanosomatid DNA in blood of 35% of opossum. Two opossums were seropositive for T. cruzi. The trypanosomatid species number infecting D. albiventris was higher in the areas with greater abundance, rather than richness of small mammals. We found D. albiventris parasitized by T. cruzi in single and co-infections with Leishmania spp., recently described molecular operational taxonomic unit (MOTU) named DID, and Trypanosoma lainsoni. We concluded that (i) trypanosome richness may be determined by small mammal abundance, (ii) D. albiventris confirmed to be bio-accumulators of trypanosomatids, and (iii) T. lainsoni demonstrated a higher host range than described up to the present.

Landscape-scale forest loss as a catalyst of population and biodiversity change

Global biodiversity assessments have highlighted land-use change as a key driver of biodiversity change. However, there is little empirical evidence of how habitat transformations such as forest loss and gain are reshaping biodiversity over time. We quantified how change in forest cover has influenced temporal shifts in populations and ecological assemblages from 6090 globally distributed time series across six taxonomic groups. We found that local-scale increases and decreases in abundance, species richness, and temporal species replacement (turnover) were intensified by as much as 48% after forest loss. Temporal lags in population- and assemblage-level shifts after forest loss extended up to 50 years and increased with species' generation time. Our findings that forest loss catalyzes population and biodiversity change emphasize the complex biotic consequences of land-use change.

The geography of biodiversity change in marine and terrestrial assemblages

Human activities are fundamentally altering biodiversity. Projections of declines at the global scale are contrasted by highly variable trends at local scales, suggesting that biodiversity change may be spatially structured. Here, we examined spatial variation in species richness and composition change using more than 50,000 biodiversity time series from 239 studies and found clear geographic variation in biodiversity change. Rapid compositional change is prevalent, with marine biomes exceeding and terrestrial biomes trailing the overall trend. Assemblage richness is not changing on average, although locations exhibiting increasing and decreasing trends of up to about 20% per year were found in some marine studies. At local scales, widespread compositional reorganization is most often decoupled from richness change, and biodiversity change is strongest and most variable in the oceans.

Inside or out? Cave size and landscape effects on cave-roosting bat assemblages in Brazilian Caatinga caves

Cave bats have an intimate association with their roosts. Size, structural heterogeneity, and microclimatic conditions are traits of caves known to affect the structure of these assemblages. The effects of the natural and anthropogenic landscape factors around caves on the structure of these assemblages are poorly known, especially in areas with large cave clusters. We assessed the effects of cave size and surrounding landscape attributes on the richness and species composition of cave-roosting bats in 13 caves distributed in two landscapes with large cave clusters in Caatinga dry forests, Brazil. In a 1-km buffer around caves, we obtained 13 internal cave and external landscape variables. Candidate univariate models using generalized linear models were constructed and the Akaike information criterion was used for model selection. The cave size model explained richness and variance in the species composition; larger caves tended to have greater richness and assemblage composition varied depending on the cave size, hence affecting the occurrence of certain species, some of conservation concern (Natalus macrourus, Furipterus horrens). The cave connectivity model affected only the richness; caves located in denser cave clusters had higher richness likely attributed to movement of bats among caves by a more diverse array of species. Both environmental and anthropic variables affected species composition, but differently depending of the landscape context of cave location (protected versus nonprotected area). The extent these landscape variables affected the species composition was due to species-specific responses, and observed in the mean colony sizes of the species shared between the cave systems. All the landscape variables that we tested affected the structuring process of cave-roosting bats assemblages, and evidences that variables found in disturbed karstic landscapes also affect the structure of the assemblage (e.g., large colonies of vampire bats). However, the ubiquitous effect of cave size on both richness and species composition reinforces the critical importance of the roost in the life of these flying mammals.

Os morcegos que se abrigam em cavernas têm uma associação muito íntima com seus abrigos. Sabe-se que as características de caverna, como o tamanho, heterogeneidade estrutural e condições microclimáticas estáveis, afetam a estrutura das assembleias dos morcegos cavernícolas. No entanto, os efeitos dos fatores externos naturais e antrópicos da paisagem em torno de cavernas na estrutura das assembleias destes morcegos são pouco conhecidos, especialmente em paisagens cársticas com grandes aglomerados de cavernas. Assim, avaliamos os efeitos do tamanho da caverna e dos atributos da paisagem circundante na riqueza e composição de espécies de morcegos em 13 cavernas distribuídas em duas paisagens de Caatinga com grandes aglomerados de cavernas no Rio Grande do Norte. Em um buffer de 1 km ao redor de cada caverna, obtivemos 13 variáveis de paisagem interna (tamanho da caverna) e externa (número de cavernas circundantes, variáveis antropogênicas e ambientais); Modelos candidatos univariados usando GLM foram construídos e o Critério de Informação de Akaike foi usado para a seleção dos modelos. O modelo de tamanho das cavernas explicou a riqueza e a variação na composição das espécies; cavernas maiores tendem a ter maior riqueza e composição da assembleia variando de acordo com o tamanho da caverna, afetando, portanto, a ocorrência de certas espécies, algumas vulneráveis (Natalus macrourus, Furipterus horrens). O modelo de conectividade da caverna afetou apenas a riqueza; cavernas localizadas em aglomerados maiores tinham maior riqueza. As variáveis ambientais e antrópicas afetaram diferentemente a composição das espécies dependendo do contexto da paisagem da localização da caverna (área protegida versus não protegida). As variáveis da paisagem afetaram a composição das espécies ocorreu de uma forma específica em algumas espécies e foi observada no tamanho médio das colônias das espécies compartilhadas entre os sistemas de cavernas. Todas as variáveis da paisagem que testamos afetaram o processo de estruturação de assembleias de morcegos cavernícolas, incluindo aquelas que são características de uma paisagem cárstica perturbada. Todas as variáveis de paisagem que testamos afetaram o processo de estruturação de assembleias de morcegos que pousam em cavernas e evidenciam que variáveis encontradas em paisagens cársticas perturbadas também afetam a estrutura da assembleia (por exemplo, grandes colônias de morcegos vampiros). No entanto, o efeito ubíquo do tamanho da caverna sobre a riqueza e a composição das espécies reforça a importância crítica do abrigo na vida desses mamíferos voadores.

Do riparian forest strips in modified forest landscapes aid in conserving bat diversity?

Agricultural practices lead to losses of natural resources and biodiversity. Maintaining forests alongside streams (riparian forest strips) has been used as a mechanism to minimize the impact of clearing for agriculture on biodiversity. To test the contribution of riparian forest strips to conserve biodiversity in production landscapes, we selected bats as a biodiversity model system and examined two dimensions of diversity: taxonomic and functional. We compared bat diversity and composition in forest, with and without stream habitat, and in narrow forest riparian strips surrounded by areas cleared for agriculture. We tested the hypothesis that riparian forest strips provide potential conservation value by providing habitat and serving as movement corridors for forest bat species. Riparian forest strips maintained 75% of the bat species registered in forested habitats. We found assemblage in sites with riparian forest strips were dominated by a few species with high abundance and included several species with low abundance. Bat species assemblage was more similar between sites with streams than between those sites to forests without stream habitat. These results highlight the importance of stream habitat in predicting presence of bat species. We registered similar number of guilds between forest sites and riparian forest strips sites. Relative to matrix habitats, stream and edge habitats in riparian forest strips sites were functionally more diverse, supporting our hypothesis about the potential conservation value of riparian forest strips. Results from this study suggest that maintaining riparian forest strips within cleared areas for agricultural areas helps conserve the taxonomic and functional diversity of bats. Also, it provides basic data to evaluate the efficacy of maintaining these landscape features for mitigating impacts of agricultural development on biodiversity. However, we caution that riparian forest strips alone are not sufficient for biodiversity maintenance; their value depends on maintenance of larger forest areas in their vicinity.

BioTIME: A database of biodiversity time series for the Anthropocene

MOTIVATION

The BioTIME database contains raw data on species identities and abundances in ecological assemblages through time. These data enable users to calculate temporal trends in biodiversity within and amongst assemblages using a broad range of metrics. BioTIME is being developed as a community-led open-source database of biodiversity time series. Our goal is to accelerate and facilitate quantitative analysis of temporal patterns of biodiversity in the Anthropocene.

MAIN TYPES OF VARIABLES INCLUDED

The database contains 8,777,413 species abundance records, from assemblages consistently sampled for a minimum of 2 years, which need not necessarily be consecutive. In addition, the database contains metadata relating to sampling methodology and contextual information about each record.

SPATIAL LOCATION AND GRAIN

BioTIME is a global database of 547,161 unique sampling locations spanning the marine, freshwater and terrestrial realms. Grain size varies across datasets from 0.0000000158 km2 (158 cm2) to 100 km2 (1,000,000,000,000 cm2).

TIME PERIOD AND GRAIN

BioTIME records span from 1874 to 2016. The minimal temporal grain across all datasets in BioTIME is a year.

MAJOR TAXA AND LEVEL OF MEASUREMENT

BioTIME includes data from 44,440 species across the plant and animal kingdoms, ranging from plants, plankton and terrestrial invertebrates to small and large vertebrates.

SOFTWARE FORMAT

.csv and .SQL.

Male-biased dispersal and the potential impact of human-induced habitat modifications on the Neotropical bat Trachops cirrhosus

Gene flow, maintained through natal dispersal and subsequent mating events, is one of the most important processes in both ecology and population genetics. Among mammalian populations, gene flow is strongly affected by a variety of factors, including the species' ability to disperse, and the composition of the environment which can limit dispersal. Information on dispersal patterns is thus crucial both for conservation management and for understanding the social system of a species. We used 16 polymorphic nuclear microsatellite loci in addition to mitochondrial DNA sequences (1.61 kbp) to analyse the population structure and the sex-specific pattern of natal dispersal in the frog-eating fringe-lipped bat, Trachops cirrhosus, in Central Panama. Our study revealed that-unlike most of the few other investigated Neotropical bats-gene flow in this species is mostly male-mediated. Nevertheless, distinct genetic clusters occur in both sexes. In particular, the presence of genetic differentiation in the dataset only consisting of the dispersing sex (males) indicates that gene flow is impeded within our study area. Our data are in line with the Panama Canal in connection with the widening of the Río Chagres during the canal construction acting as a recent barrier to gene flow. The sensitivity of T. cirrhosus to human-induced habitat modifications is further indicated by an extremely low capture success in highly fragmented areas. Taken together, our genetic and capture data provide evidence for this species to be classified as less mobile and thus vulnerable to habitat change, information that is important for conservation management.

Establishing baseline biodiversity data prior to hydroelectric dam construction to monitoring impacts to bats in the Brazilian Amazon

The modification of Amazonian rivers by the construction of megaprojects of hydroelectric dams has widely increased over the last decade. Robust monitoring programs have been rarely conducted prior to the establishment of dams to measure to what extent the fauna, and its associated habitats may be affected by upcoming impacts. Using bats as models, we performed analyses throughout the area under the influence of the Santo Antônio hydroelectric dam, Southwestern Brazilian Amazonia before its construction to estimate how the fauna and its associated habitats would be affected by the upcoming impacts. We surveyed bats in 49 plots distributed along the areas going to be inundated by the dam and those remaining dry. As predictors for the species distribution, we tested the variables of vegetation structure and topography. Species composition largely differed between the dry plots and the plots located in areas that will be flooded, and this was strongly associated with the variables of forest basal area and elevation. Vegetation-related variables also had strong influence on the guilds distribution. The flooding of lower elevations areas is expected to negatively affect the species number and abundance of frugivorous species. In contrast, it is likely that animalivores will be less vulnerable to dam-induced flooding, since they were abundant in the areas not expect to be inundated. We urge for the implementation of studies to predict impacts caused by large hydroelectric dams, including tests of the influence of the local conditions that shape diversity to avoid massive losses of the biota, and to build preventive monitoring and management actions.

Comparative landscape genetics of two frugivorous bats in a biological corridor undergoing agricultural intensification

Agricultural intensification in tropical landscapes poses a new threat to the ability of biological corridors to maintain functional connectivity for native species. We use a landscape genetics approach to evaluate impacts of expanding pineapple plantations on two widespread and abundant frugivorous bats in a biological corridor in Costa Rica. We hypothesize that the larger, more mobile Artibeus jamaicensis will be less impacted by pineapple than the smaller Carollia castanea. In 2012 and 2013, we sampled 735 bats in 26 remnant forest patches surrounded by different proportions of forest, pasture, crops and pineapple. We used 10 microsatellite loci for A. jamaicensis and 16 microsatellite loci for C. castanea to estimate genetic diversity and gene flow. Canonical correspondence analyses indicate that land cover type surrounding patches has no impact on genetic diversity of A. jamaicensis. However, for C. castanea, both percentage forest and pineapple surrounding patches explained a significant proportion of the variation in genetic diversity. Least-cost transect analyses (LCTA) and pairwise G″st suggest that for A. jamaicensis, pineapple is more permeable to gene flow than expected, while as expected, forest is the most permeable land cover for gene flow of C. castanea. For both species, LCTA indicate that development may play a role in inhibiting gene flow. The current study answers the call for landscape genetic research focused on tropical and agricultural landscapes, highlights the value of comparative landscape genetics in biological corridor design and management and is one of the few studies of biological corridors in any ecosystem to implement a genetic approach to test corridor efficacy.

Season-modulated responses of Neotropical bats to forest fragmentation

Seasonality causes fluctuations in resource availability, affecting the presence and abundance of animal species. The impacts of these oscillations on wildlife populations can be exacerbated by habitat fragmentation. We assessed differences in bat species abundance between the wet and dry season in a fragmented landscape in the Central Amazon characterized by primary forest fragments embedded in a secondary forest matrix. We also evaluated whether the relative importance of local vegetation structure versus landscape characteristics (composition and configuration) in shaping bat abundance patterns varied between seasons. Our working hypotheses were that abundance responses are species as well as season specific, and that in the wet season, local vegetation structure is a stronger determinant of bat abundance than landscape‐scale attributes. Generalized linear mixed‐effects models in combination with hierarchical partitioning revealed that relationships between species abundances and local vegetation structure and landscape characteristics were both season specific and scale dependent. Overall, landscape characteristics were more important than local vegetation characteristics, suggesting that landscape structure is likely to play an even more important role in landscapes with higher fragment‐matrix contrast. Responses varied between frugivores and animalivores. In the dry season, frugivores responded more to compositional metrics, whereas during the wet season, local and configurational metrics were more important. Animalivores showed similar patterns in both seasons, responding to the same group of metrics in both seasons. Differences in responses likely reflect seasonal differences in the phenology of flowering and fruiting between primary and secondary forests, which affected the foraging behavior and habitat use of bats. Management actions should encompass multiscale approaches to account for the idiosyncratic responses of species to seasonal variation in resource abundance and consequently to local and landscape scale attributes.

Community structure of fleas within and among populations of three closely related rodent hosts: nestedness and beta-diversity

We studied nestedness and its relationships with beta-diversity in flea communities harboured by three closely related rodent species (Rhabdomys pumilio, Rhabdomys intermedius, Rhabdomys dilectus) at two spatial scales (within and among host populations) in South Africa and asked (a) whether variation in species composition of flea communities within and among host populations follows a non-random pattern; if yes, (b) what are the contributions of nestedness and species turnover to dissimilarity (= beta-diversity) among flea communities at the two scales; and (c) do the degree of nestedness and its contribution to beta-diversity differ among host species (socialvssolitary) and between scales. We found that nestedness in flea assemblages was more pronounced (a) in social than solitary host species and (b) at lower (among host individuals within populations) than at higher scale (among host populations). We also found that higher degree of nestedness was associated with its higher contribution to beta-diversity. Our findings support earlier ideas that parasite community structure results from the processes of parasite accumulation by hosts rather than from the processes acting within parasite communities.

Null model analysis on bat species co-occurrence and nestedness patterns in a region of the Atlantic Rainforest, Brazil

This study aimed to test through null models analysis the co-occurrence and nestedness patterns of bat species in a region of the Atlantic Rainforest. Data from 10 communities were tabulated in presence-absence matrices. Two metrics have been used to test the co-occurrence patterns: C-Score, which calculates the “checkerboard” pattern testing the interspecific competition between pairs of species, and V-Ratio, which calculates the covariance between species. All analyses were performed with EcoSim software. For nestedness analyses, we utilized the NODF metric through the Aninhado software. None of all the C-Score results showed a significant pattern of species association, indicating a higher coexistence among bat species. For V-Ratio, three results indicated nonrandom associations of species. The communities are highly nested, with poor species sites being subsets of richer sites. The diversification in this group allows the coexistence of species, decreasing the niche overlap. Nested pattern is common in mammal communities, and the significance of our results is in accordance with the results of the co-occurrence test. Competitive interactions may lead to differences in abundance of species in communities. However, as the method of bat sampling is considered biased, the results using binary data, as in our study, seems to be the most trustful method.

Responses of Tropical Bats to Habitat Fragmentation, Logging, and Deforestation

Land-use change is a key driver of the global biodiversity crisis and a particularly serious threat to tropical biodiversity. Throughout the tropics, the staggering pace of deforestation, logging, and conversion of forested habitat to other land uses has created highly fragmented landscapes that are increasingly dominated by human-modified habitats and degraded forests. In this chapter, we review the responses of tropical bats to a range of land-use change scenarios, focusing on the effects of habitat fragmentation, logging, and conversion of tropical forest to various forms of agricultural production. Recent landscape-scale studies have considerably advanced our understanding of how tropical bats respond to habitat fragmentation and disturbance at the population, ensemble, and assemblage level. This research emphasizes that responses of bats are often species and ensemble specific, sensitive to spatial scale, and strongly molded by the characteristics of the prevailing landscape matrix. Nonetheless, substantial knowledge gaps exist concerning other types of response by bats. Few studies have assessed responses at the genetic, behavioral, or physiological level, with regard to disease prevalence, or the extent to which human disturbance erodes the capacity of tropical bats to provide key ecosystem services. A strong geographic bias, with Asia and, most notably, Africa, being strongly understudied, precludes a comprehensive understanding of the effects of fragmentation and disturbance on tropical bats. We strongly encourage increased research in the Paleotropics and emphasize the need for long-term studies, approaches designed to integrate multiple scales, and answering questions that are key to conserving tropical bats in an era of environmental change and dominance of modified habitats (i.e., the Anthropocene).

Ground-Vegetation Clutter Affects Phyllostomid Bat Assemblage Structure in Lowland Amazonian Forest

Vegetation clutter is a limiting factor for bats that forage near ground level, and may determine the distribution of species and guilds. However, many studies that evaluated the effects of vegetation clutter on bats have used qualitative descriptions rather than direct measurements of vegetation density. Moreover, few studies have evaluated the effect of vegetation clutter on a regional scale. Here, we evaluate the influence of the physical obstruction of vegetation on phyllostomid-bat assemblages along a 520 km transect in continuous Amazonian forest. We sampled bats using mist nets in eight localities during 80 nights (3840 net-hours) and estimated the ground-vegetation density with digital photographs. The total number of species, number of animalivorous species, total number of frugivorous species, number of understory frugivorous species, and abundance of canopy frugivorous bats were negatively associated with vegetation clutter. The bat assemblages showed a nested structure in relation to degree of clutter, with animalivorous and understory frugivorous bats distributed throughout the vegetation-clutter gradient, while canopy frugivores were restricted to sites with more open vegetation. The species distribution along the gradient of vegetation clutter was not closely associated with wing morphology, but aspect ratio and wing load differed between frugivores and animalivores. Vegetation structure plays an important role in structuring assemblages of the bats at the regional scale by increasing beta diversity between sites. Differences in foraging strategy and diet of the guilds seem to have contributed more to the spatial distribution of bats than the wing characteristics of the species alone.

Effects of land use on bat diversity in a complex plantation–forest landscape in northeastern Brazil

In fragmented areas, the persistence of different species depends on their ability to use the surrounding matrix either as a corridor or as a foraging habitat. We assessed how species richness and abundance of Neotropical bats differ among forest fragments and rubber plantations under different management regimes. Our study site was located in a heterogeneous agricultural area in the Atlantic Forest of Bahia, northeastern Brazil. By combining mist netting and acoustic monitoring as complementary techniques, we caught 28 phyllostomid species and recorded 21 aerial insectivorous species, which either forage in open space or close to forests. Open space species were equally abundant and diverse in all land use types. In contrast, assemblages of phyllostomid and aerial insectivorous forest species differed significantly among habitats, with the highest species richness recorded in forest fragments. We identified a number of forest specialists in forest fragments, which indicates a relatively intact bat fauna. In intensively used rubber-cacao plantation, we found surprisingly high bat abundance and diversity, despite the shortage of resources for bats. Our results also indicate that patches of secondary vegetation around rubber plantations are important landscape features for bats and might contribute to the persistence of highly diverse bat assemblages. We suggest that bats do not perceive plantations as a hostile matrix, but probably use them as corridors between forest fragments and patches of secondary vegetation.

Em áreas fragmentadas, a persistência de diferentes espécies depende da habilidade delas em usar a matriz ao redor como um corredor ou hábitat de forrageio. Nós avaliamos como a riqueza de espécies e abundância de morcegos neotropicais diferem entre fragmentos de mata e seringais sob diferentes regimes de manejo. Nossa área de estudo estava localizada em uma área agrícola heterogênea na Mata Atlântica da Bahia, nordeste do Brasil. Combinando capturas em redes com monitoramento acústico como técnicas complementares, capturamos 28 espécies de morcegos filostomídeos e 21 espécies de morcegos insetívoros aéreos, que forrageiam em espaço aberto ou perto de florestas. As espécies de espaço aberto foram igualmente abundantes e diversas em todas as categorias de uso da terra. Por outro lado, comunidades de filostomídeos e insetívoros aéreos de florestas diferiram significativamente entre hábitats, com a maior riqueza de espécies tendo sido registrada em fragmentos de mata. Identificamos muitos especialistas em florestas nos fragmentos de mata, o que sugere que a fauna de morcegos ainda está relativamente intacta. Em plantações mistas de cacau e seringais intensivamente usadas, encontramos uma abundância e riqueza de morcegos surpreendentemente altas, apesar da escassez de recursos para morcegos. Nossos resultados indicam que manchas de vegetação secundária ao redor de seringais são importantes elementos da paisagem para morcegos e podem contribuir para a persistência de comunidades altamente diversas. Sugerimos que morcegos não percebem as plantações como uma matriz hostil, mas provavelmente as usam como corredores entre fragmentos de mata e manchas de vegetação secundária.

Assembly patterns of mixed-species avian flocks in the Andes

The relative contribution of deterministic and stochastic processes in the assembly of biotic communities is a central issue of controversy in community ecology. However, several studies have shown patterns of species segregation that are consistent with the hypothesis that deterministic factors such as competition and niche-partitioning structure species assemblages in animal communities. Community assembly provides a theoretical framework for understanding these processes, but it has been seldom applied to social aggregations within communities. In this research, we assessed patterns of non-randomness in Andean mixed-species flocks using three assembly models: (i) co-occurrence patterns; (ii) guild proportionality; and (iii) constant body-size ratios using data from 221 species of resident and Neotropical migrant birds participating in 311 mixed-species flocks at 13 regions distributed in Venezuela, Colombia, Ecuador and Peru. Significant assembly patterns for mixed-species flocks based on co-occurrence models and guild proportionality models suggest that competitive interactions play an important role in structuring this social system in the Andes. Distribution of species among foraging guilds (i.e. insectivore, frugivore, omnivore, nectivore) was generally similar among flocks, though with some regional variation. In contrast, we found little evidence that structuring of mixed-species flocks in the Andes was mediated by body size. Rather, we found greater than expected variance of body-size ratios within flocks, indicating that birds did not segregate morphologically. Overall, our findings suggest that deterministic factors associated to competitive interactions are important contributors to mixed-species flock assemblages across the Andes.

Nestedness in forest mammals is dependent on area but not on matrix type and sample size: an analysis on different fragmented landscapes

Nestedness, the pattern in which the species of a species-poor community are a subset of species-rich communities, can provide information regarding species order of extinction, which is vital knowledge for conservation biology. We tested the hypotheses that the nestedness of mammal communities in forest remnants is influenced by sampling effort, mean remnant area, range of remnant areas, matrix type, and presence or absence of forest corridors, and compared the results with multi-taxa reviews. We used 24 published datasets to test this hypothesis and ran simple regressions for each variable. Our results provide evidence that area was the main determinant of nestedness in mammalian communities. We also found a significant effect on the range of areas as measured through area ratio. However we conclude that nestedness is not affected by sample size.

[Nested species subsets of amphibians and reptiles in Thousand Island Lake]

Habitat fragmentation is a main cause for the loss of biological diversity. Combining line-transect methods to survey the amphibians and reptiles on 23 islands on Thousand Island Lake in Zhejiang province, along with survey data on nearby plant species and habitat variables collected by GIS, we used the"BINMATNEST (binary matrix nestedness temperature calculator)" software and the Spearman rank correlation to examine whether amphibians and reptiles followed nested subsets and their influencing factors. The results showed that amphibians and reptiles were significantly nested, and that the island area and habitat type were significantly associated with their nested ranks. Therefore, to effectively protect amphibians and reptiles in the Thousand Islands Lake area we should pay prior attention to islands with larger areas and more habitat types.

Terrestrial vertebrate richness of the inhabited Torres Strait Islands, Australia

Located between New Guinea and Australia, Torres Strait and its islands provide an opportunity to examine the results of recent isolation on the Australo-Papuan fauna. However, records of the modern diversity of terrestrial vertebrates on the islands remained scattered and poorly documented. Analyses of terrestrial vertebrate inventories and physical island variables can provide insight into pre-existing conditions of the Sahul land bridge and useful strategies for conservation efforts. We collated all available records of terrestrial vertebrates from the 17 inhabited islands and supplemented these with our own systematic surveys. We used Spearman’s rank correlation coefficient and nested analysis to determine how species richness relates to physical island variables. We also used cluster analysis to group similar islands based on their vertebrate assemblages. Vertebrate richness is not correlated with Simpson’s habitat diversity but is correlated with total number of habitat types, indicating that rare habitats may contribute disproportionately to richness. The archipelago supports a depauperate Australo-Papuan fauna and the assemblages found on smaller islands are subsets of those on larger islands. Island size is the most effective predictor of species richness, and the analysis reveals that geographically related islands support similar suites of species. The frequency with which our surveys added new records to individual island inventories highlights the need for additional sampling in the region.

Assessing patterns of nestedness and co-occurrence in coastal pond anuran assemblages

Segregated species co-occurrence and nestedness are two ecological patterns used to measure assemblage structure. We investigated species co-occurrence and nestedness patterns in assemblages of tadpoles and adult anurans in 30 coastal ponds in southern Brazil. Ponds varied in hydroperiod and were classified as temporary or permanent. We explored whether co-occurrence or nestedness varied among ponds in each hydroperiod. Species co-occurrence patterns were analyzed using the C-score index and three null models. In order to quantify nestedness, we used the nestedness metric based on overlap and decreasing fill (NODF). We found seventeen anuran species; however, only 13 species were observed in breeding activity, and 11 species were observed as tadpoles. The co-occurrence and nestedness analyses showed that anuran assemblages exhibit non-random patterns that were generally contingent on the hydroperiod and pond area. Only species in non-breeding adult anurans assemblages showed significant segregation when randomizations were weighted by pond area and the pattern was similar among hydroperiods. Tadpole assemblages of permanent ponds showed an aggregated co-occurrence in weighted-fixed model. In temporary ponds, NODF showed that anuran assemblages were significantly nestedness in all three phases of life cycle. We obtained contrasting results depending on the hydroperiod. These results support the hypothesis that habitat nestedness, due to hydroperiod, might be an important factor structuring anuran assemblages along the different phases of their life cycle.

High duty cycle echolocation and prey detection by bats

There are two very different approaches to laryngeal echolocation in bats. Although most bats separate pulse and echo in time by signalling at low duty cycles (LDCs), almost 20% of species produce calls at high duty cycles (HDCs) and separate pulse and echo in frequency. HDC echolocators are sensitive to Doppler shifts. HDC echolocation is well suited to detecting fluttering targets such as flying insects against a cluttered background. We used two complementary experiments to evaluate the relative effectiveness of LDC and HDC echolocation for detecting fluttering prey. We measured echoes from fluttering targets by broadcasting artificial bat calls, and found that echo amplitude was greatest for sounds similar to those used in HDC echolocation. We also collected field recordings of syntopic LDC and HDC bats approaching an insect-like fluttering target and found that HDC bats approached the target more often (18.6% of passes) than LDC bats (1.2% of passes). Our results suggest that some echolocation call characteristics, particularly duty cycle and pulse duration, translate into improved ability to detect fluttering targets in clutter, and that HDC echolocation confers a superior ability to detect fluttering prey in the forest understory compared with LDC echolocation. The prevalence of moths in the diets of HDC bats, which is often used as support for the allotonic frequency hypothesis, can therefore be partly explained by the better flutter detection ability of HDC bats.

Spatio-temporal nested patterns in macroinvertebrate assemblages across a pond network with a wide hydroperiod range

Nestedness has been widely used to measure the structure of biological communities and occurs when species-poor sites contain subsets of species-rich ones. Here, we examine nested patterns across the macroinvertebrate assemblages of 91 ponds in Doñana National Park, Spain, and explore temporal variation of nestedness and species richness in 19 temporary ponds over 2 years with differing rainfall. Macroinvertebrate assemblages were significantly nested; both pond spatial arrangement and environmental variation being important in driving nested patterns. Despite the nested structure observed, a number of taxa and ponds deviate from this pattern (termed idiosyncratic), by occurring more frequently than expected in species-poor sites, or having assemblages dominated by species largely absent from species-rich sites. Aquatic adults of winged insects, capable of dispersal, were more highly nested than non-dispersing taxa and life-history stages. Idiosyncratic taxa were found in ponds spanning a wide range of hydroperiods, although nestedness was higher in more permanent waterbodies. Monthly sampling demonstrated a gradual increase of species richness and nestedness from pond filling to April-May, when the most temporary ponds started to dry. Although the degree of nestedness of individual pond assemblages varied from month to month, the overall degree of nestedness in the two study years was practically identical despite marked differences in hydroperiod. Our results suggest that differential colonization and environmental variation are key processes driving the nested structure of Doñana ponds, that macroinvertebrate assemblages change in a predictable manner each year in response to cycles of pond wetting and drying, and that connectivity and environmental variability maintain biodiversity in pond networks.

Habitat fragmentation and haemoparasites in the common fruit bat, Artibeus jamaicensis (Phyllostomidae) in a tropical lowland forest in Panamá

Anthropogenic influence on ecosystems, such as habitat fragmentation, impacts species diversity and interactions. There is growing evidence that degradation of habitats favours disease and hence affects ecosystem health. The prevalence of haemoparasites in the Common Fruit Bat (Artibeus jamaicensis) in a tropical lowland forest in Panamá was studied. We assessed the relation of haemoparasite to the general condition of the animals and tested for possible association of haemoparasite prevalence to habitat fragmentation, with special focus on trypanosomes. Overall, a total of 250 A. jamaicensis sampled from fragmented sites, here man-made, forested islands in Lake Gatùn, and sites in the adjacent, continuous forest in and around the Barro Colorado Nature Monument were examined. Using microscopy and DNA-sequencing 2 dominant types of haemoparasite infections, trypanosomes and Litomosoides (Nematoda) were identified. Trypanosome prevalence was significantly higher in bats from forest fragments, than in bats captured in continuous forest. We attribute this to the loss of species richness in forest fragments and specific characteristics of the fragments favouring trypanosome transmission, in particular changes in vegetation cover. Interestingly, the effect of habitat fragmentation on the prevalence of trypanosomes as multi-host parasites could not be observed in Litomosoides which probably has a higher host specificity and might be affected less by overall diversity loss.

Habitat and fig characteristics influence the bird assemblage and network properties of fig trees from Xishuangbanna, South-West China

To understand how fruit tree characteristics and microhabitats shape the assemblage of birds on fig trees and the pattern of fig–bird interactions, we observed and recorded, over 96 d and 816 h, the frugivorous birds visiting 32 individual trees belonging to 14 species of Ficus that were distributed across four different sites. A total of 30 bird species were recorded as eating figs, comprising 66.7% of the total number of frugivorous bird species recorded at the four sites. Small passerine birds such as bulbuls were the dominant frugivores for fig species. The number of bird species visiting different fig trees was significantly influenced by the crop size and canopy volume. Fruit colour and fruit size did not significantly influence the number of bird species, whereas habitats appeared to influence the composition of visiting birds. The fig–frugivorous bird interaction was asymmetrically structured, and the degree of nestedness appeared to be influenced by the forest type and degree of disturbance: the degree of nestedness in non-limestone forest tended to be higher than limestone forest; forest with less disturbance tend to be more nested compared with the open forest with high disturbance.