Neotropical Communities Research Articles

Reproductive biology and flower-visitor interactions of two bromeliad species from the Brazilian Atlantic Forest

Background and aims – The Bromeliaceae family has great importance in the maintenance of neotropical communities. In the Brazilian Atlantic Forest, bromeliads are among the major groups responsible for maintaining the local flora and fauna and participate in important ecological interactions with insects, anurans, and hummingbirds. This work reports on aspects of the reproductive biology and the interactions between two endemic bromeliad species from the Atlantic Forest (Aechmea bruggeri and Quesnelia indecora) and their floral visitors to assess the impact of these relationships on the reproductive success and conservation of these plants.Material and methods – Reproductive phenology, floral biology, pollination experiments, and the reproductive success of both species were investigated. To determine the floral visitors, we made direct observations on flowers and collected floral visitors that could not be identified in the field.Key results – Aechmea bruggeri and Quesnelia indecora presented the individual and population flowering phenological pattern classified as annual with intermediate duration. The species are partially and totally self-incompatible, respectively. Both species presented a varied visitation guild, and although Q. indecora presented flowers with ornitofilous characteristics, no hummingbirds were recorded for this species. The hummingbird Thalurania glaucopis was the main visitor for Aechmea bruggeri and the bee Trigona cf. braueri was the main visitor for Quesnelia indecora. Nectar thieving by lepidopterans was observed for both species. Pollen robbing by beetles and nectar robbing by bees were registered for Aechmea bruggeri and Quesnelia indecora, respectively. Fruit and seed set of both species were highly affected by herbivory, which may negatively affect their reproductive success.Conclusion – Our work highlights the important role of bromeliads in neotropical communities, showing how floral visitors and plants interact by participating in maintaining biological diversity in the studied forest remnant.

Influence of sampling methods on the description of a Neotropical seed dispersal network

Analysis of ecological networks is a useful approach to investigate species interactions. However, sampling method may influence the observed patterns especially in highly diverse communities. Here we evaluated how sampling decisions influence the characterization of a seed dispersal network between frugivorous birds and plants in a Neotropical community, in Brazil. We found that phytocentric and zoocentric approaches were highly complementary, with only 3.6% of the links in common between both approaches. The phytocentric network was less asymmetric and had higher values for specialization (H2’) and modularity (Qw) than the zoocentric, which in turn had more plants, and higher nestedness (NODFc). The network combining both methods was larger and had intermediate values of specialization, modularity and nestedness. Furthermore, species-level metrics: normalized degree, specialization (d') and species strength, were not correlated between the two methods for the bird and plant species in common. Our results indicate that the choice of sampling method may affect the interpretation of network structure and the role species play in the communities. Moreover, while phytocentric sampling may limit the detection of interactions to plants seen by the observer, zoocentric sampling tends to undersample bird species with higher body mass or that do not forage in the understory. We stress that the choice of sampling method requires careful consideration of the most appropriate spatial scales to describe an interaction pattern, as well as their advantages and limitations, to better understand the drivers and consequences of species interactions.

A life dedicated to the classification of neotropical plant communities: a tribute to Antoine M. Cleef

A life dedicated to the classification of neotropical plant communities: a tribute to Antoine M. Cleef

More than meets the eye: decrypting diversity reveals hidden interaction specificity between frogs and frog‐biting midges

1. Female frog‐biting midges (Diptera: Corethrellidae) eavesdrop on the nocturnal mating calls of their blood hosts – male frogs. Available data suggest variable degrees of specialisation among Corethrella‐host associations, with limited information on the mechanisms involved in host selection and partitioning on a community level.2. Our study provides a first comprehensive analysis of host interactions for a neotropical community of frog‐biting midges, based on both morphological and molecular genetic species delimitation. We used quantitative bipartite interaction networks to investigate host specificity among the midge‐frog community of La Gamba, Pacific lowland Costa Rica.3. Midges that were collected directly from frog hosts (16 frog species) showed more pronounced levels of specificity (network‐wide degree of specialisation: H2′ = 0.3) than those caught with acoustic traps broadcasting their calls (12 frog species; H2′ = 0.08). This indicates that, despite a rather generalist acoustic foraging behaviour, frog‐biting midges discriminate between potential hosts by using additional close‐range recognition cues.4. Based on COI and ITS2 sequencing data, we identified considerable levels of cryptic diversity within our five Corethrella morphotypes, with at least 17 distinct MOTUs of Corethrella in La Gamba. Including these MOTUs in bipartite network analyses produced higher resolution in species interactions, and increased estimators of network specificity (H2′ = 0.42).

Subsistence Hunting During the COVID-19 Pandemic: The Case of the White-Tailed Deer (Odocoileus virginianus) in Rural Communities of Calakmul, Campeche, Mexico

Subsistence hunting for obtaining wild meat is a common practice in rural neotropical communities. Like other peasant practices disrupted by the COVID-19 pandemic, subsistence hunting could exacerbate pressure on wild mammals whose greater size contributes to feeding the hunter and his family. Thus, in the context of the pandemic, we assessed the subsistence hunting of the white-tailed deer ( Odocoileus virginianus), one of the main traditional game species in the Calakmul region, Campeche, Mexico, and compared this activity with its pre-pandemic levels of such vertebrate species. Based on ethnographic information and hunting records from three rural communities, we found that in one trimester (July-September 2020) of the rainy season, a total of 26 white-tailed deer (923 kg of game biomass) were obtained by local peasant-hunters carrying out hunting mostly alone. Most peasant-hunters interviewed (36 of 51) stated that they hunted daily, and only a few hunted once a week or once a month (8 and 3%, respectively). This hunting activity and modalities were carried out at night (68%) versus day, stalking (21%) and opportunist (11%) near their community. The game biomass and hunting frequency in the studied communities were twice as high during the pandemic, compared to similar pre-pandemic periods in the region. Our survey highlights the need to expand monitoring and evaluation (during and after the pandemic) of subsistence hunting on key species, such as white-tailed deer, in order to ensure conservation and sustainable use of wildlife in this important Mesoamerican region.

Insectivorous birds in the Neotropics: Ecological radiations, specialization, and coexistence in species-rich communities

AbstractInsectivorous birds reach their highest diversity in the tropics and represent a striking variety of morphological and behavioral specializations for foraging, yet explanations for these patterns are inadequate because of both our limited understanding of the drivers of ecological diversification within and among clades and of coexistence mechanisms in particular. Here we synthesize recent information on Neotropical insectivorous birds, including their diversity, evolutionary ages and locations of origin, phylogenies, and both competitive and predator–prey species interactions. We propose a novel evolutionary hypothesis for the origin and coexistence of the phenotypic diversity of insectivore foraging morphologies in species-rich communities, based on their extraordinary food-resource specializations. Specifically, we develop the Biotic Challenge Hypothesis to explain the evolution of these specializations, and we provide preliminary evidence in support of this hypothesis based on a synopsis of both Neotropical insectivore specializations by family and arthropod antipredator adaptations by category. We argue that, from the perspective of tropical insectivorous birds, and particularly in the most species-rich, mainland Neotropical communities, the environment is an arthropod desert. Coexistence with all of the other insectivores requires feeding specialization to compete exploitatively and diffusely against evolutionarily diverse species and far less frequently against sister species. The arthropod desert arises primarily because of (1) the tactical diversity of arthropod predators as insectivore competitors and (2) the evolutionary arms races involving arthropod predators with their prey, which render many arthropods inaccessible to most insectivorous predators. Our idea provides an explicit mechanism for pervasive, diffuse tropical interspecific competition, for evolutionary specialization, and for positive feedback on speciation rates at low latitudes, thereby generating new predictions and insights into tropical life histories and the Latitudinal Diversity Gradient. Other recent ideas concerning the coexistence of Neotropical insectivores, including positive species interactions within mixed species flocks, are recognized and evaluated. We discuss ways to test predictions resulting from the new view of communities developed here, including a case study of diet specialization by Costa Rican tyrannid flycatchers. Our synthesis of the origin and nature of Neotropical insectivore communities injects new life into the “zombie” idea that evolution works differently in the species-rich tropics.

Can chaoborid larvae control their zooplanktonic prey populations in a neotropical lake?

AbstractAlthough it is well known that predatory Chaoborus Lichtenstein 1800 larvae have a strong negative impact on zooplankton populations in many Holarctic lakes, this top‐down control is still not entirely clear in the Neotropics. In Lake Carioca, a Brazilian monomictic lake, chaoborids became one of the main zooplankton predators after the depletion of planktivorous fish by non‐native piscivorous fish. The aim of this research was to test the hypothesis that Chaoborus spp. larvae control the density of their prey populations. Enclosures simulated conditions with higher (Pr+) and lower (Pr−) predatory Chaoborus spp. larva densities over 30 days in two periods (stratification and mixing). Our results indicated that the dominant copepod species was affected only in the stratification period when its population was smaller. In this circumstance, predated individuals were probably not replaced in the same proportion by reproductive output of the smaller population. Rotifers were not sensitive to changes in chaoborids densities in both periods. The lack of a strong top‐down effect recorded by our mesocosm experiments emphasises the importance of continuing to investigate the ecological roles played by this invertebrate predator in aquatic food webs and if its ability to regulate the zooplankton in most Holarctic lakes can (or cannot) be widely generalised to Neotropical communities. Such a result also suggests that alternative research approaches, besides in‐situ experiments, may be necessary to better clarify this topic. Specifically for cladocerans, parallel paleolimnological analyses in Lake Carioca have supported the idea of a possible negative impact of Chaoborus larvae on bosminids after the introduction of non‐native piscivorous fishes.Abstract in Portuguese is available with online material.

Geographically divergent evolutionary and ecological legacies shape mammal biodiversity in the global tropics and subtropics

Studies of the factors governing global patterns of biodiversity are key to predicting community responses to ongoing and future abiotic and biotic changes. Although most research has focused on present-day climate, a growing body of evidence indicates that modern ecological communities may be significantly shaped by paleoclimatic change and past anthropogenic factors. However, the generality of this pattern is unknown, as global analyses are lacking. Here we quantify the phylogenetic and functional trait structure of 515 tropical and subtropical large mammal communities and predict their structure from past and present climatic and anthropogenic factors. We find that the effects of Quaternary paleoclimatic change are strongest in the Afrotropics, with communities in the Indomalayan realm showing mixed effects of modern climate and paleoclimate. Malagasy communities are poorly predicted by any single factor, likely due to the atypical history of the island compared with continental regions. Neotropical communities are mainly codetermined by modern climate and prehistoric and historical human impacts. Overall, our results indicate that the factors governing tropical and subtropical mammalian biodiversity are complex, with the importance of past and present factors varying based on the divergent histories of the world's biogeographic realms and their native biotas. Consideration of the evolutionary and ecological legacies of both the recent and ancient past are key to understanding the forces shaping global patterns of present-day biodiversity and its response to ongoing and future abiotic and biotic changes in the 21st century.

Density-dependent seed predation in Attalea geraensis Barb. Rodr. (Arecaceae) caused by bruchid beetles in the Brazilian Cerrado.

Palms are an important component of Neotropical communities as they are often diverse and abundant. In some areas, palms occur in high density and act as limiting factor in tree recruitment by limiting tree seedling and sapling abundance. In this study, I evaluated the intensity of seed mortality caused by insects in Attalea geraensis, in a large area of preserved Cerrado (Serra do Cabral, MG, Brazil) during wet season when both A. geraensis fruits and bruchid beetles were abundant. I collected a total of 63 infructescences which had from 3 fruits and 7 seeds to 82 fruits and 251 seeds. Endocarps had from 1 to 6 seeds. Seed mortality per infructescence due to beetles (Pachymerus cardo) was intense, and increases positively and disproportionally according to seed number per infructescence. Besides that, average proportions of seeds preyed upon by insects were consistently high (> 0.83), irrespective of seed number per endocarp. Positive density-dependent seed mortality caused by specialized natural enemies has been assumed to promote species rarity, an important feature of species coexistence in Neotropical forests. Then, the intense seed mortality documented in this study suggests that seed predators may contribute to the richness and diversity of plant species in the Cerrado, the richest and most endangered savanna in the world.

Indigenous knowledge networks in the face of global change

Indigenous communities rely extensively on plants for food, shelter, and medicine. It is still unknown, however, to what degree their survival is jeopardized by the loss of either plant species or knowledge about their services. To fill this gap, here we introduce indigenous knowledge networks describing the wisdom of indigenous people on plant species and the services they provide. Our results across 57 Neotropical communities show that cultural heritage is as important as plants for preserving indigenous knowledge both locally and regionally. Indeed, knowledge networks collapse as fast when plant species are driven extinct as when cultural diffusion, either within or among communities, is lost. But it is the joint loss of plant species and knowledge that erodes these networks at a much higher rate. Our findings pave the road toward integrative policies that recognize more explicitly the inseparable links between cultural and biological heritage.

How flower colour signals allure bees and hummingbirds: a community-level test of the bee avoidance hypothesis.

Colour signals are the main floral trait for plant-pollinator communication. Owing to visual specificities, flower visitors exert different selective pressures on flower colour signals of plant communities. Although they evolved to attract pollinators, matching their visual sensitivity and colour preferences, floral signals may also evolve to avoid less efficient pollinators and antagonistic flower visitors. We evaluated evidence for the bee avoidance hypothesis in a Neotropical community pollinated mainly by bees and hummingbirds, the campo rupestre. We analysed flower reflectance spectra, compared colour variables of bee-pollinated flowers (bee-flowers; 244 species) and hummingbird-pollinated flowers (hummingbird-flowers; 39 species), and looked for evidence of bee sensorial exclusion in hummingbird-flowers. Flowers were equally contrasting for hummingbirds. Hummingbird-flowers were less conspicuous to bees, reflecting mainly long wavelengths and avoiding red-blind visitors. Bee-flowers reflected more short wavelengths, were more conspicuous to bees (higher contrasts and spectral purity) than hummingbird-flowers and displayed floral guides more frequently, favouring flower attractiveness, discrimination and handling by bees. Along with no phylogenetic signal, the differences in colour signal strategies between bee- and hummingbird-flowers are the first evidence of the bee avoidance hypothesis at a community level and reinforce the role of pollinators as a selective pressure driving flower colour diversity.

Seed‐dispersal networks are more specialized in the Neotropics than in the Afrotropics

AbstractAimBiogeographical comparisons of interaction networks help to elucidate differences in ecological communities and ecosystem functioning at large scales. Neotropical ecosystems have higher diversity and a different composition of frugivores and fleshy‐fruited plants compared with Afrotropical systems, but a lack of intercontinental comparisons limits understanding of (a) whether plant–frugivore networks are structured in a similar manner, and (b) whether the same species traits define the roles of animals across continents.LocationAfrotropics and Neotropics.Time period1977–2015.TaxaFleshy‐fruited plants and frugivorous vertebrates.MethodsWe compiled a dataset comprising 17 Afrotropical and 48 Neotropical weighted seed‐dispersal networks quantifying frugivory interactions between 1,091 fleshy‐fruited plant and 665 animal species, comprising in total 8,251 interaction links between plants and animals. In addition, we compiled information on the body mass of animals and their degree of frugivory. We compared four standard network‐level metrics related to interaction diversity and specialization, accounting for differences related to sampling effort and network location. Furthermore, we tested whether animal traits (body mass, degree of frugivory) differed between continents, whether these traits were related to the network roles of species and whether these relationships varied between continents.ResultsWe found significant structural differences in networks between continents. Overall, Neotropical networks were less nested and more specialized than Afrotropical networks. At the species level, a higher body mass and degree of frugivory were associated with an increasing diversity of plant partners. Specialization of frugivores increased with the degree of frugivory, but only in the Neotropics.Main conclusionsOur findings show that Afrotropical networks have a greater overlap in plant partners among vertebrate frugivores than the more diverse networks in the Neotropics that are characterized by a greater niche partitioning. Hence, the loss of frugivore species could have stronger impacts on ecosystem functioning in the more specialized Neotropical communities compared with the more generalized Afrotropical communities.

Seasonal Variation in Bee-Plant Interactions in an Inselberg in the Atlantic Forest in Southeastern Brazil

Studies on bee-plant interactions are relevant to the understanding of temporal patterns in neotropical communities. In isolated habitats such as inselbergs little is yet known about the temporal dynamics in the availability of fl oral resources and interacting bee. In the present study, the objective is to verify the eff ect of seasonality on the bee-plant interaction in an Atlantic Forest inselberg in southeastern Brazil. The bees were sampled monthly in the dry (April/2008-September/2008) and wet seasons (October/2008-March/2009) using an entomological net. A total of 322 bees of 33 species were captured on fl owers of 34 species of plants during the year. Bees richness was similar between seasons (22 species in the wet season and 21 in the dry season), but abundance was higher in the wet season (60% of individuals) and higher diversity occurred in the dry season. Augochloropsis sp1 were the most abundant species and visited the largest number of plant species at each season. In the interaction network, plants with the highest degree were distinct between the seasons. The number of possible interactions was higher in the dry season compared to the wet season and connectance was similar; nestedness however varied between the seasons. The composition of plant and bees species was distinct between the seasons, as well as the interactions between them, mainly due to the alteration in the composition of the plant species and the change in the choice of the bees for the floral resources between the seasons.

The planalto hermit, Phaethornis pretrei – a key species in a Neotropical savanna community in Central Brazil

ABSTRACTAmong vertebrate pollinators, hummingbirds are the most important group in the Neotropics as they use a wide spectrum of plant species. The hummingbird Phaethornis pretrei (Phaethornithinae) was studied in a Neotropical savanna of Central Brazil. The objectives were to: (1) record the flowering period of species used by P. pretrei as food resources and establish whether this hummingbird is their exclusive visitor; (2) determine the return time of P. pretrei to a given plant species and the number of P. pretrei that use the same individual plant; (3) assess the pollen loads transported by P. pretrei; and (4) verify whether this hummingbird is resident in the area. The flowering period of plants used by P. pretrei was recorded for 22 months between 2007 and 2008. Focal observations were made concomitantly with capture and marking of hummingbirds and collection of pollen loads using adhesive tape. Phaethornis pretrei was recorded visiting 21 plant species, being the exclusive visitor of two species and performing more than 90% of visits to another four. Nineteen of those plant species were also visited by seven other hummingbird species. The return time of P. pretrei to typically ornithophilous flowers was around 1 hour and visits to the same plants were made by two or sometimes three individuals. Phaethornis pretrei may transport pollen of up to 10 species on its bill. This hummingbird is resident in the study area and promotes the flow of pollen, favouring the reproduction of several plant species. Therefore, it is a pollinator of great importance for this plant community, being a key species in the area in question.

Combining plant–frugivore networks for describing the structure of neotropical communities

Frugivory and seed dispersal are key processes for the maintenance of biodiversity. This is particularly true in the Neotropics, where most plant species depend on animals to disperse their seeds and most birds and mammals include fruits in their diets. We performed a continental‐scale literature review to build a database of interactions between neotropical fruits and fruit‐eating birds and mammals. Our objective was to evaluate the viability of combining literature data from different studies to describe the structure of highly diverse fruit–frugivore neotropical communities. We investigated sites that had been the focus of studies of at least four different avian and/or mammalian taxonomic orders and we included in our database only those conducted for at least a 6‐month period in order to account for the seasonality in fruit availability. In spite of a large number of study sites investigated for frugivory (n = 156), we found a huge gap in the knowledge of community‐wide fruit–frugivore interactions in the Neotropics, since most studies focused on single or a few species. Nevertheless, we were able to construct diverse plant–frugivore qualitative networks for 17 areas unevenly spread throughout the neotropical region. Using complex network analyses, we found that these networks were highly informative and non‐randomly organized. Most networks were both significantly nested and modular, characteristics related to stability and resilience in biological systems. We concluded that it is possible to use merged data to build networks for sites of conservation interest. The main advantage of using this approach is to optimize resources, avoiding exhaustive, costly and time‐consuming fieldwork when data is already available. Whilst bearing in mind the shortcomings of this methodology, these results can be used in studies aiming to understand the ecological processes structuring different communities in the neotropical region and to support conservation and restoration actions.

A pan-neotropical analysis of hunting preferences

Hunting in the neotropics is a widespread form of resource extraction. However, there is increasing concern that current activities are leading to the decline and extirpation of vulnerable species; particulary ateline primates, large ungulates (such as tapirs and white-lipped peccaries) and large birds such as curassows. Hunting patterns are expected to be a product of two principal influences: the value of return for a given amount of effort invested into hunting, and cultural factors that determine the prestige and usefulness of prey. Previous work has suggested that hunting profiles change in a predictable way over time, becoming more diverse and more dependent on smaller bodied species as preferred, large-bodied prey become scarcer. In this paper, we evaluate the hunting profiles of 78 neotropical communities in Central and South America. We investigate the uniformity of species preferences, whether communities that are geographically closer have similar hunting profiles, and whether the age and size of settlements can be used to predict the type and diversity of species targeted. We found that there was only a weak correlation between the structure of communities’ hunting profiles and their geographical proximity. Neither a community’s size nor age was a good predictor of the shape and structure of its hunting profile. Our data suggest that either the availability of prey or the cultural influences dictating the value of different species can change rapidly over small distances, and that older and larger settlements do not impact prey species distributions in a predictable way.

Disassembly of a tadpole community by a multi-host fungal pathogen with limited evidence of recovery.

Emerging infectious diseases can cause host community disassembly, but the mechanisms driving the order of species declines and extirpations following a disease outbreak are unclear. We documented the community disassembly of a Neotropical tadpole community during a chytridiomycosis outbreak, triggered by the generalist fungal pathogen, Batrachochytrium dendrobatidis (Bd). Within the first 11months of Bd arrival, tadpole density and occupancy rapidly declined. Species rarity, in terms of tadpole occupancy and adult relative abundance, did not predict the odds of tadpole occupancy declines. But species losses were taxonomically selective, with glassfrogs (Family: Centrolenidae) disappearing the fastest and tree frogs (Family: Hylidae) and dart-poison frogs (Family: Dendrobatidae) remaining the longest. We detected biotic homogenization of tadpole communities, with post-decline communities resembling one another more strongly than pre-decline communities. The entire tadpole community was extirpated within 22months following Bd arrival, and we found limited signs of recovery within 10years post-outbreak. Because of imperfect species detection inherent to sampling species-rich tropical communities and the difficulty of devising a single study design protocol to sample physically complex tropical habitats, we used simulations to provide recommendations for future surveys to adequately sample diverse Neotropical communities. Our unique data set on tadpole community composition before and after Bd arrival is a valuable baseline for assessing amphibian recovery. Our results are of direct relevance to conservation managers and community ecologists interested in understanding the timing, magnitude, and consequences of disease outbreaks as emerging infectious diseases spread globally.

Ant-mediated ecosystem processes are driven by trophic community structure but mainly by the environment

The diversity and functional identity of organisms are known to be relevant to the maintenance of ecosystem processes but can be variable in different environments. Particularly, it is uncertain whether ecosystem processes are driven by complementary effects or by dominant groups of species. We investigated how community structure (i.e., the diversity and relative abundance of biological entities) explains the community-level contribution of Neotropical ant communities to different ecosystem processes in different environments. Ants were attracted with food resources representing six ant-mediated ecosystem processes in four environments: ground and vegetation strata in cropland and forest habitats. The exploitation frequencies of the baits were used to calculate the taxonomic and trophic structures of ant communities and their contribution to ecosystem processes considered individually or in combination (i.e., multifunctionality). We then investigated whether community structure variables could predict ecosystem processes and whether such relationships were affected by the environment. We found that forests presented a greater biodiversity and trophic complementarity and lower dominance than croplands, but this did not affect ecosystem processes. In contrast, trophic complementarity was greater on the ground than on vegetation and was followed by greater resource exploitation levels. Although ant participation in ecosystem processes can be predicted by means of trophic-based indices, we found that variations in community structure and performance in ecosystem processes were best explained by environment. We conclude that determining the extent to which the dominance and complementarity of communities affect ecosystem processes in different environments requires a better understanding of resource availability to different species.

Host specificity in a diverse Neotropical tick community: an assessment using quantitative network analysis and host phylogeny.

BackgroundHost specificity is a fundamental determinant of tick population and pathogen transmission dynamics, and therefore has important implications for human health. Tick host specificity is expected to be particularly high in the tropics, where communities of ticks, hosts and pathogens are most diverse. Yet the degree to which tropical tick species are host-specific remains poorly understood. Combining new field data with published records, we assessed the specificity of tick-host associations in Panama, a diverse Neotropical region.MethodsThe resulting dataset includes 5,298 adult ticks belonging to 41 species of eight genera that were directly collected from 68 vertebrate host species of 17 orders. We considered three important aspects of tick host specificity: (i) the relative ecological importance of each host species (structural specificity); (ii) relatedness among host species (phylogenetic specificity); and (iii) spatial scale-dependence of tick-host relationships (geographical specificity). Applying quantitative network analyses and phylogenetic tools with null model comparisons, we assessed the structural and phylogenetic specificity across three spatial scales, ranging from central Panama to countrywide. Further, we tested whether species-rich tick genera parasitized a wider variety of hosts than species-poor genera, as expected when ticks specialize on different host species.ResultsMost tick species showed high structural and/or phylogenetic specificity in the adult stage. However, after correcting for sampling effort, we found little support for geographical specificity. Across the three scales, adult ticks tended to be specific to a limited number of host species that were phylogenetically closely related. These host species in turn, were parasitized by tick species from distinct genera, suggesting switching among distantly related hosts is common at evolutionary timescales. Further, there was a strong positive relationship between the taxonomic richness of the tick genera and that of their hosts, consistent with distinct tick species being relatively specific to different host species.ConclusionsOur results indicate that in the adult stage, most ticks in the diverse Neotropical community studied are host specialists. This contrasts with earlier assessments, but agrees with findings from other host-parasite systems. High host specificity in adult ticks implies high susceptibility to local tick-host co-extirpation, limited ability to colonize new habitats and limited potential for interspecific pathogen transmission.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1655-6) contains supplementary material, which is available to authorized users.

The Interplay between Environmental Filtering and Spatial Processes in Structuring Communities: The Case of Neotropical Snake Communities.

Both habitat filters and spatial processes can influence community structure. Space alone affects species immigration from the regional species pool, whereas habitat filters affect species distribution and inter-specific interactions. This study aimed to understand how the interplay between environmental and geographical processes influenced the structure of Neotropical snake communities in different habitat types. We selected six studies that sampled snakes in forests, four conducted in savannas and two in grasslands (the latter two are grouped in a non-forest category). We used the net relatedness and nearest taxon indices to assess phylogenetic structure within forest and non-forest areas. We also used the phylogenetic fuzzy-weighting algorithm to characterize phylogenetic structure across communities and the relation of phylogenetic composition patterns to habitat type, structure, and latitude. Finally, we tested for morphological trait convergence and phylogenetic niche conservatism using four forest and four non-forest areas for which morphological data were available. Community phylogenetic composition changed across forest and non-forest areas suggesting that environmental filtering influences community structure. Species traits were affected by habitat type, indicating convergence at the metacommunity level. Tail length, robustness, and number of ventral scales maximized community convergence among forest and non-forest areas. The observed patterns suggested environmental filtering, indicating that less vertically structured habitats represent a strong filter. Despite the fact that phylogenetic structure was not detected individually for each community, we observed a trend towards communities composed by more closely related species in higher latitudes and more overdispersed compositions in lower latitudes. Such pattern suggests that the limited distribution of major snake lineages constrained species distributions. Structure indices for each community were also related to habitat type, showing that communities from non-forest areas tend to be more clustered. Our study showed that both environmental filtering and spatial gradients play important roles in shaping the composition of Neotropical snake communities.