Fragmentation gradients differentially affect the species range distributions of four taxonomic groups in semi‐deciduous Atlantic forest

Human activities often cause habitat fragmentation and how forest fragments affect species range distributions has implications for ecology and conservation. However, few studies have considered communities within the same landscape. Here, we analyzed metacommunity structure to determine the range distributions for species in four taxonomic groups (amphibians, birds, social wasps, and trees) in a patchy landscape of semi‐deciduous Atlantic forest in southwestern Brazil. Although trees are a key component of the environment for animals in forested patches, the ranges of bird, wasp, and amphibian species did not change in concert with the species ranges of trees. The species ranges of amphibians and social wasps were unaffected by fragmentation gradients and exhibited independent distribution patterns (i.e., random structure). In contrast, birds and trees exhibited range turnover along different fragmentation gradients, indicating that species show idiosyncratic responses to abiotic factors (i.e., Gleasonian structure). For birds, some less‐resilient species occurred only in fragments with a large area of native vegetation at a radius of 5 km from the center of the sampled forest fragments, whereas other more stress‐tolerant species occurred only in sites with small areas of native vegetation. For trees, some later succession species (e.g., animal‐dispersed seeds) occurred only in fragments with high connectivity, whereas earlier‐recruiting species (e.g., wind‐dispersed seeds) occurred in fragments with low connectivity. Thus, determining the effects of human‐modified landscapes on species range distributions, even within the same landscape, might not be a trivial task.     

Resident‐immigrant dichotomy matters for classifying wetland site groups and metacommunities

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Native forest metacommunity structures in Uruguay shaped by novel land‐use types in their surroundings

We explore the effect of land‐use change from extensively used grasslands to intensified silvi‐ and agricultural monocultures on metacommunity structure of native forests in Uruguay. We integrated methods from metacommunity studies, remote sensing, and landscape ecology to explore how woody species distribution was influenced by land‐use change from local to regional scale. We recorded richness and composition of adult and juvenile woody species from 32 native forests, created land‐use maps from satellite image to calculate spatial metrics at landscape, class, and patch levels. We also analyzed the influence of land use pattern, climate, topography, and geographic distance between sites (d) on metacommunity, and created maps to visualize species richness and (dis)similarity between communities across the country. Woody species communities were distributed in a discrete pattern across Uruguay. Precipitation and temperature seasonality shaped species distribution pattern. Species richness and community dissimilarity increased from West to East. Latitude did not influence these patterns. Number of patches, landscape complexity, and interspersion and juxtaposition indexes determine woody species distribution at landscape level. Increasing areas covered by crops and timber plantation reduced species richness and increased community dissimilarity. The spatial metrics of native forest fragments at patch level did not influence metacommunity structure, species richness, and community dissimilarity. In conclusion, Uruguayan native forests display a high range of dissimilarity. Pressure of neighborhood land uses was the predominant factor for species assemblages. Conserving landscape structures that assure connectivity within and among native forest patches is crucial. On sites with rare target species, the creation of alliances between governmental institution and landowner complemented by incentives for biodiversity conservation provides opportunities to advance in species protection focused on those less tolerant to land‐use change.     

Vertebrate metacommunity structure along an extensive elevational gradient in the tropics: a comparison of bats,rodents and birds

Aim We evaluated the structure of metacommunities for each of three vertebrate orders (Chiroptera, Rodentia and Passeriformes) along an extensive elevational gradient. Using elevation as a proxy for variation in abiotic characteristics and the known elevational distributions of habitat types, we assessed the extent to which variation in those factors may structure each metacommunity based on taxon‐specific characteristics. Location Manu Biosphere Reserve in the Peruvian Andes. Methods Metacommunity structure is an emergent property of a set of species distributions across geographic or environmental gradients. We analysed elements of metacommunity structure (coherence, range turnover and range boundary clumping) to determine the best‐fit structure for each metacommunity along an elevational gradient comprising 13 250‐m elevational intervals and 58 species of rodent, 92 species of bat or 586 species of passerine. Results For each taxon, the environmental gradient along which the metacommunity was structured was highly correlated with elevation. Clementsian structure (i.e. groups of species replacing other such groups along the gradient) characterized rodents, with a group of species that was characteristic of rain forests and a group of species that was characteristic of higher elevation habitats (i.e. above 1500 m). Distributions of bats were strongly nested, with more montane communities comprising subsets of species at lower elevations. The structure of the passerine metacommunity was complex and most consistent with a quasi‐Clementsian structure. Main conclusions Each metacommunity exhibited a different structure along the same elevational gradient, and each structure can be accounted for by taxon‐specific responses to local environmental factors that vary predictably with elevation. The structures of rodent and bird metacommunities suggest species sorting associated with habitat specializations, whereas structure of the bat metacommunity is probably moulded by a combination of species‐specific tolerances to increasingly cold, low‐productivity environs of higher elevations and the diversity and abundance of food resources associated with particular habitat types.     

A Complex Metacommunity Structure for Gastropods Along an Elevational Gradient

The metacommunity framework integrates species‐specific responses to environmental gradients to detect emergent patterns of mesoscale organization. Abiotic characteristics (temperature, precipitation) and associated vegetation types change with elevation in a predictable fashion, providing opportunities to decouple effects of environmental gradients per se from those of biogeographical or historical origin. Moreover, expected structure is different if a metacommunity along an elevational gradient is molded by idiosyncratic responses to abiotic variables (expectation=Gleasonian structure) than if such a metacommunity is molded by strong habitat preferences or specializations (expectation=Clementsian structure). We evaluated metacommunity structure for 13 species of gastropod from 15 sites along an elevational transect in the Luquillo Experimental Forest of Puerto Rico. Analyses were conducted separately for the primary axis and for the secondary axis of correspondence extracted via reciprocal averaging. The metacommunity exhibited quasi‐Clementsian structure along the primary axis, which represented a gradient of gastropod species specialization that was unassociated with elevation. The secondary axis represented environmental variation associated with elevation. Along this axis, the metacommunity exhibited Clementsian structure, with specialists characterizing each of three suites of sites that corresponded to three distinct forest types. These forest types are associated with low (tabonuco forest), mid‐ (palo colorado forest), or high (elfin forest) elevations. Thus, variation among sites in species composition reflected two independent processes: the first decoupled from elevational variation and its environmental correlates, and the second highly associated with environmental variation correlated with elevation. Abstract in Spanish is available at http://www.blackwell‐synergy.com/loi/btp .     

Do metacommunity theories explain spatial variation in fish assemblage structure in a pristine tropical river?

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