DOI: 10.5061/dryad.qbzkh18qv
title: Niche and neutral-based processes differ in importance for common and rare species in a metacommunity of anurans in subtropical grasslands

description: Most species-rich communities consist of a limited number of common
 species and many rare species. This widespread ecological pattern can
 arise due to the predominance of either niche-based or neutral-based
 processes in community structuring. We tested two hypotheses related to
 this pattern for an anuran metacommunity composed of 35
 species distributed in 187 ponds in the South Brazilian
 grasslands: (1) for common species, niche processes should prevail over
 neutral ones because common species evolved under a wider range of
 ecological filters than rare species; (2) for rare species, neutral
 processes should prevail because rare species are more prone to ecological
 drift and dispersion limitation. We found that the densities of both
 common (i.e., the 25% higher density ones) and rare (i.e., the 75% lower
 density ones) species depended mostly on pond structure and land use,
 indicating a similar response to niche-based processes in both groups of
 species. The importance of pond descriptors and type of land use, however,
 differed between the two groups, confirming that common and rare species
 represent ecologically distinct groups within the metacommunity. In
 addition, neutral processes—related to dispersion limitation or
 not—influenced both species groups, but the spatial filters selected
 explained a smaller portion of the variation in species densities compared
 to environmental descriptors. Our findings showcase the prevalence of
 niche processes in structuring communities of common and rare species of
 anurans in subtropical grasslands and indicate the variables of pond
 structure and land use that are relevant to guide conservation practices
 for the metacommunity of anurans in the South Brazilian
 grasslands. 
description: The study was conducted in the South Brazilian grasslands located
 in the state of Rio Grande do Sul, Brazil. Data were collected from 187
 ponds using the 'survey at breeding sites' method.
 For each pond, 36 environmental descriptors were measured. To
 accomplish this, we visually measured each of the 34 pond descriptors
 (e.g., type of pond edge, depth, area, type of vegetation, pH, turbidity)
 following the methodology outlined by Iop et al. (2020). Additionally, we
 recorded two variables related to the sampling date that could potentially
 impact the number of records: the length of the photoperiod and the
 percentage of lunar disk (moon phase). Landscape
 descriptors were determined through digital land use and land cover (LULC)
 mapping for the Landscape Sampling Units (LSUs), considering the base
 years of 2002. The scale was based on two false-color compositions. These
 landscape descriptors correspond to the area of each LULC class around
 each LSU. We employed three buffer zones (1 km, 3 km, and 5 km) to
 calculate these descriptors, taking into account the reported anuran
 dispersion range in the literature, which varies between 400 m and 10 km.
 In total, nine landscape descriptors (Agriculture, Forest, Pasture, Rocky
 Outcrop, Sandy, Forestry, Urban, Water, and Wetland) were measured within
 the buffers generated by the three rays. To assess
 whether geographic space influences the distribution of common and rare
 species in the metacommunity, we generated Moran’s eigenvector maps (MEM)
 using the geographic coordinates of each pond as a proxy for spatial
 patterns related to dispersion and ecological drift.
 Redundancy analysis (RDA) was employed to evaluate the role of
 environmental characteristics (local and landscape descriptors) and
 spatial patterns in the organization of the common and rare anuran
 community. RDA combines multiple regression with principal component
 analysis to identify a series of linear combinations of explanatory
 variables (i.e., local environmental descriptors, landscape descriptors,
 and spatial filters) that best explain the variation in the response
 matrix (i.e., density of species in each survey site).
description: The zip file contains five groups of txt files containing all the data and
 scripts used in the analyses of the manuscript. Analyses were conducted
 for both common and rare species. The five groups of files are: Group 1:
 contains data on the geographic coordinates of each pond used. Latitude
 and longitude are in the columns, and the ponds are in the rows. File
 names: coord.common coord.rare Group 2: contains species density data for
 each pond used. The species are in the columns, and the ponds are in the
 rows. File names: dens.common dens.rare The abbreviation of species names
 is given below: Dmin Dendropsophus minutus Dnan Dendropsophus nanus Dsan
 Dendropsophus sanborni Ebic Elachistocleis bicolor Hlep Boana leptolineata
 Hpul Boana pulchella Lcha Leptodactylus macrosternum Lfus Leptodactylus
 fuscus Lgra Leptodactylus gracilis Llati Leptodactylus latinasus Llatr
 Leptodactylus luctator Lmys Lepdodactylus mystacinus Lpla Leptodactylus
 plaumanni Matr Melanophryniscus atroluteus Oame Odontophynus asper Pbil
 Physalaemus biligonigerus Pcar Pseudis cardosoi Pcfg Physalaemus
 carrizorum Pcuv Physalaemus cuvieri Pfal Pseudopaludicola falcipes Pgra
 Physalaemus gracilis Pihe Phyllomedusa iheringii Plis Physalaemus lisei
 Pmin Pseudis minuta Prio Physalaemus riograndensis Rfer Rhinella dorbignyi
 Rict Rhinella icterica Rsch Rhinella diptycha Sfus scinax fuscovarius Sgra
 Scinax granulatus Snas Scinax nasicus Sper Scinax perereca Spin Scinax
 pinima Ssqu Scinax squalirostris Suru Scinax uruguayus Group 3: contains
 data on landscape variables for each pond used. The landscape descriptors
 are in the columns and the ponds in the lines. File names:
 landscape.common landscape.rare Below we present the specifications of
 each landscape variable evaluated for each buffer zone 1, 3, and 5 Km,
 i.e., we measured each of the landscape descriptors for the three buffer
 zones of 1, 3, and 5 km (for more detail, see Supplementary Material 2):
 Agriculture (1, 3, 5 km): total area of annual crop Forest (1, 3, 5 km):
 total area of native forest Grassland (1, 3, 5 km): total area
 recognizable as a native grassland Rock outcrop (1, 3, 5 km): total area
 of rocks Silviculture (1, 3, 5 km): total area of pine, eucalyptus, or
 acacia plantation Sandy (1, 3, 5 km): total area of beaches, and or sandy
 soil Urban (1, 3, 5 km): total urban area Water (1, 3, 5 km): total area
 of water surface free of emergent vegetation Wetland (1, 3, 5 km):
 freshwater marshes with typical presence of aquatic vegetation Group 4:
 contains data on local variables for each pond used. The local descriptors
 are in the columns, and the ponds are in the rows. File names:
 local.common local.rare Below we present the specifications of each local
 variable evaluated (for more detail, see Supplementary Material 1): Depth:
 Mean water depth Temperature: Air temperature Humidity: Air relative
 humidity pH: Water pH Conductivity: Water conductivity Dissolved oxygen:
 Water dissolved oxygen Water turbidity: Water turbidity Forest: Forest
 considering a buffer zone of 50 m around the pond Grassland: Grassland in
 a buffer zone of 50 m around the pond Agriculture: Agriculture in a buffer
 zone of 50 m around the pond Pasture: Planted pasture in a buffer zone of
 50 m around the pond Edge 1: Number of edge types Edge 2: Edge without
 vegetation and dry soil Edge 3: Edge with vegetation and dry soil Edge 4:
 Edge without vegetation and humid soil Edge 5: Edge with vegetation and
 humid soil Edge 6: Edge without vegetated and flooded soil Edge 7: Edge
 with vegetated and flooded soil Edge 8: Flat edge (180°) Edge 9: Sloping
 edge (45°) Edge 10: Steep edge (90°) Edge vegetation 1: Number of
 vegetation strata on the edge Edge vegetation 2: Creeping-herbaceous
 vegetation (up to 30 cm) on edge Edge vegetation 3: Creeping-herbaceous
 (up to 30 cm) on edge Edge vegetation 4: Herbaceous-shrub (31 to 70 cm) on
 edge Edge vegetation 5: Shrub (71 to 99 cm) on edge Shadow: Shadow in the
 water surface Emergent plant: Emerging hydrophytes Aquatic vegetation 1:
 Number of vertical vegetation strata on the water surface Aquatic
 vegetation 2: Vegetation up to 30 cm Aquatic vegetation 3: Vegetation from
 31 cm to 60 cm Aquatic vegetation 4: Vegetation greater than 1 m
 Invertebrates: Presence of predatory invertebrates Fish: Presence of
 predatory fish Photoperiod: Length of day Moon: Lunar disk percentage 5\)
 We present the R script for analysis. Below is a description of each file:
 script common x rare - here, we present all the steps for RDA analysis.
 script Graphics - here, we present all the steps for build Graphics.
 script MEM - here, we present all the steps for build MEM.