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

Abstract

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.

Local and Landscape Factors Driving the Structure of Tropical Anuran Communities: Do Ephemeral Ponds have a Nested Pattern?

“…, Gómez‐Rodríguez et al . , Moreira & Maltchik ), but not in others (Urban ). Nestedness in ephemeral ponds was studied mostly for tadpoles, and in the tropics only in a protected area (Moreira & Maltchik ).…”

“…, Moreira & Maltchik ), but not in others (Urban ). Nestedness in ephemeral ponds was studied mostly for tadpoles, and in the tropics only in a protected area (Moreira & Maltchik ). Many organisms use ephemeral ponds and amphibian species that can disperse to and reproduce in these ponds are more likely to persist in a disturbed landscape.…”

“…Nestedness in frog communities was detected in some lentic environments, such as ponds or wetlands, in communities comprising the entire life cycle (eggs, larvae, adults; Hecnar & M'Closkey 1997), or just tadpoles (Beja & Alcazar 2003, Baber et al 2004, Werner et al 2007, G omez-Rodr ıguez et al 2010, Moreira & Maltchik 2012, but not in others (Urban 2004). Nestedness in ephemeral ponds was studied mostly for tadpoles, and in the tropics only in a protected area (Moreira & Maltchik 2012). Many organisms use ephemeral ponds and amphibian species that can disperse to and reproduce in these ponds are more likely to persist in a disturbed landscape.…”

Peer Review #2 of "Effect of fragmentation on the Costa Rican dry forest avifauna (v0.1)"

“…To test for species nestedness in the dry forest patches we used presence/absence matrices in which rows and columns were patches and species respectively, and then sorted rows (assemblages) and columns (species) by a gradient of patch sizes, and a gradient of rainfall seasonality. We calculated the NODF metric (Almeida-Neto et al 2008, Ulrich et al 2009, Moreira and Maltchik 2012 and used 999 permutations with the 'quasiswap' algorithm to construct a null distribution of NODF values (Miklós and Podani 2004). During each permutation the 'quasiswap' algorithm randomly shuffles values of rows and columns but maintains constant marginal frequencies (total frequencies of rows and columns).…”

Does intensification of the rice cultivation cycle influence anuran diversity in rice fields?

“…The reduction in the amount of fallow time in rice production has occurred in the last years to increase the grain production and to sustain the global market. Some studies have shown environmental problems with reduced fallow time and it could influence negatively the pond anuran diversity (Huston 1994;Sparling et al 2001;Moreira et al 2010;Moreira and Maltchik 2012). The present study tested three hypotheses: (1) amphibian richness and abundance will be greater in natural areas than rice fields; (2) rice fields with a fallow period will have greater amphibian richness and abundance than fields without this period; and (3) changes in the species composition between natural ponds and rice fields with and without a fallow period will be determined by community nestedness over the agricultural intensification gradient-natural ponds (no impact), fields with fallow period (medium impact) and fields without fallow period (greatest impact).…”