Drivers of assemblage‐wide calling activity in tropical anurans and the role of temporal resolution

Abstract

Temporal scale in animal communities is often associated with seasonality, despite the large variation in species activity during a diel cycle. A gap thus remains in understanding the dynamics of short‐term activity in animal communities. Here we assessed calling activity of tropical anurans and addressed how species composition varied during night activity in assemblages along gradients of local and landscape environmental heterogeneity. We investigated 39 anuran assemblages in the Pantanal wetlands (Brazil) with passive acoustic monitoring during the peak of one breeding season, and first determined changes in species composition between night periods (early, mid and late) using two temporal resolutions (1‐ and 3‐hr intervals). Then, we addressed the role of habitat structure (local and landscape heterogeneity variables from field‐based and remote sensing metrics) and ecological context (species richness and phylogenetic relatedness) in determining changes in species composition (a) between night periods and (b) across days. Nocturnal calling activity of anuran assemblages varied more within the 1‐hr resolution than the 3‐hr resolution. Differences in species composition between early‐ and late‐night periods were related to local habitat structure and phylogenetic relatedness, while a low variation in compositional changes across days was associated with low‐heterogeneous landscapes. None of these relationships were observed using the coarser temporal resolution (3 hr). Our findings on the variation of calling activity in tropical anuran assemblages suggest potential trade‐offs mediated by fine‐temporal partitioning. Local and landscape heterogeneity may provide conditions for spatial partitioning, while the relatedness among co‐signalling species provides cues on the ecological overlap of species with similar requirements. These relationships suggest a role of niche dimensional complementarity on the structuring of these anuran assemblages over fine‐temporal scales. We argue that fine‐temporal differences between species in breeding activity can influence the outcome of species interaction and thus, addressing temporal scaling issues can improve our understanding of the dynamics of animal communities.

Acoustic indices as proxies for biodiversity: a meta‐analysis

“…competition and environmental filtering) and stochastic forces (e.g. dispersal and random population fluctuations) that shape the organisation of the acoustic space (Chek, Bogart & Lougheed, 2003 ; Roca & Proulx, 2016 ; Sugai et al ., 2021 a , b ).…”

Competition for acoustic space in a temperate-forest bird community

“…Sounds that overlap in frequency and time result in acoustic interference, which can mask or alter some parts of the signal, limit signal detection, and—particularly in the case of broadcast signals—can lead to lower reproductive success or survival ( Bradbury and Vehrencamp 2011 ). In natural communities, interspecific competition for acoustic signal space can occur between closely related species within, for example, birds ( Planqué and Slabbekoorn 2008 ; Kirschel et al 2009 ; Luther 2009 ; Krishnan and Tamma 2016 ; Bolanos-Sittler et al 2021 ), or anurans ( Hodl 1977 ; Narins 1995 ; Chek et al 2003 ; Allen-Ankins and Schwarzkopf 2021 ; Sugai et al 2021 ), as well as between phylogenetically divergent taxonomic groups such as birds and cicadas ( Hart et al 2015 ; Stanley et al 2016 ), or frogs and insects ( Greenfield 1994 ). Noise can also reduce acoustic space available to animals, leading to competition avoidance.…”

Community Bioacoustics: Studying Acoustic Community Structure for Ecological and Conservation Insights

“…For example, acoustic competition (i.e., competition between signalers to communicate without interference) is predicted to lead to divergence in signal parameters of coexisting species, particularly those that are closely related, such that each species in an assemblage occupies a unique region in signal space [birds: (Planqué and Slabbekoorn, 2008;Luther, 2009;Krishnan and Tamma, 2016;Krishnan, 2019a;Chitnis et al, 2020), anurans: (Littlejohn, 1959;Duellman and Pyles, 1983;Chek et al, 2003), insects: (Schmidt et al, 2013;Jain et al, 2014)]. In a scenario where competition drives signal evolution, sympatric species may also signal at different times [birds: (Ficken et al, 1974;Fleischer et al, 1985;Popp et al, 1985;Brumm, 2006;Luther, 2008;Planqué and Slabbekoorn, 2008), anurans: (Sugai et al, 2021b), fish: (Ruppé et al, 2015)] or locations in space [birds: (Nemeth et al, 2002;Chitnis et al, 2020), anurans: (Hodl, 1977), insects: Jain and Balakrishnan, 2012), bats: (Kennedy et al, 2014)]. The distributions of species in signal space represent a "signature" of each community, a definitive pattern that can be monitored to track ecological changes.…”