Vocal networks remain stable after a disturbance in Emei music frogs.

Ke Deng,Jian-Guo Cui

doi:10.1002/ece3.5473

Abstract

Social network analysis has been widely used to investigate the dynamics of social interactions and the evolution of social complexity across a range of taxa. Anuran species are highly dependent on vocal communication in mate choice; however, these species have rarely been the subject of social network analysis. The present study used social network analysis to investigate whether vocal network structures are consistent in Emei music frog (Babina daunchina) after the introduction of a simulated exotic rival of varying competitiveness into the social group. We broadcasted six categories of artificial calls (either highly sexually attractive calls produced from inside male nests or calls of low sexual attractiveness produced outside nests with three, five or seven notes, respectively) to simulate an intruder with different levels of competitiveness. We then constructed vocal networks for two time periods (before and after the disturbance) and quantified three network metrics (strength, closeness, and betweenness) that measure different aspects of individual‐level position. We used the mean values of these network metrics to evaluate group‐level changes in network structure. We found that the mean strength, mean closeness and mean betweenness were consistent between two time periods in all ponds, despite the fact that the positions of some individuals had changed markedly after disturbance. In addition, there was no significant interaction effect between period and numbers of notes on the three network metrics. These finding suggest that the structure of vocal networks in Emei music frogs remain stable at the group level after a conspecific disturbance, regardless of the intruder's competitiveness.

Highlights

In recent years, social network analysis (SNA) has become a widely used framework in biology for investigating the links between in‐ dividual behavior and group‐level patterns and processes (Croft, Darden, & Wey, 2016; Pinter‐Wollman et al, 2014; Sih, Hanser, &McHugh, 2009)
The dynamic patterns of interactions among indi‐ viduals generally vary based on ecological context such as climate, reproductive condition, and conspecific competition, which may result in temporal changes in group‐level network structure (Deng, Liu, & Wang, 2017; Patriquin, Leonard, Broders, & Garroway, 2010; Wey, Burger, Ebensperger, & Hayes, 2013)
We found that some individuals' position in the net‐ work changed markedly after the disturbance (Figure 1), the mean strength, mean closeness, and mean betweenness of the network were consistent between two time periods, regardless of the intruder's competi‐ tiveness

Summary

| INTRODUCTION

Social network analysis (SNA) has become a widely used framework in biology for investigating the links between in‐ dividual behavior and group‐level patterns and processes Males are capable of interval timing and normally avoid producing advertisement calls that overlap the calls of other individuals (Fang et al, 2014) In view of these factors, it is logical to hypothesize that the vocal competitive patterns are influenced by conspecifics' vocalizations, leading to changes in network structure. We focused on three network metrics that describe an individual's direct interac‐ tions in a group: strength, closeness centrality, and betweenness centrality (Croft et al, 2008) We chose these metrics because they measure different aspects of individual‐level position and permit us to understand group‐level structure (Farine & Whitehead, 2015; Wey et al, 2008). We predicted that male frogs would increase the rate of vocalizations, and the means of strength and closeness would increase, and the means betweenness would decrease when the competitiveness of the playback stimulus increased

| MATERIALS AND METHODS

| DISCUSSION

Findings

CONFLICT OF INTEREST