Individual Variation in Advertisement Calls of Territorial Male Green Frogs, Rana clamitans: Implications for Individual Discrimination

Abstract

2000: Individual variation in advertisement calls of territorial male green frogs, Rana clamitans: implications for individual discrimination. Ethology 107, 65Ð84. AbstractIndividuals of many territorial species discriminate between familiar territorial neighbors and unfamiliar strangers based on individual dierences in acoustic signals. Many anuran amphibians are territorial and use primarily acoustic communication during social interactions, but evidence for acoustically mediated individual discrimination is available only for one species. As a ®rst step in research designed to investigate individual discrimination in a second species of territorial frog, we examined patterns of within-male and among-male variability in 198 advertisement calls of 20 male green frogs, Rana clamitans. The aim was to determine which acoustic properties could be used by males to recognize their territorial neighbors and to estimate limits of reliability aorded by these properties for identifying dierent neighbors. All of the call properties that we examined exhibited signi®cant inter-individual variation. Discriminant function analyses assigned between 52% and 100% of calls to the correct individual, depending on sample size and the call properties included in the model. This suggests that there is sucient among-male variability to statistically identify individuals by their advertisement calls. The call properties of fundamental frequency and dominant frequency contributed the most towards discrimination among individuals. Based on their natural history and behavior and the results reported here, we suggest that male green frogs likely discriminate between strangers and adjacently territorial neighbors based on individual variation in advertisement calls.

Temporal and spectral variation in advertisement call of males Microhyla achatina (Tschudi, 1838) are sufficient for individual discrimination

“…We intentionally collected just a tiny samples of frogs as Petittt et al [5] suggested that sample size which biologically meaningful is the sample size that relevance with actual size in natural breeding aggregations. The use large sample size into analysis may overestimate the complexity of recognition problem [2]. Although M. achatina often congregate in quite a large number during breeding sessions, their distribution is not technically random over a breeding area.…”

“…The initial step to evaluate whether an individual could be distinguished from the others is by inspecting disparities of particular signal characters among individuals or by comparing the different levels of variability within the population. Individuality occurs in a population if the value of some characteristics exhibit greater among-individual variation than within-individual variation [2].…”

“…Static properties are more likely to be used for species recognition because the values are at or near population mean [5]. In contrast, dynamic properties had values that far away from population means and regarded as a cue for individual distinctiveness [2,6]. However, accurate identification of these properties as individual recognition cues could only be met if such properties have greater variation among individuals than within individuals [7].…”

“…Previous studies of frogs' call have shown that some acoustic properties demonstrate a high level among-individual variation and these properties could potentially be used as individual identity [2,5,8]. Among all of the properties, temporal properties are components that contribute mostly to individual distinctiveness.…”

On the distinctive call of a threatened phenotype of Allobates femoralis (Anura: Aromobatidae) and its recognition by allopatric conspecific males

“…duration, bandwidth, peak frequency) of elements that constitute the acoustic signal, or more obvious shifts in composition of elements of call repertoire (Bee et al, 2001;Ryan & Rand, 2003;Boul et al, 2007;Guerra & Ron, 2008;Rodríguez et al, 2010). Although intraspecifi c variation of discrete elements occurs to some extent among acoustic signals of sympatric males of Neotropical anurans (e.g., Guerra & Ron, 2008;, fi xed diff erences have also been reported among allopatric groups of individuals, and these diff erences have been generally attributed to evolutionary eff ects of isolation by distance or vicariance, potentially reinforced by sexual selection (Boul et al, 2007;Guerra & Ron, 2008;Amézquita et al, 2009).…”