Variation In Advertisement Research Articles

Intraspecific variation in advertisement call characteristics and acoustic strategies among male forest green tree frogs

AbstractFrogs are a representative taxon that use advertisement calls to aid in reproduction. In most frog species, calls vary with body size, and allometric constraints between body size and call frequency have been widely reported among anuran species. Although this variation is an important driver of sexual selection in frogs, male advertisement call strategies may also vary according to body size. In this study, we conducted playback experiments on the male forest green tree frog (Zhangixalus arboreus) to determine whether male advertisement call characteristics and strategies vary according to body size and the amplitude of intraspecific chorus noise. The results indicated that the calls of larger individuals are louder and lower than those of smaller ones, who call more frequently; moreover, the calls become lower, and the number of calls decreases, as noise levels increase. These findings suggest that forest green tree frog emits lower calls or refrains from calling when chorus noise increases, and that intraspecific variation in advertisement call characteristics can induce different strategies in response to chorus noise. Because advertisement call variation with body size is common among frog species, intraspecific variation in male advertisement call strategies may also be a common phenomenon.

Advertisement call of two Liuixalus species (Anura: Rhacophoridae) endemic to Hainan Island, China

Advertisement calls potentially represent honest signals for delimiting species and sexual selection. Quantitative statistics of individual variation in advertisement call properties can be used to predict female preferences for particular signal properties. In this study, advertisement call properties and their individual variation was analyzed in two endemic treefrog species, Liuixalus hainanus and L. ocellatus. Together with the description of the advertisement calls, our goals included determining whether call properties can be used to distinguish between the two species on the field, which acoustic properties are likely play a role in species or individual recognition, and whether they could predict the signaler’s body size. We found that the dominant frequency, call duration, inter-call interval, and note number of monosyllabic calls in L. hainanus were significantly higher or longer than those in L. ocellatus. The dominant frequency was classified as a static property; the call duration, inter-call interval, inter-note interval, and note number were classified as dynamic properties in both species. The inter-note interval of multisyllabic calls was correlated with body mass, and the pulse number of monosyllabic calls was correlated with snout-vent length in L. ocellatus. These results indicate that the dominant frequency strongly contributed to species recognition of L. hainanus and L. ocellatus males. Acoustic properties reflected the signaler’s body size in L. ocellatus but did not in L. hainanus. The difference in advertisement call characteristics between the two species may be due to the different reproductive strategies associated with different selection pressures and may promote the sharing of similar habitats by the two species.

Reproductive biology and geographic variation of Zachaenus carvalhoi (Anura: Cycloramphidae), a Brazilian Atlantic Forest frog

Information is presented on the reproductive biology, habitat, behavior, morphology, and variation in advertisement call in Zachaenus carvalhoi, a rare frog for which basic natural history data are lacking. The species inhabits forest leaf litter in the states of Minas Gerais and Espírito Santo in southeastern Brazil. Reproductive individuals were found from October to December; females are slightly larger than males. The International Union for Conservation of Nature currently lists Zachaenus carvalhoi as Data Deficient. We suggest transferring the species to the Near Threatened category based on the IUCN criteria A2 because of the decline of the size and quality of its severely fragmented habitat

First record of the torrent frog Hylodes heyeri (Anura, Hylodidae) in Santa Catarina State, South Brazil and acoustic comparison with the cryptic species Hylodes perplicatus (Anura, Hylodidae)

Herein, we report the first record of the torrent frog Hylodes heyeri in Santa Catarina State, South Brazil, previously known from localities along the Atlantic Rainforest in the states of Sao Paulo and Parana. We also performed an acoustic comparison between the calls of H. heyeri and H. perplicatus due to their morphological similarity and because now they could be found in sympatry. There was a greater variation in advertisement call duration for both species, than previously stated in the literature, probably related to variation in air temperature. To distinguish the two species, besides the differences in dominant frequency, a temporal parameter that could be used was the interval between notes, but call duration should not be used due to the influence of air temperature. Our findings reinforce the urgency for more field activities to enhance our knowledge of the geographic distribution of anuran amphibians, to promote their conservation, and to call attention to the importance of detailed acoustic analysis to distinguish cryptic species.

Intra-specific variation in advertisement call of Odontophrynus cordobae (Anura, Cycloramphidae): a multilevel and multifactor analysis

Advertisement call is a complex signal that can vary at different scales and the characterization of this variation is crucial to understand its adaptive function. In our study, we examined different factors that could influence intra and inter-population call variation in Odontophrynus cordobae. We analyzed calls of individuals from different breeding sites across the species distribution, including a syntopic site with their related species O. americanus. Dominant frequency, pulse rate, call duration and pulses/call were the acoustic parameters that showed the lowest intra-individual variation (CV ≤ 3%). The discriminant function analysis (DFA) assigned 92% of calls to the correct individual, indicating that the advertisement calls of O. cordobae are individually distinctive. Univariate and multivariate statistical analysis showed a significant contribution of pulse rate in differentiation of populations. Interpulse interval and pulse rate showed a moderate clinal variation, even when syntopic populations were excluded from the analysis. We found no association between acoustic and linear geographical or altitudinal distances and observed an evident divergence between the syntopic population and the other populations analyzed. This result is reinforced by DFA, which showed a differentiation among syntopic and allopatric populations of O. cordobae. We discuss our results from the hypothesis of a possible character displacement influencing call properties in this species in syntopy with their related species O. americanus. However, new syntopic areas and tests of female preferences would be needed to strengthen our results.

Geographic variation in the advertisement call of Crinia signifera (Anura:Myobatrachidae) on Kangaroo Island and across southern south-eastern Australia

The male advertisement call of anuran amphibians has a major role in mate choice, and regional variation in this attribute can act as an indicator of speciation and a marker for genetic differentiation. As part of a regional study of geographic variation in the male advertisement call of Crinia signifera across south-eastern Australia and adjacent larger continental islands, samples of advertisement calls from two populations on Kangaroo Island and two populations on the adjacent Fleurieu Peninsula were compared. Four call attributes were considered: pulse number, call duration, pulse rate and dominant frequency. Pulse number is considered the most reliable for comparative purposes because it is not influenced by effective temperature or audio recording and analysis. The two island populations (central and eastern, ~24 km apart) differ significantly in pulse number, with contact but no overlap of interquartile ranges. The eastern sample differs markedly from those on the nearby Fleurieu Peninsula – which are both similar to the more distant central island sample. Geographic variation in pulse number in these four samples and 11 others from two recent publications is then interpreted in the light of land bridges and lower temperatures of the late Pleistocene and early Holocene.

Temporal and Geographic Variation in the Advertisement Call of the Booroolong Frog (Litoria booroolongensis: Anura: Hylidae)

AbstractThe mechanisms that underlie sexual selection rely upon within‐ and among‐individual variability in the targeted traits. In this study, we examined variation in the advertisement call of the booroolong frog (Litoria booroolongensis) at several different levels: between populations, between breeding seasons in the same population, among males within a population, within males between nights and within males in a single calling bout. The call of L. booroolongensis has multiple notes with a pulsed structure. We detected considerable variation in advertisement call structure between breeding seasons and between populations. The measured call properties ranged from static to dynamic; however, most properties were intermediate between the criteria that have been traditionally used to define call traits as static or dynamic (≤5 and ≥12% respectively). We compared actual and relative repeatabilities and found that the temporal call properties associated with the structure of the note had the highest values, suggesting that these characters in particular may respond to selection. We argue that relative repeatabilities are a particularly useful measure of the potential for evolutionary response to selection as they account for an individual's relative performance during the period of assessment in an ever‐changing breeding arena.

Geographic Variation in Calls of Males and Determination of Species Boundaries in Tetraploid Frogs of the Australian Genus Neobatrachus (Myobatrachidae)

I analysed geographic variation in advertisement call of tetraploid forms of Neobatrachus. Comparing five regional samples spanning the range of N. kunapalari, there was significant geographic variation in pulses per call but not in dominant frequency, pulse rate, pulse duration or percentage rise time. The call of N. kunapalari was significantly different from four other samples covering the geographic range of tetraploid forms across Australia in all but percentage rise time. Calls of frogs from Mt Magnet in Western Australia (WA) differed from calls from Port Hedland (WA) in pulse duration and in multivariate descriptions but were similar in pulse rate. Pulse rates of calls from N. centralis on Eyre Peninsula in South Australia (SA) were distinct from all other populations sampled but in multivariate space these calls were similar to calls of N. sudellifrom eastern Australia. There may be an eastwest cline in call from N. sudelli to calls of N. aquilonius and N. centralis in WA. Call data support the recognition of two tetraploid species: N. kunapalari and N. sudelli. N. sudelli exhibits geographic variation in call, but the status of N. aquilonius and N. centralis as possible synonyms of N. sudelli was not resolved.

Sexual Selection and Calling Behavior in the American Toad (Bufo americanus)

Mating system structure, variation in advertisement and release calls, and calling behavior were investigated during a three-year period in Bufo americanus in east-central Maine. Although the breeding season was relatively brief, chorus size was small, and males participated in chorus activity for an average of six or seven nights within a season. Pulse rate and duration of the advertisement call were significantly correlated with temperature, but neither frequency nor call rate was influenced by temperature over a 10 C range. Dominant frequency was the only advertisement call variable significantly (negatively) correlated with snout-vent length in one of two years for one of two populations studied. Similarly, dominant frequency was the only release call variable significantly (negatively) correlated with male size (snout-vent length and mass). Males exhibited consistency in both call rate and call duration as measured over a series of nights of chorus activity: repeatability (intraclass correlation coefficient) was 0.52 for call duration and 0.24 for call rate. Females did not discriminate between high and low frequency calls in discrimination experiments; however, females did prefer calls broadcast at relatively high call efforts (rate x duration).

Variation in Advertisement and Release Calls, and Social Influences on Calling Behavior in the Gulf Coast Toad (Bufo valliceps)

We examined variation in calls and calling behavior in two populations of Bufo valliceps in south-central Texas. Both pulse rate of advertisement calls and call rate were positively related to body temperature, whereas call duration was negatively correlated with body temperature. Advertisement call frequency was not significantly correlated with toad temperature, but was negatively correlated with SVL. Of the temporal advertisement call variables, only call duration was significantly correlated (positively) with SVL. Release call frequency was negatively correlated with SVL. Field observations revealed significantly greater variation among than within males for call rate, call duration, and calling effort. However, despite the consistency of individual calling behavior, calling activity varied with social context. Calling effort was weakly, positively correlated with male density. Call rate and calling effort varied nonlinearly with nearest neighbor distance. Both variables were highest at intermediate distances (2.5-7.5 m), decreasing as nearest neighbors became very close ( 7.5 m).