Variation In Advertisement Calls Research Articles

Colour patterns to sequences: a perspective on the systematics of the Hyperolius viridiflavus group (Anura: Hyperoliidae) using mitochondrial DNA.

African reed frogs are widespread and highly polymorphic for colour pattern. The Hyperolius viridiflavus complex includes 121 described taxa, including subspecies, which are presently synonymised as 16 species. However, the taxonomy is confused as colour patterns have been used to identify species, despite an inadequate understanding of pattern variation and overlap. This study examined 267 sequences of the 16S rRNA fragment from individuals across the range of the group, from Senegal to Ethiopia, and to the southern tip of Africa. Maximum likelihood analysis showed that there were 14 species that only partially agreed with existing taxonomy. This study recognised the following species: Hyperolius viridiflavus, H. marmoratus, H. marginatus, H. parallelus, H. nitidulus, H. glandicolor, H. tuberculatus, H. mariae, H. noblei, H. goetzei, H. spatzi, H. bangwae, H. dintelmanni and an undescribed species from southern Cameroon. Hyperolius swynnertoni was found to be embedded within H. marmoratus, H. hutsebauti was embedded within H. parallelus, H. rhodesianus and H. pyrrhodictyon were embedded within H. marginatus and H. sheldricki was embedded within H. glandicolor. There was no sequence information to determine the status of Hyperolius nimbae. The ranges of the species are presented, although these are expected to change as more sequences become available. The use of DNA sequences to identify animals is recommended in this group, as the variation in advertisement calls and morphology is not well understood.

Male movement patterns and bioacoustic activity of the Western Cuban Grassfrog, Eleutherodactylus varleyi (Anura: Eleutherodactylidae)


 
 
 
 In this study, we examined movement patterns, vocal activity, and variation in advertisement calls at individual and populational levels in a population of Western Cuban Grassfrogs (Eleutherodactylus varleyi) at the National Botanical Garden of Cuba in July and September in 2007. Males appear to be very sedentary with peaks of movement early in the night and just before dawn that could be related with the search of calling sites and diurnal retreats, respectively. We detected eight patterns of frequency modulation of advertisement calls for note 1 and six for note 2. Patterns II and VI were the most frequent for note 1 and note 2, respectively. Note duration was the only acoustic parameter that was significantly variable among individuals for note 1, whereas the maximum frequency and rise time were signifi- cantly variable within individuals for note 2, suggesting that the latter is more reliable for distinguishing individual calls.
 
 
 

Individual variation in advertisement calls of the pale-shouldered horned toad (Xenophrys boettgeri)

The characteristics of male anurans’ calls play an important role in mating success during the breeding season. In this study, we analyzed intra- and inter-individual variability of the advertisement calls of the pale-shouldered horned toad (Xenophrys boettgeri) in the field during its breeding season in Lishui, Zhejiang Province, China. The results showed that some acoustic parameters were significantly correlated with morphological features and air temperature. Most acoustic parameters including note numbers, call duration, and dominant frequency were static, whereas the call interval was intermediate. The CVb/CVw ratio was greater than 1.0 for all acoustic parameters analyzed, with between-individual variation being higher than within-individual variation. Furthermore, the acoustic parameter results of principle component analysis and discriminant function analysis indicated that note numbers and call interval are potentially useful for individual discrimination of X. boettgeri.

Territorial olive frogs display lower aggression towards neighbours than strangers based on individual vocal signatures

Some territorial animals display a form of social recognition in which they direct low levels of aggression towards established neighbours, but maintain greater readiness to respond aggressively towards unfamiliar individuals. In many taxa, such as songbirds, this so-called ‘dear enemy’ effect involves discrimination between neighbours and strangers based on individually distinctive vocal signatures. Although most anuran amphibians (frogs and toads) are highly vocal, and many are also territorial, we know very little about neighbour–stranger discrimination in this group. In the present study of the olive frog, Babina adenopleura (Ranidae), we show that the vocal signals of males are individually distinct, and that territory holders use this information to direct lower levels of aggression towards their nearby neighbours. Analyses of individual variation in advertisement calls revealed many individually distinctive spectral and temporal acoustic properties, with spectral properties contributing most towards statistical discrimination among individuals. In a field playback experiment that simulated territorial intrusions, territorial males had higher thresholds for producing aggressive calls in response to the advertisement calls of their nearby neighbours compared with those of strangers. A simple model based on sound attenuation due to spherical spreading estimated that males responded aggressively to strangers at distances that were approximately twice as far away as for neighbours and that were similar to intermale distances recorded in the field. Together, results from this study indicate that territorial male olive frogs develop vocally mediated dear enemy relationships with their nearby neighbours. These results highlight the potential for convergence in social recognition systems across diverse taxa.

Geographic variation in advertisement calls of a Microhylid frog - testing the role of drift and ecology.

Acoustic signals for mating are important traits that could drive population differentiation and speciation. Ecology may play a role in acoustic divergence through direct selection (e.g., local adaptation to abiotic environment), constraint of correlated traits (e.g., acoustic traits linked to another trait under selection), and/or interspecific competition (e.g., character displacement). However, genetic drift alone can also drive acoustic divergence. It is not always easy to differentiate the role of ecology versus drift in acoustic divergence. In this study, we tested the role of ecology and drift in shaping geographic variation in the advertisement calls of Microhyla fissipes. We examined three predictions based on ecological processes: (1) the correlation between temperature and call properties across M. fissipes populations; (2) the correlation between call properties and body size across M. fissipes populations; and (3) reproductive character displacement (RCD) in call properties between M. fissipes populations that are sympatric with and allopatric to a congener M. heymonsi. To test genetic drift, we examined correlations among call divergence, geographic distance, and genetic distance across M. fissipes populations. We recorded the advertisement calls from 11 populations of M. fissipes in Taiwan, five of which are sympatrically distributed with M. heymonsi. We found geographic variation in both temporal and spectral properties of the advertisement calls of M. fissipes. However, the call properties were not correlated with local temperature or the callers' body size. Furthermore, we did not detect RCD. By contrast, call divergence, geographic distance, and genetic distance between M. fissipes populations were all positively correlated. The comparisons between phenotypic Q st (P st) and F st values did not show significant differences, suggesting a role of drift. We concluded that genetic drift, rather than ecological processes, is the more likely driver for the geographic variation in the advertisement calls of M. fissipes.

Intraspecific Call Variation in the Mimic Poison Frog Ranitomeya imitator

Abstract: Calls are important premating isolating barriers in frogs; therefore, studying intraspecific variation in calls might allow the assessment of patterns of call divergence during the early stages of speciation. Ranitomeya imitator, a species of dart-poison frog (Dendrobatidae), has undergone extensive color-pattern diversification through a Mullerian mimetic radiation, establishing four distinct morphs in north-central Peru (striped, banded, varadero, and spotted). Partial reproductive isolation exists between certain color morphs, although the specific mechanisms responsible for this isolation are poorly understood. We conducted a species-wide analysis of variation in advertisement calls to investigate whether distinct mimetic morphs show advertisement call differences. We found that different color morphs generally show weak or no differences in advertisement calls, with two exceptions. First, call pulse rates differed between the striped and banded morphs, and that difference coincides geograp...

No reproductive character displacement in male advertisement signals of Hyla japonica in relation to the sympatric H. suweonensis

Reproductive interaction between closely related taxa may leave a distinctive signature in which populations of interacting taxa are more dissimilar in sympatry than in allopatry. An ideal condition for such a pattern of reproductive character displacement (RCD) may occur when a population has limited gene flow and experiences strong selection pressure, exerted by an interacting taxon in areas of sympatry. In Korea, there are two closely related treefrog species: Hyla japonica, which is distributed widely throughout the country, and Hyla suweonensis, which occurs sympatrically in a narrow strip of western coastal plains. H. suweonensis is only found within the distribution of H. japonica. These two species have a similar single-note call structure. Here, we tested the possibility of RCD in H. japonica by examining geographic variation in advertisement calls. Although means of temporal and spectral characters were significantly different between the two species, sympatric populations of H. japonica and H. suweonensis overlapped in distributions of most characters. Furthermore, allopatric and sympatric H. japonica populations did not differ in all call characters. Weak genetic differentiation between sympatric and allopatric populations of H. japonica implied either substantial gene flow or recent genetic isolation. Possible explanations for no RCD in male advertisement calls of H. japonica include a difference in fine temporal characteristics between the two species, migration between sympatric and allopatric localities in H. japonica, RCD in female preferences in H. japonica, and weak selection pressure by H. suweonensis.

Geographic variation in advertisement calls in a tree frog species: gene flow and selection hypotheses.

BackgroundIn a species with a large distribution relative to its dispersal capacity, geographic variation in traits may be explained by gene flow, selection, or the combined effects of both. Studies of genetic diversity using neutral molecular markers show that patterns of isolation by distance (IBD) or barrier effect may be evident for geographic variation at the molecular level in amphibian species. However, selective factors such as habitat, predator, or interspecific interactions may be critical for geographic variation in sexual traits. We studied geographic variation in advertisement calls in the tree frog Hyla japonica to understand patterns of variation in these traits across Korea and provide clues about the underlying forces for variation.MethodologyWe recorded calls of H. japonica in three breeding seasons from 17 localities including localities in remote Jeju Island. Call characters analyzed were note repetition rate (NRR), note duration (ND), and dominant frequency (DF), along with snout-to-vent length.ResultsThe findings of a barrier effect on DF and a longitudinal variation in NRR seemed to suggest that an open sea between the mainland and Jeju Island and mountain ranges dominated by the north-south Taebaek Mountains were related to geographic variation in call characters. Furthermore, there was a pattern of IBD in mitochondrial DNA sequences. However, no comparable pattern of IBD was found between geographic distance and call characters. We also failed to detect any effects of habitat or interspecific interaction on call characters.ConclusionsGeographic variations in call characters as well as mitochondrial DNA sequences were largely stratified by geographic factors such as distance and barriers in Korean populations of H. japoinca. Although we did not detect effects of habitat or interspecific interaction, some other selective factors such as sexual selection might still be operating on call characters in conjunction with restricted gene flow.

Ancient phylogeographic divergence in southeastern Australia among populations of the widespread common froglet, Crinia signifera

Geographic patterns of species diversity in southeast Australia have been attributed to changes in Pleistocene climate, but related phylogeographic patterns and processes are relatively understudied. 12S and 16S mitochondrial DNA sequences in Crinia signifera populations were used to infer historical patterns and processes in southeast Australia. Phylogenetic analysis identified three geographically restricted ancient lineages and several geographically restricted sub-clades. Present-day features that may prevent gene flow are absent between these geographic regions. Divergence among the three lineages corresponds to a late Miocene origin, approximately 9 million years ago (mya). The geographic breaks among the lineages are consistent with Miocene–Pliocene uplift in the Great Dividing Range and elevated sea levels in East Gippsland. Divergence among sub-clades in Victoria and South Australia is estimated to be within the early Pliocene, whereas sub-clades in New South Wales are estimated to have diverged near the Plio-Pleistocene boundary, approximately 2mya. Geographic limits of sub-clades are consistent with geographic variation in advertisement calls, but are inconsistent with phylogeographic limits previously identified in other southeastern species.

GEOGRAPHIC VARIATION IN ADVERTISEMENT CALL AND GENETIC STRUCTURE OF COLOSTETHUS PALMATUS (ANURA, DENDROBATIDAE) FROM THE COLOMBIAN ANDES

Among frogs endemic to the Colombian Andes, the dendrobatid Colostethus palmatus has an exceptionally wide geographic distribution. We examined the patterns of variation in calls and genetic properties to determine whether this variation is associated with geographic barriers and distances between populations. We analyzed variation in advertisement calls and RAPD products in seven populations along a 346-km transect from south to north throughout the Cordillera Oriental covering an extensive part of the geographical range of C. palmatus. Populations of this species inhabit both slopes of the Cordillera Oriental, and are separated by a continuous ridge along these mountains. We found more inter- than intrapopulational variation. Four call variables and male snout–vent length exhibited clinal variation, generating a predictable geographic pattern which coincided with a climatic gradient of increasing moisture and seasonality. The genetic relations between populations are explained by their location on the A...

Geographic variation in advertisement calls of Crinia signifera (Anura:Myobatrachidae) in the Bass Strait area of south-eastern Australia

The structure of recorded advertisement calls of a total of 176 males of Crinia signifera from eight localities on the south-eastern Australian mainland and Tasmania was investigated. On the basis of number of pulses per call (samples from all localities) and call duration adjusted to 13.0°C (samples from six localities), two geographic groups are recognised: (1) south-central Victoria, and (2) the extreme south-eastern mainland and Tasmania. This pattern of variation is postulated to reflect expansion of a differentiated Tasmanian stock on to the extreme south-eastern Australian mainland along the eastern sill of the Bassian Isthmus during the lower sea levels of the Late Pleistocene. Geographic variation in pulse rate (derived from number of pulses and call duration) was also considered because of its use in previous studies. The variation in dominant frequency in samples from five localities, adjusted for snout–vent length, does not conform to that for number of pulses and call duration, and is attributed to differences in demographic structure and recruitment.

Within-individual variation in bullfrog vocalizations: Implications for a vocally mediated social recognition system

Acoustic signals provide a basis for social recognition in a wide range of animals. Few studies, however, have attempted to relate the patterns of individual variation in signals to behavioral discrimination thresholds used by receivers to discriminate among individuals. North American bullfrogs (Rana catesbeiana) discriminate among familiar and unfamiliar individuals based on individual variation in advertisement calls. The sources, patterns, and magnitudes of variation in eight acoustic properties of multiple-note advertisement calls were examined to understand how patterns of within-individual variation might either constrain, or provide additional cues for, vocal recognition. Six of eight acoustic properties exhibited significant note-to-note variation within multiple-note calls. Despite this source of within-individual variation, all call properties varied significantly among individuals, and multivariate analyses indicated that call notes were individually distinct. Fine-temporal and spectral call properties exhibited less within-individual variation compared to gross-temporal properties and contributed most toward statistically distinguishing among individuals. Among-individual differences in the patterns of within-individual variation in some properties suggest that within-individual variation could also function as a recognition cue. The distributions of among-individual and within-individual differences were used to generate hypotheses about the expected behavioral discrimination thresholds of receivers.

Neighbour–stranger discrimination by territorial male bullfrogs (Rana catesbeiana): I. Acoustic basis

Some territorial animals discriminate among neighbours and strangers based on individual differences in acoustic signals. Male North American bullfrogs, Rana catesbeiana, display this form of discrimination based on individual variation in advertisement calls. In this study, we investigated the acoustic basis of neighbour–stranger discrimination to determine how individual identity might be encoded by particular properties of bullfrog advertisement calls. We analysed patterns of within-male and between-male variability in 1078 bullfrog advertisement calls recorded from 27 territorial males. All call properties that we examined varied significantly among males. However, fundamental frequency and dominant frequency showed the lowest within-male variation and the highest repeatability between two recording sessions, and both properties were highly correlated with the first canonical root from discriminant function analyses, which typically accounted for 70–80% of the variability between males. We suggest that neighbour–stranger discrimination in bullfrogs is partially mediated by between-male differences in the spectral or fine temporal properties of advertisement calls.

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

Individuals of many territorial species discriminate between familiar territorial neighbors and unfamiliar strangers based on individual differences 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 first 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 afforded by these properties for identifying different neighbors. All of the call properties that we examined exhibited significant 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 sufficient 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.

ALLOZYME AND ADVERTISEMENT CALL VARIATION IN THE TÚNGARA FROG, PHYSALAEMUS PUSTULOSUS.

We analyzed variation in advertisement calls and allozymes in 30 populations along a 5000-km transect throughout most of the range of the túngara frog, Physalaemus pustulosus. All 12 call variables measured show significant differences among populations despite the importance of the advertisement call in species recognition. Some call variables exhibited clinal variation, whereas most others differed between the two major allozyme groups that have invaded Panama at different times, perhaps 4-4.5 million yr apart. Call variables that primarily affect discrimination among conspecifics tended to exhibit greater variation than call variables that are crucial for species recognition. The proximate mechanism of production underlying a call variable, however, is a better predictor of its variation. Contrary to predictions of some sexual selection models, call variation exhibits predictable patterns of geographical variation, although a substantial portion of variation among populations is not explained by geographic position. Although allozymes, calls, and geography usually covary, closer populations can have more similar calls independent of allozyme similarity.

Systematics of the Bufo woodhousii Complex (Anura: Bufonidae): Advertisement Call Variation

To determine whether Bufofowleri, Bufo woodhousii woodhousii, and Bufo woodhousii australis are diagnosable taxa, we examined variation in advertisement calls and body size across the range of the Bufo woodhousii complex. Calls were recorded and toads measured in six regions consisting of California, Arizona, Utah, Texas, Nebraska and Iowa, and New Jersey. Pulse rate and call duration, but not frequency, were significantly related to temperature. Dominant frequency was the only call variable of the three analyzed that correlated with snout-vent length. When adjusted for temperature and size effects, calls of B. fowleri had a shorter duration and higher dominant frequency than the other two members of the B. woodhousii complex. Discriminant analysis using call variables and body size provided clear separation of B. fowleri from B. w. woodhousii and B. w. australis. Univariate and multivariate analyses revealed that toads from southern California were most similar to toads from south-central Arizona currently recognized as B. w. australis. We conclude that B. fowleri should be recognized as a species. Continued recognition of B. w. australis and B. w. woodhousii as western forms of the B. woodhousii complex is reasonable.