Geographic Variation In Vocalizations Research Articles

Structure and divergence of vocal traits in the Acorn Woodpecker (Melanerpes formicivorus)

Studies of geographic variation of bird vocalizations facilitate the understanding of species' divergence and evolutionary histories, as vocal traits vary in response to different factors including the environment, morphology, culture, and inheritance. The Acorn Woodpecker (Melanerpes formicivorus) is a non-passerine species of the family Picidae, and therefore its vocalizations are not acquired through learning. It is widely distributed throughout the Americas and exhibits distinctive morphological and genetic differences among the 7 allopatric subspecies, but little is known about geographic variation in the structure of its vocalizations and whether vocal variation corresponds with their genetic differences. We collected recordings throughout the species' range and assessed the frequency and temporal features of their most common calls to study geographic variation in vocalizations. Specifically, we tested whether divergence in vocal traits mirrored subspecies limits. Our results showed the formation of 2 vocal groups that do not reflect subspecies limits. The genetic divergence described in previous studies coincides with the vocal divergence found in this study, with 2 areas promoting the greatest divergence: the Isthmus of Tehuantepec and the Gulf of California. Previously described morphological variation in bill sizes also coincides with the vocal groups found in this study, in which large and small sizes are grouped separately.

Variation in the ecstatic display call of the Gentoo Penguin (Pygoscelis papua) across regional geographic scales

ABSTRACT Geographic variation in bird vocalizations is common and has been associated with genetic differences and speciation, as well as with short-term changes in response to anthropogenic noise. Because vocalizations are used for individual recognition in many species, geographic variation in these traits may affect mate choice, pair bonding, and territory defense. Anecdotal evidence suggests the existence of geographic variation in vocalizations between isolated populations of Gentoo Penguins (Pygoscelis papua), but there have been no comprehensive studies of Gentoo Penguin vocalizations across a broad geographic range. We used acoustic recordings of ambient colony sound at 22 breeding colonies in the Antarctic Peninsula and South Shetland Islands, South Georgia, the Falkland Islands, and Argentina to address 2 main questions regarding Gentoo Penguin vocalizations: (1) How do ecstatic display calls vary both within and between individuals, colonies, and regions? (2) Can ecstatic display calls be used ...

Geographic variation and phylogenetic relationships of Myiopagis olallai (Aves: Passeriformes; Tyrannidae), with the description of two new taxa from the Northern Andes

Geographic variation in vocalizations, morphology and plumage patterns in New World flycatchers is little understood, particularly in rare species with disjunct distributions. We discovered a distinct new flycatcher of the genus Myiopagis from cloud forests of the northern Central Andes in Antioquia, Colombia. Comparisons of vocalizations and external morphology, and molecular phylogenetic analyses, demonstrate that the "Antioquia Myiopagis" is a unique lineage of the M. caniceps-olallai group. We show that three specimens collected in 1940-1951 from cloud forests of Serranía de Perijá in Venezuela, and traditionally assigned to M. caniceps, represent another distinct taxon that is closer to the "Antioquia Myiopagis" and M. olallai. Both new taxa, from Antioquia and Perijá, are described as subspecies of M. olallai. We present a phylogenetic hypothesis for the M. caniceps-olallai group, in which M. olallai and the "Antioquia Myiopagis" are phylogenetically nested within the polytypic M. caniceps, which consists of at least four distinct lineages, indicating that species diversity in this group could be underestimated.

Taxonomy and conservation: a tale of two tinamou species groups (Tinamidae, Crypturellus)

Species delimitation has important consequences for the management of endangered species. Species‐level taxonomy in the genus Crypturellus (Tinamidae) has been based largely on plumage characters and species limits in several groups have been difficult to establish. Because some of the forms of uncertain taxonomic status are currently threatened with extinction, a basic understanding of species limits is crucial not only for taxonomists but also for conservation biologists and managers. We analysed vocal variation to assess species limits in two Crypturellus species‐groups, the red‐legged complex (Crypturellus erythropus and allied forms) and the brown tinamou Crypturellus obsoletus. In the red‐legged complex, where several species‐level taxa have been recognized by some authors, there is no obvious geographic variation in vocalizations and populations appear mostly continuously distributed, with plumage variation largely explicable in terms of environmental conditions. In the brown group, a single species is recognized, but we found marked geographic variation in vocalizations and populations have disjunct distributions; we propose that at least one of the populations in this group likely merits recognition as a separate species. We conclude that incomplete knowledge of patterns of variation in relevant traits in addition to the momentum carried by traditional taxonomy may potentially mislead conservation actions.

Systematics of the Tawny-bellied Seedeater (Sporophila hypoxantha). I. Geographic Variation, Ecology, and Evolution of Vocalizations

Abstract. Geographically isolated populations diverging in vocalizations and habitat use are prime candidates for diversification along the speciation/differentiation continuum. The Tawny-bellied Seedeater (Sporophila hypoxantha) is relatively widespread, thus potentially variable across its range. We investigated geographic variation in vocalizations, habitat use, and migratory behavior, identifying five regiolects (song variants encompassing extensive subpopulations of a species and all individuals within this large range), which correspond with different patterns of habitat use but arose independently of migratory behavior. Given the low level of genetic divergence in the capuchinos, a subset of the genus Sporophila that includes S. hypoxantha, the phylogenetic potential for learning in the genus, the fast temporal changes evident within regiolects (chronolects), the existence of environmental sound assimilation, and the singing of subsongs by young males, we conclude that geographic variation is due m...

Geographic variation in vocalizations of pups and mother-pup behavior of harp seals Pagophilus groenlandicus

All harp seal populations form breeding aggregations on the Arctic pack ice. However, pack ice conditions vary spatially and temporally among these aggregations with variation in envi- ronmental and oceanographic conditions, which may affect the behavioral interactions between mothers and their newborn pups. We investigated the variation in mother-pup behavior between harp seal breeding aggregations in the NE (Greenland Sea) and NW Atlantic coastal shelf region (Front). Acoustic cues provided by the pups are thought to be important in facilitating reunions with their mothers. Consequently, we measured variation in vocal parameters among seals to investigate geographic differences in pup vocalizations. Classification trees showed a distinctive split between Front and Greenland Sea pup vocalizations. There were no clear differences between male and female pups at the Front, where 42% of male and 38% of female pup calls could be attributed to a given individual. This contrasts with the Greenland Sea, where 55% of vocalizations of female pups were attributed to individuals compared with only 8% for males. Analyses of behavioral observations of mother-pup pairs made in the afternoon and evening showed that pups in the Greenland Sea suck- led more and were more alert than pups in the Front. Further, mother-pup attendance patterns dif- fered between sites. Mothers at the Front attended their pups 85.1% of the time, whereas mothers in the Greenland Sea attended their pups 52.2% of the time. These substantial differences between sites might be related to evolutionary changes in behavior resulting from commercial hunting or vari- able environmental conditions.

Song dialects do not restrict gene flow in an urban population of the orange-tufted sunbird, Nectarinia osea

Geographic variation in vocalizations is widespread in passerine birds, but its origins and maintenance remain unclear. In this study, we test the hypothesis that song dialect, a culturally transmitted trait, is related to the population genetic structure of the orange-tufted sunbird, Nectarinia osea. To address this, we compared mitochondrial DNA (mtDNA) sequence variation together with allele frequencies at five microsatellite loci from an urban population of sunbirds exhibiting two distinct song dialects on a microgeographic scale. Our findings reveal no association between dialect membership and genetic composition. All genetic measures, from both mitochondrial and nuclear DNA, indicate high levels of gene flow between both dialect populations. The low F ST values obtained from mtDNA and microsatellite analysis imply that the variation among dialects does not account for more than 2%, at best, of the overall genetic variation found in the entire population. These measures fall well within the range of similar measures obtained in other studies of species exhibiting vocal dialects, most of which fail to detect any dialect-based genetic differentiation. The persistence of dialects in the orange-tufted sunbird may thus best be explained by dispersal of individuals across dialect boundaries and possibly from surrounding areas, followed by postdispersal vocal matching. Because genetic structuring appears weaker than cultural structure in this species, we discuss the behavioral mechanisms underlying dialect maintenance in the presence of apparent gene flow.

Geographic Variation in the Long Calls of Male Orangutans (Pongo spp.)

AbstractRelatively few data exist on population differences in the vocal behavior of mammals. Geographic variation in calls is of special interest because of the implications for resolving evolutionary and behavioral questions. For example, information on geographic variation in vocalizations complements morphological and molecular data used to infer phylogenetic relationships and provides evidence for the mechanisms underlying call development. A quantitative acoustic analysis of orangutan long calls was undertaken, comparing flanged adult males from four geographically distinct sites across Borneo and Sumatra, revealing consistent differences among the calls of individuals. Long calls produced by orangutans from the four sites in Borneo and Sumatra differ in quantitative acoustic measures. Discriminant function analysis reveals that acoustic variables can be used in combination to assign calls to the correct individual, site and island at rates higher than that expected by chance. Specifically, four acoustic parameters proved reliable for distinguishing among the individuals, between sites, and across the two islands that arguably represent populations from separate species or subspecies. Although Bornean and Sumatran long calls share a repetitive structure and show similar call rates (0.100–0.500 LCs/h) and maximum frequency bands (0.400–1.500 kHz), they differ significantly in the number of pulses per call, call speed, call duration, bandwidth, pulse duration, and dominant frequency. Strong consistency in these acoustic parameters is also seen among males within sites and the observed variation may allow for individual recognition. Individual identification by call structure presumably benefits dispersed orangutans, where individuals characteristically forage independently and both encounters and interactions with signaling males are highly variable and largely dependent on context. Acoustic recognition of callers facilitates the choice of which males to join or avoid, thus allowing receivers to manipulate potential costs and benefits of association.

Phylogeographic patterns, molecular and vocal differentiation, and species limits in Schiffornis turdina (Aves)

Establishing species limits can be challenging for organisms in which few variable morphological characters are available, such as Schiffornis turdina, a Neotropical suboscine bird of long-debated taxonomic affinities. Apart from its dull plumage and secretive behavior, this taxon is well-known for its subtle but discrete within-species geographic variation in vocalizations. Phylogeographic reconstruction based on three mitochondrial markers sampled across much of the species’ range reveals substantial structuring, concordant with recognized areas of endemism in Neotropical lowland forests. Monophyly of S. turdina was weakly supported by the combined dataset, as was the basal position of the Guyanan Shield population with regard to other S. turdina clades. Based on the results from both genetic and a preliminary, qualitative analysis of vocalizations, I recommend revised species limits to reflect more accurately the evolutionary history of this complex.

GENETIC POPULATION STRUCTURE AND CALL VARIATION IN A PASSERINE BIRD, THE SATIN BOWERBIRD, PTILONORHYNCHUS VIOLACEUS

Geographic variation in vocalizations is widespread in passerine birds, but its origins and maintenance remain unclear. One hypothesis to explain this variation is that it is associated with geographic isolation among populations and therefore should follow a vicariant pattern similar to that typically found in neutral genetic markers. Alternatively, if environmental selection strongly influences vocalizations, then genetic divergence and vocal divergence may be disassociated. This study compared genetic divergence derived from 11 microsatellite markers with a metric of phenotypic divergence derived from male bower advertisement calls. Data were obtained from 16 populations throughout the entire distribution of the satin bowerbird, an Australian wet-forest-restricted passerine. There was no relationship between call divergence and genetic divergence, similar to most other studies on birds with learned vocalizations. Genetic divergence followed a vicariant model of evolution, with the differentiation of isolated populations and isolation-by-distance among continuous populations. Previous work on Ptilonorhynchus violaceus has shown that advertisement call structure is strongly influenced by the acoustic environment of different habitats. Divergence in vocalizations among genetically related populations in different habitats indicates that satin bowerbirds match their vocalizations to the environment in which they live, despite the homogenizing influence of gene flow. In combination with convergence of vocalizations among genetically divergent populations occurring in the same habitat, this shows the overriding importance that habitat-related selection can have on the establishment and maintenance of variation in vocalizations.

GENETIC POPULATION STRUCTURE AND CALL VARIATION IN A PASSERINE BIRD, THE SATIN BOWERBIRD, PTILONORHYNCHUS VIOLACEUS

Geographic variation in vocalizations is widespread in passerine birds, but its origins and maintenance remain unclear. One hypothesis to explain this variation is that it is associated with geographic isolation among populations and therefore should follow a vicariant pattern similar to that typically found in neutral genetic markers. Alternatively, if environmental selection strongly influences vocalizations, then genetic divergence and vocal divergence may be disassociated. This study compared genetic divergence derived from 11 microsatellite markers with a metric of phenotypic divergence derived from male bower advertisement calls. Data were obtained from 16 populations throughout the entire distribution of the satin bowerbird, an Australian wet-forest-restricted passerine. There was no relationship between call divergence and genetic divergence, similar to most other studies on birds with learned vocalizations. Genetic divergence followed a vicariant model of evolution, with the differentiation of isolated populations and isolation-by-distance among continuous populations. Previous work on Ptilonorhynchus violaceus has shown that advertisement call structure is strongly influenced by the acoustic environment of different habitats. Divergence in vocalizations among genetically related populations in different habitats indicates that satin bowerbirds match their vocalizations to the environment in which they live, despite the homogenizing influence of gene flow. In combination with convergence of vocalizations among genetically divergent populations occurring in the same habitat, this shows the overriding importance that habitat-related selection can have on the establishment and maintenance of variation in vocalizations.

Vocal dialects, sex‐biased dispersal, and microsatellite population structure in the parrot Amazona auropalliata

Geographic variation in microsatellite allele frequencies was assessed at nine sites in two regional vocal dialects of the parrot Amazona auropalliata (yellow-naped amazon) to test for correspondence between dialects and population structure. There was no relationship between the genetic distances between individuals and their dialect membership. High rates of gene flow were estimated between vocal dialects based on genetic differentiation. In addition, 5.5% of pairs of individuals compared across the dialect boundary were estimated to be related at the level of half siblings, indicating that dispersal is ongoing. The number of effective migrants per generation between dialects estimated with the microsatellite data was roughly one-seventh the number estimated with mitochondrial control region sequence data from the same individuals, suggesting that gene flow may be female-biased. Together, these results suggest that the observed mosaic pattern of geographic variation in vocalizations is maintained by learning of local call types by immigrant birds after dispersal. We found no evidence that ongoing habitat fragmentation has contributed to cryptic population structure.

Relationships between underwater vocalizations and mating systems in phocid seals

In this paper, we considered the number and diversity of underwater vocalizations given by aquaticbreeding phocids, and two species that copulate both in the water and on ice, in relation to what is known or hypothesized about their mating systems. Underwater recordings made throughout the year by both bearded ( Erignathus barbatus ) and Weddell (Leptonychotes weddellii ) seals indicated that most of the vocalizations could be attributed to males and were given almost exclusively during the breeding season. Less extensive studies of other species indicated the same pattern. Thus, for this study, we considered only underwater vocalizations known, or suspected, to be given by adult males during intra-specie c agonistic behaviour, defence of territories or access to females, or attraction of females. A one-way ANOVA and linear regression indicated a signie cant relationship between the numbers of underwater vocalizations given by individual species and their mating systems. A Pearson’ s correlation analysis discerned the following: the mating system and the number of vocalizations were positively correlated; female gregariousness was positively correlated with the number of underwater vocalizations and geographic variation in vocalizations, but there was no correlation with the duration of lactation. The degree of predation was negatively correlated with the number of vocalizations, geographic variation in vocalizations, and the number of days of lactation. A principal component analysis showed that 66.1% of the variation in this data set was explained by Factor 1, a suite of variables that included mating system, number of underwater vocalizations, intensity of predation, female gregariousness, and geographic variation in vocalizations. The number of days of lactation explained an additional 19.5% of the variability. These results suggest that additional selection pressures, more specie c to the ecological circumstances of individual species, also ine uence the size of the underwater repertoire. The development of a diverse underwater repertoire with geographic variations was consistently associated with the development of population genetic structure and geographic e delity. Within each category of social system, the species with the greatest number of underwater vocalizations consistently occurred at higher densities during the breeding season than did the species with the lowest vocal diversity. The role of predators on the evolution of social systems is not well known, but could be signie cant for some species. Characteristics of the underwater vocalizations of walruses during the breeding season were found to share similar characteristics to phocids occurring at similar densities in similar habitats, suggesting that the most important selection factors ine uenced both phocids and odobenids similarly. On the basis of the available information from better-studied species, some testable hypotheses are proposed for further investigations of spotted ( Phoca largha ), Ross (Ommatophoca rossii ), Hawaiian monk (Monachus schauinslandi), and ribbon ( Phoca fasciata) seals.

Geographic Variation in Syllables of House Finch Songs

Bird songs often can be described as strings of individually distinct units called syllables. Toward furthering our understanding of the processes and consequences of vocal learning, geographic variation in vocalizations may be as important at the syllable level as it is at the song level. To examine geographic patterns of song variation at the syllable level in House Finches (Carpodacus mexicanus), we analyzed the syllable repertoires of 91 males at 21 sites in northern Colorado. Analyses were performed and comparisons were made among individual birds within and between sites. Using Jaccard's similarity coeffi- cient, we determined that syllable sharing among birds was significantly greater within sites and among sites less than 5 km apart than at greater distances. Within a site, any two birds usually did not share the majority of their syllable types, but discriminant function analysis showed that approximately 63% of the birds possessed syllable repertoires that matched most closely those of other birds at the same site. Less than 5% of the birds sang syllables that most closely matched those of birds at a site more than 20 km away. Our results suggest that House Finches in northern Colorado exhibit localized syllable sharing and that syllable sharing decreases exponentially with distance, but we found no evidence for discrete syllable dialects. Geographic variation in bird song typically has been evaluated using whole songs. Depending on how birds assess the singing behavior of other individuals and perceive dif- ferences in songs, it may be important to examine geographic variation and population dif- ferences at the syllable level as well. Received 8 January 1998, accepted 17 November 1998.

Geographic Variation in Vocalizations and Evolution of North American Pine Grosbeaks

Geographic Variation in Vocalizations and Evolution of North American Pine Grosbeaks

Geographic Variation in the "Hoy" Call of the Bobwhite

-Intraspecific geographic variation in the hoy call of female Bobwhite (Colinus virginianus) was studied. Twelve morphometric characters of sonograms of this call for 38 individuals, recorded in the field at the 4 extreme corners of the species' contiguous range in the U.S., were examined by univariate and multivariate statistical techniques. In spite of the absence of striking qualitative differences apparent dialects have been detected for the four populations. Department of Zoology, University of Nebraska, Lincoln, Nebraska 68508. Present address: Department of Biology, Creighton University, Omaha, Nebraska 68178. Accepted 1 June 1976. THE study of individual variation in avian vocalizations attempts to define the limits of variation for single populations (Borror 1959, 1965; Marler and Isaac 1960a, 1960b, 1961; Konishi 1964; Hutchison et al. 1969; Hekenlively 1970; Heinz and Gysel 1970; Emlen 1971a; Williams 1972; Beightol and Samuel 1973), failing to address the dimensionality of the species. Only through detailed analyses of intraspecific variation can one approach the systematics of a species. Many studies of geographic variation in passerine vocalizations (Thielcke 1969; Lemon 1969, 1971; Nottebohm 1969; Shiovitz and Thompson 1970; Bertram 1970; Emlen 197 ib; Harris and Lemon 1972; Baker 1975; Orejuela and Morton 1975) have been reported while only two such studies (Wiley 1971, Van Der Weyden 1973) have been published concerning nonpasserines. All of these studies have dealt with qualitative differences, or at best a few quantitative differences of sonograms, treated univariately, in discussing the species' variability. This study attempts to discern geographic variation in the vocalizations of four populations of the Bobwhite (Colinus virginianus) within its contiguous range in the United States, through multivariate analysis of quantitative morphometric characters of sonograms of one of its calls. The Bobwhite provides an excellent opportunity for study of geographic variation of vocalizations. With the exception of populations in northern Sonora, Mexico, Oregon, Washington, and Idaho, its range is continuous through much of the United States and Mexico. The contiguous U.S. populations have been divided into 3, 4, and 6 subspecies (Aldrich 1946, Ridgway and Friedmann 1946, A.O.U. 1957). Measurements of these subspecies (Aldrich 1946) reveal only slight morphological variation. On the basis of limited samples, Holman (1961) detected a north-south decrease in mean size of skeletal elements to be the only osteological trend for these populations. Ripley (1960) identified a similar trend in the weights of Bobwhites in the east. Aldrich (1946) and Rosene (1969) reported some color variation but suggested that this might be more ecotypic than geographic. The fact remains that several American subspecies of Bobwhite are recognized (A.O.U. 1957), implying a degree of genetic isolation among the contiguous populations. This reduction in gene exchange might be a result of pair formation taking place within coveys, while they are still intact (Stoddard 1931), but unmated males may still pair with females separated from their mates after the coveys disperse. Coupled with the random movement of birds after the breeding season (Stoddard 1931, Agee 1957, Rosene 1969), this would allow for gene exchange between coveys. The low vagility of the Bobwhite (Stoddard 1931, Leopold 1933, Murphy and Bas85 The Auk 95: 85-94. January 1978 This content downloaded from 157.55.39.78 on Mon, 20 Jun 2016 07:25:04 UTC All use subject to http://about.jstor.org/terms 86 RAYMOND B. GOLDSTEIN [Auk, Vol. 95