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Selected AbstractsTemporal and Geographic Variation in the Advertisement Call of the Booroolong Frog (Litoria booroolongensis: Anura: Hylidae)ETHOLOGY, Issue 12 2005Michael J. Smith The 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. [source] Changes in the Frequency Structure of a Mating Call Decrease Its Attractiveness to Females in the Cricket Frog Acris crepitans blanchardiETHOLOGY, Issue 8 2001Klaudia Witte In many species, females often prefer male signals that are more complex than in nature or beyond the range of calls naturally produced by conspecific males in spectral, temporal and amplitude features. In this study we examined both the ability of females to recognize signals outside the normal range of spectral frequency variation seen in male advertisement calls, and the influence of increasing call complexity by adding spectral components to enhance the attractiveness of a male advertisement call in the cricket frog Acris crepitans blanchardi, while keeping its amplitude constant. We used two different natural male call groups and created the following synthetic call groups: with a dominant frequency at 3500 Hz, i.e. at the normal dominant frequency with a frequency band within the sensitivity range of the inner ear basilar papilla; with a dominant frequency at 700 Hz, i.e. outside the normal range of variation and with a frequency band outside the sensitivity range of the basilar papilla but within the range of the amphibian papilla; with two dominant frequencies, one at 700 Hz and another at 3500 Hz, stimulating the basilar and amphibian papilla simultaneously. In double choice experiments we tested all combinations of the three call groups, and we tested the 3500 Hz call groups against the same natural call groups. Additionally, we tested the 700 Hz call groups against white noise to see whether these signals are meaningful in mate choice. Females preferred 3500 Hz call groups over all other call groups. The synthetic call group was as attractive to females as the same natural call group. The 700 Hz call group was not meaningful in mate choice. The combined (700 Hz + 3500 Hz) call group was significantly less attractive to females than the 3500 Hz call group. Thus, making a call more spectrally complex without increasing its overall amplitude decreases its attractiveness to cricket frog females. [source] Discordance in body size, colour pattern, and advertisement call across genetically distinct populations in a Neotropical anuran (Dendropsophus ebraccatus)BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 2 2009MICHEL E. OHMER Patterns of intraspecific geographic variation in morphology and behaviour, when examined in a phylogenetic context, can provide insight into the microevolutionary processes driving population divergence and ultimately speciation. In the present study, we quantified behavioural and phenotypic variation among populations from genetically divergent regions in the Central American treefrog, Dendropsophus ebraccatus. Our fine-scale population comparisons demonstrated regional divergence in body size, colour pattern frequencies, and male advertisement call. None of the characters covaried with phylogenetic history or geographic proximity among sampled populations, indicating the importance of highly localized selection pressures and genetic drift in shaping character divergence among isolated regions. The study underscores how multiple phenotypic characters can evolve independently across relatively small spatial scales. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 298,313. [source] Release vocalizations in neotropical toads (Bufo): ecological constraints and phylogenetic implicationsJOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 1-2 2001Di Tada The release vocalizations of four nominal neotropical toad taxa (Bufo achalensis, Bufo limensis, Bufo spinulosus, Bufo arenarum) which compose three sympatric species pairs, were quantitatively analysed and homologous call types statistically compared. The first three taxa are closely related members of the mainly Andean Bufo spinulosus species group in which advertisement calls are absent. The specific vocal repertoire consisted of a uniform, unpulsed release call and one (in B. arenarum, two) pulsed release trill(s) which were given either singly or in series of up to three single calls. The uniform call was similar in structure and dominant (= basic) frequency in all taxa and probably represents an unspecific acoustic signal which is used to avoid heterospecific amplexus between sympatric toads. The release trills significantly differed in most call features among the taxa and, using discriminant analyses, even single calls were correctly assigned to sympatric pairs of species. In contrast, calls of allopatric pairs of species were confounded at rates of up to 36% indicating that selection towards species-specific signals increases when different species live in sympatry. The release trills of two allopatric populations (Perú, Argentina) assigned to B. spinulosus were similar in structure, but nevertheless features of pulse train permitted an unequivocal distinction, suggesting a long-lasting independent evolution. The taxonomic significance of this finding remains to be evaluated in further investigations. The complex vocal repertoire also offered the opportunity to assess phylogenetic relationships among the taxa. The extra-Andean B. achalensis seems to be closer related to the Andean B. spinulosus than this species is to the widely sympatric B. limensis– a species with several primitive character states indicating an early separation from the ancestral stock. Befreiungsrufe neotropischer Kröten (Bufo): Ökologische Einflüsse und phylogenetische Bedeutung Die Befreiungsrufe vier nomineller neotropischer Krötentaxa (Bufo achalensis, Bufo limensis, Bufo spinulosus, Bufo arenarum), die drei sympatrisch lebende Paare bilden, wurden quantitativ untersucht und homologe Ruftypen statistisch verglichen. Die drei erstgenannten Taxa sind nahverwandte Mitglieder der hauptsächlich andinen Bufo spinulosus Artengruppe, die keinen Paarungsruf besitzt. Das artspezifische Rufrepertoire umfaßte einen gleichförmigen, nicht-gepulsten Befreiungsruf und einen (bei B. arenarum zwei) aus Impulsen bestehenden Befreiungstriller. Diese Rufe werden entweder einzeln oder als Rufserien mit bis zu drei Einzelrufen abgegeben. Der gleichförmige Ruf war bei allen Taxa strukturell ähnlich und ist wahrscheinlich ein nichtartspezifischer Teil des Kommunikationssytems, der zur Vermeidung heterospezifischer Amplexus zwischen sympatrischen Kröten dient. Die Triller unterschieden sich in den meisten Merkmalen signifikant zwischen den Arten und auch Einzelrufe wurden bei sympatrischen Arten mittels Diskriminanzanlyse korrekt klassifiziert. Hingegen betrugen bei allopatrischen Arten die Fehlklassifikationen bis zu 36%. Dies weist auf einen starken Selektionsdruck zu artspezifischen Signalen bei Sympatrie hin. Die Triller zweier allopatrischer Populationen (Perú, Argentina) von B. spinulosusähnelten sich zwar strukturell, liessen sich aber ohne Fehlklassifikation voneinander unterscheiden, wahrscheinlich ein Hinweis auf eine längere unabhängige Evolution. Zur Klärung der taxonomischen Bedeutung dieses Befundes sind jedoch weitere Untersuchungen nötig. Der komplexe Aufbau der Rufe eröffnete auch die Möglichkeit, mittels bioakustischer Merkmale die phylogenetischen Beziehungen zwischen den Taxa abzuleiten. Die extraandine B. achalensis scheint mit der andinen B. spinulosus näher verwandt zu sein als diese Art mit der weitgehend sympatrischen B. limensis. Letztere Art zeigt eine Reihe primitiver Merkmale, die auf eine frühe Trennung vom der ancestralen Evolutionlinie hinweisen. [source] | ||||||||||