Responses to neighbours and non-neighbours in the buff-banded rail (Gallirallus philippensis): no dear-enemy relationships

Territorial individuals often respond less aggressively to intrusions by their neighbours than to intrusions by unfamiliar individuals. This commonly observed strategy, the dear-enemy phenomenon, is thought to minimise the costs associated with territory defence. This study determined whether an insular population of territory-holding buff-banded rails (Gallirallus philippensis) exhibits dear-enemy relationships and whether males and females differ in their responses to neighbours and non-neighbours. Playback techniques were used to examine and compare the vocalisations and movements of focal individuals in response to the territorial advertisement calls of their neighbours and of unfamiliar individuals (non-neighbours). Results showed that focal birds did not respond differently to the calls of neighbours and non-neighbours; thus, no evidence for the dear-enemy phenomenon was found in this species. We suggest that this result is due to the significant threats posed by neighbours to territory owners in this territorial system, in addition to a high level of territorial instability in the population. Males and females were shown to differ qualitatively in their general territorial response to intruders but not in their relative responses to neighbours and non-neighbours, suggesting that the relative threats posed by neighbours and non-neighbours do not differ between the sexes.

The effect of provocation in the form of mild erotica on attitude to the ad and corporate image: Differences between cause-related and product-based advertising

Provocative advertising is characterized by a deliberate attempt to gain attention through shock. This research investigates the reactions of individuals to a provocative appeal for a cause as opposed to a provocative advertisement for a standard consumer product, using mild erotica as the element of provocative imagery. An experiment using 391 adult subjects was conducted, and two analyses were performed. The first examined the effect of stimulus type (mildly erotic/nonerotic) by product category (cause appeal/consumer product) on attitude to the ad. The second examined the effect of stimulus type (mildly erotic/nonerotic) by cause (AIDS [acquired immunodeficiency syndrome]/SIDS [sudden infant death syndrome]) on corporate image. Both analyses also included gender as a third independent variable. The results suggest that people prefer mildly erotic ads generally, that an organization using mild erotica in appeals for a cause will be viewed more favorably where the erotica is congruent with the cause, and that women may be more responsive to mild erotica in cause appeals than are men.

The media, marketing, and single sex schooling

The Australian media's interest in education, as in many Anglophone countries, is frequently dominated by concerns about boys in schools. In 2002, in a country region of the Australian State of Queensland, this concern was evident in a debate on the merits of single sex schooling that took place in a small local newspaper. The debate was fuelled by the inclusion in this newspaper of an advertising brochure for an elite private girls' school. The advertisement utilized the current concerns about boys in schools to advocate the benefits of girls' only schools. Drawing on research that suggests that boys are a problem in school, and utilising a peculiar mix of liberal feminism alongside a neo-liberal class politics, it implicitly denigrated the education provided by government co-educational schools. The local government high and primary school principals, incensed at this advertisement, contacted the paper to refute many of its claims and assumptions and to assert the benefits, to both boys and girls, of their particular schools. A letters to the editor debate then followed an article representing these government school principals' views. These letters were from two private school principals. This country newspaper thus became a medium through which various school principals engaged with the current boys' debate, and research associated with it, in order to market their schools. This paper examines this particular newspaper debate and argues that, in the absence of nuanced, research based, and thoughtful policy responses to gender issues, many school policies on gender are being shaped through and by the media in ways that elide the complexities of the issues involved.

Experimental evidence for multivariate stabilizing sexual selection

Stabilizing selection is a fundamental concept in evolutionary biology. In the presence of a single intermediate optimum phenotype (fitness peak) on the fitness surface, stabilizing selection should cause the population to evolve toward such a peak. This prediction has seldom been tested, particularly for suites of correlated traits. The lack of tests for an evolutionary match between population means and adaptive peaks may be due, at least in part, to problems associated with empirically detecting multivariate stabilizing selection and with testing whether population means are at the peak of multivariate fitness surfaces. Here we show how canonical analysis of the fitness surface, combined with the estimation of confidence regions for stationary points on quadratic response surfaces, may be used to define multivariate stabilizing selection on a suite of traits and to establish whether natural populations reside on the multivariate peak. We manufactured artificial advertisement calls of the male cricket Teleogryllus commodus and played them back to females in laboratory phonotaxis trials to estimate the linear and nonlinear sexual selection that female phonotactic choice imposes on male call structure. Significant nonlinear selection on the major axes of the fitness surface was convex in nature and displayed an intermediate optimum, indicating multivariate stabilizing selection. The mean phenotypes of four independent samples of males, from the same population as the females used in phonotaxis trials, were within the 95% confidence region for the fitness peak. These experiments indicate that stabilizing sexual selection may play an important role in the evolution of male call properties in natural populations of T. commodus.

Geographic variation in vocalisations of Satin Bowerbirds, Ptilonorynchus violaceus, in south-eastern Queensland

Geographic variation in the advertisement call of the male Satin Bowerbird, Ptilonorhynchus violaceus, was investigated in three populations in south-eastern Queensland. The call was found to differ significantly among the three geographically distinct populations. A discriminant function analysis using five measurements of call frequency and duration provided 100% classification success of the 25 individuals. The observed geographic variation in this call may result from adaptation to the local acoustic environment in these populations, or from genetic or cultural divergence among populations. Further research involving the acoustic properties of the habitats, population genetics and a larger number of populations is required to fully understand this pattern of call variation.

Habitat type and density influence vocal signal design in satin bowerbirds

This study provided a thorough test of the acoustic adaptation hypothesis using a within-species comparison of call structure involving a wide range of habitat types, an objective measure of habitat density and direct measures of habitat-related attenuation. The structure of the bower advertisement call of the satin bowerbird was measured in 16 populations from throughout the species' range and related to the habitat type and density at each site. Transmission of white noise, pure tones and different bowerbird dialects was measured in five of six habitat types inhabited by satin bowerbirds. Bowerbird advertisement call structure converged in similar habitats but diverged among different habitats; this pattern was apparent at both continent-wide and local geographical scales. Bowerbirds' call structures differed with changes in habitat density, consistent with the acoustic adaptation hypothesis. Lower frequencies and less frequency modulation were utilized in denser habitats such as rainforest and higher frequencies and more frequency modulation were used in the more open eucalypt-dominated habitats. The white noise and pure tone transmission measurements indicated that different habitats varied in their sound transmission properties in a manner consistent with the observed variation in satin bowerbird vocalizations. There was no effect of geographical proximity of recording locations, nor was there the predicted inverse relationship between frequency and body size. These findings indicate that the transmission qualities of different habitats have had a major influence on variation in vocal phenotypes in this species. In addition, previously published molecular data for this species suggest that there is no effect of genetic relatedness on call similarity among satin bowerbird populations.

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.

Patterns of painting in satin bowerbirds Ptilonorhynchus violaceus and males' responses to changes in their paint

Satin bowerbirds Ptilonorhynchus violaceus have an elaborate multi-component sexual display, some components of which have been extensively studied. We describe a relatively unstudied component of this display, bower painting, and birds' responses to manipulations of their paint. Males of this species focus their display around a stick bower constructed on the forest floor which they decorate with a variety of objects and paint. Painting involves a male masticating plant material and wiping the plant-saliva mixture onto the inside walls of the bower; during courtship visits to bowers, females nibble at this paint. We found that 93% of 53 males painted their bowers at our study site and the time males spent painting their bowers accounted for 24% of their time at the bower. We experimentally removed and added paint to bowers to test whether males respond to these changes in their paint. Males gave more advertisement calls and spent less time manipulating sticks at the bower when we added fresh wet paint to their bowers compared to older dried paint or a control treatment. They did not respond to the removal of paint from their bowers, perhaps because it was primarily older dried paint that was removed. We also found that males painted more frequently when there was measurable wind in their bowers, which could have degraded the quality of the signal. Our findings indicate that fresh wet paint is more important to males than older dried paint and, together with previous work at this site, suggest that paint may act as a signal to females. Given that females nibble bower sticks during courtship, we suggest that bower paint may function as a chemical sexual signal rather than a visual signal.