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Sexual Signalling (sexual + signalling)
Selected AbstractsFemale Attraction to Conspecific Chemical Cues in the Palmate Newt Triturus helveticusETHOLOGY, Issue 8 2005Jean Secondi Although chemosignals are largely used in sexual communication in urodeles, olfactometer studies in newts provided contrasting results about the sex specificity of female behavioural responses. Because long-range sexual advertisement is believed to be costly, some species might restrain this activity to close interactions with conspecifics. We tested chemical-mediated sexual attraction in female palmate newt (Triturus helveticus) by measuring the attraction to male and female odours in a linear water olfactometer. Unexpectedly, females were attracted towards conspecifics regardless of sex. They did not show attraction towards Limnaea stagnalis, a common sympatric aquatic gastropod. These results do not support the use of long-range male sexual signalling in the palmate newt. Instead, conspecific attraction is likely to promote aggregation of males and females in breeding ponds. Observations in the field and in the laboratory tend to support the aggregative behaviour of this species. We discuss the possible function of conspecific attraction in this context. Heading towards any conspecific would increase the probability of finding potential mates. Chemical cues do not need to be sex-specific at that stage so that long-range sexual advertisement might be unnecessary. This work emphasizes the need for studies investigating the evolutionary relationships between sexual signalling systems and population-distribution patterns. [source] Different roles of natural and sexual selection on senescence of plumage colour in the barn swallowFUNCTIONAL ECOLOGY, Issue 2 2009Ismael Galván Summary 1Colour may show effects of senescence because the pigment or structures involved in production of colouration deteriorate with age. 2We tested this hypothesis by investigating age-related changes in plumage colour for two feather tracts coloured by eumelanin or pheomelanin in a longitudinal study of a cohort of barn swallows Hirundo rustica that reached very old age (at least 5 years). 3The level of melanization of the throat increased with age in both sexes, but particularly in females. In contrast, the black colour of the plumage of the back was unrelated to age in both sexes. 4These age-dependent patterns of colouration of different feather tracts of male and female barn swallows suggest that effects of senescence are trait-specific depending on their importance in sexual signalling. The red throat colour based on pheomelanin is involved in sexual selection, with a strong effect in males, but not in females. In contrast, the black colour of the back based on eumelanin is unrelated to sexual selection, but is under natural selection due to intense abrasion of this feather tract. 5These findings suggest that the relative importance of natural and sexual selection are important determinants of the pattern and rate of senescence of colour. [source] Male choice generates stabilizing sexual selection on a female fecundity correlateJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 5 2007S. F. CHENOWETH Abstract We know very little about male mating preferences and how they influence the evolution of female traits. Theory predicts that males may benefit from choosing females on the basis of traits that indicate their fecundity. Here, we explore sexual selection generated by male choice on two components of female body size (wing length and body mass) in Drosophila serrata. Using a dietary manipulation to alter female size and 828 male mate choice trials, we analysed linear and nonlinear sexual selection gradients on female mass and wing length. In contrast to theoretical expectations and prevailing empirical data, males exerted stabilizing rather than directional sexual selection on female body mass, a correlate of fecundity. Sexual selection was detected only among females with access to standard resource levels as an adult, with no evidence for sexual selection among resource-depleted females. Thus the mating success of females with the same body mass differed depending upon their access to resources as an adult. This suggests that males in this species may rely on signal traits to assess body mass rather than assessing it directly. Stabilizing rather than directional sexual selection on body mass together with recent evidence for stabilizing sexual selection on candidate signal traits in this species suggests that females may trade-off resources allocated to reproduction and sexual signalling. [source] Modulation of sexual signalling by immune challenged male mealworm beetles (Tenebrio molitor, L.): evidence for terminal investment and dishonestyJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 2 2006B. SADD Abstract Organisms partition resources into life-history traits in order to maximise fitness over their expected lifespan. For the males of many species fitness is determined by qualitative and quantitative aspects of costly sexual signals: The notion that epigamic traits are costly forms the cornerstone of those theories that propose parasites drive sexual selection. Consequently studies examining this notion assume sexual signalling is honest (i.e. driven by cost) when they seek to identify correlations or causal links between male immune function and attractiveness. We demonstrate that immune challenged males of the mealworm beetle, Tenebrio molitor, increased their investment in epigamic pheromone signals: these males became significantly more attractive to females whilst increasing the activity of a key immune effector system. In other words males increase terminal reproductive effort (invest in attractiveness) in response to a survival threat (immune insult). Consequently the signal preferred by the female is dishonest when considering the male's condition. [source] Heightened condition dependence is not a general feature of male eyespan in stalk-eyed flies (Diptera: Diopsidae)JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 6 2004S. Cotton Abstract Stalk-eyed flies are exemplars of sexual selection leading to the evolution of exaggerated male ornaments (eyespan). In Sphyracephala beccarri, there is no evidence for female mate choice for exaggerated male eyespan and only minor sex differences in eyespan. We used S. beccarri to test whether heightened condition dependence only evolves when male eyespan becomes sexually exaggerated. Male eyespan showed heightened condition dependence under food stress compared with a control trait (wing length). However, female eyespan displayed a similar pattern and there was no sex difference in the degree of increased eyespan sensitivity. The finding that eyespan is a sensitive indicator of food stress, even in an unexaggerated state, suggests that this may have acted as a pre-adaptation to the role of eyespan in sexual signalling in other Diopsid species. These results are consistent with handicap theory and Fisher's view of how sexual selection is initiated. [source] Three-spined sticklebacks Gasterosteus aculeatus as a model for exploring behavioural biologyJOURNAL OF FISH BIOLOGY, Issue 8 2009F. A. Huntingford Niko Tinbergen chose the three-spined stickleback Gasterosteus aculeatus for his classic behavioural studies because they are small, robust, common and easy to house in the laboratory under reasonably natural conditions and also because their behaviour, while sufficiently simple to be tractable, is still sufficiently complex to be interesting. An analysis of citation records shows that this was an inspired choice. Research on these small fish has addressed all four of Tinbergen's famous questions (causation, development, functions and evolution) and has contributed to the understanding of many different behavioural systems. The G. aculeatus literature is used here to explore several themes in fundamental behavioural biology (diet choice, shoaling, behavioural syndromes and sexual signalling) and the extent to which research using G. aculeatus has informed both fundamental and applied behavioural biology, the latter in the context of aquaculture research. [source] Animal allure and health linked by plant pigmentsBIOESSAYS, Issue 8 2003Peeter Hőrak Darwin1 introduced the idea that ornamental secondary sexual traits have evolved in response to female preferences for showy males. Among such traits, yellow and red carotenoid-based ornaments have been considered as particularly good candidates for explaining why and how females would benefit from mating with showy partners. Because carotenoids can be used for promotion of both health and appearance, colourful male ornaments should honestly reveal the vigour of the bearers. Two recent experiments with birds2,3 now show how allocation of bodily carotenoids to sexual signalling is traded off against the use of carotenoids for boosting immune function. BioEssays 25:746,747, 2003. © 2003 Wiley Periodicals, Inc. [source] | ||||||||||