Home About us Contact
|
Home About us Contact | ||
|
|
||
Display Traits (display + trait)
Selected AbstractsSEXUAL SELECTION DRIVES RAPID DIVERGENCE IN BOWERBIRD DISPLAY TRAITSEVOLUTION, Issue 1 2000J. Albert C. Uy Abstract., Sexual selection driving display trait divergence has been suggested as a cause of rapid speciation, but there is limited supporting evidence for this from natural populations. Where speciation by sexual selection has occurred in newly diverged populations, we expect that there will be significant differences in female preferences and corresponding male display traits in the absence of substantial genetic and other morphological differentiation. Two allopatric populations of the Vogelkop bowerbird, Amblyornis inornatus, show large, qualitative differences in a suite of display traits including bower structure and decorations. We experimentally demonstrate distinct male decoration color preferences within each population, provide direct evidence of female preferences for divergent decoration and bower traits in the population with more elaborate display, and show that there is minimal genetic differentiation between these populations. These results support the speciation by sexual selection hypothesis and are most consistent with the hypothesis that changes in male display have been driven by divergent female choice. [source] Reproductive character displacement is not the only possible outcome of reinforcementJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 1 2004A. R. Lemmon Abstract We study the form of the clines in a female mating preference and male display trait using simulations of a hybrid zone. Allopatric populations of two species are connected by demes in a stepping stone arrangement. Results show that reproductive character displacement (a pattern of increased prezygotic isolation in sympatry compared with allopatry) may or may not result when there is reinforcement (defined here as the strengthening of prezygotic isolation as a result of selection against hybrids, relative to the amount of prezygotic isolation present when hybrids are not selected against). Further, reproductive character displacement of the preference may or may not occur when it occurs in the male display. We conclude that the absence of reproductive character displacement is not evidence against the operation of reinforcement. [source] EVOLUTION OF COLORFUL DISPLAYEVOLUTION, Issue 3 2007Gerald Borgia How the displays of bowerbirds have evolved has attracted widespread interest. Endler et al. (2005) analyzed color use in display in a subset of bowerbird species and generalized their results to all bowerbirds. Here we discuss problems with their analysis that calls into question their conclusions. For example, they state that bowerbirds do not use decorations that match their background, but this is not supported by their results. They reconstruct historical patterns of sexual dimorphism in plumage display using questionable methodology. The high lability of these display traits makes these reconstructions unreliable and, using accepted methods and acknowledging the lability problem, we were unable to support their conclusions. Their claim that plumage differences between sympatric species are due to character displacement is not supported by the available data. Their focus is on visual contrast as the cause for display color and we offer additional hypotheses that may contribute to explaining color use. We support studies of spectral analysis of display traits but urge greater care in using this information to reach conclusions about how colorful displays have evolved. [source] MULTIVARIATE QUANTITATIVE GENETICS AND THE LEK PARADOX: GENETIC VARIANCE IN MALE SEXUALLY SELECTED TRAITS OF DROSOPHILA SERRATA UNDER FIELD CONDITIONSEVOLUTION, Issue 12 2004Emma Hine Abstract Single male sexually selected traits have been found to exhibit substantial genetic variance, even though natural and sexual selection are predicted to deplete genetic variance in these traits. We tested whether genetic variance in multiple male display traits of Drosophila serrata was maintained under field conditions. A breeding design involving 300 field-reared males and their laboratory-reared offspring allowed the estimation of the genetic variance-covariance matrix for six male cuticular hydrocarbons (CHCs) under field conditions. Despite individual CHCs displaying substantial genetic variance under field conditions, the vast majority of genetic variance in CHCs was not closely associated with the direction of sexual selection measured on field phenotypes. Relative concentrations of three CHCs correlated positively with body size in the field, but not under laboratory conditions, suggesting condition-dependent expression of CHCs under field conditions. Therefore condition dependence may not maintain genetic variance in preferred combinations of male CHCs under field conditions, suggesting that the large mutational target supplied by the evolution of condition dependence may not provide a solution to the lek paradox in this species. Sustained sexual selection may be adequate to deplete genetic variance in the direction of selection, perhaps as a consequence of the low rate of favorable mutations expected in multiple trait systems. [source] SEXUAL SELECTION DRIVES RAPID DIVERGENCE IN BOWERBIRD DISPLAY TRAITSEVOLUTION, Issue 1 2000J. Albert C. Uy Abstract., Sexual selection driving display trait divergence has been suggested as a cause of rapid speciation, but there is limited supporting evidence for this from natural populations. Where speciation by sexual selection has occurred in newly diverged populations, we expect that there will be significant differences in female preferences and corresponding male display traits in the absence of substantial genetic and other morphological differentiation. Two allopatric populations of the Vogelkop bowerbird, Amblyornis inornatus, show large, qualitative differences in a suite of display traits including bower structure and decorations. We experimentally demonstrate distinct male decoration color preferences within each population, provide direct evidence of female preferences for divergent decoration and bower traits in the population with more elaborate display, and show that there is minimal genetic differentiation between these populations. These results support the speciation by sexual selection hypothesis and are most consistent with the hypothesis that changes in male display have been driven by divergent female choice. [source] Body shape vs. colour associated initial divergence in the Telmatherina radiation in Lake Matano, Sulawesi, IndonesiaJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 3 2007D. ROY Abstract Highly polymorphic colouration patterns are often associated with sexual selection in fish and can be the initial cause of divergence among closely related taxa. Here we use genetic, body colour and geometric morphometric data collected on 118 fish from Lake Matano, Sulawesi, Indonesia to test if colouration is the initial cause of divergence in the radiating Telmatherina genus. Results reveal that all Telmatherina previously described in this system can be categorized into three mitochondrial lineages and that colouration is only weakly associated with early divergence. Clade-specific body shapes, however, likely adapted to microenvironments are key to the initial divergence in this system. Data also show that although colourations were not likely instrumental in seeding divergence in these fish, they appear to have developed in parallel within each clade. Our results are consistent with an emerging pattern repeated in many vertebrate radiations, whereby divergence by colouration or other display traits is preceded by specialization to environmental adaptive peaks. [source] The evolution of male mate choice in insects: a synthesis of ideas and evidenceBIOLOGICAL REVIEWS, Issue 3 2001RUSSELL BONDURIANSKY ABSTRACT Mate choice by males has been recognized at least since Darwin's time, but its phylogenetic distribution and effect on the evolution of female phenotypes remain poorly known. Moreover, the relative importance of factors thought to underlie the evolution of male mate choice (especially parental investment and mate quality variance) is still unresolved. Here I synthesize the empirical evidence and theory pertaining to the evolution of male mate choice and sex role reversal in insects, and examine the potential for male mating p to generate sexual selection on female phenotypes. Although male mate choice has received relatively little empirical study, the available evidence suggests that it is widespread among insects (and other animals). In addition to ,precopulatory' male mate choice, some insects exhibit ,cryptic' male mate choice, varying the amount of resources allocated to mating on the basis of female mate quality. As predicted by theory, the most commonly observed male mating p are those that tend to maximize a male's expected fertilization success from each mating. Such p tend to favour female phenotypes associated with high fecundity or reduced sperm competition intensity. Among insect species there is wide variation in mechanisms used by males to assess female mate quality, some of which (e.g. probing, antennating or repeatedly mounting the female) may be difficult to distinguish from copulatory courtship. According to theory, selection for male choosiness is an increasing function of mate quality variance and those reproductive costs that reduce, with each mating, the number of subsequent matings that a male can perform (,mating investment'). Conversely, choosiness is constrained by the costs of mate search and assessment, in combination with the accuracy of assessment of potential mates and of the distribution of mate qualities. Stronger selection for male choosiness may also be expected in systems where female fitness increases with each copulation than in systems where female fitness peaks at a small number of matings. This theoretical framework is consistent with most of the empirical evidence. Furthermore, a variety of observed male mating p have the potential to exert sexual selection on female phenotypes. However, because male insects typically choose females based on phenotypic indicators of fecundity such as body size, and these are usually amenable to direct visual or tactile assessment, male mate choice often tends to reinforce stronger vectors of fecundity or viability selection, and seldom results in the evolution of female display traits. Research on orthopterans has shown that complete sex role reversal (i.e. males choosy, females competitive) can occur when male parental investment limits female fecundity and reduces the potential rate of reproduction of males sufficiently to produce a female-biased operational sex ratio. By contrast, many systems exhibiting partial sex role reversal (i.e. males choosy and competitive) are not associated with elevated levels of male parental investment, reduced male reproductive rates, or reduced male bias in the operational sex ratio. Instead, large female mate quality variance resulting from factors such as strong last-male sperm precedence or large variance in female fecundity may select for both male choosiness and competitiveness in such systems. Thus, partial and complete sex role reversal do not merely represent different points along a continuum of increasing male parental investment, but may evolve via different evolutionary pathways. [source] | ||||||||||