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Plumage Characters (plumage + character)
Selected AbstractsCLIMATIC AND TEMPORAL EFFECTS ON THE EXPRESSION OF SECONDARY SEXUAL CHARACTERS: GENETIC AND ENVIRONMENTAL COMPONENTSEVOLUTION, Issue 3 2004Dany Garant Abstract Despite great interest in sexual selection, relatively little is known in detail about the genetic and environmental determinants of secondary sexual characters in natural populations. Such information is important for determining the way in which populations may respond to sexual selection. We report analyses of genetic and large-scale environmental components of phenotypic variation of two secondary sexual plumage characters (forehead and wing patch size) in the collared flycatcher Ficedula albicollis over a 22-year period. We found significant heritability for both characters but little genetic covariance between the two. We found a positive association between forehead patch size and a large-scale climatic index, the North Atlantic Oscillation (NAO) index, but not for wing patch. This pattern was observed in both cross-sectional and longitudinal data suggesting that the population response to NAO index can be explained as the result of phenotypic plasticity. Heritability of forehead patch size for old males, calculated under favorable conditions (NAO index median), was greater than that under unfavorable conditions (NAO index < median). These changes occurred because there were opposing changes in additive genetic variance (VA) and residual variance (VR) under favorable and unfavorable conditions, with VA increasing and VR decreasing in good environments. However, no such effect was detected for young birds, or for wing patch size in either age class. In addition to these environmental effects on both phenotypic and genetic variances, we found evidence for a significant decrease of forehead patch size over time in older birds. This change appears to be caused by a change in the sign of viability selection on forehead patch size, which is associated with a decline in the breeding value of multiple breeders. Our data thus reveal complex patterns of environmental influence on the expression of secondary sexual characters, which may have important implications for understanding selection and evolution of these characters. [source] RECONSTRUCTING PLUMAGE EVOLUTION IN ORIOLES (ICTERUS): REPEATED CONVERGENCE AND REVERSAL IN PATTERNSEVOLUTION, Issue 6 2000Kevin E. Omland Abstract. Several empirical studies suggest that sexually selected characters, including bird plumage, may evolve rapidly and show high levels of convergence and other forms of homoplasy. However, the processes that might generate such convergence have not been explored theoretically. Furthermore, no studies have rigorously addressed this issue using a robust phylogeny and a large number of signal characters. We scored the appearance of 44 adult male plumage characters that varied across New World orioles (Icterus). We mapped the plumage characters onto a molecular phylogeny based on two mitochondrial genes. Reconstructing the evolution of these characters revealed evidence of convergence or reversal in 42 of the 44 plumage characters. No plumage character states are restricted to any groups of species higher than superspecies in the oriole phylogeny. The high frequency of convergence and reversal is reflected in the low overall retention index (RI = 0.66) and the low overall consistency index (CI = 0.28). We found similar results when we mapped plumage changes onto a total evidence tree. Our findings reveal that plumage patterns and colors are highly labile between species of orioles, but highly conserved within the oriole genus. Furthermore, there are at least two overall plumage types that have convergently evolved repeatedly in the three oriole clades. This overall convergence leads to significant conflict between the molecular and plumage data. It is not clear what evolutionary processes lead to this homoplasy in individual characters or convergence in overall pattern. However, evolutionary constraints such as developmental limitations and genetic correlations between characters are likely to play a role. Our results are consistent with the belief that avian plumage and other sexually selected characters may evolve rapidly and may exhibit high homoplasy. The overall convergence in oriole plumage patterns is an interesting evolutionary phenomenon, but it cautions against heavy reliance on plumage characters for constructing phylogenies. [source] Inferring the phylogeography and evolutionary history of the splendid fairy-wren Malurus splendens from mitochondrial DNA and spectrophotometryJOURNAL OF AVIAN BIOLOGY, Issue 1 2009Anna M. Kearns The phylogeographic structure of the widely distributed arid and semi-arid Australian splendid fairy-wren Malurus splendens was investigated by using variation in plumage characters and mitochondrial DNA (mtDNA). We examined sequences of the mtDNA ND2 gene and used spectrophotometry to quantify chromatic variation in plumage in order to test the current morphology-based intraspecific taxonomy of M. splendens and to discriminate between hypotheses invoking allopatric and parapatric processes in the origin of diversity in the complex. Genetic diversity of M. splendens fell into three divergent geographically structured clades. One represents populations ascribed to the western subspecies M. s. splendens, the other populations of central M. s. musgravi and the third all eastern populations currently ascribed to M. s. emmottorum and M. s. melanotus. Plumage patterns clearly differentiate M. s. splendens and M. s. musgravi, and spectrophotometry identified a step-wise transition in spectra between M. s. melanotus and M. s. emmottorum. Congruence of patterns of phenotypic and genetic variation among western, central and eastern populations of M. splendens strongly suggests that these populations have diverged in allopatry on either side of historical biogeographic barriers in this region. Decoupled patterns of phenotypic and genetic diversity suggest that the divergence of M. s. melanotus and M. s. emmottorum may have occurred without periods of isolation perhaps in response to differences in local environmental conditions, or alternatively, mtDNA and plumage may have different rates of evolution. Critically, we encountered issues with the placement of the root of the M. splendens complex. The root was placed within the subspecies M. s. splendens separating its northern and southern populations and rendering the subspecies paraphyletic. [source] Co-evolution of plumage characteristics and winter sociality in New and Old World sparrowsJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 12 2009E. A. TIBBETTS Abstract Understanding the evolution of phenotypic diversity, including the stunning array of avian plumage characters, is a central goal of evolutionary biology. Here, we applied a comparative analysis to test factors associated with the origin and maintenance of black chest and throat patches, which in some taxa are referred to as ,badges-of-status'. Specifically, we tested whether the evolution of black colour patches in Old and New World sparrows is consistent with a signalling function during the nonbreeding season or breeding season. We found no positive associations between patch evolution and polygyny or summer sociality. Instead, patch evolution is significantly associated with sociality during the nonbreeding season. Additionally, unlike typical plumage characteristics under sexual selection, these patches are visible throughout the nonbreeding season. Further, the pattern of patch dimorphism uncovered in this study does not match expectations for a trait that evolved in a reproductive context. In particular, patch dimorphism is not associated with polygyny or the presence of extra-pair mating although other types of plumage dimorphism are strongly associated with nonmonogamous mating systems. Overall, patterns of patch evolution suggest that they are more strongly associated with social competition during the nonbreeding season than sexual competition during the breeding season. These results clarify why some previous work has uncovered puzzling relationships between black plumage patches and reproductive behaviour. We discuss these findings in the context of signal theory and previous work on badges-of-status. [source] | ||||||||||