Oolon Colluphid
16 Apr 2009, 03:56 PM
'Research Highlights' from Nature 458, 682 (9 April 2009)
Biologists believe that some butterflies send mixed signals. Wings with brightly coloured topsides attract mates, for example, whereas camouflaged undersides protect against predators.
Jeffrey Oliver of Yale University and his colleagues compared the rates of wing-pattern evolution in 54 species of the genus Bicyclus (pictured, Bicyclus anynana). Because eyespots are evolving at different rates on the upper and lower surfaces of Bicyclus wings, the team concludes that markings on different parts of the wings are probably used for different purposes and suggest this separation of signals allows butterflies to be simultaneously attractive to mates and safe from predators.
Royal Society Proceedings B
Accommodating natural and sexual selection in butterfly wing pattern evolution
Oliver, Robertson and Monteiro
Published online before print April 1, 2009, doi: 10.1098/rspb.2009.0182
Visual patterns in animals may serve different functions, such as attracting mates and deceiving predators. If a signal is used for multiple functions, the opportunity arises for conflict among the different functions, preventing optimization for any one visual signal.
Here we investigate the hypothesis that spatial separation of different visual signal functions has occurred in Bicyclus butterflies. Using phylogenetic reconstructions of character evolution and comparisons of evolutionary rates, we found dorsal surface characters to evolve at higher rates than ventral characters.
Dorsal characters also displayed sex-based differences in evolutionary rates more often than did ventral characters. Thus, dorsal characters corresponded to our predictions of mate signalling while ventral characters appear to play an important role in predator avoidance.
Forewing characters also fit a model of mate signalling, and displayed higher rates of evolution than hindwing characters.
Our results, as well as the behavioural and developmental data from previous studies of Bicyclus species, support the hypothesis that spatial separation of visual signal functions has occurred in Bicyclus butterflies.
This study is the first to demonstrate, in a phylogenetic framework, that spatial separation of signals used for mate signalling and those used for predator avoidance is a viable strategy to accommodate multiple signal functions. This signalling strategy has important ramifications on the developmental evolution of wing pattern elements and diversification of butterfly species.
Biologists believe that some butterflies send mixed signals. Wings with brightly coloured topsides attract mates, for example, whereas camouflaged undersides protect against predators.
Jeffrey Oliver of Yale University and his colleagues compared the rates of wing-pattern evolution in 54 species of the genus Bicyclus (pictured, Bicyclus anynana). Because eyespots are evolving at different rates on the upper and lower surfaces of Bicyclus wings, the team concludes that markings on different parts of the wings are probably used for different purposes and suggest this separation of signals allows butterflies to be simultaneously attractive to mates and safe from predators.
Royal Society Proceedings B
Accommodating natural and sexual selection in butterfly wing pattern evolution
Oliver, Robertson and Monteiro
Published online before print April 1, 2009, doi: 10.1098/rspb.2009.0182
Visual patterns in animals may serve different functions, such as attracting mates and deceiving predators. If a signal is used for multiple functions, the opportunity arises for conflict among the different functions, preventing optimization for any one visual signal.
Here we investigate the hypothesis that spatial separation of different visual signal functions has occurred in Bicyclus butterflies. Using phylogenetic reconstructions of character evolution and comparisons of evolutionary rates, we found dorsal surface characters to evolve at higher rates than ventral characters.
Dorsal characters also displayed sex-based differences in evolutionary rates more often than did ventral characters. Thus, dorsal characters corresponded to our predictions of mate signalling while ventral characters appear to play an important role in predator avoidance.
Forewing characters also fit a model of mate signalling, and displayed higher rates of evolution than hindwing characters.
Our results, as well as the behavioural and developmental data from previous studies of Bicyclus species, support the hypothesis that spatial separation of visual signal functions has occurred in Bicyclus butterflies.
This study is the first to demonstrate, in a phylogenetic framework, that spatial separation of signals used for mate signalling and those used for predator avoidance is a viable strategy to accommodate multiple signal functions. This signalling strategy has important ramifications on the developmental evolution of wing pattern elements and diversification of butterfly species.