Tails has sex

Recent work on birds suggests that certain morphological differences between the sexes may have evolved as an indirect consequence of sexual selection because they offset the cost of bearing extravagant ornaments used for fighting or mate attraction. For example, long-tailed male sunbirds and widowbirds also have longer wings than females, perhaps to compensate for the aerodynamic costs of tail elaboration. We used comparative data from 57 species to investigate whether this link between sexual dimorphism in wing and tail length is widespread among long-tailed birds. We found that within long-tailed families, variation in the extent of tail dimorphism was associated with corresponding variation in wing dimorphism. One nonfunctional explanation of this result is simply that the growth of wings and tails is controlled by a common developmental mechanism, such that long-tailed individuals inevitably grow long wings as well.

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Experimental Analyses of Sexual and Natural Selection on Short Tails in a Polygynous Warbler

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Experimental Analyses of Sexual and Natural Selection on Short Tails in a Polygynous Warbler

We believe that no experimental study has yet tested Darwin's idea that, as well as generating trait elaboration, intersexual selection might sometimes drive sex-biased trait reduction. Here we present the results of two experiments exploring the negative relationship between tail length and reproductive success in male golden-headed cisticolas Cisticola exilis. In the first experiment, artificially shortening a male's tail produced a dramatic increase in his reproductive success, measured as either the number of females nesting or number of chicks Hedged on his territory. A second experiment, in which manipulated birds were flown through a maze, revealed that short tails also impose costs by reducing aerodynamic performance during slow-speed foraging flight. Because tail shortening yields reproductive benefits and viability costs, we conclude it has evolved via sexual selection.
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Tails tell the tale of dinosaur sex

The fossil remains of two oviraptorosaurs — nicknamed 'Romeo and Juliet' — were reported in Researchers think they have come up with a way to tell fossils of male dinosaurs from those of females — at least for some small feathered species. The key differences between the sexes lie in bones near the base of the tail, the scientists reported on 31 March in Scientific Reports 1.
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