{'fraction_non_alphanumeric': 0.015663643858202802, 'fraction_numerical': 0.00247320692497939, 'mean_word_length': 5.423280423280423, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Song versus plumage in some North American Oscines: Testing Darwin’s hypothesis

Abstract Sexual selection is thought to have favored the development of both song and plumage, but other selective pressures may impose constraints. Darwin suggested that there is a negative correlation between song and plumage complexity, but this hypothesis, which we dubbed the trade-off hypothesis, has seldom been tested. We examined the trade-off hypothesis on 123 species of North American Oscines. Canonical correlation analyses were used to assess the relationship between a set of variables measuring plumage conspicuousness and another measuring song complexity. Data were corrected to take phylogenetic autocorrelation into account. A weak positive correlation was found between plumage conspicuousness and song complexity. The positive correlation can be explained by the evolution of traits that may help a male to mate rapidly in regions where the breeding season is short. Factors such as the influence of habitat structure on the evolution of songs and plumages, predation rates, differences in mating systems and in targets of sexual selection, and experimental errors may explain the weakness of this correlation.