Birdsong, sexual selection, and the flawed taxonomy of canaries, goldfinches and allies

Song divergence between subspecies of reed bunting is more pronounced in singing styles under sexual selection

“…Interestingly, our findings oppose the expected latitudinal gradient resulting from higher rates of evolution of syllable diversity and song length in north European passerines than in Mediterranean passerines (Cardoso, Hu, & Mota, 2012;Weir & Wheatcroft, 2011). Bill morphology has also been shown to affect song output (Christensen et al, 2006;Huber & Podos, 2006;Podos, 1997; but see Grant, B.R.…”

The relationship between latitude, migration and the evolution of bird song complexity

“…Irwin 2000, Mahler & Gil 2009, Weir & Wheatcroft 2011, Cardoso et al 2012; Table 1). Hypotheses proposed to explain this variation invoke both ecological selection (Weir et al 2012) and sexual selection (Catchpole 1982) as the causes of these patterns (Table 2).…”

“…Twelve studies mention complexity but do not offer explicit definitions or are vague in their use of the term; complexity is instead defined implicitly using statistics (e.g. Cardoso et al 2012) or in the text (e.g. 'complex syllables' in Nelson et al 1996).…”

Full Issue

“…In the years since Catchpole (1982) hypothesized that migratory songbird species might be expected to sing more elaborate songs than nonmigratory species, several broad comparative studies have found a positive association between song elaboration and migratory distance Weary 1992, Mountjoy andLeger 2001) or breeding latitude (Botero et al 2009, Mahler and Gil 2009, Weir and Wheatcroft 2011, Cardoso et al 2012). These empirical findings are intriguing, but they are also puzzling, because it is not clear why migration and song elaboration would be linked.…”