title: Evolution of leaf warbler songs (Aves: Phylloscopidae).
abstract: Songs in passerine birds are important for territory defense and mating. Speciation rates in oscine passerines are so high, due to cultural evolution, that this bird lineage makes up half of the extant bird species. Leaf warblers are a speciose Old-World passerine family of limited morphological differentiation, so that songs are even more important for species delimitation. We took 16 sonographic traits from song recordings of 80 leaf warbler taxa and correlated them with 15 potentially explanatory variables, pairwise, and in linear models. Based on a well-resolved molecular phylogeny of the same taxa, all pairwise correlations were corrected for relatedness with phylogenetically independent contrasts and phylogenetic generalized linear models were used. We found a phylogenetic signal for most song traits, but a strong one only for the duration of the longest and of the shortest element, which are presumably inherited instead of learned. Body size of a leaf warbler species is a constraint on song frequencies independent of phylogeny. At least in this study, habitat density had only marginal impact on song features, which even disappeared through phylogenetic correction. Maybe most leaf warblers avoid the deterioration through sound propagation in dense vegetation by singing from exposed perches. Latitudinal (and longitudinal) extension of the breeding ranges was correlated with most song features, especially verse duration (longer polewards and westwards) and complexity (lower polewards). Climate niche or expansion history might explain these correlations. The number of different element types per verse decreases with elevation, possibly due to fewer resources and congeneric species at higher elevations.
authors.affiliation: Institute of Ecology, Evolution and Diversity, Goethe University Max-von-Laue-Straße 13, 60439, Frankfurt am Main, Germany ; Institute of Pharmacy and Molecular Biotechnology, Heidelberg University Im Neuenheimer Feld 364, 69120, Heidelberg, Germany.
authors.forename: Dieter Thomas
authors.initials: DT
authors.lastname: Tietze
authors.affiliation: Institute of Zoology, Johannes Gutenberg University 55099, Mainz, Germany.
authors.forename: Jochen
authors.initials: J
authors.lastname: Martens
authors.affiliation: Institute of Ecology, Evolution and Diversity, Goethe University Max-von-Laue-Straße 13, 60439, Frankfurt am Main, Germany.
authors.forename: Balduin S
authors.initials: BS
authors.lastname: Fischer
authors.affiliation: Key Laboratory of Animal Ecology and Conservation, Institute of Zoology, Chinese Academy of Sciences 100101, Beijing, China.
authors.forename: Yue-Hua
authors.initials: YH
authors.lastname: Sun
authors.affiliation: Institute of Ecology, Evolution and Diversity, Goethe University Max-von-Laue-Straße 13, 60439, Frankfurt am Main, Germany ; Zoologisches Forschungsmuseum Alexander Koenig Adenauerallee 160, 53113, Bonn, Germany.
authors.forename: Annette
authors.initials: A
authors.lastname: Klussmann-Kolb
authors.affiliation: Senckenberg Natural History Collections, Museum of Zoology Königsbrücker Landstraße 159, 01109, Dresden, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Päckert
keywords: Model of evolution; Phylloscopus; Seicercus; phylogenetic signal; song evolution