Evolution of leaf warbler songs (Aves: Phylloscopidae)

Area of Science:

• Ornithology
• Bioacoustics
• Evolutionary Biology

Background:

• Passerine bird songs are vital for territory defense and mating, driving high speciation rates in oscine passerines.
• Leaf warblers, a speciose Old-World passerine family, exhibit limited morphological differentiation, making vocalizations critical for species delimitation.

Purpose of the Study:

• To investigate the evolutionary drivers of song divergence in leaf warblers.
• To correlate sonographic song traits with ecological and geographical variables, accounting for phylogenetic relatedness.

Main Methods:

• Analysis of 16 sonographic traits from 80 leaf warbler taxa song recordings.
• Correlation analysis with 15 explanatory variables using pairwise and linear models.
• Phylogenetic correction using phylogenetically independent contrasts and generalized linear models based on a molecular phylogeny.

Main Results:

• A significant phylogenetic signal was detected in most song traits, particularly element duration, suggesting potential heritability.
• Body size constrains song frequencies independently of phylogeny.
• Geographic range extension correlated with song features like verse duration and complexity; elevation influenced element type diversity.

Conclusions:

• Song evolution in leaf warblers is shaped by a combination of phylogenetic constraints, body size, and geographic factors.
• While some song traits show strong phylogenetic influence, others are linked to ecological variables, highlighting the complex interplay in avian vocal communication.