Does behavior reflect phylogeny in swiftlets (Aves: Apodidae)? A test using cytochrome b mitochondrial DNA sequences

Area of Science:

• Ornithology
• Evolutionary Biology
• Bioacoustics

Background:

• Swiftlets are small, insectivorous birds, many of which inhabit caves and utilize echolocation.
• Traditional swiftlet taxonomy relies on echolocation and nesting characteristics due to limited morphological distinctions.
• The monophyly and phylogenetic relationships within swiftlets remain incompletely understood.

Purpose of the Study:

• To construct an independent molecular phylogeny for swiftlets and their relatives.
• To assess the reliability of echolocation and nest characters in swiftlet taxonomy.
• To clarify the evolutionary history and taxonomic நிலை of swiftlet species.

Main Methods:

• Mitochondrial cytochrome b DNA sequences were utilized to build a molecular phylogenetic tree.
• Phylogenetic analysis was conducted on swiftlets and closely related avian taxa.
• Statistical methods were employed to test the fit of behavioral characters (echolocation, nest traits) to the molecular phylogeny.

Main Results:

• The molecular phylogeny broadly aligns with the higher classification of swifts but refutes the monophyly of swiftlets.
• Echolocating swiftlets (Aerodramus) and the non-echolocating Hydrochous gigas form a distinct clade.
• Non-echolocating Collocalia swiftlets are not closely related to the Aerodramus/Hydrochous group.
• Nest characteristics did not show a significant correlation with the molecular phylogenetic data.

Conclusions:

• Echolocation is likely a shared ancestral trait within the Aerodramus genus, potentially lost in Hydrochous gigas.
• Current swiftlet classification based on echolocation and nest features requires revision.
• Molecular phylogenetics provides a more robust framework for understanding swiftlet evolution than behavioral traits.