Strong bat predation and weak environmental constraints predict longer moth tails.

Area of Science:

• Evolutionary biology
• Macroevolutionary studies
• Animal behavior

Background:

• Elaborate traits evolve under strong selective pressures, often overcoming ecological limitations.
• Hindwing tails in moon moths (Saturniidae) are an adaptation against bat predation, with longer tails offering greater protection.
• Understanding the balance between predation and environmental factors is crucial for explaining the evolution of such elaborate traits.

Purpose of the Study:

• To investigate the evolutionary interplay between predation pressure and environmental constraints on the elongation of moth hindwing tails.
• To reconstruct the evolutionary history and biogeography of tailed moth lineages (Actias + Argema).
• To quantify the influence of predation and environmental variables on moth tail length and body size.

Main Methods:

• Inferred a time-calibrated phylogeny for the moth group (Actias + Argema).
• Performed ancestral state reconstruction and biogeographical analyses.
• Estimated bat abundance using species distribution models and bioclimatic variables for environmental metrics.
• Developed a novel method to measure wing lengths from un-scaled photographs of moths.
• Utilized phylogenetically informed mixed models to analyze trait evolution.

Main Results:

• Found a positive correlation between bat predation pressure and increased moth tail length and body size.
• Observed a negative association between environmental factors and these morphological traits.
• Identified that regions with higher insectivorous bat abundance and stable temperatures support longer-tailed moths.

Conclusions:

• Predation pressure is a significant driver for the evolution of elaborate traits like moth hindwing tails.
• Environmental factors can impose constraints on the development of these traits, creating evolutionary trade-offs.
• This study offers insights into how biotic pressures and abiotic conditions shape complex adaptations across diverse species.