Estimating field metabolic rates for Australian marsupials using phylogeny

Area of Science:

• Zoology
• Ecology
• Evolutionary Biology

Background:

• Field metabolic rate (FMR) estimates energy expenditure in free-ranging animals.
• Allometric equations based on body mass (BM) are commonly used for FMR prediction.
• Phylogenetic methods enhance FMR estimates by incorporating evolutionary history, but often discard incomplete data.

Purpose of the Study:

• To predict the FMR for most Australian marsupial species using a novel phylogenetic method.
• To develop a method that can utilize incomplete data (isolated BM and FMR measurements).
• To investigate the co-evolution of FMR and BM and compare energy expenditure across dietary groups.

Main Methods:

• Utilized a phylogenetic method designed to handle incomplete datasets.
• Incorporated 35 FMR samples and 130 BM samples from Australian marsupials.
• Validated the accuracy of FMR predictions through cross-validation.

Main Results:

• Developed a prediction equation: FMR (kJ/day) = 5.27 BM (g)^0.69.
• Demonstrated a strong phylogenetic correlation between FMR and BM (r=0.96), indicating co-evolution.
• Herbivorous marsupials (e.g., macropods) showed significantly lower relative FMR than carnivorous marsupials (e.g., dasyurids).

Conclusions:

• Phylogenetically informed FMR estimates are now available for most Australian marsupial species.
• The new method effectively uses incomplete data, improving predictive power.
• Diet plays a significant role in the energy expenditure of marsupials, with herbivores being more energy-conservative.