Ecological and evolutionary correlates of metabolic

capacities in anuran amphibians

Metabolic capacities in vertebrates

• Aerobic capacity is the maximum rate of oxygen consumption during vigorous, exhaustive exercise. Generated principally by the sustained contraction of oxidative muscle fibers and measured as VO2max.

• Anaerobic capacity is the maximum rate of energy production from anaerobic glycolysis during exercise. Generated principally by the power contribution of glycolytic muscle fibers and estimated by the accumulation of lactic acid.

Functional correlates of inter- and intra-specific variation in metabolic capacities

• Ecological--predict or account for patterns of distribution and activity

• Evolutionary--contribute to an understanding of the evolutionary origin of complex physiological structures (oxidative fibers) and processes (endothermy)

Natural History of American Toads

Measurements of VO2rest and VO2max

Exhaustive locomotor exercise

Development of aerobic capacity and dispersal in toads

Body mass at dispersal

Behavioral correlates of inter-specific variation in metabolic capacities

Study included 17 species of frogs and toads from around the world, representing broad ecological, morphological, and behavioral ranges

Metabolic variation among species

Ambush foragers--high anaerobic capacity

QuickTime™ and a decompressor

are needed to see this picture.

Burrowing/active foragers--high aerobic capacities

QuickTime™ and a decompressor

are needed to see this picture.

Aerobic capacity model for the evolution of endothermy

• Proposed by Bennett and Ruben, 1979• Focus of selection for metabolic physiology is

on activity, not temperature• High aerobic capacities correlate with

endurance and stamina• High aerobic capacity for exercise is

functionally linked to resting or basal metabolism

VO2rest and VO2max among 17 anuran species

Correlation between resting and activity metabolism in frogs

Dart poison frogs & a coqui

Coqui of Puerto Rico (and Hawaii, regrettably)

Metabolic characteristics of Dart poison frogs

Foraging behavior and metabolic

characteristics

Bocas del Toro, Panama

Remote chain of islands in the Caribbean, located between Costa Rica and Panama

Red (Isla Bastimentos) andGreen (Isla Colon) Frogs of Bocas

The Bocas del Toro “Experiment in Nature” may

be over

Wells and Taigen and UConn Physiological Ecology Class

Reproductive behavior and aerobic capacities of male

American toads (Bufo americanus): Is behavior constrained by physiology?

No, at least not that night

Metabolic costs of vocalization

Measurement of VO2calling

Repeated gas samples taken from enclosed metabolic chamber while animals are stimulated to call. The microphone records vocal behavior and calling activity

Oxygen consumption while calling in Spring peepers

Comparison of VO2calling with VO2 during exhaustive locomotor exercise in Spring peepers

Calling Muscles in Frogs

Comparison of male and female trunk muscles in Spring peepers

Enzyme profiles of muscles used in calling

VO2 during locomotor exercise and citrate synthase activity

Citrate synthase in vertebrate muscles

Does individual variation in CS activity correlate with calling

behavior?

Yes, in a complicated way…

Comparison of low and high-calling male Spring peepers

Physiological/biochemical correlates of calling behavior

Factors correlated with calling rate