Ecological and evolutionary correlates of metabolic capacities in anuran amphibians

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Ecological and evolutionary correlates of
metabolic capacities in anuran amphibians
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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.

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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)

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Natural History of American Toads
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Measurements of VO2rest and VO2max
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Exhaustive locomotor exercise
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Development of aerobic capacity and dispersal in
toads
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Body mass at dispersal
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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

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Metabolic variation among species
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Ambush foragers--high anaerobic capacity
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Burrowing/active foragers--high aerobic capacities
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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

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VO2rest and VO2max among 17 anuran species
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Correlation between resting and activity
metabolism in frogs
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Dart poison frogs a coqui
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Coqui of Puerto Rico (and Hawaii, regrettably)
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Metabolic characteristics of Dart poison frogs
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Foraging behavior and metabolic characteristics
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Bocas del Toro, Panama

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

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Red (Isla Bastimentos) andGreen (Isla Colon)
Frogs of Bocas
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The Bocas del Toro Experiment in Nature may be
over
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Wells and Taigen and UConn Physiological Ecology
Class

• Reproductive behavior and aerobic capacities of
  male American toads (Bufo americanus) Is
  behavior constrained by physiology?

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No, at least not that night
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Metabolic costs of vocalization
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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

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Oxygen consumption while calling in Spring
peepers
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Comparison of VO2calling with VO2 during
exhaustive locomotor exercise in Spring peepers
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Calling Muscles in Frogs
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Comparison of male and female trunk muscles in
Spring peepers
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Enzyme profiles of muscles used in calling
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VO2 during locomotor exercise and citrate
synthase activity
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Citrate synthase in vertebrate muscles
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Does individual variation in CS activity
correlate with calling behavior?

• Yes, in a complicated way

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Comparison of low and high-calling male Spring
peepers
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Physiological/biochemical correlates of calling
behavior
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Factors correlated with calling rate