Allometry in Biological Growth

The study of how body size influences physiological characteristics.

Changes in proportions of body parts related to changes in overall body size.

The relationship between body size and basal metabolic rate (BMR) follows a power law, meaning that the rate of metabolism increases with body size, but not at the same rate.

The specific formula that describes the relationship between body mass (M) and basal metabolic rate (BMR). The exponent 'b' is the key factor in understanding how BMR scales with size.

A straight line can be created by plotting BMR and body mass on log axes.

The rate at which the heart beats per minute.

The relationship between heart rate and body mass in mammals is described by a mathematical equation known as the allometric equation. This equation predicts the heart rate based on the animal's mass.

Indicates that certain physiological properties scale differently with body mass than the expected pattern. This suggests unique adaptations or constraints.

The maximum rate of oxygen consumption during intense exercise.

The relationship between metabolic rate (BMR) and body mass (M) follows a power law, meaning that BMR increases with M, but not at the same rate. It can be represented by the equation: BMR = 70M^0.72

The exponent 'b' in the allometric equation (BMR = aM^b) determines how BMR scales with body mass. For mammals, the exponent is typically around 0.75.

The metabolic rate per gram of body mass decreases as body size increases. This means that larger animals have lower mass-specific metabolic rates compared to smaller animals.

The rate at which an animal can use oxygen during maximal physical exertion. It reflects the animal's peak aerobic capacity.

A straight line can be created by plotting BMR and body mass on log axes. The slope of this line represents the exponent 'b' in the allometric equation.

The body's surface area (SA) to volume ratio (V) is smaller in larger animals. This leads to a reduced relative heat loss, explaining why larger animals have lower mass-specific metabolic rates.

Although the SA/V ratio explanation for allometry is plausible, it doesn't fully explain the observed scaling patterns. For example, the mass exponent 'b' is often different from the expected -0.67 value

Ectotherms, also known as cold-blooded animals, have similar allometric scaling patterns as endotherms (warm-blooded animals), even though heat loss is less of a factor for them.