Final answer:
The question deals with population dynamics in biology, representing the rate of population change using differential calculus to determine the instant-specific growth rate. It is related to demography, which studies population changes statistically, though the question's focus is centered on ecology.
Step-by-step explanation:
The subject of the question pertains to the model of population dynamics within the discipline of biology, specifically within the area of ecology. The formula given, dp/dt = db/dt − dd/dt, uses differential calculus to represent the rate of population change (P(t)) over time (t). This is not strictly a demographic equation, as it incorporates concepts from calculus. However, demography is related as it considers the statistical study of population changes over time, such as birth rates, death rates, and life expectancies.
Demography, in a broader sense, is used to study the dynamics of a population. Demographic-based population models consider various features such as the intrinsic rate of increase and factors affecting birth and death rates. Nevertheless, the particular model discussed involves differential calculus to assess the instantaneous growth rate, showing the change in population size as an immediate rate measured at a specific instant.
In ecology, the instantaneous growth rate of a population is given by the formula dN = (b - d)N, which represents the births and deaths per capita in a given population. Here 'b' stands for the per capita birth rate, 'd' for the per capita death rate, and 'N' for the number of individuals in the population. The intrinsic rate of increase 'r' is sometimes used to simplify the relationship between birth and death rates.