Evolutionary Optimality of Body Features. Species-Specific Lifespan as a Product of Evolution

Abstract

According to Darwin’s theory of natural selection, the fittest population survives in the course of competition for a food resource. The values of the features of individuals of the surviving population are considered evolutionarily optimal. A model of a biological community consisting of competing populations and a plant resource was built. The model included an equation of population dynamics, an equation of the energy balance of a sexually mature individual, and equations of the dynamics of the density of the food resource. To determine the evolutionarily optimal values, a criterion was proposed by Khanin and Semevsky, according to which the evolutionarily optimal values of features provide the maximum of the reproduction coefficient; it is equal to zero in the equilibrium state of the community. It was shown that there is an equivalent criterion based on the minimum energy received by an individual. Using these criteria, a method for determining the evolutionarily optimal values of body weight and coat thickness of an individual was demonstrated. It was assumed that species-specific lifespan, like other features of an organism, is also a product of evolution. Using the criterion of the minimum energy received by an individual, the species-specific lifespan was determined as a function of external factors and other parameters of the organism. The results were confirmed by numerical experiments for specific values of the parameters.