Individual Differences Between Animals and the Natural Regulation of their Numbers

Abstract

(1) A model of population regulation by emigration is developed based on and temporal heterogeneity of natural environments; (ii) unequal resource pa among individuals of single species populations. This latter phenomenon has viously been taken into account by theoretical ecologists, although it is of basic tance for regulation of population density. (2) Unequal resource partitioning increases the stability of a confined popu allows emigration of some population members into suboptimal and hostil evolve by individual selection. (3) In a local habitat supplied by a constant inflow of food, animal density is lo food density is higher when emigration occurs, than without emigration. (4) Regulation of population density by emigration allows for the adjustme density to the amount of food, in such a way that mortality is not directly due shortage but to other agents (predators, adverse weather conditions, etc.). (5) Animals with overlapping generations and cyclic changes in population dens emigrate at lower density level, than that determined by food supply at any given time. At high densities such populations can also exhibit reduced reproductio under certain circumstances can be considered as an adaptation. (6) Population outbreaks are thought of as a failure of population regula emigration resulting from spatial homogeneity of the environment. Hom diminishes both differences among individuals in local populations and dif between local habitats and their surroundings, these in turn can make regu emigration impossible

Intraspecific genetic variation and competition interact to influence niche expansion

“…The degree of individual variation in niche use has significant implications for population ecological and evolutionary dynamics (see Bolnick et al 2003 for a review). For instance, individual niche variation can substantially alter population dynamics (Lomnicki 1978;Kendall & Fox 2002) and species coexistence (Lichstein et al 2007). Depending on other conditions such as niche-based assortative mating (Snowberg & Bolnick 2008), niche variation can allow populations to undergo subsequent adaptive diversification and speciation (Dieckmann & Doebeli 1999).…”

Seasonal dispersal in non-cyclic populations of Clethrionomys glareolus and Apodemus flavicollis

“…Much has already been written about its evolution, adaptive value, role in density regulation, and possible role as a driving force of the rodent density cycles (e.g. Krebs & Myers, 1974;Lidicker, 1975;Łomnicki, 1978;Stenseth, 1983;Bondrup-Nielsen. 1985).…”

What elk, wolves and caterpillars have in common—The perfect forager theorem

“…The position of a given forager (its α 1 ) in relation to the hub (α) would indicate the efficiency of the individual forager. Plotting the values of α for the individual animals in a population would illustrate the variability in that population (efficient and less efficient foragers) which could indicate potential competition for resources, unequal distribution of resources, and therefore, stability of the population [41].…”