On the (dis) advantages of cannibalism

Abstract

Abstract. Cannibalism is an interaction between individuals that can produce counterintuitive effects at the population level. A striking effect is that a population may persist under food conditions such that the non-cannibalistic variant is doomed to go extinct. This so-called life boat mechanism has received considerable attention. Implicitly, such studies sometimes suggest, that the life boat mechanism procures an evolutionary advantage to the cannibalistic trait.Here we compare, in the context of a size structured population model, the conditions under which the life boat mechanism works, with those that guarantee, that a cannibalistic mutant can invade successfully under the steady environmental conditions as set by a non-cannibalistic resident. We find qualitative agreement and quantitative difference. In particular, we find that a prerequisite for the life boat mechanism is, that cannibalistic mutants are successful invaders. Roughly speaking, our results show that cannibalism brings advantages to both the individuals and the population when adult food is limiting.

Xeno-Cannibalism as an Exacerbation of Self-Cannibalism: A Possible Fruitful Survival Strategy for Cancer Cells

“…In fact, individual cannibalic behavior procures a survival advantage and represents a benefit either for the individual or for the population in highly limiting food supply [29]. This hypothesis is in line with studies coming from diverse investigation fields, for instance in population studies in humans.…”

Guppy populations differ in cannibalistic degree and adaptation to structural environments

“…These two facts suggest that there is more intense intraspeciWc competition for resources in low predation localities (Reznick et al , 2002Arendt and Reznick 2005). Several authors have argued that cannibalism is favoured in environments with high resource competition or low productivity (Stenseth 1985;van den Bosch et al 1988;Elgar and Crespi 1992;Getto et al 2005). Cannibals are favoured both by the immediate energy acquisition and the decrease in competition for food by killing a conspeciWc.…”

“…A number of suggestions have been put forward to explain the large variation in cannibalism between individuals and between species including both evolutionary and behavioural factors (Elgar and Crespi 1992). For example, cannibalism has been suggested to be more common when resource competition is strong in a population (Van den Bosch et al 1988;Elgar and Crespi 1992;Getto et al 2005). The trophic position of a species and whether it is an eYcient predator may also aVect how eYcient it is as a cannibal.…”

Cannibalism in discrete-time predator–prey systems

“…This population interaction results in a predator-prey system with the prey population being cannibalistic. There are many existing mathematical models in the literature including partial/ordinary differential equations and difference equations with different modeling assumptions exploring cannibalism [3,[5][6][7]9,10,[13][14][15]25]. It has been concluded in these mathematical models that cannibalism can have important effects on population dynamics.…”

“…Suppose now R 0 > 1. Then Equation (27) has another boundary steady state E 1 = (x 1 ,x 2 , 0), wherex 2 satisfies Equation (7) andx 1 is given by Equation (9). The Jacobian matrix of Equation (27) evaluated at E 1 is given by…”