Sexual selection enhances population extinction in a changing environment

Animal communication systems (sexual and social communications) may cause an extra selection load on populations because of the cost of the signals. Under environmental deterioration, the cost of signaling must increase, resulting in an evolutionary reduction in the signal if it is maintained by natural selection vs. sexual selection balance. And in turn, the degeneration of the signal tends to reduce the selection load imposed by the cost. But if female preference resides in a population, sexual selection may prevent rapid degeneration of the signal, which is increasingly costly. Hence sexual selection may enhance populational extinction by increasing selection load under environmental changes. This paper evaluates the extra selection load that a communication system suffers when an environment deteriorates or the ecological optimum for a signal changes in the opposite direction to the sexual selection optimum. (C) 1966 Academic Press Limited