The sexual strategies of natural populations of newts and salamanders

Because urodele amphibians tend to breed in relatively inaccessible habitats, little is known about the sexual strategies of natural populations. This review attempts to integrate knowledge of urodele sexual strategies based on field and laboratory studies of population dynamics, competition between males for females, mate choice, parental care, and physiological constraints on reproduction. Data are considered in the context of current theories in the behavioral ecology of sexual strategies. The duration of the breeding period is an important determinant of the sexual strategy of a population, exerting its major influence through the operational sex ratio. When breeding periods are short, males aggregate and scramble for matings by interfering with one another's attempts to inseminate females. In some species, these aggregations resemble leks. With prolonged breeding periods, males are more likely to defend exclusive areas to which females are attracted for mating. Opportunities for mate choice probably are greatest when breeding periods are long. Parental care, especially when provided by males, may select for mate choice by both sexes. These conclusions must be treated as provisional as they are based on data of limited quality and quantity.