A Statistical Study of Mate Choice: Sexual Selection in a Plethodontid Salamander (Desmognathus ochrophaeus)

Abstract

Our experiment revealed the existence of significant variation in mating success in a salamander species in which males do not provide courtship feeding, nest sites, or parental care. Differences in mating success were based on natural variation among adult males and females, rather than on traits of an artificially selected set of potential mates. Courtship encounters deliberately involved only one male and one female, thus eliminating the potentially confounding effects of male-male competition and variations in mate encounter rate. Even after eliminating these effects and random error, some females were more likely than others to elicit spermatophore deposition by a male, and some males were more likely than others to inseminate a female. Such variation among individuals represents an opportunity for sexual selection to act on phenotypic characters that affect mating success. We advocate the use of a factorial experimental design to analyze sexual selection. This approach permits the statistical evaluation of separate male and female effects, interaction between these effects, and random effects. Designs which combine the evaluations of mating success and courtship behaviors could estimate the force of sexual selection on behavior.

Multiple paternity in a natural population of a salamander with long‐term sperm storage

“…Thus, polyandry and resulting sperm competition may be important factors shaping the mating system of D. ocoee. High population densities in the field (Petranka et al 1993), a long breeding season (Organ 1961;Tilley 1977;Sever & Hamlett 1998), and observations of high insemination rates in the laboratory (Houck et al 1985a;up to 26 males in a single breeding season) suggested that female D. ocoee might mate frequently in the field and produce clutches sired by many males. While female multiple mating appears to be almost ubiquitous in the population we sampled, only a few males sire offspring in each clutch.…”

“…Maternal care ends after hatching, and males are not known to provide resources to either the female or her offspring. Laboratory-based studies of mating behaviour in D. ocoee have shown that females may be inseminated up to 26 times by different males during a single breeding season (Houck et al 1985a), although whether this high rate of insemination also occurs in the field is unknown. Apparent multiple paternity in nature has been documented in two studies of this species.…”

The Evolution of Asymmetry in Sexual Isolation: A Model and a Test Case

“…We test some of the assumptions and predictions of our model with an experimental study of the mountain dusky salamander, Desmognathus ochrophaeus. Courtship behavior and sexual isolation have been studied extensively in the genus Desmognathus (Organ 1961;Houck et al 1985;Houck et al 1988;Verrell 1988aVerrell ,b, 1989Verrell , 1990aVerrell and Tilley 1992;Maksymovitch andVerrell 1992, 1993;Uzendoski and Verrell 1993). We have surveyed sexual isolation among a series of 12 allopatric D. ochrophaeus populations whose phylogenetic relationships have been estimated from allozyme data (Verrell and Arnold 1989;Tilley et al 1990).…”

An Experimental Study of the Behavioral Basis of Sexual Isolation between Two Sympatric Plethodontid Salamanders, Desmognathus imitator and D. ochrophaeus

“…The cloaca of the female was checked for the presence of a sperm mass, a certain indicator of insemination. This mass remains externally visible for as long as 24 h after mating (HOUCK et al 1985).…”