No Evidence That Polyandry Benefits Females in Drosophila Melanogaster

Abstract

Understanding the evolution of polyandry (mating with multiple males) is a major issue in the study of animal breeding systems. We examined the adaptive significance of polyandry in Drosophila melanogaster, a species with well-documented costs of mating in which males generally cannot force copulations. We found no direct fitness advantages of polyandry. Females that mated with multiple males had no greater mean fitness and no different variance in fitness than females that mated repeatedly with the same male. Subcomponents of reproductive success, including fecundity, egg hatch rate, larval viability, and larval development time, also did not differ between polyandrous and monogamous females. Polyandry had no affect on progeny sex ratios, suggesting that polyandry does not function against costly sex-ratio distorters. We also found no evidence that polyandry functions to favor the paternity of males successful in precopulatory sexual selection. Experimentally controlled opportunities for precopulatory sexual selection had no effect on postcopulatory sperm precedence. Although these results were generally negative, they are supported with substantial statistical power and they help narrow the list of evolutionary explanations for polyandry in an important model species.

Patterns of Sperm Precedence Are Not Affected by Female Mating History in Drosophila Melanogaster

“…Although our estimates of paternity were measured in a laboratory-adapted base population with a very specific culturing regimen, they also agree with the findings published in many other studies of D. melanogaster. Our values for P 2 (two-male experiment; 0.79) and P 3 (three-male experiment; 0.77) are similar to those previously reported in the LH M base population (experimentwide P 2 ϭ 0.83 Ϯ 0.01, Brown et al 2004) and falls within the broad range of values estimated from other strains of D. melanogaster (P 2 ϭ 0.82 from Boorman and Parker 1976; P 2 ϭ 0.750-0.836 from Clark et al 2000; P 2 ϭ 0.31-1.00, from Simmons 2001). Moreover, it is thought that the mechanism of sperm competition in Drosophila occurs through sperm mixing, rather than sperm stratification (Scott and Richmond 1990).…”

“…These means, and all others reported below, are weighted values, with weights being the family size of each female assayed. These values are similar to those previously reported in the LH M population (experiment-wide P 2 ϭ 0.83 Ϯ 0.01 Brown et al 2004) and falls within the broad range of values estimated from other strains of D. melanogaster (P 2 ϭ 0.82 from Boorman and Parker 1976; P 2 ϭ 0.31-1.00 from Simmons 2001).…”

The effect of mating frequency and mating pattern on female reproductive fitness in cabbage beetle, Colaphellus bowringi

“…Some studies showed that polyandrous females have greater reproductive fitness than monogamous females, because polyandrous females lay more eggs (Lewis & Austad, 1994;Eady et al, 2000;Worden & Parker, 2001;Dunn et al, 2005;Simmons, 2005), or achieve a significantly higher egg-hatching success than monogamous females (Ivy & Sakaluk, 2005;Engqvist, 2006;Haddrill et al, 2007;Gowaty et al, 2010), because polyandrous females allocate more resources to egg production and more energy to reproduction. On the other hand, some species show a reduction or no effect on female fecundity (Tregenza & Wedell, 1998;Brown et al, 2004;Schwartz & Peterson, 2006;Ronkainen et al, 2010) or on fertility (Dunn et al, 2005;Jennions et al, 2007;House et al, 2009;Ronkainen et al, 2010). In our data, we also found that there was no effect of mating pattern on female fecundity between polyandrous and monogamous females, but polyandrous matings (five males) significantly decreased egg hatching success as well as female longevity, compared to repeated matings (five times with the same male).…”

Mating-Induced Recombination in Fruit Flies

“…We did not design the experiment to address this idea, thus we cannot eliminate birth-order effects or egg production as potential sources of variation in recombination rate. However, several previous studies have found no effects of mating and mating frequency on egg production at early ages in the Dahomey line used in experiment 2 (Fowler and Partridge 1989;Friberg and Arnqvist 2003;Brown et al 2004;Priest 2006). In addition, mating did not affect egg production during the collection interval and there was no correlation between egg production and recombination rate in experiment 2.…”