Poisson distribution of male mating success in laboratory populations of Drosophila melanogaster

Abstract

SummaryVariation among males and females in reproductive success is a major determinant of effective population size. Most studies of male mating success in Drosophila, however, have been done under conditions very different from those in typical cultures. We determined the distribution of male mating success in five laboratory populations of D. melanogaster maintained on a 14 d, discrete generation cycle fairly representative of standard Drosophila cultures. Mating success was measured as the number of matings a male could achieve under conditions closely approximating a regular culture vial of these populations. Preliminary studies determined that most mating in these populations occurred within 14 h of the flies attaining sexual maturity. Consequently, individual virgin males were marked with white paint on their thorax, put into vials with varying numbers of unmarked virgin flies of both sexes, and monitored continuously for matings over a period of up to 14 h. At various times during the assay, virgin males and females were added to these vials in proportions simulating the pattern of eclosion in culture vials. The observed variation in the number of matings per male in the five populations was, by and large, consistent with a Poisson distribution, suggesting that male mating success in short-generation-time, discrete-generation laboratory cultures of D. melanogaster may fulfil a fundamental assumption of the Wright-Fisher model of genetic drift in finite populations.

Evolution of reduced pre-adult viability and larval growth rate in laboratory populations of Drosophila melanogaster selected for shorter development time

“…In the case of both dry weight at eclosion and larval growth rate, the fractional reduction, relative to controls, in FEJ males was greater than that seen in FEJ females. This is not altogether surprising, given that weight at eclosion is clearly important to females due to its relationship to early life fecundity (Mueller, 1985), whereas male size is not strongly related to reproductive success in laboratory cultures maintained at low larval densities (Joshi et al, 1999). Part of the decrease in growth rate of the FEJ populations relative to the JB controls was actually due to an increase in JB growth rates as selection proceeded (Fig.…”

“…Even though females in Drosophila cultures typically eclose earlier than males and, therefore, males should experience stronger selection in a regime selecting for faster development, male and female development times have not previously been seen to respond differentially to selection. Possible explanations for this apparent paradox have been that the difference in male and female development times can be ameliorated by either high (Zwaan et al, 1995) or variable (Joshi et al, 1999) larval densities in the culture vials, or the suggestions that sex-specific expression of heritable variation for development time is lacking in these populations (Chippindale et al, 1997), or that the sexual dimorphism in development time is subject to strong canalizing influences (Chippindale et al, 1997). While one or more of these explanations may, in fact, be operating to ameliorate the selection differential between males and females in a culture subjected to truncation selection for fast development, our results clearly indicate that the sexual dimorphism in development time in Drosophila can, nevertheless, respond to selection in the manner expected, with males gradually narrowing the development time gap with females.…”

Correlates of sexual dimorphism for dry weight and development time in five species of Drosophila

“…The greater development time of males is known to be the result of a longer pupal, rather than larval, duration in males (Bakker & Nelissen, 1963;Nunney, 1983), and it has been speculated that the reason for this is the time-consuming process of sperm maturation (Nunney, 1996). The degree of sexual dimorphism in development time in D. melanogaster is environment sensitive, and is more prominent at low or moderate larval density (Zwaan, Bijlsma & Hoekstra, 1995;Joshi, Do & Mueller, 1999). There is also evidence for the evolution of dimorphism in development time in D. melanogaster populations subjected to selection for faster development, with the difference between male and female development time being reduced from 4.5 h to 1.4 h over c. 70 generations of selection (Prasad et al, 2000).…”

Estimation of effective population size using bivariate discrete distributions for modeling family size in beef cattle

“…This may induce an overestimation of N e , as the information from a portion of sires of cows and most dams of cows is not used in the estimation process. Family size of dairy bulls has been considered to follow a Poisson distribution (Goddard and Smith, 1990), and there was experimental evidence for a Poisson male family size in Drosophila melanogaster (Joshi et al, 1999). However, our analysis shows that this was not the case for the family sizes of beef bulls as there was considerable overdispersion, i.e.…”

“…It is frequently assumed that the random variable family size in different animal species follows a Poisson distribution (Harris and Allenford, 1989;Goddard and Smith, 1990;Caballero, 1994;Joshi et al, 1999) in which mean and variance are equal. This assumption is unlikely to be fulfilled for most farm animal species where a small group of sires have a large contribution to the progeny pool.…”