Differential Mating Success Research Articles

Fertility Differences as a Factor in the Maintenance of the "Sex Ratio" Polymorphism in Drosophila pseudoobscura

"Sex ratio" (SR) males of Drosophila pseudoobscura produce more than 95% female progeny. Previous workers have had varying opinions on the roles played by differential mating success and fertility of SR and normal (ST) males, if any, in the maintenance of the SR/ST polymorphism. In order to assess the importance of these roles, virgin D. pseudoobscura females were marked and released in the Santa Catalina mountains near Tucson, Arizona. Marked and unmarked females, and males, were collected over a period of about 2 wk, and total numbers of male and female progeny produced by individual flies were counted. The results show that SR males, which appear to produce about half as many sperm as ST males, fertilize as many eggs per insemination as ST males but inseminate only half their share of females. This means that SR males produce as many daughters as ST males, and is consistent with earlier observations that natural populations appear to be in Hardy-Weinberg equilibrium for SR. If the mating disadvantage of SR males is caused directly by reduced sperm production, then SR is not a case of meiotic drive balanced by selection, and the population dynamics of SR in D. pseudoobscura may be representative of other species having SR. If the mating disadvantage is not directly related to reduced sperm production, then SR is a case of meiotic drive balanced by selection. The selection in this case would be the mating disadvantage. If this is the correct explanation then the equilibrium involving SR may be different in every population.

A maximum likelihood statistical method for analyzing frequency-dependent fitness experiments

Experiments on frequency-dependent fitness often consist of forming pairwise mixtures of distinguishable types at several frequency combinations. These mixtures are allowed to undergo competition, after which the performance of each type is enumerated. A statistical method for analyzing such experiments is described in this article. This method, suggested previously for other purposes, is superior to the statistical procedures now commonly employed. It involves the maximum likelihood estimation of parameters for two logistic regression models: one which assumes that fitness is frequency-dependent, the other that fitness is constant over changing frequency. Estimators for both models can be calculated without difficulty using an iterative numerical algorithm implemented in a Fortran computer program available from the authors. Fitting both models allows for the construction of a likelihood ratio statistical test for whichever model is more appropriate. The method is illustrated by application to publishedDrosophila data from differential mating success experiments.

Social organization and mating success in local song populations of village indigobirds, Vidua chalybeata.

Behavioral interactions among color-marked individual Vidua chalybeata that shared common song dialects were observed for 5 years in two populations at Lochinvar National Park, Zambia. Social interactions involved males visiting and competing for mating sites and female visiting male in an apparent sampling of potential copulating partners. Differences in mating success among the polygynous males were compared with male behavior and territory resources, and criteria were developed to test the importance of intrasexual male competition and female mate choice in explaining the mating system of the populations. Song behavior best explained differences in mating success of males, with lesser effects of neighboring males and the defensible resources around the call-sites. The social organization of song populations resembles that of a dispersed lek with females visiting many males but mating with few males. We discuss the observations on indigobirds in relation to behavioral selection, sexual selection, and mating systems. Mating systems of certain populations and species are compared using statistics of individual mating success.

Far Infrared Stimulation of Insects with the Glagolewa-Arkadiewa "Mass Radiator"

Several species of insects were subjected to far infrared (IR) radiation from a Glagolewa-Arkadiewa mass IR radiator. All insects responded to the radiator with antennae movement, antennae cleaning behavior, or oviposition. In antennectomized male corn earworm moths, Heliothis zea (Boddie), significant differences in mating success were related to the length of antennae removed. This indicates that the antennal sensilla, whose pattern is repeated on each segment, and not the total antenna, is responsible for far IR detection.

Reproductive Biology of the Lesser Cornstalk Borer. II. Cage Conditions and Sex Ratios for Mating12

Elasmopalpus lignosellus (Zeller) mated in 40-dr clear plastic vials but not in 4-dr glass shell vials. In the 40-dr vials no significant differences in mating success occurred in cage position, cage top materials, and fed vs. unfed moths for a single mating per pair. Fed moths multiple mated significantly more frequently than unfed moths. No significant differences in male mating frequencies occurred when 1 male was exposed to 1 to 4 females. In the sex ratio test, males passed no more than 1 spermatophore per night.