EXPERIMENTAL MEASURES OF FITNESS IN DROSOPHILA

DAVID STEVEN HAYMER, Purdue University

Abstract

The ability to adequately define and assess fitness has long been elusive in evolutionary studies despite general agreement as to the prime importance of this concept. In response to this, a variety of methods have been proposed as measures of fitness. In this study, strains of Drosophila melanogaster were systematically subjected to each of several of these techniques. Several components of fitness were independently estimated for these strains as well. Four of the techniques used in this study were single-generation tests that defined fitness operationally as the competitive ability of a strain. Although some important differences between these techniques became evident, the competitive abilities of the strains were largely consistent as assessed in each of these techniques. However, a longer term test also based on competition and a noncompetitive test were clearly shown to be measuring something very different than the single-generation tests. Therefore, although all of these techniques refer to a net parameter called fitness, they cannot all be said to be measuring the same thing. In addition, individual components of fitness could not be consistently correlated with overall fitness. It was also demonstrated in the case of the sex ratio that extreme deviations from the norm can have substantial populational effects, suggesting that similar phenomena may apply to the relationship between fitness and fitness components.

Degree

Ph.D.

Subject Area

Genetics

COinS