Larval competition in Drosophila melanogaster. II. Comparing biological and competitive parameters

Abstract

Recent developments in the analysis of density dependent competition in Drosophila melanogaster have identified two distinct parameters, namely the competitive pressure or aggression exerted by a genotype and the sensitivity or response of a genotype to such aggression. Assuming that response is more related to the efficiency of utilising available resources and aggression to the ability to acquire those resources, we attempt to relate estimates of aggression and response obtained from a range of genotypes to estimates of larval feeding rates and conversion efficiences. No significant correlations were found and we conclude that other characteristics must be involved in a more complex determination of competitive ability.

Analysis of dominance for competitive ability in Drosophila melanogaster

“…Estimates of the correlation between inter-genotypic pressure and inter-genotypic sensitivity (a) there was no significant correlation between these estimates, supporting the contention that they are, at least in part, independent of each other (de Miranda and Eggleston, 1988b;1988c;Hemmat and Eggleston, 1988). The 16 F1 hybrids can also be analysed amongst themselves by separating the general contributions of each haploid autosome (g) and the specific interaction between pairs of homologues (s) as shown in fig.…”

On the use of tester stocks to predict the competitive ability of genotypes

“…Our aim was not to dismiss their approach to analysing competition phenomena. On the contrary, this is a very useful experimental design and can give, when used appropriately, important insights into the complex interactions displayed by organisms which are in competition with one another (Mather et al, 1982;Mather & Caligari, 1983;De Miranda & Eggleston, 1988;Hemmat & Eggleston, 1990a, b). The method is an application of the powerful least squares estimation procedure to competition experiments but misinterpretation of the results can occur if this statistical tool is applied in an inappropriate way (see e.g.…”

Larval competition in Drosophila melanogaster. I. Estimation of larval growth parameters

“…The yeast used as a starter for the culture (Sigma YSC-2) was the same as that used in the accompanying analysis of competitive behaviour (de Miranda and Eggleston, 1987). For the second instar assays 200 pCi S35/100 ml LSM was used whereas the third instar assays used 100 iCi S/iOO ml LSM.…”

“…(Linney et a!., 1971), and they were maintained by sibmating. Their chromosomal constitution is described in the accompanying paper (de Miranda and Eggleston, 1987 hour larvae) was deposited in a 5 cm petri dish and dried to a uniformly solid consistency at 25°C. Prior to each assay 2 small samples (approximately 30 mg) of the thickened yeast were weighed and dissolved in 50 ml of water to determine the radioactivity per g yeast which was used to convert all radioactivity estimates to estimates of the amount of yeast consumed.…”

“…In an accompanying paper (de Miranda and Eggleston, 1987) we attempt to correlate these parameters with statistical parameters derived from the analysis of competitive ability (Mather andCaligari, 1981, 1983).…”