EFFECTS ON FITNESS COMPONENTS OF P-ELEMENT INSERTS INDROSOPHILA MELANOGASTER: ANALYSIS OF TRADE-OFFS

Abstract

Abstract-s-we analyzed the trade-offs between fitness components detected in four experiments in which traits were manipulated by inserting small (control) and large (treatment) P-elements into the Drosophila melanogaster genome, Treatment effects and the interactions of treatment with temperature, experiment, and line were caused by the greater length and different positions of the treatment insert. In inbred flies, the treatment decreased early and total fecundity. Whether it increased the lifespan of mated females depended upon adult density. Analysis of line-by-treatment-bytemperature interactions revealed hidden trade-offs that would have been missed by other methods. They included a significant trade-off between lifespan and early fecundity. At 25°C high early fecundity was associated with decreased reproductive rates and increased mortality rates 10-15 days later and persisting throughout life, but not at 29.5°C. Correlations with Gompertz coefficients suggested that flies that were heavier at eclosion also aged more slowly and that flies that aged more slowly had higher fecundity late in life at 25°C. The results support the view that lifespan trades off with fecundity and that late fecundity trades off with rate of aging in fruitflies. Genetic engineering is an independent method for the analysis of trade-offs that complements selection experiments.

A comparative analysis of senescence in adult damselflies and dragonflies (Odonata)

“…Second, the semi‐log plots at each time step show, as might be expected, an increase in variance as the size of the surviving population diminishes. Although qualitative evidence of senescence is sometimes based on directly regressing age‐specific mortality against age (see for example Hughes & Charlesworth, 1994; Stearns & Kaiser, 1996), the regression method alone is not a reliable test of senescence, because it does not incorporate information on the variances of estimated probabilities of survival (Slade, 1995). One potential solution to the problem is to conduct a standard linear regression of hazard rate vs. age, yet weight the hazard rate by the square root of the number alive at age x (Promislow, 1991).…”

Model fitting and hypothesis testing for age-specific mortality data

“…After choosing the appropriate model, we need an efficient method for estimating the parameters of that model from the data. Traditionally, Gompertz parameters were estimated by linear regression of log‐mortality rates on age (Hughes & Charlesworth, 1994; Orr & Sohal, 1994; Stearns & Kaiser, 1996). Parameters estimated in this way can be highly biased – small samples result in large over‐estimates of the initial mortality parameter and under‐estimates of the rate parameter (Mueller et al ., 1995; Promislow et al ., 1997; Pletcher, unpublished results).…”

“…In the evolutionary literature, age‐specific mortality is often analysed by using linear or nonlinear regression with age‐specific mortality (or its natural logarithm) as the dependent variable and age as the predictor variable (Hughes & Charlesworth, 1994; Stearns & Kaiser, 1996). The mortality rate at age x can be estimated from empirical data using the approximation…”

Quantitative trait loci for lifespan of mated Drosophila melanogaster affect both sexes

“…In the former case, mutations were either induced (for instance, by transpositions of P-element derivatives (Stearns & Kaiser, 1996)) or spontaneous (Houle et al, 1994 ;Pletcher et al, 1998). Both mutations accumulated in common isogenic background and alleles distinguishing independent wild-type stocks have been studied.…”