Long-term laboratory evolution of a genetic life-history trade-off in Drosophila melanogaster. 1. The role of genotype-by-environment interaction

• Published in: Evolution 1994-08, Vol.48 (4), p.1244-1257
• Main Authors: Leroi, A.M, Chippindale, A.K, Rose, M.R
• Format: Article
• Language: English
• Subjects: Animal reproduction; Antagonistic pleiotropy; artificial selection; Diptera; Drosophila; Drosophila melanogaster; Drosophilidae; Ecological life histories; Eggs; Evolution; Fecundity; Female animals; Genetics; genotype × environment interaction; genotype-environment interaction; Insects; life cycle (organisms); life history; Longevity; nutrient availability; Ovaries; Oviposition; pleiotropy; population density; Starvation; starvation resistance; trade‐offs; weight; Yeasts
• ISSN: 0014-3820; 1558-5646
• DOI: 10.1111/j.1558-5646.1994.tb05309.x

Trade-offs among life-history traits are often thought to constrain the evolution of populations. Here we report the disappearance of a trade-off between early fecundity on the one hand, and late-life fecundity, starvation resistance, and longevity on the other, over 10 yr of laboratory selection for late-life reproduction. Whereas the selected populations showed an initial depression in early-life fecundity, they later converged upon the controls and then surpassed them. The evolutionary loss of the trade-off among life-history traits is considered attributable to the following factors: (1) the existence of differences in the culture regimes of the short- and long-generation populations other than the demographic differences deliberately imposed; (2) adaptation of one or both of these sets of populations to the unique aspects of their culture regimes; (3) the existence of an among-environment trade-off in the expression of early fecundity in the two culture regimes, as reflected in assays that mimic those regimes. The trade-off between early and late-life reproductive success, as manifest among divergently selected populations, is apparent or not depending on the assay environment. This demonstration that strong genotype-by-environment interactions can obscure a fundamental trade-off points to the importance of controlling all aspects of the culture regime of experimental populations and the difficulty of doing so even in the laboratory.