Reply to Etges

Abstract

Etges constructively points out errors in Stearn''s interpretations of Birch et al. and of Dobzhansky et al., and usefully extends the list of studies on the heritability of fitness traits. There are still differences on several points. First, there is disagreement over the reliability of genetic correlations. Measuring them is essential to progress in life-history work, but measurements done in single environments are not sufficient. To be useful, genetic correlations must be measured in several environments, one of which should be the field. The influence of developmental plasticity on genetic correlations in different environments remains fundamental. Second, Etges relies extensively on Fisher''s fundamental theorem. While it certainly would strengthen the inferences made if it were true, its general applicability remains questionable because of the effects of strong selection, linkage, age-structure and density-dependence. Third, the genetical point of view that permeates both Etges'' paper and the Modern Synthesis is not to be preferred as an exclusive alternative. It must be combined with the organismal point of view to be fruitful. Fourth, recent discoveries in molecular biology may bring about a sweeping reassessment of population and quantitative genetics, and are at least sufficiently unsettling to make an agnostic stance wise in the interim.