Abstract
How consistent quantitative genetic estimates are across environments is unclear and under discussion. Heritability (h2) estimates of hind tibia length (body size), development time and diapause induction in the yellow dung fly, Scathophaga stercoraria, generated with various methods in various environments are reported and compared. Estimates varied considerably within and among studies, but yielded good overall averages. The genetic correlations between the sexes for body size and development time were expectedly high (r(sex) = 0.57–0.78) but clearly less than unity, implying independent evolution of both traits in males and females of this sexually dimorphic species. Genetic and environmental variance components increased in proportion at variable field relative to constant laboratory conditions, resulting in overall similar h2. Heritabilities for males and females were also similar, and h2 of the morphological trait hind tibia length was not necessarily greater than that of the two life history traits. Full-sib (broad-sense) estimates (h2 = 0.7–1.1) were 2–3 times greater than half-sib and parent/offspring (narrow-sense) estimates (h2 = 0–0.6). Common environment (i.e., among-container) variance averaged 38.3% (body size) and 16.8% (development time) of the broad-sense genetic variance in two laboratory studies. The broad-sense h2, therefore, may contain substantial amounts (12–50%) of dominance variance and/or variance due to maternal effects. A general conclusion emerging from this and similar studies appears to be that whether field and laboratory genetic estimates differ depends on the environment, trait and species under consideration.
Blanckenhorn, Wolf U