A quantitative investigation of dominance plasticity for a developmental threshold trait in a laboratory population of Tribolium castaneum.

摘要

Antagonistic pleiotropy may enable balancing selection to maintain genetic variation for multiple traits, but only if dominance effects change their relationships with additive effects so as to make these interactions consistently favorable with respect to fitness. This adaptive dominance plasticity is expected to generate patterns of non-additive genetic covariance that may become particularly strong with inbreeding. Importantly, inbreeding may cause dominance covariance to contribute to parent-offspring regressions and, consequently, the indirect response to selection. Adaptive dominance plasticity has been discounted on theoretical grounds as mechanistically unlikely, although its existence is indirectly suggested by earlier empirical studies.; By articulating dominance plasticity and pleiotropy in terms of patterns of genetic variance and covariances, I develop an empirical approach with which to estimate these diagnostic measures in inbreeding populations. This design follows from novel theory that interprets the among-line variation in inbreeding depression in terms of genetic variance components. It is applied to a polymorphic threshold trait in a laboratory population of Tribolium castaneum responsible for a life-history trade-off between fast development and pupal size.