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THE DIMENSIONALITY OF GENETIC VARIATION FOR WING SHAPE IN DROSOPHILA MELANOGASTER
Author(s) -
Mezey Jason G.,
Houle David
Publication year - 2005
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/j.0014-3820.2005.tb01041.x
Subject(s) - biology , wing , variation (astronomy) , context (archaeology) , evolutionary biology , genetic variation , drosophila melanogaster , rank (graph theory) , constraint (computer aided design) , pleiotropy , range (aeronautics) , selection (genetic algorithm) , genetics , phenotype , mathematics , computer science , gene , combinatorics , artificial intelligence , paleontology , physics , geometry , materials science , astrophysics , engineering , composite material , aerospace engineering
Absolute constraints are limitations on genetic variation that preclude evolutionary change in some aspect of the phenotype. Absolute constraints may reflect complete absence of variation, lack of genetic variation that extends the range of phenotypes beyond some limit, or lack of additive genetic variation. This last type of absolute constraint is bidirectional, because the mean cannot evolve to be larger or smaller. Most traits do possess genetic variation, so bidirectional absolute constraints are most likely to be detected in a multivariate context, where they would reflect combinations of traits, or dimensions in phenotype space that cannot evolve. A bidirectional absolute constraint will cause the additive genetic covariance matrix ( G ) to have a rank less than the number of traits studied. In this study, we estimate the rank of the G ‐matrix for 20 aspects of wing shape in Drosophila melanogaster . Our best estimates of matrix rank are 20 in both sexes. Lower 95% confidence intervals of rank are 17 for females and 18 for males. We therefore find little evidence of bidirectional absolute constraints. We discuss the importance of this result for resolving the relative roles of selection and drift processes versus constraints in the evolution of wing shape in Drosophila .