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1 August 2004 EVOLUTION AND STABILITY OF THE G-MATRIX ON A LANDSCAPE WITH A MOVING OPTIMUM
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Abstract

In quantitative genetics, the genetic architecture of traits, described in terms of variances and covariances, plays a major role in determining the trajectory of evolutionary change. Hence, the genetic variance-covariance matrix (G-matrix) is a critical component of modern quantitative genetics theory. Considerable debate has surrounded the issue of G-matrix constancy because unstable G-matrices provide major difficulties for evolutionary inference. Empirical studies and analytical theory have not resolved the debate. Here we present the results of stochastic models of G-matrix evolution in a population responding to an adaptive landscape with an optimum that moves at a constant rate. This study builds on the previous results of stochastic simulations of G-matrix stability under stabilizing selection arising from a stationary optimum. The addition of a moving optimum leads to several important new insights. First, evolution along genetic lines of least resistance increases stability of the orientation of the G-matrix relative to stabilizing selection alone. Evolution across genetic lines of least resistance decreases G-matrix stability. Second, evolution in response to a continuously changing optimum can produce persistent maladaptation for a correlated trait, even if its optimum does not change. Third, the retrospective analysis of selection performs very well when the mean G-matrix () is known with certainty, indicating that covariance between G and the directional selection gradient β is usually small enough in magnitude that it introduces only a small bias in estimates of the net selection gradient. Our results also show, however, that the contemporary -matrix only serves as a rough guide to . The most promising approach for the estimation of is probably through comparative phylogenetic analysis. Overall, our results show that directional selection actually can increase stability of the G-matrix and that retrospective analysis of selection is inherently feasible. One major remaining challenge is to gain a sufficient understanding of the G-matrix to allow the confident estimation of .

Adam G. Jones, Stevan J. Arnold, and Reinhard Burger "EVOLUTION AND STABILITY OF THE G-MATRIX ON A LANDSCAPE WITH A MOVING OPTIMUM," Evolution 58(8), 1639-1654, (1 August 2004). https://doi.org/10.1554/03-651
Received: 10 November 2003; Accepted: 4 May 2004; Published: 1 August 2004
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