1 December 2009 The Evolvability of Growth form in a Clonal Seaweed
Keyne Monro, Alistair G. B. Poore
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Although modular construction is considered the key to adaptive growth or growth-form plasticity in sessile taxa (e.g., plants, seaweeds and colonial invertebrates), the serial expression of genes in morphogenesis may compromise its evolutionary potential if growth forms emerge as integrated wholes from module iteration. To explore the evolvability of growth form in the red seaweed, Asparagopsis armata, we estimated genetic variances, covariances, and cross-environment correlations for principal components of growth-form variation in contrasting light environments. We compared variance—covariance matrices across environments to test environmental effects on heritable variation and examined the potential for evolutionary change in the direction of plastic responses to light. Our results suggest that growth form in Asparagopsis may constitute only a single genetic entity whose plasticity affords only limited evolutionary potential. We argue that morphological integration arising from modular construction may constrain the evolvability of growth form in Asparagopsis, emphasizing the critical distinction between genetic and morphological modularity in this and other modular taxa.

© 2009 The Society for the Study of Evolution.
Keyne Monro and Alistair G. B. Poore "The Evolvability of Growth form in a Clonal Seaweed," Evolution 63(12), 3147-3157, (1 December 2009). https://doi.org/10.1111/j.1558-5646.2009.00802.x
Received: 5 December 2007; Accepted: 1 July 2009; Published: 1 December 2009

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cross-environment genetic correlation
genetic variance and covariance
growth-form plasticity
modular organism
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