Is modularity necessary for evolvability? Remarks on the relationship between pleiotropy and evolvability.

Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA.
Biosystems (Impact Factor: 1.47). 06/2003; 69(2-3):83-94.
Source: PubMed

ABSTRACT Evolvability is the ability to respond to a selective challenge. This requires the capacity to produce the right kind of variation for selection to act upon. To understand evolvability we therefore need to understand the variational properties of biological organisms. Modularity is a variational property, which has been linked to evolvability. If different characters are able to vary independently, selection will be able to optimize each character separately without interference. But although modularity seems like a good design principle for an evolvable organism, it does not therefore follow that it is the only design that can achieve evolvability. In this essay I analyze the effects of modularity and, more generally, pleiotropy on evolvability. Although, pleiotropy causes interference between the adaptation of different characters, it also increases the variational potential of those characters. The most evolvable genetic architectures may often be those with an intermediate level of integration among characters, and in particular those where pleiotropic effects are variable and able to compensate for each other's constraints.


Available from: Thomas F Hansen, Jun 07, 2015
  • [Show abstract] [Hide abstract]
    ABSTRACT: Evolutionary developmental biology (evo-devo) is a rapidly growing discipline whose ambition is to address questions that are of relevance to both evolutionary biology and developmental biology. This field has been increasingly progressing as a new and independent comparative science. However, we argue that evo-devo's comparative approach is challenged by several metaphysical, methodological and socio-disciplinary issues related to the foundation of heuristic functions of model organisms and the possible criteria to be adopted for their selection. In addition, new tools have to be developed to deal with newly chosen model organisms. Therefore, we present a modelling framework suitable to integrate data on individual variation into evo-devo studies on new model organisms and thus to compensate for current idealization practices deliberately suppressing variation.
    History & Philosophy of the Life Sciences 08/2014; 36(1):42-59. DOI:10.1007/s40656-014-0004-3 · 0.32 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We investigated patterns of evolutionary integration in the appendicular skeleton of mammalian carnivores. The findings are discussed in relation to performance selection in terms of organismal function as a potential mechanism underlying integration. Interspecific shape covariation was quantified by 2B-PLS analysis of 3D landmark data within a phylogenetic context. Specifically, we compared pairs of anatomically connected bones (within-limbs) and pairs of both serially homologous and functional equivalent bones (between-limbs). The statistical results of all the comparisons suggest that the carnivoran appendicular skeleton is highly integrated. Strikingly, the main shape covariation relates to bone robustness in all cases. A bootstrap test specifically developed to compare the degree of integration between specialized cursorial taxa (i.e., those whose forelimbs are primarily involved in locomotion) and non-cursorial species (i.e., those whose forelimbs are involved in more functions than their hind limb) showed that cursors have a more integrated appendicular skeleton than non-cursors. The findings demonstrate that natural selection can influence the pattern and degree of morphological integration by increasing the degree of bone shape covariation in parallel to ecological specialization.This article is protected by copyright. All rights reserved.
    Evolution 11/2014; 69(2):321-340. DOI:10.1111/evo.12566 · 4.66 Impact Factor
  • Source