Developmental constraints versus flexibility in morphological evolution

Institute of Evolutionary and Ecological Sciences, Leiden University, PO Box 9516, 2300 RA Leiden, The Netherlands.
Nature (Impact Factor: 42.35). 05/2002; 416(6883):844-7. DOI: 10.1038/416844a
Source: PubMed

ABSTRACT Evolutionary developmental biology has encouraged a change of research emphasis from the sorting of phenotypic variation by natural selection to the production of that variation through development. Some morphologies are more readily generated than others, and developmental mechanisms can limit or channel evolutionary change. Such biases determine how readily populations are able to respond to selection, and have been postulated to explain stasis in morphological evolution and unexplored morphologies. There has been much discussion about evolutionary constraints but empirical data testing them directly are sparse. The spectacular diversity in butterfly wing patterns is suggestive of how little constrained morphological evolution can be. However, for wing patterns involving serial repeats of the same element, developmental properties suggest that some directions of evolutionary change might be restricted. Here we show that despite the developmental coupling between different eyespots in the butterfly Bicyclus anynana, there is great potential for independent changes. This flexibility is consistent with the diversity of wing patterns across species and argues for a dominant role of natural selection, rather than internal constraints, in shaping existing variation.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Phylogenetic niche conservatism (PNC) typically refers to the tendency of closely related species to be more similar to each other in terms of niche than they are to more distant relatives. This has been implicated as a potential driving force in speciation and other species-richness patterns, such as latitudinal gradients. However, PNC has not been very well defined in most previous studies. Is it a pattern or a process? What are the underlying endogenous (e.g. genetic) and exogenous (e.g. ecological) factors that cause niches to be conserved? What degree of similarity is necessary to qualify as PNC? Is it possible for the evolutionary processes causing niches to be conserved to also result in niche divergence in different habitats? Here, we revisit these questions, codifying a theoretical and operational definition of PNC as a mechanistic evolutionary process resulting from several factors. We frame this both from a macroevolutionary and population-genetic perspective. We discuss how different axes of physical (e.g. geographic) and environmental (e.g. climatic) heterogeneity interact with the fundamental process of PNC to produce different outcomes of ecological speciation. We also review tests for PNC, and suggest ways that these could be improved or better utilized in future studies. Ultimately, PNC as a process has a well-defined mechanistic basis in organisms, and future studies investigating ecological speciation would be well served to consider this, and frame hypothesis testing in terms of the processes and expected patterns described herein. The process of PNC may lead to patterns where niches are conserved (more similar than expected), constrained (divergent within a limited subset of available niches), or divergent (less similar than expected), based on degree of phylogenetic relatedness between species.
    Biological Reviews 11/2014; DOI:10.1111/brv.12154 · 10.26 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Background Mammals show a predictable scaling relationship between limb bone size and body mass. This relationship has a genetic basis which likely evolved via natural selection, but it is unclear how much the genetic correlation between these traits in turn impacts their capacity to evolve independently. We selectively bred laboratory mice for increases in tibia length independent of body mass, to test the hypothesis that a genetic correlation with body mass constrains evolutionary change in tibia length.ResultsOver 14 generations, we produced mean tibia length increases of 9-13%, while mean body mass was unchanged, in selectively bred mice and random-bred controls. Using evolutionary scenarios with different selection and quantitative genetic parameters, we also found that this genetic correlation impedes the rate of evolutionary change in both traits, slowing increases in tibia length while preventing decreases in body mass, despite the latter¿s negative effect on fitness.Conclusions Overall, results from this ongoing selection experiment suggest that parallel evolution of relatively longer hind limbs among rodents, for example in the context of strong competition for resources and niche partitioning in heterogeneous environments, may have occurred very rapidly on geological timescales, in spite of a moderately strong genetic correlation between tibia length and body mass.
    BMC Evolutionary Biology 12/2014; 14(1):258. DOI:10.1186/PREACCEPT-8844566431425109 · 3.41 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Correlation patterns have been widely used in evolutionary studies for exploring the role of development in channelling morphological evolution. The approach was firstly introduced by Olson and Miller in the 1950s, but it did not gain prominence until the 1980s, due to some extent to Gould and Lewontin's (Proc R Soc Lond B 205:581-598, 1979) assertion of the importance of considering organisms as integrated entities, where the internal organization of a structure, and not only the selective regime acting upon it, would play a fundamental role in its evolution. Here we show that this approach, mainly focused on the study of small, quantitative shape changes of existing structures, does not deal with a fundamental aspect of developmental systems, that is, their intrinsic capacity of originating morphological novelties. We show that only when the physicochemical processes underlying morphogenesis and pattern formation are taken into account, would the causal role of development be fully incorporated into the evolutionary view.
    Evolutionary Biology 09/2014; 41(3):494-502. DOI:10.1007/s11692-014-9275-6 · 3.27 Impact Factor

Full-text (2 Sources)

Available from
Oct 8, 2014