Developmental constrains versus flexibility in morphological evolution

Institute of Evolutionary and Ecological Sciences, Leiden University, PO Box 9516, 2300 RA Leiden, The Netherlands.
Nature (Impact Factor: 41.46). 05/2002; 416(6883):844-7. DOI: 10.1038/416844a
Source: PubMed


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.

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Available from: Patrícia Beldade, Oct 08, 2014
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    • "However, wings with these divergent patterns (i.e. negative correlations between eyespots ) were effectively obtained under artificial selection (Beldade et al. 2002) (Fig. 1). Similar results have been reported for the allometric pattern between forewing area and body size (Frankino et al. 2005). "
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    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.
    Full-text · Article · Aug 2014 · Evolutionary Biology
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    • "Tel +61 (0)2 6125 0641; Fax +61 (0)2 6125 5573; e-mail: Correction added after first online publication on 20 December 2013: grammatical error corrected in Fig. 1 patterns are more easily produced than others (Foote, 1994; Beldade et al., 2002). The evolution of different morphologies could be a consequence of environmental, developmental and/or evolutionary constraints (Losos & Miles, 1994). "
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    ABSTRACT: Body shape is predicted to differ among species for functional reasons and in relation to environmental niche and phylogenetic history. We quantified morphological differences in shape and size among 98.5% of the 129 species and all 21 genera of the Australo-Papuan endemic myobatrachid frogs to test the hypothesis that habitat type predicts body shape in this radiation. We tested this hypothesis in a phylogenetic context at two taxonomic levels: across the entire radiation and within the four largest genera. Thirty-four external measurements were taken on 623 museum specimens representing 127 species. Data for seven key environmental variables relevant to anurans were assembled for all Australian-distributed species based on species' distributions and 131,306 locality records. The Australo-Papuan myobatrachid radiation showed high diversity in adult body size, ranging from minute (15 mm snout-vent length) to very large species (92 mm), and shape, particularly sin relative limb length. Five main morphological and environmental summary variables displayed strong phylogenetic signal. There was no clear relationship between body size and environmental niche, and this result persisted following phylogenetic correction. For most species, there was a better match between environment/habitat and body shape, but this relationship did not persist following phylogenetic correction. At a broad level, species fell into three broad groups based on environmental niche and body shape: 1) species in wet habitats with relatively long limbs, 2) species in arid environments with relatively short limbs (many of which are forward or backward burrowers) and 3) habitat generalist species with a conservative body shape. However, these patterns were not repeated within the four largest genera - Crinia, Limnodynastes, Pseudophryne and Uperoleia. Each of these genera displayed a highly conservative anuran body shape, yet individual species were distributed across the full spectrum of Australian environments. Our results suggest that phylogenetic legacy is important in the evolution of body size and shape in Australian anurans, but also that the conservative body plan of many frogs works well in a wide variety of habitats.
    Full-text · Article · Dec 2013 · Journal of Evolutionary Biology
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    • "This suggests that eyespot size evolution in Junonia is relatively free from constraints of general body size. Furthermore, we found no correlation between sizes of eyespots in the two compartments, supporting the idea that selection on eyespot size in individual compartments is not strongly constrained by developmental underpinnings (Beldade et al. 2002). "
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    ABSTRACT: Eyespots are conspicuous circular features found on the wings of several lepidopteran insects. Two prominent hypotheses have been put forth explaining their function in an antipredatory role. The deflection hypothesis posits that eyespots enhance survival in direct physical encounters with predators by deflecting attacks away from vital parts of the body, whereas the intimidation hypothesis posits that eyespots are advantageous by scaring away a potential predator before an attack. In the light of these two hypotheses, we investigated the evolution of eyespot size and its interaction with position and number within a phylogenetic context in a group of butterflies belonging to the genus Junonia. We found that larger eyespots tend to be found individually, rather than in serial dispositions. Larger size and conspicuousness make intimidating eyespots more effective, and thus, we suggest that our results support an intimidation function in some species of Junonia with solitary eyespots. Our results also show that smaller eyespots in Junonia are located closer to the wing margin, thus supporting predictions of the deflection hypothesis. The interplay between size, position, and arrangement of eyespots in relation to antipredation and possibly sexual selection, promises to be an interesting field of research in the future. Similarly, further comparative work on the evolution of absolute eyespot size in natural populations of other butterfly groups is needed.
    Full-text · Article · Nov 2013 · Ecology and Evolution
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