Conserved patterns of integrated developmental plasticity in a group of polyphenic tropical butterflies

Abstract

BackgroundDevelopmental plasticity is thought to have profound macro-evolutionary effects, for example, by increasing the probability of establishment in new environments and subsequent divergence into independently evolving lineages. In contrast to plasticity optimized for individual traits, phenotypic integration, which enables a concerted response of plastic traits to environmental variability, may affect the rate of local adaptation by constraining independent responses of traits to selection. Using a comparative framework, this study explores the evolution of reaction norms for a variety of life history and morphological traits across five related species of mycalesine butterflies from the Old World tropics.ResultsOur data indicate that an integrated response of a suite of key traits is shared amongst these species. Interestingly, the traits that make up the functional suite are all known to be regulated by ecdysteroid signalling in Bicyclus anynana, one of the species included in this study, suggesting the same underlying hormonal regulator may be conserved within this group of polyphenic butterflies. We also detect developmental thresholds for the expression of alternative morphs.ConclusionsThe phenotypic plasticity of a broad suite of morphological and life history traits is integrated and shared among species from three geographically independent lineages of mycalesine butterflies, despite considerable periods of independent evolution and exposure to disparate environments. At the same time, we have detected examples of evolutionary change where independent traits show different patterns of reaction norms. We argue that the expression of more robust phenotypes may occur by shifting developmental thresholds beyond the boundaries of the typical environmental variation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-017-0907-1) contains supplementary material, which is available to authorized users.

Does phenotypic plasticity initiate developmental bias?

“…This conservation of responses in butterflies occurs despite considerable periods of independent evolution in widely different environments (van F I G U R E 3 Potential mechanisms of developmental bias in the preorbital region of Malawi cichlids could lie in patterns of modularity (a, b), and the reliance of phenotypic variation on a limited number of developmental pathways (c, d). Note that the orbital bone has been highlighted in these pictures, and that swelling of the eye has occurred due to staining and preservation methods [Color figure can be viewed at wileyonlinelibrary.com] Bergen et al, 2017). The preorbital region (blue lines connecting landmarks) comprises a distinct variational module in Malawi cichlids (b).…”

“…These relatively similar phenotypic responses to different molecular targets suggest that craniofacial development in cichlids is developmentally limited with particularly strong effects on the preorbital region. Note that the orbital bone has been highlighted in these pictures, and that swelling of the eye has occurred due to staining and preservation methods [Color figure can be viewed at wileyonlinelibrary.com] Bergen et al, 2017). However, plasticity integration can vary both among populations and genotypes, suggesting it can evolve rapidly (Plaistow & Collin, 2014).…”

Developmental bias in the fossil record

“…A growing body of work is exploring the implications of constructive development and developmental plasticity in extant systems (Levis & Pfennig, 2019;van Bergen et al, 2017) but research from a paleontological perspective has so far been limited. A growing body of work is exploring the implications of constructive development and developmental plasticity in extant systems (Levis & Pfennig, 2019;van Bergen et al, 2017) but research from a paleontological perspective has so far been limited.…”

To mate, or not to mate: The evolution of reproductive diapause facilitates insect radiation into African savannahs in the Late Miocene

“…In contrast, the dry season form generally lack these eyespots, and they rely mainly on crypsis when at rest on dead leaf litter for survival against predators hunting by sight (Lyytinen et al, 2003(Lyytinen et al, , 2004Prudic et al, 2015). Along with the wing pattern changes, both forms differ in a suite of other morphological, behavioural, physiological and life-history traits, as an integrated response which is linked by a common hormonal switch as has been extensively explored in laboratory settings in a single species Bicyclus anynana (Oostra et al, 2010(Oostra et al, , 2014van Bergen & Beldade, 2019;van Bergen et al, 2017). Such an integrated system helps to maintain a season-specific adaptive phenotype by making use of environmental cues to predict approaching seasonal shifts (Brakefield & Reitsma, 1991;Kooi & Brakefield, 1999).…”