Re‐emergence of the Painted Turtle (<i>Chrysemys picta</i>) as a reference species for evo‐devo

Cordero, Gerardo A.

doi:10.1111/ede.12082

Cited by 6 publications

(6 citation statements)

References 58 publications

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“…We instead chose Chrysemys picta as a comparative reference. This model emydid species features a fully sequenced nuclear genome and extensive developmental data (reviewed in Cordero, ).…”

Section: Methodsmentioning

confidence: 99%

Gene network variation and alternative paths to convergent evolution in turtles

Cordero

Wimalanathan³

et al. 2018

Evolution and Development

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Diversification of the turtle's shell comprises remarkable phenotypic transformations. For instance, two divergent species convergently evolved shell-closing systems with shoulder blade (scapula) segments that enable coordinated movements with the shell. We expected these unusual structures to originate via similar changes in underlying gene networks, as skeletal segment formation is an evolutionarily conserved developmental process. We tested this hypothesis by comparing transcriptomes of scapula tissue across three stages of embryonic development in three emydid turtles from natural populations. We found that alternative strategies for skeletal segmentation were associated with interspecific differences in gene co-expression networks. Notably, mesenchyme homeobox 2 (MEOX2) and HOXA3-5 were central hubs driving the activity of 2,806 genes in a candidate network for scapula segmentation, albeit in only one species. Even so, scapula muscle overgrowth corresponded to the activity of similar myogenic networks in both species. This and other derived developmental processes were not observed in the third species, which displayed the ancestral (unsegmented) scapula condition. Differential gene expression tests against this reference lineage supported histological and network analyses. Our findings illustrate that molecular underpinnings of convergent evolution, including during the diversification of the atypical turtle "body plan," are influenced by variation in underlying developmental processes.

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“…We instead chose Chrysemys picta as a comparative reference. This model emydid species features a fully sequenced nuclear genome and extensive developmental data (reviewed in Cordero, ).…”

Section: Methodsmentioning

confidence: 99%

Gene network variation and alternative paths to convergent evolution in turtles

Cordero

Wimalanathan³

et al. 2018

Evolution and Development

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“…For instance, the likelihood of trait convergence might be higher in species groups that exhibit morphological stasis owing to design limitations imposed by underlying developmental processes [14,15]. The atypical turtle body plan is an outstanding model to examine such a phylogenetic pattern [16,17].…”

Section: Introductionmentioning

confidence: 99%

Delayed trait development and the convergent evolution of shell kinesis in turtles

2018

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Understanding developmental processes is foundational to clarifying the mechanisms by which convergent evolution occurs. Here, we show how a key convergently evolving trait is slowly ‘acquired’ in growing turtles. Many functionally relevant traits emerge late in turtle ontogeny, owing to design constraints imposed by the shell. We investigated this trend by examining derived patterns of shell formation associated with the multiple (at least 8) origins of shell kinesis in small-bodied turtles. Using box turtles as a model, we demonstrate that the flexible hinge joint required for shell kinesis differentiates gradually and via extensive repatterning of shell tissue. Disproportionate changes in shell shape and size substantiate that this transformation is a delayed ontogenetic response (3–5 years post-hatching) to structural alterations that arise in embryogenesis. These findings exemplify that the translation of genotype to phenotype may reach far beyond embryonic life stages. Thus, the temporal scope for developmental origins of adaptive morphological change might be broader than generally understood. We propose that delayed trait differentiation via tissue repatterning might facilitate phenotypic diversification and innovation that otherwise would not arise due to developmental constraints.

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“…The painted turtle, Emydidae: Chrysemys picta, was sampled. This species was chosen because it features a sequenced genome and extensive anatomical and developmental data (reviewed in Cordero, 2014;Shaffer et al, 2013). Eggs were field-collected in Illinois and Nebraska, USA (see , transported to Iowa State University (ISU) within 24-48 h of oviposition, and half-buried in moist vermiculite (−150 kPa water potential) for incubation in an environmental chamber set to a constant 27°C.…”

Section: Acquisition and Incubation Of Eggsmentioning

confidence: 99%

Transcriptomic similarities and differences between the limb bud AER and unique carapacial ridge of turtle embryos

Cordero

2020

Evolution and Development

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Evolutionary innovation may arise via major departures from an ancestral condition. Turtle shell morphogenesis depends on a unique structure known as the carapacial ridge (CR). This lateral tissue protrusion in turtle embryos exhibits similar properties as the apical ectodermal ridge (AER)—a well‐known molecular signaling center involved in limb development. Still, how the CR influences shell morphogenesis is not entirely clear. The present study aimed to describe the CR transcriptome shortly before ribs were halted within its mesenchyme, as required for shell development. Analyses exposed that the mesenchymal marker VIM was one of the most highly co‐expressed genes and numerous appendage formation genes were situated within the core of CR and AER co‐expression networks. However, there were tissue‐specific differences in the activity of these genes. For instance, WNT5A was most frequently assigned to appendage‐related annotations of the CR network core, but not in the AER. Several homeobox transcription factors known to regulate limb bud patterning exhibited their highest expression levels in the AER, but were underexpressed in the CR. The results of this study corroborate that novel body plans often originate via alterations of pre‐existing genetic networks. Altogether, this exploratory study enhances the groundwork for future experiments on the molecular underpinnings of turtle shell development and evolution.

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Re‐emergence of the Painted Turtle (Chrysemys picta) as a reference species for evo‐devo

Cited by 6 publications

References 58 publications

Gene network variation and alternative paths to convergent evolution in turtles

Gene network variation and alternative paths to convergent evolution in turtles

Delayed trait development and the convergent evolution of shell kinesis in turtles

Transcriptomic similarities and differences between the limb bud AER and unique carapacial ridge of turtle embryos

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