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Cardiopharyngeal deconstruction and ancestral tunicate sessility
Alfonso Ferrández-Roldán1,2, Marc Fabregà-Torrus1,2, Gaspar Sánchez-Serna1,2
1Departament de Genètica, Microbiologia i Estadística, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.
Nature
|November 18, 2021
Summary
Appendicularians evolved by losing ancestral genes, deconstructing their cardiopharyngeal gene regulatory network. This supports an evolutionary shift from sessile to free-living lifestyles in tunicates.
Area of Science:
- Evolutionary biology
- Developmental biology
- Genetics
Background:
- The evolution of chordate lifestyles, particularly sessility in ascidians versus the free-living appendicularian style, is a key question.
- The cardiopharyngeal gene regulatory network is hypothesized to be crucial for understanding chordate lifestyle evolution.
- Understanding gene regulatory network evolution provides insights into the transition between different life strategies.
Purpose of the Study:
- To investigate the role of the cardiopharyngeal gene regulatory network in the evolutionary divergence of tunicate lifestyles.
- To determine whether the appendicularian free-living style is a primitive or derived trait within tunicates.
- To elucidate the genetic basis for the transition from sessile to pelagic lifestyles.
Main Methods:
- Comparative genomics analysis of cardiopharyngeal genes in tunicates.
- Investigating gene losses and subfunction changes within the cardiopharyngeal gene regulatory network.
- Reconstructing ancestral tunicate gene regulatory networks and lifestyle evolution.
Main Results:
- Appendicularians exhibit massive ancestral losses of cardiopharyngeal genes and subfunctions.
- This gene loss led to the deconstruction of ancestral tunicate cardiopharyngeal gene regulatory network modules.
- The deconstruction involved the loss of siphon muscle development, suggesting ancestral tunicates were sessile.
- Gene deconstruction accelerated cardiogenesis and redesigned the heart in appendicularians for a pelagic lifestyle.
Conclusions:
- The evolution of appendicularians involved significant gene loss and 'deconstruction' of ancestral gene regulatory networks.
- This genetic remodeling supports an evolutionary trajectory from sessile, ascidian-like ancestors to the free-living appendicularian form.
- The findings provide a genetic explanation for the adaptive radiation of tunicates and their diverse lifestyles.
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