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Evolution and development of budding by stem cells: ascidian coloniality as a case study.
Federico D Brown1, Billie J Swalla
1Biology Department, University of Washington, Seattle, 98195, USA. fd.brown46@uniandes.edu.co
Developmental Biology
|June 23, 2012
Summary
The evolution of budding in tunicates, a type of marine invertebrate, is linked to developmental flexibility. Colonial ascidians may have evolved budding through new larval stem cell lineages and larger egg sizes.
Area of Science:
- Developmental biology
- Evolutionary biology
- Marine biology
Background:
- Budding is a key developmental process in metazoans, but its evolutionary mechanisms remain unclear.
- Ascidians (tunicates) offer a model system to study the evolution of coloniality due to variations in their life histories.
Purpose of the Study:
- To investigate the cellular and developmental basis for the evolution of budding in ascidians.
- To contrast the life histories of solitary and colonial ascidian forms.
Main Methods:
- Comparative analysis of solitary and colonial ascidian life histories.
- Review of hypotheses regarding stem cell lineage changes in colonial species.
Main Results:
- Colonial ascidians exhibit greater developmental flexibility during larval stages compared to solitary species.
- Acquisition of new larval stem cell lineages may be a preadaptation for budding evolution.
- Brooding in colonial ascidians leads to larger egg sizes, facilitating developmental flexibility.
Conclusions:
- Developmental flexibility, driven by new stem cell lineages and increased egg size, is crucial for the evolution of budding in colonial ascidians.
- Further research into stem cell dynamics is needed to fully understand the evolution of budding.
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