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Evolution of sensory structures in basal metazoa.
Dave K Jacobs1, Nagayasu Nakanishi, David Yuan
1*Department of Ecology and Evolutionary Biology, UCLA, 621 Young Drive South, Los Angeles, CA 90095-1606, USA; Department of Molecular, Cellular and Developmental Biology, UCLA, 621 Young Drive South, Los Angeles, CA 90095-1606, USA; Department of Molecular and Cell Biology, 142 Life Sciences Addition, University of California, Berkeley, CA 94720, USA.
Integrative and Comparative Biology
|June 15, 2011
Summary
Sponges and cnidarians possess genes for sensory and neural functions, challenging the view of cnidarians as the most basal animals. This suggests ancient sensory structures evolved into diverse organs in later animals.
Area of Science:
- Zoology
- Developmental Biology
- Evolutionary Biology
Background:
- Cnidaria were considered the most basal animals with complex sensory structures.
- Sponges exhibit a surprising number of genes associated with sensory and neural functions found in Bilateria.
Purpose of the Study:
- To investigate sensory and neural gene regulation in basal animals.
- To explore the evolution of sense organs from a common ancestor.
- To analyze sensory capabilities across Cnidarian life stages.
Main Methods:
- Review of regulatory genes (e.g., sine oculis, Brain 3, eyes absent) in cnidarian sense organs.
- Assessment of sensory features in Cnidarian planula, polyp, and medusa stages.
- Discussion of physiological and molecular data in sponges indicating sensory/neural processes.
Main Results:
- Sense organ regulatory genes are expressed in cnidarian sense organs.
- Cnidarian life stages possess distinct sensory features.
- Evidence suggests sponges have sensory and neural processes.
- Shared developmental gene regulation exists across bilaterian sense organs and basal metazoans.
Conclusions:
- Multiple bilaterian organs may have evolved from fewer ancestral sensory structures.
- Developmental genetic similarities suggest sense organs and appendages/kidneys evolved from composite structures in a common ancestor.
- Divergent evolution from a common ancestral condition is a plausible explanation for shared genetic regulation.
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