AB 4:243-252 (2009)  -  DOI: https://doi.org/10.3354/ab00115

Microgeographical differentiation between morphotypes of Trididemnum orbiculatum (Tunicata: Ascidiacea) in southeastern Brazil

Gustavo Muniz Dias1,3,*, Aluana Gonçalves Abreu2, Fábio de Oliveira Morais e Silva2, Vera Nisaka Solferini2

1Pós-Graduação em Ecologia, and 2Departamento de Genética e Evolução, Instituto de Biologia, Universidade Estadual de Campinas, CP 6109, CEP 13083-970 Campinas SP, Brazil
3Present address: School of Integrative Biology, University of Queensland, 4072 Queensland, Australia

ABSTRACT: Ascidians, like most encrusting organisms, present polymorphisms in shape and color that are frequently attributed to the environmental conditions in which the adults live. In southeastern Brazil, the ascidian Trididemnum orbiculatum presents 2 morphotypes that occur along different parts of the rocky shoreline. Between the intertidal and subtidal zones, the morphotypes differ in numerous characters, such as the pigmentation of zooids, growth pattern of the colony and abundance of spicules. We assessed the differentiation between the morphotypes using morphological and allozyme data. Characters traditionally used in ascidian taxonomy did not separate the morphotypes into distinct species, but the intertidal morphotype presented consistently smaller zooids, larvae and colony thickness, possibly caused by the harsh conditions of this zone. Although most of this divergence could be caused by phenotypic plasticity, clear genetic structure was observed between morphotypes. We propose that the morphotype from the subtidal zone constitutes a different species from that in the intertidal zone. In addition, morphological and genetic data suggest that colonies from the intertidal zone constitute more than one genetic entity.


KEY WORDS: Ascidian · Allozyme · Intertidal zone · Subtidal zone


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Cite this article as: Dias GM, Abreu AG, Silva FOM, Solferini VN (2009) Microgeographical differentiation between morphotypes of Trididemnum orbiculatum (Tunicata: Ascidiacea) in southeastern Brazil. Aquat Biol 4:243-252. https://doi.org/10.3354/ab00115

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