Análise comparativa entre técnicas morfométricas aplicadas a Odontesthes bonariensis (Valenciennes) e Odontesthes humensis De Buen (Osteichthyes, Atherinopsidae)

AUTOR(ES)
FONTE

Revista Brasileira de Zoologia

DATA DE PUBLICAÇÃO

2002-09

RESUMO

The objective of this study was to compare two different morphometric methodologies - traditional measurements and truss networks - based on two species of silversides, Odontesthes bonariensis (Valenciennes, 1835) and O. humensis De Buen, 1953, to determine which of the methods results in more reliable distinction between groups. The traditional measures do not represent the true fish form because it does not take into account alometric variations or distinct growth stages. The measures with truss networks extend over the fish form thoroughly resulting in complete representation of the fish's body when homologous morphologic points are connected. The two sets of measures used in the principal components analysis resulted in two groups. The first principal component presented similar positive coefficients, being interpreted as a variation of "size", due to different stages of fish growth. The second component presented positive and negative coefficients, with different values that were interpreted as changes in the "shape" of the organisms. As the groups overlapped partially on the second component axis (the one that represents shape), data were adjusted to exclude the size effect. The first component, then, presented positive and negative coefficients that were related to changes in the shape of organisms. The variables with positive coefficients were related to the anterior area of the body, while the negative coefficients were associated with the caudal peduncle. These variables were the same ones found in both the adjusted and non-adjusted analysis. This study showed that measures with truss networks represented more clearly the difference between groups of O. bonariensis and O. humensis, than with the traditional measures.

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