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

Abstract

ABSTRACT. Comparative analys is among two different m orph om etric techniques used in Odolllesthes bOllariellsis and Odollleslhes Izum ellsis (At her inopsid ae). The objecl ive ofthis sludy was 10 compare lWO different morphometric methodologies -traditional measuremenls and truss networks -based on lwo species of s il versides, Odollfesfhes brmariell sis (Valenciennes, 1835) and O. hume l/sis De Bue n, 1953 , 10 determine whieh of lhe melhods results in more re li ab le distinetion between gro ups. The traditional measures do nol represenl lhe true fish fo rm beeause il does nol take into acco unl alomelric variations or di slincl growlh slages. The meas ures wilh lruss networks extend over lhe fis h form Ihoro ughl y res ult ing in co mplete represenlation of lhe fish's body when homologolls morphologic poi nts are connected. The lwo seIs of measures used in lhe principal eomponents analysis resu lted in two groups. The first principal eomponent presented sim ilar posilive coefticients, being interpreted as a variation of "size", due to different stages of fi sh groWlh. T he second eo mponent presented posili ve and negati ve eoeffieients, wit h differenl values lhat were interpreted as ehange in lhe "shape" of the organisms. As the groups overlapped part iall y on the second eomponenl axis (the one lhat represenls shape), dala were adj usted to exclude lhe size effeel. The firsl co mponenl , lhen, presenled posili ve and negali ve eoefticients lhat were related to changes in the shape of organi sms. T he variables wilh positi ve coefficienls were relaled 10 lhe anleri or areaofl he body, whi le lhe negalive coefticienls were assoc ialed wilh lhe caudal peduncle. These variables were lhe same ones found in bolh lhe adjusted and non-adju sted analysis. Thi study showed Ihat meas ures wilh Iru ss network s represenled more clearly lhe difference belween groups of O. bO l1 ariellSis and o. hlllllellSis, lhan wilh the lradilional measures.KEY WORDS . Alherinopsidae, mullivariate morphomelry, truss nelworks, sil verside Estudos da forma do corpo em re lação ao tamanho por métodos num éricos são de grande importância na área da biologia evoluti va (R EYMENT et aL. 1984;REIS 1988;ROHLF 1990). O desenvolvimento de métodos de análi se multi variada e a disponibilidade de pacotes estatísticos te m permi tido uma avaliação da variação integrada do organismo e comparações de formas e estru turas, necessárias ao estudo da sistemática

Distribuição, dominância e estrutura de tamanhos da assembleia de peixes da lagoa Mangueira, sul do Brasil

“…A identificação das espécies foi feita com auxílio de bibliografia (REIS, 1983;BUCKUP & REIS, 1997;RODRIGUES & BEMVENUTI, 1997;BEMVENUTI & RODRIGUES, 2002; e de especialistas. As espécies foram identificadas por amostrador e foi verificada a contribuição percentual das mesmas nas diferentes unidades taxonômicas.…”

Morphofunctional variations of the Echinometra lucunter (Echinoidea) on Bahia Coast, Brazil

“…The life history of organisms can be elucidated from a morphological point of view, being very useful for understanding the biodiversity and the structure of ecosystems [1,2]. In particular, morphometric methods-the study of body shape or parts of it-have been proven not only to be effective for interpreting and comparing the character variations between populations, but also to be useful for correlating environmental variations with phenotypic differentiations [3][4][5][6][7][8].…”