ON A LOGISTIC MODEL FOR MORPHOLOGICAL COVARIATION PATTERNS BETWEEN Colossoma macropomum AND THE HYBRID Colossoma macropomum (♀) x Piaractus orinoquensis (♂)
DANNY VILLEGAS RIVAS *
Facultad de Ingeniería Forestal y Ambiental, Universidad Nacional de Jaén, Cajamarca, Perú.
MANUEL MILLA PINO
Facultad de Ingeniería Civil, Universidad Nacional de Jaén, Cajamarca, Perú.
ZADITH GARRIDO CAMPAÑA
Facultad de Ingeniería Civil, Universidad Nacional de Jaén, Cajamarca, Perú.
MARTÍN GRADOS VÁSQUEZ
Escuela de Postgrado, Universidad César Vallejo, Perú.
ERICK DELGADO BAZAN
Facultad de Ingeniería Civil, Universidad Nacional de Jaén, Cajamarca, Perú.
CÉSAR OSOSRIO CARRERA
Escuela de Postgrado, Universidad César Vallejo, Perú.
YDALIA VELASQUEZ CASANA
Escuela de Postgrado, Universidad Nacional de Trujillo, Perú.
WILFREDO RUIZ CAMACHO
Facultad de Ingeniería Forestal y Ambiental, Universidad Nacional de Jaén, Cajamarca, Perú.
RICARDO SHIMABUKU YSA
Facultad de Ingeniería Mecánica y Eléctrica, Universidad Nacional de Jaén, Cajamarca, Perú.
JOSÉ PAREDES CARRANZA
Escuela de Postgrado, Universidad César Vallejo, Perú.
MANUEL LIZARZABURU AGUINAGA
Escuela de Postgrado, Universidad César Vallejo, Perú.
*Author to whom correspondence should be addressed.
Abstract
Currently, great importance has been given to the study of external morphology, especially in fish, when it is used as a means of identifying hybrids. This paper considers a multiple logistic regression model based on the truss protocol to compare morphological covariation patterns between specimens of C. macropomum and the hybrid C. macropomum (♀) x P. orinoquensis (♂). In this study, 25 specimens of C. macropomum and 20 specimens of the hybrid C. macropomum (♀) x P. orinoquensis (♂), respectively, were analyzed. The method "Truss protocol" or "trusses" was used. Multiple logistic regression model based on the morphological covariation patterns between the two species showed a good fit and allowed to correctly classify most of the specimens. Only two covariates were significant; eye diameter and fat fin base. Differences between the hybrid and its parent were observed in the head area and in the anterior part of the fish, which were associated with hydrodynamic abilities and with foraging.
Keywords: Morphometry, truss protocol, fishes, nonlinear regression