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SEXUAL DIMORPHISM IN BLACK JAW TILIAPIA (Sarotherodon melanotheron) AND BANDED JEWELFISH (Hemichromis fasciatus) FROM THE GREAT KWA RIVER, CALABAR, NIGERIA

Oju Richard Ibor

Sažetak

In this study, the pattern and magnitude of sexual dimorphic differences
have been investigated in black jaw tilapia (Sarotherodon melanotheron)
(n = 160; 74 males and 86 females) and banded jewelfish (Hemichromis
fasciatus) (n = 120; 42 males and 78 females) from the Great Kwa River,
Calabar, Nigeria. Fish samples were collected between July and December
2015. Fourteen morphometric variables, including body weight, total
length, standard length, body depth, cheek depth, pre-orbital length, postorbital
length, pectoral fin length (right and left), pelvic fin length (right and
left), head length, gonad weight, eye diameter and four meristic variables,
including number of pectoral fins (right and left) and number of pelvic
fins (right and left), were taken using standard methods. Size-adjusted
morphometric measurements subjected to step-wise discriminant function
analysis were used to determine predictor variables to morphologically
differentiate sexes for both species; magnitude of dimorphism between
sexes was estimated using percentage classification accuracy of the
discriminant function analysis. From the discriminant function analysis, the
pectoral fin length and gonad weight positively contributed significantly
to morphometric dimorphism (magnitude=69.2%) in male and female S.
melanotheron suggesting adaptation for reproductive function; while for H.
fasciatus the body depth and standard length were important contributors
to sexual dimorphism (magnitude=84.2%) suggesting size dimorphism for
aggressiveness, territorial behavior and improving swimming performance.
Overall, our results indicate that the different magnitude of sexual
dimorphism between the two species could be attributable to the type and
functional role of sexual dimorphic traits.

Ključne riječi

Morphometric measurement; Sexual dimorphism; Cichlids; Great Kwa River; Nigeria

Hrčak ID:

186843

URI

https://hrcak.srce.hr/186843

Datum izdavanja:

28.9.2017.

Podaci na drugim jezicima: hrvatski

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