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Sexual dimorphism based on body proportions and ontogenetic changes in the Brazilian electric ray Narcine brasiliensis (von Olfers, 1831) (Chondrichthyes: Narcinidae)

Sexual dimorphism based on body proportions and ontogenetic changes in the Brazilian electric ray... Sexual dimorphism in the Brazilian electric ray Narcine brasiliensis from the south‑western Atlantic coast was evaluated based on body proportions and ontogenetic changes. All regions of the body were found to have differences in body proportions between the sexes, except the spiracles. The nature of allometric and isometric relationships differed mainly in terms of the six largest body dimensions. Some of these differences can be supported by the species’ life history. Principal components analysis (PCA) and analysis of similarities (ANOSIM) distinguished the adults’ body proportions by sex. Similarity percentage analysis (SIMPER) selected six variables that best discriminated between the sexes with a cumulative difference up to 70% (tail width, disc width, length between snout and first dorsal fin, pelvic fin width, length between snout and the widest part of the disc, and disc length). It was possible to select seven stable dimensions, both ontogenetic and sexual, that are recommended for use in taxonomic studies. These dimensions were interspiracular distance, spiracle length and width, upper and lower tooth band width, pelvic fin length, and length of posterior lobe of the pelvic fin. It is important to consider the differences in body proportions within a species in order to properly characterise the population and estimate its most reliable parameters. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png African Journal of Marine Science Taylor & Francis

Sexual dimorphism based on body proportions and ontogenetic changes in the Brazilian electric ray Narcine brasiliensis (von Olfers, 1831) (Chondrichthyes: Narcinidae)

Sexual dimorphism based on body proportions and ontogenetic changes in the Brazilian electric ray Narcine brasiliensis (von Olfers, 1831) (Chondrichthyes: Narcinidae)

Abstract

Sexual dimorphism in the Brazilian electric ray Narcine brasiliensis from the south‑western Atlantic coast was evaluated based on body proportions and ontogenetic changes. All regions of the body were found to have differences in body proportions between the sexes, except the spiracles. The nature of allometric and isometric relationships differed mainly in terms of the six largest body dimensions. Some of these differences can be supported by the species’ life history. Principal...
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Publisher
Taylor & Francis
Copyright
© 2015 NISC (Pty) Ltd
ISSN
1814-2338
eISSN
1814-232X
DOI
10.2989/1814232X.2015.1032350
Publisher site
See Article on Publisher Site

Abstract

Sexual dimorphism in the Brazilian electric ray Narcine brasiliensis from the south‑western Atlantic coast was evaluated based on body proportions and ontogenetic changes. All regions of the body were found to have differences in body proportions between the sexes, except the spiracles. The nature of allometric and isometric relationships differed mainly in terms of the six largest body dimensions. Some of these differences can be supported by the species’ life history. Principal components analysis (PCA) and analysis of similarities (ANOSIM) distinguished the adults’ body proportions by sex. Similarity percentage analysis (SIMPER) selected six variables that best discriminated between the sexes with a cumulative difference up to 70% (tail width, disc width, length between snout and first dorsal fin, pelvic fin width, length between snout and the widest part of the disc, and disc length). It was possible to select seven stable dimensions, both ontogenetic and sexual, that are recommended for use in taxonomic studies. These dimensions were interspiracular distance, spiracle length and width, upper and lower tooth band width, pelvic fin length, and length of posterior lobe of the pelvic fin. It is important to consider the differences in body proportions within a species in order to properly characterise the population and estimate its most reliable parameters.

Journal

African Journal of Marine ScienceTaylor & Francis

Published: Apr 3, 2015

Keywords: Elasmobranchii; morphometry; relative growth; Torpediniformes

References