Computational Ecology and Software, 2016, 6(3): 95-105
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Relative warp analysis in determining morphological variation and sexual dimorphism between sexes of flathead goby (Glossogobius giuris)

C.C. Cabuga, Jr.1, C.B.E. Masendo1, B.J.H. Hernando1, C.C.D. Joseph1, J.P.B. Velasco1, M.K.A. Angco1, M. A. Ayaton1, O.L.P. Obenza1, J. H. Jumawan1, J.C. Jumawan1, E.A. Requieron2, M.A.J. Torres3, H.C. Havana4
1Biology Department, College of Arts and Sciences, Caraga State University- Main Campus-Ampayon, Butuan City 8600, Philippines
2Science Department, College of Natural Sciences and Mathematics, Mindanao States University - General Santos City Campus, 9500 Fatima, General Santos City, Philippines
3Department of Biological Sciences, College of Science and Mathematics, Mindanao State University - Iligan Institute of Technology, Iligan City, Philippines
4Cagbas Elementary School, Bayugan City, Agusan Del Sur, 8502, Philippines

Received 2 June 2016;Accepted 20 June 2016;Published online 1 September 2016

Landmark-based geometric morphometrics is an effective tool for measuring the biological shape, shape variation and covariation both for biotic and abiotic elements. It ensures graphical illustrations of shape changes that are visually interesting and instinctual. Using the results from relative warp analysis, histograms, CVA and PCA were generated to visualize morphological variations and sexual dimorphism. A total of 60 individuals (30 males and 30 females) were subjected to landmark-based analysis. This application will demonstrate morphological variation and sexual dimorphism on the body shape of Glossogobius giuris using geometric morphometry by means of Relative Warp Analysis. Sixteen landmarks generated 19 relative warps for each sample and showed slight morphological variation were females obtained the highest percentage than males. The MANOVA test value shows non-significant value (P=0.1655) on the left lateral side between sexes. This indicates that there were no shape variations and may be due to behavior and ecology of the organism to compete with others for food haunting, mating and to buffer environmental condition. While the right lateral side shows significant value (P<0.05) between sexes this reason explains that they were sexually dimorphic. That was essential for its adaptation and reproduction. The results of Principal Component Analysis (PCA) and Canonical Variance Analysis (CVA) show no significant body variations between sexes. This study was employed to identify the importance or relative warp analysis in detecting and morphological variations and sexual dimorphism of G. giuris collected at Lower Agusan River, Butuan City, Philippines.

Keywords relative warp analysis;landmark-based;sexual dimorphism;Glossogobius giuris.

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