Landmark-based geometric morphometrics in visualizing body shape dimorphism in the endemic cyprinid, Puntius tumba (Herre,1924), from Lake Lanao, Philippines

The major objective of this study is to determine shape dimorphism between sexes of the endemic cyprinid P. tumba from Lake Lanao, Philippines using landmark-based geometric morphometrics. A total of 84 specimens (41 female, 43 males) were analysed. Nineteen landmark points were digitized on the specimens from whom relative warp scores were derived. Discriminant function analysis and thin-plate spline showed significant difference between body shapes of the sexes with males exhibiting bigger head, shallower body and longer anal and dorsal fin base. Sexual selection co-acting with ecological selection could account for expression of such dimorphism.