Fluctuating asymmetry of guppy, Poecilia reticulata (Peters, 1860) as a stress indicator in Lake Sebu, South Cotabato, Philippines.

Guppies (Poecilia reticulata) were reported as indicators of waters in poor conditions, representing one of the most significant models in evolutionary ecology due to the species' quick response to natural selection. The inability of these species to develop perfect symmetry can be associated to the disturbances in their environment. Determining the fluctuating asymmetry (FA) as a measure of the species developmental instability of P. reticulata found in Lake Sebu, South Cotabato, Philippines is an effective tool in finding out the ecological health and to fully understand the shape variability of guppies found in the area. Landmark-based geometric morphometries was used in the study to analyze the biological shape information of the samples. Procrustes ANOVA was employed for the assessment of FA. Statistical analyses showed that there is a significant FA on both sexes of the fishes (p<0.05) while individual symmetry showed otherwise. Results revealed that female guppy showed higher value in FA (83.69%) compared to male's (81.63%). The results taken reflect a high FA in the body shapes of P. reticulata, thus, imply a high level of stress in the water systems in Lake Sebu. This study proves the effectiveness of FA studies to indicate perturbations in the water environment using guppies as stress indicators. [ABSTRACT FROM AUTHOR]