The effect of clearing and staining technique differentially affects morphometric and allometric analysis in fixed Chloroscombrus chrysurus (Perciformes: Carangidae) species

Abstract

Background. In morphometric and allometric analysis, the degree of variation attributable to non-biological causes is ignored. The effects of this variation on subsequent statistical analyzes are unknown. It is unclear whether sample conservation induces substantial variation in shape and whether such variation affects subsequent statistical inference and interpretation. Therefore, in fish skeletal studies, fish are routinely prepared for osteological studies using a common procedure known as clearing and staining, but clearing samples are frequently measured after this process. In various studies it has been determined that the fixation of fishes produces deformation, with a decrease in the size, but the effect has not been evaluated process of clearing-staining on the morphometric and allometric analysis Objective. Determine the effect of the clearing and staining process on the morphometric and allometric analyses. Methods. Thirty-three specimens of the species Chloroscombrus chrysurus (Linnaeus, 1766) previously fixed within 10% formalin. These were measured before and after the clearing process and alizarin red S staining. Three shape analyzes were applied: morphometric analysis, deformation analysis and allometric analysis. Only the statistically significant results were used. Results. It was found that the procedure affected 90% of the morphometric indices, as well as 90.9% of the morphometric measurements, where 54.5% decreased and 36.4% increased. With respect to the allometric analysis, 80% of the length-length relationships remain the same. Conclusions. The clearing and staining process affects C. chrysurus’s morphological variation, determined by the morphometric analysis variables using morphometric and allometric methods