Usefulness of Discriminant Analysis in the Morphometric Differentiation of Six Native Freshwater Species from Ecuador

SIMPLE SUMMARY: Ecuador is among the 25 highest fish producers in the world and the fishing sector contributes 7% to the national consumption of animal proteins. This country has a high number of native freshwater species, some of which are endangered due to the modification, fragmentation and destruction of habitats; introduction of foreign species; overfishing with illegal gear; environmental pollution; development of large-scale intensive forestry practices; loss of ecological continuity between different rivers; and climate change. The Guayas, the largest basin (CHG) in the Pacific Ocean located in Ecuador, constitutes an important biodiversity reserve of native freshwater. Most part of these 125 species are endemic and threatened or in an at-risk situation. It would be useful to analyze the morphological differences among six existing species in the CHG, and to select a reduced number of direct, simple and low-cost measurements to be applied in marginal communities. In this work, the usefulness of discriminant analysis was proven in the differentiation of six native freshwater species. Results represent a new step in the development of breeding and conservation plans for this native zoogenetic resource. ABSTRACT: The aim of this research was to find out the morphometric differentiation of six native freshwater species in the Guayas Hydrographic Basin (Ecuador) by means of discriminant analysis. A total of 1355 mature fishes (Cichlasoma festae, Andinoacara rivulatus, Dormitator latifrons, Bryncon dentex, Hoplias microlepis and Leporinus ecuadorensis) were captured and 27 morphometric measurements and 20 landmarks were used. Two-way analysis of variance with species and sex as fixed factors and discriminant analysis were applied. The selection of the most discriminant variables was made applying the F of Snedecor, Wilks’-Lambda and the 1-Tolerance. While sex within species had no significant effect on the morphology, differences among species were significant. Twenty-seven morphological variables showed highly significant differences among six native freshwater species. Nine biometric variables with high discriminant power were selected. The six species analyzed were discriminated by the morphometric models generated, thus showing that discriminant analysis was useful for differentiating species. The morphometric differentiation by discriminant analysis is a direct, simple and economic methodology to be applied in situ in rural communities. It favors the implementation of a livestock development program and it could be used with other native freshwater species in the Guayas Hydrographic Basin.