Ecomorphological diet predictions : an assessment using inland silverside (Menidia beryllina) and longear sunfish (Lepomis megalotis) from Lake Texoma

Abstract

The functions of an organism‘s morphological structures indicatethe organism‘s potential resource use (fundamental niche). Whilethis information often is also used to predict differences inactual resource use (realized niche) among individuals or species,such predictions may not be accurate because the maximum abilitiesmay not be useful to the organism under specific conditions or inspecific environments. We investigated the importance of sixpreviously studied morphologically based performanceabilities/constraints in structuring the diet of Menidiaberyllina (inland silverside) and Lepomis megalotis (longearsunfish) in Lake Texoma, a reservoir in the Red River basin(Oklahoma-Texas, USA). Of the six morphological characteristicsmeasured (number of gill rakers, length of gill rakers, spacebetween gill rakers, eye lens diameter, mouth size, mouthprotrusibility), only one characteristic for M. beryllina(mouth size) and three for L. megalotis (space betweenrakers, mouth size, and raker length) correlated with the gutcontents as predicted by previous functional morphology studies.This indicates that caution should be exercised when makinguntested predictions about the ecology of an organism based on itsfunctional morphology.