NEW VISUAL RECORDS OF PLANTS CONSUMED BY 10 LIZARD SPECIES ON ISLANDS OF THE GULF OF CALIFORNIA, AND IMPLICATIONS FOR THE INSULAR ECOLOGY AND TROPHIC WEBS

Abstract

II present an unpublished list of 59 plant species of 19 families that constitute a source of food for the insular reptiles Ctenosaura conspicuosa, C. hemilopha, Sauromalus varius, S. hispidus, S. slevini, S. klauberi, S. ater, Dipsosaurus dorsalis, D. catalinensis, and Petrosaurus thalassinus on 15 islands of the Gulf of California based on 711 direct observations of feeding events. Two reptile species climb to the tops of cardon cacti branches to purposely eat flowers and fruits and accidentally dislodge plant parts that partially subsidize ground organisms; the rest forage mainly on the ground, but do show a strong evolutionary, ecological, and behavioral tendency to climb on low trees and bushes to eat leaves and flowers. The reptiles’ food habits influence other populations, species, trophic levels, and even the whole insular communities, both up (to predators), down (to producers and primary consumers) and horizontally (to competitors). Insular herbivorous and omnivorous lizards, as primary and secondary consumers, and even as predators, are in the middle of complex food webs. In these interactions, the cardon cactus provides vast amounts of biomass and energy to the whole insular communities.