RESUMO
The relationship between microhabitat use and morphology in Anolis lizards has been well studied in the Caribbean islands. However, studies of ecomorphology are scarce for the vast majority of mainland Anolis species. Thus there is a great lack of knowledge on how microhabitat use may influence the morphology of most mainland Anolis species. In this study we evaluated the relationship between morphology and microhabitat use in three sister species of the genus Anolis (A. sericeus, A. unilobatus and A. ustus) inhabiting the mainland and examined whether sympatric coexistence with other Anolis species affects microhabitat use and morphology of Anolis sericeus. The results of this study showed that A. ustus perches on higher, thinner, and warmer branches than its sister species (A. sericeus and A. unilobatus), and that snout-vent length, arm, forearm and femur length and weight of the three species are positively correlated with perch diameter, while the number of subdigital lamellae and weight are slightly correlated with perch height. In addition, the absence of sympatric Anolis species increases the variability in perch height, weight, arm and forearm length, and hip width observed in A. sericeus. Differences in limbs length, head length, weight and number of lamellae enabled the identification of two groups of species exploiting statistically different microhabitats. The relationship between microhabitat use and morphology indicates that some morphological traits, such as locomotor structures, weight and number of subdigital lamellae of the three species are influenced by microhabitat use and that interspecific competition may reduce variability in the height of perches used.
Assuntos
Ecossistema , Lagartos , Animais , Lagartos/anatomia & histologia , MéxicoRESUMO
ABSTRACT The genera Iguana and Ctenosaura belong to the Iguanidae family, and populations of most species of these genera have decreased due to anthropogenic effects. The natural history of most species of this family is poorly known, including Ctenosaura similis. Therefore, this study documents some ecological aspects of the species, such as its feeding habits, and habitat and microhabitat use in a population of Isla Contoy in Quintana Roo, Mexico. The data showed that even though C. similis is distributed throughout the island, individuals more commonly use human construction (buildings) of Parque Nacional Isla Contoy (PNIC) and mangrove areas. Microhabitats most used by all age classes and sexes were rocks and trees. The diet of the species is omnivorous; however, the frequency of prey type consumed changes with the age of the individuals (hatchlings, juveniles, and adults), as well as with the season of the year. The practice of cannibalism by some individuals is also reported, as well as coprophagy and scavenging. This work provides general information on the life history of C. similis, complementing the scarce information that is currently available.
RESUMEN Las iguanas de los géneros Iguana y Ctenosaura son algunas de las especies de escamados que han tenido una importante disminución en sus poblaciones naturales, principalmente por factores antropogénicos. No obstante, a pesar de esto existen especies de las que el conocimiento sobre su historia natural es escaso, como es el caso de la iguana negra Ctenosaura similis. Por lo que, en este trabajo se documentan algunos aspectos de la ecología, tal como los hábitos alimentarios y uso del hábitat y del microhábitat de la población de la iguana negra (C. similis) en Isla Contoy, en el estado de Quintana Roo, México. Los análisis de este estudio revelaron que a pesar de que C. similis se distribuye en toda la isla, utiliza con mayor frecuencia las instalaciones del Parque Nacional Isla Contoy (PNIC) y la zona de manglar; los microhábitats más usados por las diferentes clases de edad y los diferentes sexos, fueron las rocas y los árboles. En general, la dieta de esta especie es omnívora, pero la frecuencia con la que consumen ciertas categorías de presa cambia con la edad del individuo (cría, juvenil y adulto), así como a través de las estaciones del año. Además, se observó que algunos individuos practicaron el canibalismo, la coprofagia y la carroñeria. Este trabajo aporta datos generales de la historia natural de C. similis, lo que complementa la escasa información que hasta ahora se tiene disponible.
RESUMO
Polymorphism among individuals of the same population has generally been linked to alternative reproductive tactics, where different morphs can exhibit differences in their morphological, ecological, and behavioral attributes. These differences may result in a divergence in diet between morphs due to differential exploitation of habitat, morphological differences that influence prey selection, or differential energy expenditure that results in different nutritional needs. The present study analyzes the morphology (morphometry and body mass) and diet of red and yellow male morphs in a population (El Enzuelado) of the lizard Sceloporus minor from central Mexico. No differences between morphs were found for any of the morphometric variables analyzed (snout-vent length, tail length, jaw length, jaw width, head length, head width, head height, tibia length, femur length, forearm length and ventral patch length). In both morphs, allometric growth was observed in all body features analyzed, as well as in morphometric features of the head across seasons. Analysis of stomach contents showed that the diet of red males was composed of 12 categories of prey, while that of yellow males was composed of 10 categories; those categories of diet not shared between morphs (e.g., Isoptera, Psocoptera) were consumed by their respective morph in very low proportions. Categories of diet with the highest values of food importance for both groups were Coleoptera, Orthoptera, and leaves; a similar pattern was seen across seasons. This, in turn, is reflected in low niche breadth values for each morph and a very high niche overlap. There were no significant differences between morphs overall, or between morphs per season, in the weight and volume of stomach contents or in the number of prey items found in stomachs; however, differences in these variables across all males (independent of morph) were recorded between seasons. Likewise, no significant correlations were found between body size (snout-vent length) and the volume of stomach contents for either morph or between lizard mandibular dimensions and the volume of stomach contents for red morph males. For the yellow morph, prey volume unexpectedly decreased significantly with jaw size rather than increasing as expected. Overall, this study adds new information about the morphology and feeding of males in this species, and suggests that in this population, color morphs lack the morphological and ecological differences found in some other species of polymorphic lizard.