Autoecologia comparativa de duas espécies de quelônios (Phrynops geoffroanus e Mesoclemmys tuberculata) em áreas de Caatiga e Mata Atlântica no Nordeste do Brasil

Abstract

The present study had as main objectives to evaluate how populations of Phrynops geoffroanus and Mesoclemmys tuberculata from Caatinga and Atlantic forest areas use the spatial, temporal and trophic resources available in the environment, as well as the influence of environmental conditions such as different rain regimes And availability of food resources, in the diet, reproduction, parasitism, population structure of the species. In the first chapter we tested the hypothesis of which intraspecific factors determine more than environment differences in the determination of autoecological parameters of P. geoffroanus and M. tuberculata. More specifically, we evaluated the proportion between the sexes, the presence of sexual dimorphism, and we described the morphometric and reproductive aspects. The results showed that the reproductive males of both species were recorded throughout the study period (dry and rainy), while the presence of eggs and oocytes was recorded exclusively in females collected during the rainy season. In general, the autoecological parameters evaluated were not different in P. geoffroanus and M. tuberculata, presenting similar patterns in both the Caatinga and the Atlantic Forest, probably this absence of variation is related to the period of existence of the biomes, the Caatinga being temporarily more recent, when compared to the Atlantic Forest. Thus, the elapsed time may not have been sufficient to induce differences between the populations of these biomes with different seasonal conditions. In the second chapter, a comparison was made of the diets of P. geoffroanus and M. tuberculata at different stages of life (adults and juveniles), sex, season and occurrence biome, in order to determine if differences in resource use may have links with Habitat characteristics. We analyzed frequency of occurrence, abundance, volume, index of relative importance and niche widths for each species of chelonium. In addition, we evaluated if there is a higher trophic niche overlap in the Caatinga because it presents a stochastic pluvial regime, a more irregular food resource, when compared to the predictable Atlantic Forest pattern. Our results indicated that the most important prey in the diet of P. geoffroanus were Animal Material, Baetidae and Caridae. The high consumption of animal material (viscera and fish scales) as the main food item of P. geoffroanus, indicated a strong association with the anthropic behavior in the region of our study. However, M. tuberculata presented Ampularidae, Plant Material and Belastomatidae as the most important items consumed, including adaptations for the consumption of molluscs. We did not find significant differences in niche widths between males and adult females of both species, however, diets differed significantly in ontogeny (adults and juveniles) possibly related to differences in size of individuals and use of specific microhabitats. The season (dry and rainy) and biome (Caatinga and Atlantic forest) also differed significantly these verified temporal and regional differences represent an interesting ecological adjustment and indicates strong influence of the biome and the seasonal variation in the available prey and composition of the diet of P. geoffroanus and M. tuberculata. In the third chapter, we identified the endoparasite fauna that infect P. geoffroanus and M. tuberculata, evaluating the effect of host conditions (body size and sex), seasonality (dry and rainy season) and biome about the abundance and composition of endoparasites. Seven species of endoparasites were found, being a Cestoda, a Digenea, a Monogenea, and four Nematodas. Among the helminths, Camallanus amazonicus was first recorded parasitizing P. geoffroanus and M. tuberculata. The monogenetic Polystomoides brasiliensis parasitizing M. tuberculata also represents a new host for the species. For both chelonians, we found no difference in the abundance of endoparasites in relation to sex, probably this similarity in the parasite rates are related to the high food overlap that the sexes present, since similar feeding habits of the hosts allow them to be infected by the same endoparasites. We observed significant differences in the levels of infection between the biomes and the seasons (dry and rainy), where the Atlantic Forest specimens showed higher infection rates when compared to the Caatinga and the highest rates occurring in the dry season. Finally, in general, many parasitological parameters evaluated were different in P. geoffroanus and M. tuberculata in the studied biomes, showing that the variations in the characteristics of the habitats directly influenced the levels of parasitic infection. In the fourth chapter we identified the fauna of ectoparasites that infest P. geoffroanus and M. tuberculata, evaluating the effect of host conditions and seasonality (dry and rainy season), on the abundance and composition of ectoparasites, we describe the patterns in the use of the microhabitat (body surfaces of the chelonians), as well as the influence of the biome on infestation rates. We verified the presence of four species of leeches of the family Glossiphoniidae, and one monogeneo of the family Polystomatidae. In both chelonians, we observed a significant difference in the abundance of ectoparasites in relation to sex, biome, season, however there was no relation in length and mass. Regarding the positioning, the leeches were more frequent in the cavities of the hind limbs in P. geoffroanus, whereas in M. tuberculata it was in the cavities of the anterior limbs. The spatial niche overlap of the leeches in general was high, except for P. brasiliensis, single species showed no overlap with the other species, exclusively using the mouths of the hosts as their microhabitat. We obtained the first report of the presence of Oligobdella brasiliensis and Polystomoides brasiliensis in M. tuberculata, and Helobdella cf. adiastola parasitizing P. geoffroanus and M. tuberculata. The differences in the infestation levels found may be a reflection of the ecological factors, differences in the behavioral patterns of the hosts, as well as the different anthropic alterations suffered in the Caatinga and Atlantic forest biomes. The fifth chapter refers to the review manuscript titled "Mesoclemmys tuberculata (Luederwaldt, 1926) –Tuberculate Toadhead Turtle" published in the journal Chelonian Research Monographs of the “Tortoise and Freshwater Turtle Specialist Group (IUCN/SSC)”, where we present the information related to M. tuberculata species available in the literature, the main objective of this work is to help define the conservation status of the species in IUCN. The sixth chapter corresponds to the manuscript entitled “Hatchling morphology of the Tuberculate Toadhead Turtle (Mesoclemmys tuberculata [Lüederwaldt, 1926]) from northeastern Brazil (Testudines: Chelidae)” published in the journal Herpetology Notes of the “Publication of the Societas Europaea Herpetologica” where we describe the morphometric and color aspects of M. tuberculata hatchlings previously unknown in the literature.