Ectoparasitas de pequenos mamíferos: fatores determinantes da estrutura de comunidades em paisagens fragmentadas no cerrado brasileiro

Abstract

Through an extensive sampling effort, I investigated the relationships of ectoparasites (Ixodidae, Mesostigmata, Phthiraptera and Siphonaptera) with small mammals in remnants of savanna in central-western Brazil, addressing questions relating to species diversity, population dynamics, specificity in host-parasite relationship, and the importance of several factors in the structural organization of ectoparasites communities. In general, I expand the known occurrence area for 30 ectoparasite species and also show 49 new host-parasite association records. Considering the populational fluctuation, I evaluated the effect of seasonality and host gender on the prevalence and mean intensity of infestation of various species of ectoparasites. I found that, overall, ticks are more influenced by seasonality than other species, while the host gender does not influence the prevalence and mean intensity of ectoparasite infestation. About specificity, I investigated the association degree of both: ectoparasites (mites, lice and fleas) with their hosts and hosts with their ectoparasites. As a result, I noticed that each host species has a particular parasitic fauna and there is a high specificity of these ectoparasites with their hosts. I also evaluated the importance of host traits (identity, gender, body mass, vertical space use, and capture seasonality) on the structural organization of the entire ectoparasite community, as well as of mites, ticks and lice separately. I found that the host identity plays an important role in the ectoparasites community organization more than the other factors. Mites are also mainly influenced by the host identity. The host mass has a strong influence on the richness and abundance of ticks, while lice are little influenced by the factors analyzed, with the exception of species richness, which is highly influenced by the host identity. The other analyzed factors had little or no influence on the different groups evaluated. Finally, I evaluated the habitat fragmentation effect (area size and natural vegetation amount in the landscape) on the entire ectoparasite community, and mites, ticks and lice separately. I also analyzed the fragmentation effect on the Didelphis albiventris ticks and all ectoparasites of Thrichomys fosteri, since they are ecologically opposite in the landscape As a result, I observed that, in general, fragmentation influences the ectoparasite community, and that ticks are benefited by fragmentation, lice are negatively affected, and mites are not affected. However, in most cases this influence is dependent on the host species composition or abundance. Exceptions were T. fosteri ectoparasites which, in addition of being affected by the abundance of their host, had a direct relationship with area size and landscape vegetation cover. Understanding host-ectoparasite relationships, as well as the ectoparasite relationship with the environment, provide a valuable opportunity for understanding different ecological processes other than those patterns seen only by their hosts. Also, understand how ectoparasites react to the fragmentation provides insights about how local diversity is being affected and its consequences.