DIFERENCIAÇÃO DE NICHO E PALEODISTRIBUIÇÃO POTENCIAL DE DUAS ESPÉCIES DE AVES COM DISTRIBUIÇÃO DISJUNTA EM FLORESTAS SECAS DA AMÉRICA DO SUL

Abstract

Niche divergence and potential paleodistribution of two bird species with disjunct distribution in South America dry forest Evolution studies of species have shown that ecological requirements of lineages can be conserved, with species retaining traits of their ancestral niche. Opportunity to test whether ecological factors played a key role in allopatric speciation process can be observed in organisms associated with o Seasonally Dry Tropical Forests in South America. To test these hypotheses, we compared niche overlap, equivalence and similarity of two allopatric populations of birds dependent on dry forests: Myrmorchilus strigilatus and Stigmatura budytoides. In both taxas, one population occur in the Caatinga and Chaco region. We also explore the potential paleodistribution of these species to verify the possibility of connection, expansion and/or retraction of their distributions during different Quaternary climatic periods using the Maxent algorithm. Niche and paleodistribution analyzes were based on the current species distribution. Based on hypotheses already postulated, if significant differences of niche between sister taxa suggest speciation events, our data show that there is an ecological differentiation among allopatric populations, similar to expected in lineages considered full species distributed allopatrically. A climatic period similar to Last Interglacial Maximum may have provided adequate areas for a connection between these disjunct populations. These probabilities were no found during glacial periods. The niche similarity found between disjunct populations may be associated with historical climatic stability on Caatinga and Chaco region, however, the niche divergence may be associated with filtering by diferents climatic variables on two stable areas.