Diversidade morfológica de aves e extinções na Região Metropolitana de Belém, Pará, Brasil

Abstract

Morphological diversity, a concept intimately related to functional diversity, involves the characterization of the diversity of phenotypic characters and can be used as a measure of diversity in communities. The morphological approach has traditionally been applied in studies on structuring bird communities. In this study, we evaluated if bird extinctions documented in the Metropolitan Region of Belém (MRB), located in the northeast of the State of Pará, may have altered the morphological space of birds in the region. Initially, bird records for the MRB were compiled from the literature, resulting in 490 species documented. The database on regional extinctions of birds or endangered species was determined for the MRB, from literature, which resulted in four lists (subsets of the total species list in the MRB). In the final phase of data acquisition, we organized a morphological matrix for the birds of the MRB, defined by measurements of 2,360 individuals and nine characters commonly used in studies on bird ecology and morphology (beak, wing, tail, and tarsus length data). The morphological space occupied by the bird fauna in the MRB was described by a Principal Component Analysis. Morphological diversity metrics (MPD and MNND) were used to compare observed values with scenarios of extinctions in the MRB (the four lists of species that were a subset of the regional fauna). Simulated extinctions of MRB’s bird fauna were used to determine expected values in random extinction models or probability models of extinction. The results suggest that if the MRB lose species that delimit the periphery of the morphological space, changes in the morphological structure of the bird fauna can be expected, although a relatively small number of species disappear. Simulated models of extinction indicate a monotonic relationship between morphological diversity and species richness, strictly decreasing, indicating that the MRB will lose functional diversity with accumulated extinction of species; on the other hand, morphological space structure (such as MPD and MNND), suggest a greater functional redundancy of birds in the region. Taken together, the results indicate significant effects of regional extinctions on the morphological structure of MRB birds, with possible functional consequences for the region.