Biodiversity, evolution, endemism and conservation of the Medusozoa from the Southwestern Atlantic

Abstract

Although the medusozoans constitute a diverse and widely distributed group, with complex life histories and many species economically significant, there is a lack of biogeographical studies in general, either with descriptive or interpretative approaches. Indeed, considering the knowledge hitherto, there is not a single analysis in which areas of endemism are inferred based on medusozoan distributions. This lack of studies precludes a better understanding of its general evolution, besides of its troubled taxonomy and many complexities as a result to the presence of two distinct life cycle forms, the polyp and the medusa. In a higher level, these deficiencies of knowledge conceal conservation actions. Recent compilations indicate the presence of 384 species reported for the Brazilian coast, most of which included within the Hydrozoa. The present project aims to study the diversity of medusozoans in the Western South Atlantic, from Cabo Frio (RJ, Brazil) to Tierra del Fuego (Argentina), correlating distribution and life cycles. The study has two complementary approaches: a) to determine the pattern of present distribution of species and the recognition of areas of endemism and b) to provide explanations for the patterns of distribution observed and understand the factors affecting species distribution and evolution, particularly related to the biology and life history of the groups under study. Within this framework, we plan to 1) survey and evaluate the biodiversity of Medusozoa in the area under study, 2) identify areas of endemism, based on parsimony analyses of endemicity, in order to understand the general patterns of (macro-)distribution, 3) promote phylogeographycal studies that, together with life cycle and biology studies, aims the understand of the general and specific patterns of (micro-)distribution. An important byproduct of this study is to conserve and curate the collected medusozoan specimens into the collection of the Museu de Zoologia of the Universidade de São Paulo (MZUSP). The project will carry out benthic and planktonic surveys along the area under study, and will also consider the available previous collections undertaken between Cabo Frio and southern coast of Brazil. The coast of Uruguay and Argentina will be surveyed with the collaboration of Argentinan colleagues, a work that will also provide a baseline for taxonomic and distributional studies for the whole southwestern Atlantic. (AU)