Biodiversity and areas of endemism of benthic hydroids (Cnidaria, Hydrozoa) from southern South America and Antarctica

Author(s)

Thaís Pires Miranda

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB)
• Defense date: 2014-11-13

Examining board members

Antonio Carlos Marques; Eduardo Carlos Meduna Hajdu; André Carrara Morandini; Ricardo Pinto da Rocha; Rosana Moreira da Rocha

• Advisor: Antonio Carlos Marques; Alvaro Luis Peña Cantero

Abstract

The southern South America (SSA) coast and the Southern Ocean (SO) have a high differentiation of habitats and are historically connected since the opening of the Drake Passage. The marine fauna of both regions are connected, highly diverse and many species are contradictory distributed, such as the benthic hydroids (Cnidaria, Hydrozoa). All this faunistic heterogeneity calls attention for additional biogeographic investigations, involving the search for areas of endemism and other geographic distribution patterns. An update of the taxonomic status of the species of benthic hydroids from SSA and SO was carried out, gathering information about their richness, endemicity level, biological substrates and geographic distribution. A total of 5.621 samples and 359 morphospecies of benthic hydroids were surveyed for the studied area and taxonomically checked, being 256 identified up to the specific level. The records of presence-absence along the SSA and SO were used in a Bray-Curtis similarity analysis and the results were synthesized in hierarchical clusters and nMDS. The level of endemism at both the SSA and the SO is 54%, being the SO responsible for 88% of the records of endemic species. Leptothecate species had the widest horizontal and vertical distribution and most part of the benthic hydroids surveyed were considered substrate-generalists. Thirteen ecological assemblages of benthic hydroids were found along the SSA and SO and compared with the oceanographic dynamics of the area, as well as with earlier ecoregions, realms, assemblages, and areas of endemism delimited for the region. Areas of endemism were hypothesized for the SSA and SO using the Endemicity Analysis (EA) through an optimization performed by the software NDM-VNDM, with a 10° latitude X 10° longitude grid. Nine (F=0.5) and 10 (F=1.0) consensus areas of endemism were historically related with the isolation of Antarctica, and compared with previous hypotheses for the SSA and SO. All areas were discussed in the context of vicariance/dispersal processes, and concerning the real degree of endemicity that they represent. PAE was also performed but only with 61 endemic species of benthic hydroids for the region above the 45°S. This analysis was carried out with the aim to reanalyze previous data already published by Marques & Peña Cantero (2010), inserting a complementary dataset in order to obtain a better definition and accuracy in the areas of endemism delimited for the region. Eight areas of endemism were defined as subregions of the patterns previously found. The use of different techniques and biogeographic datasets are alternative strategies to clarify general patterns of areas of endemism, as well as other patterns related with ecological communities and studies in conservation biology (AU)

• FAPESP's process: 10/06927-0 - Biodiversity and areas of endemism of benthic hydroids (Cnidaria, Hydrozoa) from southern South America and Antarctica
• Grantee: Thaís Pires Miranda
• Support Opportunities: Scholarships in Brazil - Doctorate