Relações filogenéticas entre os golfinhos da família Delphinidae: mammalia : cetacea

• Ano de defesa: 2008
• Autor(a) principal: Moreno, Ignacio Benites
• Orientador(a): Reis, Roberto Esser dos
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Pontifícia Universidade Católica do Rio Grande do Sul; Porto Alegre
• Palavras-chave em Português: GOLFINHOS; CETÁCEOS; ZOOLOGIA
• Link de acesso: http://hdl.handle.net/10923/5312

The family Delphinidae is the most diverse among all living Cetacea and includes many distinct morphotypes. At the moment, 17 genera and approximately 37 species are recognized in the family. The diversity and present abundance of delphinids are related to the explosive evolution that probably occurred in the Pliocene. The abrupt radiation of delphinids in the Pliocene is a remarkable phenomenon in cetacean evolution. This period matches a global temperature decline that likely resulted in habitat changes and ecological replacement of kentriodontids by modern delphinids. There is still no consensus about subdivisions within the Delphinidae, and the current use of subfamilies is based around Delphinus (Delphininae), Steno (Steninae), Lissodelphis (Lissodeiphinae), Cephalorhynchus (Cephalorhynchinae), and Globicephala (Globicephalinae). These groups were based mostly on phenetic judgments of one single line of evidence (e. g. nasofacial muscles, basicranial sinuses, or tympanoperiotic) and resulted in contradictory classifications. In this study, 147 morphological characters from 43 living Odontocetes were codified by direct examination of specimens. The ingroup thus totals 35 different OTUs (31 species + 3 subspecies + 1 population). All of the 17 genera of the Delphinidae are represented by at least one species. This is the first attempt to produce a cladistic anatysis of the Delphinidae using morphology with a comprehensive data set (skull, tympanoperiotic, external morphology and coloration). Approximately 57 of the 147 characters are original to this work. The analysis of the 147 character matrix with 43 taxa resulted in four equally most parsimonious trees with a length of 1034 steps. A strict consensus of the four primary trees revealed only two polytomies. The first involves the relationships of the three families in Delphinoidea (Monodontidae, Phocoenidae and Delphinidae), while the other refers to the relationships of Lagenorhynchus acutus within the Dephininae. The monophyly of the three families of Delphinoidea was recovered. The families Monodontidae and Phocoenidae were supported by five exclusive synapomorphies each. The famiiy Delphinidae was supported by four exclusive synapomorphies. This study shows that the former group called “blackflsh” is polyphyletic and should be split in three subfamilies: (Orcininae, Orcaellinae and a new subfamiIy). Another new subfamily, Lagenorhynchinae, should be created to place Lagenorhynchus albirostris. This study recovered a Lissodelphininae monophyletic with 10 species in three genera. In this study, a well supported Steninae was found, with Sousa deeply nested in the subfamily clade as the sister group to Sotalia. Leucopleurus acutus is nested within the subfamily Delphinidae. The subfamily Delphininae should include only the genera Delphinus, Leucopleurus, Lagenodelphis, Stenella, “Stenella” longirostris and Tursiops. The morphological results presented here are promissory. This study makes clear that a comprehensive cladistic analysis can help to resolve the relationship within delphinids.