Inferências evolutivas com base na filogenia molecular de Spiruromorpha (De Ley & Blaxter, 2002) (Nematoda: Rhabditida)

Abstract

The development of new techniques for studying the evolution of nematode traits has brought solutions to several problems encountered in classical studies. However, several obstacles have also arisen to resolve important issues, such as incompatibility between molecular and morphological data, as well as data bias. Some previous studies have already raised data and hypotheses about the emergence of observable character states in living species, however there are still many questions about the value of these characters in the evolutionary success of parasitic nematodes. The infraorder Spiruromorpha, for example, is currently represented by ten superfamilies of morphologically heterogeneous species, characterized by nematodes with a parasitic and heteroxenous lifestyle. In order to elucidate the evolutionary relationships in Spiruromorpha by associating factors such as the different types of cephalic structures, the type of vertebrate host thermoregulatory mechanism, and the infection site, genetic data from the 18S rRNA region available in electronic biorepositories were collected and processed for phylogenetic reconstruction and subsequent phylogenetic signal estimation of characters and their states. The cephalic structures represent a morphological trait of great importance for taxonomy and demonstrated through the positive sign to have a direct influence on the evolutionary process of the species. The physiological mechanism of thermoregulation of the vertebrate host and the site of infection of the parasite in the host also represented a significant value in the proposed analysis, which demonstrates that the states associated with these characters were paramount to the evolutionary success of the species studied.