Potentially endemic ciliates of phytotelma exhibit high macroevolutionary rates

Abstract

This work aimed to infer the time of origin and the mode of evolution of the potentially endemic ciliates of the phytotelmata, as well as delimit their dispersal routes until reaching this environment. We estimate a dated molecular phylogeny from the 18Sr-RNA sequence available from GenBank. We inferred the habitat ancestral state and the dynamics of the diversification rates related to assessed habitats. Our results showed that the arrival to phytotelmata habitats is recent and occurred numerous times and independently over evolutionary time, being the origin of potentially endemic ciliates after the appearance of bromeliads. Our data also revealed that the arrival of the ciliates to the phytotelma occurred through four distinct routes: (i) from a marine/brackish ancestor, (ii) a freshwater ancestor, (iii) a terrestrial ancestor, or (iv) a symbiotic ancestor. In addition, we noticed a significant increase in the diversification rates of potentially endemic ciliates to bromeliad phytotelma. Several ecological, morphological and evolutionary hypotheses help to explain these ciliates' evolutionary success. However, more studies with this group are needed to define complex hypotheses explaining such a process. It emphasizes the need to dedicate efforts to develop ecological and molecular studies with this group.