Uma estrutura evolucionária para entender a origem dos eucariotos

sexta-feira, junho 03, 2016

Biology 2016, 5(2), 18; doi:10.3390/biology5020018


An Evolutionary Framework for Understanding the Origin of Eukaryotes

Neil W. Blackstone

Department of Biological Sciences, Northern Illinois University, DeKalb, IL 60115, USA; Tel.: +1-815-753-7899; Fax: +1-815-753-0461

Academic Editor: John S. Torday

Received: 28 February 2016 / Accepted: 25 April 2016 / Published: 27 April 2016


Two major obstacles hinder the application of evolutionary theory to the origin of eukaryotes. The first is more apparent than real—the endosymbiosis that led to the mitochondrion is often described as “non-Darwinian” because it deviates from the incremental evolution championed by the modern synthesis. Nevertheless, endosymbiosis can be accommodated by a multi-level generalization of evolutionary theory, which Darwin himself pioneered. The second obstacle is more serious—all of the major features of eukaryotes were likely present in the last eukaryotic common ancestor thus rendering comparative methods ineffective. In addition to a multi-level theory, the development of rigorous, sequence-based phylogenetic and comparative methods represents the greatest achievement of modern evolutionary theory. Nevertheless, the rapid evolution of major features in the eukaryotic stem group requires the consideration of an alternative framework. Such a framework, based on the contingent nature of these evolutionary events, is developed and illustrated with three examples: the putative intron proliferation leading to the nucleus and the cell cycle; conflict and cooperation in the origin of eukaryotic bioenergetics; and the inter-relationship between aerobic metabolism, sterol synthesis, membranes, and sex. The modern synthesis thus provides sufficient scope to develop an evolutionary framework to understand the origin of eukaryotes.

Keywords: comparative method; eukaryotes; evolutionary theory; levels of selection; mitochondria; modern synthesis; phylogenetic systematics