Diversification of Early Life and the Origin of the Three Domains
Kandler, O.
Botanical Institute of the University of Munich, Menzinger Straße 67, D-80638 München, Germany
A critical consideration of the relationship of basic phenetic characteristics of the three domains of life shows that each of the three statistically possible pairs among the three domains appears to be a sister group depending on the characters considered [1]. The thereby indicated quasi random distribution of basic characters among the three domains can neither be explained by any order of dichotomous branching of a common ancestral cell nor by chimarism between the domains at an early evolutionary stage.
Therefore it is proposed that the proto-cells of each of the three domains were formed successively at different evolutionary stages by independent cellularization events in founder groups of an evolving pre-cellular population. Accordingly, a "first cell", ancestral to the three domains, has never existed. Thus, the figural representation of the genealogical relationship among all extant living beings results in a tripartite "phylogenetic bush" rooted in a pre-cellular population rather than a traditional monorooted dichotomously branched phylogenetic tree. A scheme depicting the proposed evolution of life beginning with spontaneous synthesis of carbon compounds from volcanic gasses in a heated primeval inorganic world and proceeding via progenotic and mesogenetic stages to the extant genotic stage is presented [1].
It is suggested that the formation of the two procaryotic domains comprising early hyperthermophilic lineages occurred in a heated archaic environment, while the domain Eucarya embracing exclusively mesophilic members sprang from a much further evolved pre-cellular population in an early proterozoic mesophilic environment.
[1] Kandler, O. (1994) The early diversification of life, in Bengtson, S. (ed.). Early Life on Earth. Nobel Symposium Nr. 84, pp. 152-161, New York: Columbia U.P.
| LOCATION |
DATE |
TIME |
| Lecture Hall I |
Tuesday, April 7 |
10:30 am |