Symbiosis in Evolution: Origins of Cell Motility

Abstract

Summary. Using symbiosis in the DeBary sense of “living together of unlike organisms,” K.S. Mereschkowsky (1855–1921), on the basis of his original work, rejected Darwinian natural selection as source of evolutionary innovation [1]; he invented the term “symbiogenesis” referring to the appearance of new organisms emerging from prolonged symbiotic associations. A.S. Famintzyn (1835–1918) taught B.M. Kozo-Polyanski (1890–1957) who, in his 1924 text on new concepts in biology, attempted to unite Darwinian natural selection with symbiogenesis [2]. Kozo-Polyanski even claimed that cell motility was derived symbiotically from “flagellated cytodes” by which he meant “primitive flagellated bacteria.” The American I.E. Wallin (1883–1969) developed his theory of “symbionticism and the origin of species” [3] in the absence of direct communication with these Russian scientists, and he also elucidated the importance of symbiosis as the source of novelty in evolution.

Molecular biology and ultrastructural analysis has increased greatly the probability that these early biologists were correct in asserting the importance of symbiosis in evolution. The bacterial ancestry of plastids (from cyanobacteria) and mitochondria (from respiring bacteria) is now well established. Our independently- derived version of Kozo-Polyanski’s prophetic suggestion requires more rigorous proof; the status of the symbiotic origin of undulipodia is reviewed here.