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Symbiogenesis as a Partner of Mutation
Tom Wakeford. Liaisons of Life: From Hornworts to Hippos, How the Unassuming Microbe has Driven Evolution. New York: Wiley, 2001 Pp. 212. $24.95.
The networks of my ever-scrambled brain tubulin flash somewhat disparate thoughts in the biology quadrant. First, my mind can flip through the pages of most any biology text, whether old, quite old, or new, and under headings having to do with novelty, variety, and how evolution works, there will be the well-lit neural highways of mutation and recombination. Crossing over at the metaphase plate, and random genetic mutations, most of them lethal, are seemingly the everlasting mantra. But now another image shuffles by, that of the room in which I sit. Everything here has its cultural history, its evolved state through human use, disuse, whim, and conviction. On a deeper plane, each object--from Quercus floor slats to the quirky plastic clicker ever-ready at the sofa--also has its earth history.The elements all came from somewhere on or in the planet. Yet the wholeness of the room, its assembled parts, did not gradually evolve--the room and its inhabitants did not await a slow, ever-changing, random expression that is now this orderliness. [End Page 287] Instead, parts were acquired.The old Victorian chair was brought in one day whole and complete and even a bit worn.
Like this room, the cellular compartments of kangaroos, orchids, paramecia, and people are the result of acquisitions, wherein the sets of genes wrapped within a free-living proto-mitochondrion or a pre-plastid entity became in a random moment tolerated by some semi-nucleated host. Soon after, their invasive selves became useful for survival--i.e., leaving more offspring--and the rest is not just history, but all around us. Such juxtaposed images come clearly into focus when the hodgepodge of symbiotic biological systems known as coral reefs, rhizospheres, thalli, and guts are considered. Could it be that the great driving force in evolution--the source of novelty and change--involves not just the marriage of recombination and mutation, but a third significant other, symbiogenesis?
In Liaisons of Life: From Hornworts to Hippos, How the Unassuming Microbe Has Driven Evolution, Tom Wakeford joins symbiosis pioneer Lynn Margulis, an emerging array of researchers from a wide variety of biology sub-disciplines, and most of my microbial symbiosis course students in giving a resounding "yes." But Wakeford's work is not merely an echo. It is more like a beacon that guides would-be symbiotic sailors to an acceptable place, an island that anyone who dares to discover the full story of evolution will find accessible.
A biologist from the University of Sussex, Wakeford realizes that the original A. B. Frank and Anton DeBary's late-19th-century definition of symbiosis as "unlike organisms living together" (Sapp 1994) needs a modern-day revisit. Moreover, Wakeford leads us away from the "war on germs" of Pasteur and what the author calls "antimicrobial paranoia" to the more liberating, albeit dirty, work of entomology researchers like Vincent Wigglesworth, who in the early aseptic 1950s discovered that sterile onion fly larvae are doomed without intimate internal liaisons with bacteria.
But this enlightening journey does not really get rolling until Wakeford relates the story of the legendary children's tale writer Beatrix Potter. An unabashed lichen-lover, Potter's greatest talents resided in her deft and colorful botanical drawings and scientific curiosity. Along with the Swiss researcher Simon Schwendener, Potter insisted on the dual intimate nature of the cryptogams, only to be scoffed at for such romantic un-biological notions. Indeed, symbiosis from early on was labeled a kind of soft, "feminine" science (Reinheimer 1913, p. 19; Sapp 1994), emphasizing a swooning accommodation rather than a tough competition; it took later, saner decades to realize that the internal dance of vastly different genomes need not circumvent or contradict even the most vigorous of Darwin's "most fit" themes. In 1896, Potter brought her...