DARWIN鈥橲 finches, move over. Before any animal could draw a breath, the
course of evolution covered the Earth with a dazzling variety of green,
oxygen-giving organisms. In The Evolutionary Biology of Plants
(University of Chicago Press, 拢51.95/$65, ISBN 0 226 58082 2), Karl
Niklas reflects on this original green revolution, from the origin of life to
the many startling convergences in today鈥檚 plants.
The author of that splendid work Plant Biomechanics and Plant
Allometry gives plant evolution the full attention usually reserved for
organisms with guts and brains. Niklas throws a few bones to his zoocentric
colleagues. For instance, ferns are the amphibians of the plant world, and seeds
are the functional equivalent of amniotic eggs.
Niklas begins by reviewing the basic evolutionary principles from a botanical
perspective, and tracing the resplendent history of plant life. Then he turns to
the meat, so to speak, of the matter and his own interest in the relationship
between plant form and function. Niklas applies computer simulations to chart
hypothetical evolutionary paths through multivariable 鈥渕orphospaces鈥�.
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The morphological variables chosen are necessarily simplified, and the
assumptions seem drastic at times. But the results resonate with what is known
about the history of plants and add exciting new insights to the evolutionary
debate.
Niklas relies heavily on evolutionary biologist Sewall Wright鈥檚 metaphor of a
鈥渇itness landscape鈥� where populations blunder through maladaptive valleys to
reach new fitness peaks. He calls his morphological simulations 鈥渁daptive walks鈥�
over such landscapes. And although Niklas has his idiosyncrasies and opinions,
this powerful metaphor provides a balanced approach uncommon in evolutionary
debates. The landscape allows equal time to random mechanisms and natural
selection, and illustrates how evolution depends on the interaction of the
two.
The Evolutionary Biology of Plants will make an engaging text for
any course in evolution, and a valuable addition to the library of those
interested in the history of plants.