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from
Life Ascending by Nick Lane (2009)
Plants
are the most implausible of sexual organisms, yet the
overwhelming majority of them are exactly that; only
dandelions, along with a handful of other species, cock a
snook at sex. The rest find a way, the most spectacular
being the exquisite beauty of flowering plants, which
swept through the world some 80 million years ago, turning
the dull green forests into the magical painted glades we
know today. Although they first evolved in the late
Jurassic, perhaps 160 million years ago, their global
takeover was long delayed, and ultimately tied to the rise
of insect pollinators like bees, Flowers are pure cost to
plant. They must attract pollinators with their flamboyant
colours and shapes; produce sweet nectar to make such
visits worthwhile (nectar is a quarter sugar by weight);
and distribute themselves with finesse - not too close (or
inbreeding makes sex pointless) and not too far (or the
pollinators will never make it to fertilise a partner).
Having settled on a pollinator of choice, the flower and
pollinator evolve in tandem, each imposing costs and
benefits on the other. |
