The Elements of Evolution (160-2) Ginkgo



The ginkgo tree is from the era of dinosaurs; but while the dinosaur has been extinguished, the modern ginkgo has not changed. ~ Japanese organic chemist Koji Nakanishi

The ginkgo arose during the Permian (before the dinosaurs). Like the fern, the gingko had staying power. The success of both owe to simplicity.

The gingko is a seed plant closely related to conifers, with 1 major difference: motile sperm. This was a holdover from aquatic algae, and a trait retained in bryophytes, before vascular tissue became all the rage.

Swimming sperm are common in the animal kingdom, but not vascular plants. Ginkgo and the earlier-evolved cycads, which arose in the early Permian, are the only vascular plants with motile sperm.

Though the ginkgo evolved genetically, it never showed much speciation. The ginkgo did tinker with elaboration. But, like the evolutionary trajectory of the horse, the ginkgo winnowed to a single family. The ginkgo survived 270 million years, through 3 major extinction events, much the same as it started.

The ginkgo is the floral equivalent of the shark: admirably adapted in its early form, with an adept portfolio of life-history variables. Its sexual flexibility is exemplary.

Ginkgo are modularly constructed. Their sex is determined at the tissue level. Trees can produce branches of the opposite sex.

Ginkgo have other vegetative reproductive traits, including sprouting. They produce lignotubers, which are a safeguard against destruction by fire.

55 MYA, the ginkgo’s range extended beyond the Arctic circle. Iceland at the time was lush forest of redwoods, oak, swamp cypress, and ginkgo. Adapted to a warm temperate climate, global cooling 15.5 MYA contracted the ginkgo’s presence.