This is driving me mad!
So ginkgos have separate male and female plants, i.e. they are dioecious. This is thought to be in order to prevent self pollination and self fertilisation, thereby guaranteeing that the offspring will be genetically different to the parent plants.
BUT the ginkgo is a “fossil plant”, and it’s a poster child for evolutionary stasis. It’s barely changed over millions of years of evolution.
WHY has is remained so conserved over evolutionary time despite the genetic variation that should arise from it being dioecious??
In the book “Ginkgo” by Peter Crane, some explanations are offered:
1. Ginkgo has tracked the same environmental conditions for more than 200 million years.
2. In spite of genetic variation, the same form has been maintained by stabilising selection.
3. Or there is some kind of developmental constraint that has kept ginkgo almost completely unchanged for a long period of time.
But I’m not fully satisfied by these explanations and can’t find any literature on the subject. Can anyone help me out??
(first image from Zhou, Z.-Y. & Zhang, B.-L. Palaeontographica B 211, 113–133 (1989).
second image from wikipedia)