Evolution: plant blooms (Introduction)

by David Turell , Thursday, September 16, 2021, 19:52 (953 days ago) @ David Turell

This issue bothered Darwin, but it is similar to the Cambrian explosion:

https://phys.org/news/2021-09-evolved-complexity-burstswith-million-year-hiatus.html

"A Stanford-led study reveals that rather than evolving gradually over hundreds of millions of years, land plants underwent major diversification in two dramatic bursts, 250 million years apart. The first occurred early in plant history, giving rise to the development of seeds, and the second took place during the diversification of flowering plants.

"... While scientists have long assumed that plants became more complex with the advent of seeds and flowers, the new findings, published Sept. 17 in Science, offer insight to the timing and magnitude of those changes.

"'The most surprising thing is this kind of stasis, this plateau in complexity after the initial evolution of seeds and then the total change that happened when flowering plants started diversifying," said lead study author Andrew Leslie, an assistant professor of geological sciences at Stanford's School of Earth, Energy & Environmental Sciences (Stanford Earth). "The reproductive structures look different in all these plants, but they all have about the same number of parts during that stasis."

"Flowers are more diverse than every other group of plants, producing colors, smells and shapes that nourish animals and delight the senses. They are also intricate: petals, anthers and pistils interweave in precise arrangements to lure pollinators and trick them into spreading pollen from one flower to another.

"This complexity makes it difficult for scientists to compare flowering plants to plants with simpler reproductivesystems, such as ferns or some conifers. As a result, botanists have long focused on characteristics within family groups and typically study evolution in non-flowering plants separately from their more intricate flowering relatives.

"Leslie and his co-authors overcame these differences by designing a system that classifies the number of different kinds of parts in reproductive structures based on observation alone. Each species was scored according to how many types of parts it has and the degree to which it exhibited clustering of those parts. They categorized about 1,300 land plant species from about 420 million years ago until the present."

Comment: Doesn't solve Darwin's problem, just defined it in time in a better way. But still another unexplained gap.