In the end they didn’t use the text that I sent back to them, so I thought that I’d share it on the blog:
The evolution of the angiosperms was arguably one of the most significant events in the history of life on Earth, but the timing of the origin of this group of plants remains a hotly debated topic, with conflicting evidence coming from the fossil record and molecular biology. This important new study has developed a novel statistical approach to reconcile these two lines of evidence, and comes down firmly on the side of the molecular evidence to conclude that angiosperms originated much earlier than the fossil record suggests. This will be sure to stir up further debate that can only be resolved by finding well preserved and accurately interpreted fossils of an appropriate age. In the future I would like to see Silvestro et al.’s technique applied to the major groups of pollinators such as bees and wasps (Hymenoptera) and butterflies and moths (Lepidoptera) where there is likewise a discrepancy between what the fossils and DNA are telling us. Pollinators have had a profound influence on angiosperm evolution and we might expect a close correlation between the origin and subsequent diversification of these different groups of organisms. This would certainly support the findings from Silvestro et al.’s study. It’s an exciting time for researchers in this field: a world without flowers and pollinators would look very different
This commentary brings together some recent findings in palaeontology, molecular phylogenetics, and pollinator sensory physiology and behaviour, to discuss the progress that’s been made in understanding the deep-time evolution of this most familiar and charismatic of ecological interactions.
The short version is that the old conceptual models are absolutely wrong. Some version of “first came the gymnosperms and they were primitive and unsuccessful because they were wind pollinated. Then, at the start of the Cretaceous, the angiosperms evolved and they were insect pollinated and advanced and so more successful” continues to appear in text books. But we’ve known for a long time that many of the Jurassic gymnosperms were insect pollinated. This may (or may not) predate insect pollination of angiosperms: there are huge disagreements between palaeobotanists and molecular phylogeneticists about when the first flowering plants evolved. The graphic above comes from our essay and shows just how big the discrepancy is: molecular models suggest an origin for the angiosperms about 70 million years prior to the first confirmed fossils. That’s about equivalent to the whole of the Jurassic period! There are similar disagreements when it comes to the evolution of pollinating insects: for the Lepidoptera (butterflies and moths) the difference between the earlier molecular and later fossil evidence may be as much as 100 million years.
As we discuss, there are huge implications in these discrepancies for understanding not just how major elements within the Earth’s biodiversity evolved, but also for the origins of pollinator sensory physiology. Insect behaviours linked to colour vision and odour reception may in turn influence effective crop and wild plant pollination.
The image accompanying our essay is by the very talented biologist, science communicator and graphic designer Elzemiek Zinkstok – follow that link and check out her work.
It’s been a couple of years since I posted my previous “virtual conferences” on Pollinators, Pollination and Flowers and Ecology and Climate Change, a lapse that has largely been due to lack of time (my default excuse for most things these days….). However Judith Trunschke at Uppsala University in Sweden has risen to the challenge of guest-curating her own virtual conference*. The theme here is how pollinators impose (or sometimes don’t impose) natural selection on flowers that results in the formation of new plant species: