As the pandemic swept the world and brought social activities close to a full stop, people looked to more personal experiences to pass the time. Someone you may know may have geared themselves towards taking care of plants. Thing is, these plants may not have only impacted your life; these plants—especially those with pretty flowers—may have shaped the course of life’s evolution here on Earth more than we had previously known.
This certainly appears to be the case if you ask researchers from the University of Bristol, who performed a sweeping literature review to identify exactly how the appearance of flowering plants gave momentum to the shift in Earth’s lifeforms, from predominantly water-based to land-based. Their review was published in the journal New Phytologist.
The thinking goes that prior to the emergence of true angiosperms, or flowering plants, as far back as at least 134 million years ago, most life on Earth existed in the seas. This meant that for the majority of Earth’s history, flowering plants weren’t around at all.
The first land plants to fully take advantage of Earth’s unclaimed land were the gymnosperms, which are the oldest branch of seed-producing plants around. This group of plants includes cycads, conifers, and the plant order Ginkgoales, among others.
During the time of the reign of gymnosperms on land, the majority of animal diversity on Earth existed in the seas. Then, some 300 million years ago, the common ancestor of all living angiosperms split off from the gymnosperm lineage; the change would be gradual, as what would be considered as “true’ angiosperms wouldn’t appear until some 170 million years later.
According to the team of scientists working on the paper, the timing of the sudden diversification of life on land coinciding with the proliferation of angiosperms on Earth—an event collectively known as the Angiosperm Terrestrial Revolution (ATR)—wasn’t a coincidence.
“Flowering plants might have been around for some time, but they began to appear more commonly in the Cretaceous, in the last 70 million years of the age of dinosaurs,” said Professor Michael Benton, lead author and from the University of Bristol. “But it seems that dinosaurs didn’t choose to eat them, and continued chomping ferns and conifers such as pines. However, it was only after the dinosaurs had gone that angiosperms really took off on evolutionary terms.”
Pennsylvania State University paleobotanist Peter Wilf explained further: “The [ATR] […] marked a huge change in ecosystems and biodiversity on land. More than a million species of modern insects owe their livelihoods to angiosperms, as pollinators such as bees and wasps, as leaf-eaters such as beetles, locusts, and bugs, or feeding on nectar such as butterflies. And these insects are eaten by spiders, lizards, birds, and mammals. After the dinosaur extinction, the great tropical rainforests began to flourish, and angiosperms began to dominate life on land.”
To the team, this diversification was given even more opportunities to do so after the sudden disappearance of the non-avian dinosaurs during the Cretaceous-Paleogene extinction event, which left vast swaths of now-vacated ecological niches available for both angiosperms and land animals to occupy.
The relatively greater efficiency that angiosperms possessed in converting sunlight into energy compared to their gymnosperm peers meant that more energy and nutrients were made available for animals—a fact that pollinators very much took advantage of. This led to a mutual boost in diversity for both pollinators and flowering plants, giving rise to the many forms of the two groups of organisms that we see today.
Prof. Benton continued in an official statement: “The angiosperms […] created enormous numbers of niches for other plants and animals, so you get tens more species on each hectare of the Earth’s surface than you would if angiosperms had not become established when they did.”
(For more plant finds, read further with our article about the full sequencing of the Oriental mangrove genome. After that, read about how orchids producing “counterfeit” pollen manage to fool pollinators.)
References
- Benton, M. J., Wilf, P., & Sauquet, H. (n.d.). The Angiosperm Terrestrial Revolution and the origins of modern biodiversity. New Phytologist, n/a(n/a). https://doi.org/10.1111/nph.17822
- Koumoundouros, T. (2022, January 8). How ‘flower power’ quite literally transformed earth millions of years ago. ScienceAlert. https://www.sciencealert.com/flower-power-fueled-a-massive-boost-in-biodiversity-after-the-cretaceous
- The University of Bristol. (2021, November 17). November: Flowering plants evolution. The University of Bristol. http://www.bristol.ac.uk/news/2021/november/flowering-plants-evolution.html
