Study: Earth’s first flowering plants were pollinated by insects | Ski.News

Most living angiosperms (flowering plants) are pollinated by insects, and the new reconstruction of angiosperms’ ancestral pollination pattern suggests that their most recent common ancestor was also insect pollinated.

Macroevolution of pollination modes across flowering plants, showing the proportional marginal probability of pollination mode at ancestral nodes for each flowering plant order.  Image credit: Stephens et al., doi: 10.1111/nph.18993.

Macroevolution of pollination modes across flowering plants, showing the proportional marginal probability of pollination mode at ancestral nodes for each flowering plant order. Image credit: Stephens et al., doi: 10.1111/nph.18993.

Pollination is a key ecological process that has influenced the diversification of many seed plant families throughout evolutionary history, said the Macquarie University Ph.D. student Ruby Stephens and colleagues.

Both gymnosperms and angiosperms depend on pollination to reproduce sexually, with pollen transfer done by insects, vertebrates, wind or water as vectors.

Shifts between different pollinators or modes of pollination are often implicated in the speciation of closely related plants, and pollination shifts of angiosperms have driven the evolution of the wide range of floral forms present today.

Precisely how the first angiosperms were pollinated and how pollination patterns evolved over time remains a key question in angiosperm macroevolution, they added.

Most angiosperms are pollinated by animals, especially insects (e.g. bees, flies, wasps, moths, butterflies, beetles and thrips) but also vertebrates (e.g. birds, bats, lizards and small mammals).

In fact, although some flowers are self-pollinating, up to a third of flowering plants produce no seed without animal pollination.

However, abiotic pollination by wind or water also occurs in many different plant lineages, and wind pollination is estimated to have evolved at least 65 times across flowering plants.

3D model of the ancestral flower reconstructed by the eFLOWER team.  Image credit: Sauquet et al, doi: 10.1038/ncomms16047.

3D model of the ancestral flower reconstructed by the eFLOWER team. Image credit: Sauquet et aldoi:10.1038/ncomms16047.

In their research, the scientists used a state-of-the-art evolutionary tree of all flowering plants, unveiling data on what pollinates 1,160 species in all major flowering plant families.

The evolutionary tree shows us which plant families evolved when, Stephens said.

By running several models, we can map backwards from what pollinates a plant in the present, to what that plant’s ancestor may have pollinated in the past.

This is a significant discovery, revealing a key aspect of the origin of nearly all plants on Earth today.

Plants are the lifeblood of our planet, and our study underscores the importance of insects for plant reproduction throughout Earth’s history.

Our research has uncovered insights into the evolution of other forms of pollination, said Herv Sauquet, a researcher at the Botanic Gardens of Sydney.

Pollination by vertebrate animals such as birds, bats, small mammals, even lizards, has evolved and regressed numerous times throughout history.

Wind pollination has also evolved many times over, but it’s more difficult to reverse: once plants are wind pollinated, they rarely come back.

The research also reveals that wind pollination is more likely to evolve in open habitats towards the poles, while animal pollination is more likely to occur in closed rainforests near the equator.

About 90 percent of the estimated 330,000 angiosperm species today depend on animals for pollination, said Washington University professor Susanne Renner, who was not involved in the study.

The new findings confirm that insects have been pollinating flowering plants for most of the plant lineage’s history.

This underlines the need for insect conservation: their role as pollinators is essential for the continued existence of plants.

The results appear in the journal New phytologist.

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Ruby E. Stephens et al. Insect pollination for most of the evolutionary history of flowering plants. New phytologist, published online June 5, 2023; doi: 10.1111/nph.18993

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