The impact of thermogenesis on the origin of insect pollination

Thermogenesis in plants is the ability to raise their temperature above that of the surrounding air through metabolic processes, and is especially detected in reproductive organs. Warming benefits plants by facilitating the transmission of odours and compounds that attract insects. As a result, these plants increase their odds of being pollinated by the attracted insect. Modern thermogenesis has been reported in extant cycads and a small number of angiosperm lineages. Although thermogenesis is not directly preserved in the fossil record, it can be inferred by examining extant thermogenic plant lineages and comparing their features with those of the fossil record. We suggest that thermogenesis has probably occurred in seed plants for at least the past 200 million years, long before the origin of angiosperms. Thermogenesis in plants is an important factor that facilitated entomophilous pollination by enhancing the attraction of insects, complementary to other factors, thereby participating in the success of the two groups of organisms and providing many facets of past and recent reproductive biology for future exploration. Thermogenesis, which is present in a small but diverse range of extant plant lineages, increases the odds of pollination by providing heat rewards for insect pollinators and enhancing the transmission of attractants. In this Review, exploration of the fossil record uncovers the evolutionary history of thermogenic plants, revealing a close relationship with insect pollinators since the Palaeozoic era.