Abstract
Flowering plants have evolved an extraordinary variety of signalling traits to attract their pollinators. Most flowers rely on visual and chemical signals, but some bat-pollinated plants have evolved passive acoustic floral signals. All known acoustic flower signals rely on the same principle of increased sonar reflectivity. Here, we describe a novel mechanism that relies on increased absorption of the area surrounding the flower. In a bat-pollinated cactus (Espostoa frutescens) we found a hairy inflorescence zone, a so-called cephalium. Flowers solely emerge out of this zone. We measured the echoes of cephalia, flowers and unspecialized column surfaces and recorded echolocation calls of approaching bats. We found that the cephalium acts as a strong ultrasound absorber, attenuating the sound by -14 dB. The absorption was highest around the echolocation call frequencies of approaching bats. Our results indicate that, instead of making flowers more reflective, plants can also evolve structures to attenuate the background echo, thereby enhancing the acoustic contrast with the target.
Original language | English |
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Article number | jeb245263 |
Pages (from-to) | 1-5 |
Number of pages | 5 |
Journal | The Journal of experimental biology |
Volume | 226 |
Issue number | 5 |
DOIs | |
Publication status | Published - Mar 2023 |
Bibliographical note
Publisher Copyright:© 2023. Published by The Company of Biologists Ltd.
Funding
This work was supported by the Deutsche Forschungsgemeinschaft (HE 1180/15). Some of the observations and measurements were conducted during a National Geographic Magazine field trip for the story ‘Call of the Bloom’ (McGrath, 2014). Open access funding provided by Vrije Universiteit Amsterdam. Deposited in PMC for immediate release.
Funders | Funder number |
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Deutsche Forschungsgemeinschaft | HE 1180/15 |
Keywords
- Bat pollination
- Cactaceae
- Cephalium
- Chiropterophily
- Echolocation
- Floral acoustics
- Ultrasound absorption