Reproductive biology of the threatened and highly fragmented shrub Persoonia hirsuta (Proteaceae)
Nathan J. Emery
A * and Catherine A. Offord A
+ Author Affiliations
- Author Affiliations
A The Australian PlantBank, Australian Institute of Botanical Science, Australian Botanic Garden, Mount Annan, NSW 2567, Australia.
Australian Journal of Botany 70(1) 56-62 https://doi.org/10.1071/BT21068
Submitted: 1 June 2021 Accepted: 10 November 2021 Published: 7 December 2021
© 2022 The Author(s) (or their employer(s)). Published by CSIRO Publishing. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND)
Abstract
The Australian Proteaceous genus Persoonia is known to be pollinated by bees and have variable breeding systems that range from strictly self-incompatible to differing levels of self-compatibility. The endangered Persoonia hirsuta (Hairy Geebung) is a species currently in decline throughout its distribution, with many populations occurring in fragmented habitats comprising fewer than 10 plants or a single isolated individual. Despite its threatened status and recent population decline, the reproductive biology of P. hirsuta is unknown. In this study, we surveyed floral visitors and their foraging behaviour, and investigated the breeding system of P. hirsuta by conducting experimental hand-pollinations at two of the largest known populations. P. hirsuta was almost exclusively visited by native bees, including Leioproctus, Megachile and Tetragonula species. This study was the first to report Xylocopa bees and Zizinia butterflies visiting Persoonia flowers. On average, both foraging time per flower and the number of flowers visited per plant varied significantly among insect genera. Notably, Xylocopa bees visited more flowers per plant than did any other pollinator (22.1 ± 10.8 flowers). P. hirsuta has a breeding system that displays partial self-incompatibility with significantly higher fruit set in the cross- and open-pollination treatments at both populations (19.4 ± 10.8 to 44.8 ± 8.2%) than in the autogamy and selfed treatments (0.6 ± 0.6 to 9.0 ± 5.1%). The results of this study are critical to the future management of P. hirsuta, and suggest that its small and isolated populations may produce very few viable fruits in the absence of outcrossing.
Keywords: bees, breeding system, habitat fragmentation, hairy geebung, Leioproctus, Megachile, pollination, self-incompatibility, Xylocopa.
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