A1 Journal article (refereed)
Geranium sylvaticum increases pollination probability by sexually dimorphic flowers (2022)

Soininen, J. O. S., & Kytöviita, M. (2022). Geranium sylvaticum increases pollination probability by sexually dimorphic flowers. Ecology and Evolution, 12(12), Article e9670. https://doi.org/10.1002/ece3.9670

JYU authors or editors

Publication details

All authors or editors: Soininen, Jaakko O. S.; Kytöviita, Minna‐Maarit

Journal or series: Ecology and Evolution

eISSN: 2045-7758

Publication year: 2022

Volume: 12

Issue number: 12

Article number: e9670

Publisher: Wiley

Publication country: United Kingdom

Publication language: English

DOI: https://doi.org/10.1002/ece3.9670

Publication open access: Openly available

Publication channel open access: Open Access channel

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/84715

Abstract

Sexual dimorphism is expressed as different morphologies between the sexes of a species. Dimorphism is pronounced in gynodioecious populations which consist of female and hermaphrodite individuals. The small size of female flowers in gynodioecious species is often explained by resource re-allocation to seed production instead of large flowers. However, pollinator attraction is critical to female fitness, and factors other than resource savings are needed to explain the small size of female flowers. We hypothesized that the floral size dimorphism in the perennial gynodioecious Geranium sylvaticum (L.) is adaptive in terms of pollination. To test this “pollination hypothesis,” we video recorded the small female and large hermaphrodite G. sylvaticum flowers. We parameterized floral visitor behavior when visiting a flower and calculated pollination probabilities by a floral visitor as the probability of touching anther and stigma with the same body part. Pollination probability differed in terms of flower sex and pollinator species. Bumblebees had the highest pollination probability. The small female flowers were more likely to receive pollen via several pollinator groups than the large hermaphrodite flowers. The pollen display of hermaphrodites matched poorly with the stigma display of hermaphrodites, but well with that of females. Although the small size of female flowers is commonly explained by resource re-allocation, we show that sexual dimorphism in flower size may increase the main reproductive functions of the females and hermaphrodites. Dimorphism increases pollination probability in females and fathering probability of the hermaphrodites likely driving G. sylvaticum populations towards dioecy.

Keywords: pollination; pollinators; pollen; flowers (plants); types and species; gender

Free keywords: disruptive selection; flower size; Geranium sylvaticum; gynodioecy; pollination; sexual dimorphism

Contributing organizations

Ministry reporting: Yes

VIRTA submission year: 2022

JUFO rating: 1