Abstract
Leaves are critical to plant photosynthesis and the loss of leaf area can have negative consequences for an individual's performance and fitness. Variation in plant defenses plays a large role in protecting their leaves from attack by insect herbivores. However, trade-offs in allocation among growth, reproduction, and defense may limit the availability of resources for any one aspect of a plant's life-history strategy, which would lead to greater herbivory in those plants that allocate more resources to growth or reproduction than to defense. Patterns of sex-biased herbivory in dioecious plants are well documented yet are known to vary in the direction (female or male) of their bias. A greater concentration of conspecifics may also increase herbivore attack through negative density dependence. In order to test the hypothesis that sex-biased herbivory varies as a function of conspecific density, we measured standing herbivory on 2350 leaves on 302 trees of the dioecious understory tree Iryanthera hostmannii (Myristicaceae) situated in a large forest dynamics plot in a lowland tropical rain forest in Ecuador. We found no difference in standing herbivory between the 169 male and 133 female trees, nor for focal trees surrounded by higher densities of conspecifics. The slow-growing, shade-tolerant growth patterns of I. hostmannii may contribute to suppressed differential expression of secondary sex characters in leaf defenses, leading to similar levels of herbivory between males and females. Considering the factors that most strongly affect herbivory in dioecious species is important in understanding the evolution of sex-related traits more broadly.
| Original language | English |
|---|---|
| Article number | e70006 |
| Journal | Biotropica |
| Volume | 57 |
| Issue number | 2 |
| State | Published - 31 Jan 2025 |
Bibliographical note
Publisher Copyright:© 2025 Association for Tropical Biology and Conservation.
Funding
We are very grateful to Emma Grover, Mila Pruiett, Emilio Trujillo, and Sof\u00EDa Montalvo for assistance in the field, as well as Pablo Alvia and Milton Zambrano for help with species identification and deep knowledge of the Yasun\u00ED site. We thank the Pontificia Universidad Cat\u00F3lica del Ecuador and Yasun\u00ED Scientific Research Station for providing logistical support. The Ecuadorian Ministry of the Environment graciously approved this work (permit MAAE\u2010ARSFC\u20102021\u20101403). The Forest Dynamics Plot of Yasun\u00ED National Park has been made possible through the generous support of the Pontifical Catholic University of Ecuador (PUCE) funds of , the government of Ecuador, the US National Science Foundation, the Andrew W. Mellon Foundation, the Smithsonian Tropical Research Institute, and the University of Aarhus of Denmark. Leah Genth was supported by an NSF International Research Experience for Students grant (award number 2107117) during this study. We thank the two anonymous reviewers and Francis Brearley, whose suggestions improved the manuscript. donaciones del impuesto a la renta This work was supported by Office of International Science and Engineering, 2107117. Funding: Funding: This work was supported by Office of International Science and Engineering, 2107117. We are very grateful to Emma Grover, Mila Pruiett, Emilio Trujillo, and Sof\u00EDa Montalvo for assistance in the field, as well as Pablo Alvia and Milton Zambrano for help with species identification and deep knowledge of the Yasun\u00ED site. We thank the Pontificia Universidad Cat\u00F3lica del Ecuador and Yasun\u00ED Scientific Research Station for providing logistical support. The Ecuadorian Ministry of the Environment graciously approved this work (permit MAAE-ARSFC-2021-1403). The Forest Dynamics Plot of Yasun\u00ED National Park has been made possible through the generous support of the Pontifical Catholic University of Ecuador (PUCE) funds of donaciones del impuesto a la renta, the government of Ecuador, the US National Science Foundation, the Andrew W. Mellon Foundation, the Smithsonian Tropical Research Institute, and the University of Aarhus of Denmark. Leah Genth was supported by an NSF International Research Experience for Students grant (award number 2107117) during this study. We thank the two anonymous reviewers and Francis Brearley, whose suggestions improved the manuscript.
| Funders | Funder number |
|---|---|
| National Science Foundation | |
| University of Aarhus of Denmark | |
| Andrew W. Mellon Foundation | |
| Pontifical Catholic University of Ecuador | |
| Smithsonian Tropical Research Institute | |
| Office of International Science and Engineering | 2107117 |
| Pontificia Universidad Católica del Ecuador and Yasuní Scientific Research Station | MAAE-ARSFC-2021-1403 |
Keywords
- dioecy
- female
- lowland tropical forest
- standing herbivory
- understory
