Reproductive biology of Eremanthus incanus (Less.) Less., an endemic exploited Asteraceae from Brazil

Key message

Eremanthus incanus depends on outcrossing for reproduction, and the loss of pollinators can severely compromise the viability of populations of this species.

Abstract

Pollination biology is crucial for understanding the processes underlying the sexual reproduction of plants and the long-term sustainability of populations, especially in the face of increasing anthropogenic pressures. In this context, we aimed to investigate the reproductive and pollination system of Eremanthus incanus, an endemic species from Brazil, predominantly distributed in the Campos Rupestres of the Espinhaço Range and subjected to intense exploitation pressure. We selected 15 mother trees, on which we applied three pollination treatments: open pollination, non-pollination, and manual cross-pollination. When the fruits reached maturation, we collected the material to evaluate fecundity (number of seeds formed). Subsequently, we conducted experiments that included germination under laboratory conditions, seedling emergence, and initial sapling growth under nursery conditions. All pollination treatments resulted in high fecundity. However, the non-pollination treatment was unsuccessful in germination and seedling emergence, inferring the existence of a self-incompatibility mechanism in E. incanus. Open pollination and manual cross-pollination methods were not statistically different regarding sapling survival and initial growth. Although survival rate decreased over time, it remained consistently high, and the increase in sapling height and diameter was modest at each assessment, reflecting a slow growth strategy. We concluded that E. incanus is dependent on pollinators and does not face pollen limitation in the studied area. Furthermore, the observed variability among mother trees highlights the complexity of the species’ reproductive ecology, emphasizing the importance of considering intraspecific diversity in conservation strategies.