Bryan Rojas González
Mestrado | 1° ano
Plant species coexistence mediated by hummingbirds
Plant species coexistence mediated by hummingbirds
How biodiversity is maintained in most ecosystems is a question that many scientists are still trying to address. The called negative density dependence effect is known to stabilize and maintain diversity in several communities. Recent research point not just competitive but facilitative interactions as main population and community process drivers. In plant communities, an interplay of these forces are intimate related with resources, such as space, nutrients, light, thus, resource availability shape competition strength and direction. A clear example of this is facilitation via pollinator attraction by flower density in plant communities. In pollination networks, plants may compete for pollinators resulting in fitness outcomes due to pollen dispersion. On the other hand, high conspecific and heterospecific abundance of flowers can have facilitative effects on plant fitness. Furthermore, nectar sugar resource have also showed positive effects on plant fitness and especially in the attraction of hummingbird pollinators. Hummingbirds play an important role as effective pollinators in the Americas thus, testing the effect of facilitation on plant-hummingbird communities considering these approaches is necessary to have a better understanding of the processes underlying this system. Hence, in this study we aim to explore the effect of plant and flower density and fine-grained resource availability (nectar sugar content) to test dense-dependent responses on hummingbird visitation in a plant-hummingbird network in the Atlantic forest. In order to test this, we will use GPS data of plants to establish plots and quantify flower abundance to estimate conspecific and heterospecific density. We will use sugar quantity of nectar and hummingbird visitation rate (visits per day) data from a southeastern Atlantic forest, Espirito Santo. Data was taken in a monthly basis for 9 months from November 2018 to July 2019. Data will be analyzed with GLMs to quantify the effect of flower abundance and nectar sugar content on hummingbird visitation rate. We expect a positive relation of nectar sugar content and hummingbird visitation rate. We expect that flower visitation by hummingbirds will present a negative dense-dependent response on abundant plant species (high conspecific flower density) but a positive dense-dependent response on rare species (low conspecific density).