|TERFer Brenda Alvarado hard at work counting seeds|
The relationship between the plants and their pollinators is what Brenda has chosen to study for her project. She is partnered with a Tyson undergraduate fellow who is also studying pollinators, and she is taking ownership of parts of the fellow's project, doing the data collection, processing, and analysis herself (with some help from her mentors).
The question Brenda is asking is whether pollen limitation -- reduced access to pollen due to fewer visits by pollinators -- decreases the ability of some non-invasive exotic plants to make seeds. She is focusing on exotic species (species that are not native, but that do not massively disrupt the ecosystem) to explore a question related to the main project question: why are some exotic species not invasive? Trying to figure out what keeps some exotic species in check might help us determine how best to control invasive relatives of those species.
The two species Brenda is focusing on are Verbascum thapsis and Potentilla recta. For both species, the methods are the same: multiple flowers on the same plant are placed in different treatments -- pollen supplement, pollen limitation, and control -- and allowed to mature, and when they go to seed, the seeds are counted and collected to determine reproduction. In the pollen supplement treatment, pollen from another flower is added to the treatment flower using a paintbrush, which gives the flower an abundance of pollen to see if that increases reproduction. In the pollen limitation treatment, the flower is covered with a mesh bag to keep pollinators from getting to it, which might decrease reproduction. Nothing is done to the flower in the control treatment, which gives a baseline for reproduction. If adding pollen to the plant increases reproduction, that suggests that the species is pollen limited, and maybe poor visitation from pollinators in its new range is what is keeping it from becoming an invasive species.
Part of Brenda's work for her project involves going into the field to add pollen to the supplement flowers and check if the seeds are ready to be collected, and part involves counting seeds. For the larger pollination project, she repeats her methods on other invasive and native plants, and she also helps collect pollinators that visit focal species to get an idea of how the plants and pollinator network fit together. In addition, she helps with competitor removal treatments and measuring plants in the larger project plots and aids the other members of her team with their independent projects whenever they need help. Brenda is getting a wide range of experiences as a TERFer this summer.