Marilia Gaiarsa: Pollinator Behavior and Fitness

UC Merced assistant professor Marilia Palumbo Gaiarsa will present a seminar to the UC Davis Department of Entomology and Nematology (ENT) on "From Foraging to Fiitness: How Individual Behavior Shapes Plant-Pollinator Interactions" on Wednesday, Nov. 19 in 122 Briggs Hall.

Her seminar, set for 12:10 p.m., also will be on Zoom. The link: https://ucdavis.zoom.us/j/95882849672

"As pollinators move through ecological landscapes, the foraging decisions they make influence not only their short-term energetic balance but also plant reproduction and persistence—shaping the vulnerability of entire communities to extinction drivers," Gaiarsa writes in her abstract. "At the smallest scale, observed patterns emerge from how individuals within species exploit their resources, ultimately shaping population--and community--level structures. Understanding how individual behavior scales up to observed interactions is therefore key to predicting pollinator responses to stressors such as habitat destruction, heat waves, and species invasions."

"Our research," she said, "investigates how fine-scale drivers of individual foraging behavior —such as temperature, resource abundance, and functional traits—shape plant-pollinator interactions and fitness outcomes. In this talk, I will explore (i) how variations in resource availability affect interaction patterns and reproductive success, (ii) how temperature shapes foraging activity and dietary breadth, and (iii) how heatwaves affect the persistence of plant-pollinator interactions in California. By linking behavioral ecology to population persistence under environmental change, our work provides mechanistic insights into how pollination function can be maintained in a rapidly changing world."

A native of Brazil, Gaiarsa joined the UC Merced faculty in 2023. She holds a doctorate in ecology (2017) from the Universidade de São Paulo USP, Brazil. She received her master's degree (2010) and her bachelor's degree (2007) from Universidade Estadual Paulista UNESP, Botucatu, Brazil.

Gaiarsa served as a 2017-2018 postdoctoral fellow at UC Riverside and at the Bascompte lab at Zürich University, Switzerland. At UC Riverside, she was a 2018-2020 Chancellor's Fellow.

"​My ultimate goal is to contribute to the understanding of the intrinsic organization of biological communities and the role species interactions play in the maintenance and persistence of biodiversity. I started my career focusing on predator-prey interactions between snakes and frogs, working with different research groups, both in the lab and in the field," Gaiarsa says on her website. "I was  mesmerized by how complex network theory gives us insight into a deeper understanding of the inherent structure of entire communities of organisms, as well as understanding how species depend on one another. My focus has then shifted to mutualistic interactions, specifically plant-pollinator interactions."

Her current research addresses "different dimensions of ecological interactions to help build a mechanistic understanding of community structure and to unravel the mechanisms underlying biodiversity maintenance. At a smaller ecological scale, I am exploring how interactions change as communities assemble, and how individual patterns translate to the network scale and affect ecosystem function. At a larger scale, I am looking at how climate change affects species interactions."

One of her recent publications is "Hidden Effects of Habitat Restoration on the Persistence of Pollination Networks," published in August 2022 in Ecology Letters. "Past and recent studies have focused on the effects of global change drivers such as species invasions on species extinction. However, as we enter the United Nations Decade of Ecosystem Restoration, the aim must switch to understanding how invasive‐species management affects the persistence of the remaining species in a community. Focusing on plant‐pollinator interactions, we test how species persistence is affected by restoration via the removal of invasive plant species. Restoration had a clear positive effect on plant persistence, whereas there was no difference between across treatments for pollinator persistence in the early season, but a clear effect in late season, with higher persistence in unrestored sites. Network structure affected only pollinator persistence, while centrality had a strong positive effect on both plants and pollinators. Our results suggest a hidden effect of invasive plants—although they may compete with native plant species, invasive plants may provide important resources for pollinators, at least in the short term."