Dr Johanna Yourstone

Biography

I am an ecologist with a broad interest in how biodiversity responds to human-driven environmental change.

I did my Bachelor and Master's programs at Lund University, which included practical conservation work in the nature reserve Riet Vell in the Ebro Delta in Spain (5 months, 2013), work with children's educational material to protect raptors in Georgia (2012), and a Bachelor's thesis where I investigated the impact of seed-coating oil-seed rape with a neonicotinoid pesticide on the fitness of a solitary bee (2013-2014, part of Nature publication). 

In my PhD thesis (Dep. of Biology, Lund University, Sweden; 2023) I investigated the impact on bees of foraging resources that vary in space and time in agricultural landscapes, as well as the importance of bees and other pollinators on crop pollination. I worked in large-scale, often experimental, landscape systems, and mixed landscape ecological approaches with foraging theory to better understand how bees respond to changes in flower resource amount. For example, I investigated effects on bee fitness of spatial and temporal availability to a mass-flowering crop, as well as trees, and different forb groups. We discovered that oak, which is considered to be wind-pollinated, was one of the most important resources for a solitary bee. I also conducted research in Andhra Pradesh, South India, where we investigated the effect of landscape complexity on bees in agriculture, and found that insect pollination was much more important to chili crop pollination than previous thought.    

After my PhD I joined a team at the Centre for Environmental and Climate science in Lund, Sweden, where I used existing solitary bee and sophisticated remote sensing tree data, to investigate the importance of trees on bee abundance and diversity. I also joined the expert group in a project lead by the Swedish Research Council FORMAS, to work on a review and meta-analysis about the impact of crop diversity in time and space on biodiversity. 

Research Overview

I have a broad interest in how biodiversity responds to human-driven environmental change. My research focuses particularly on wild bees and the challenges they face in modern landscapes, such as the loss of flower-rich habitats and changes in the spatial and temporal distribution of floral resources.

A central theme in my work is understanding how bees with different functional traits respond to these challenges, and how competition between species influence responses. Methods I use include a combination of behavioural observations, field surveys of bees and plants, pollen analyses, and assessments of nesting success in real-world settings.

During my three-year postdoctoral position in Aberdeen (2024-2027), I will focus on the impacts of competition and pathogen spillover from managed honeybees to rare bumblebee species. This work will include field studies in the Hebrides, a region home to several of these vulnerable bumblebees. In Aberdeen, I am eager to expand my methodological toolkit by incorporating molecular approaches, which will allow me to explore the underlying mechanisms of bees’ responses to environmental stressors in greater detail.

Current Research

My current three-year research project is exploring whether managed honeybees are affecting rare bumblebees, and if so, how.

Managed honeybees can compete with bumblebees for flowers and may also spread diseases to them. However, we do not yet know if this is a serious issue for rare bumblebee species that basically only remain in flower-rich places. This knowledge would help protect rare bumblebees that support pollination of wild plants and crops, and promote sustainable coexistence with managed honeybees.

I conduct fieldwork in bumblebee attractive machair habitat in the Hebrides. The area provides a unique opportunity to study responses in the rare bumblebees that reside there, as the beekeeping practices vary between islands; making it possible to compare bumblebees between sites and islands with and without honeybees. 

I use both ecological and molecular approaches to study potential honeybee impacts on rare bumblebees:

• Numbers and size
  Are there fewer bumblebees where there are honeybees? Are they smaller due to lack of food?
• Physiological stress
  Are bumblebees expressing genes, that relate to stress response, differently in presence of honeybees? 
• Virus transfer
  Are rare bumblebees infected by honeybee viruses in the Hebrides?
• Diet
  Is the bumblebee diet expanded or shifted in response to honeybees?

The project is funded by the Wenner-Gren Foundations, as a 3-year postdoctoral fellowship. I regularly give updates on the project's Instagram: HebriBees