Project A.20

The pollination services offered by wild and managed bees play a crucial role in maintaining ecosystem health and stability, as well as human agriculture. However, many essential pollinators are currently facing severe population declines, which are attributed to a range of anthropogenic factors, such as climate change, habitat fragmentation, and increased pesticide use. Moreover, many of these species also lack genomic resources, which are key for conservation genomics approaches, which this project aims to help address.

Solitary bees pose a particularly vulnerable group of insect pollinators as they lack the buffering capacities associated with their social relatives, such as honey bees and bumble bees, which are predicted to help mitigate the impacts of environmental stressors (Straub et al., 2015). Moreover, despite constituting more than 75% of all bee species (Danforth et al., 2019), our understanding of solitary bees suffers from a scarcity of resources and studies. Thus, strategies to safeguard natural populations must rely on research performed on social bees, which may not always be generalizable.

A powerful approach for assessing how populations will respond to ongoing and future challenges is population genomics, which can provide high-quality insights into millions of genomic bases simultaneously across individuals within a population. Such approaches have been increasingly used in conservation genomics to inform on genetic variation (Colgan et al., 2022), demographic history and population structure (Hohenlohe et al., 2020), and targets of selection (Nielsen, 2005) to assess the genetic adaptation and adaptive potential of wild populations (Eizaguirre & Baltazar-Soares, 2014).

However, such analyses and associated resources are largely missing for solitary bees. This not only restricts our fundamental understanding of their biology, but also our ability to assess and address the specific challenges they are facing, highlighting the urgency of comprehensive studies and conservation efforts.

Therefore, in this project, I will study the genetic variation and selection patterns in populations of three representative solitary bees:

1. the red mason bee (Osmia bicornis, Family: Megachilidae)
2. the orange-tailed mining bee (Andrena haemorrhoa, Family: Andrenidae)
3. the hairy-footed flower bee (Anthophora plumipes, Family: Apidae)

To provide insights into how solitary bee species adapt to changing local environments, I am pursuing the following aims:

1. Comparing currently available genomic resources in public online databases across all bee families to determine the appropriateness of existing datasets for conservation purposes.
2. Investigating intraspecific genetic variation, effective population size, demographic history, population-scaled recombination rates, population structure and gene flow for three common solitary bees using samples from wild populations across Germany.
3. Assessing the extent and targets of recent selection, as well as their conservation, as conserved targets of selection would provide insight into genetic adaptation to common pressures in the local environment.
4. Comparing and contrasting genetic diversity and signatures of selection between solitary and social bees to understand whether solitary bees harbor lower diversity or reduced patterns of selection.

Collectively, this study will represent one of the first population genomic analyses of solitary bees and thus greatly add to our understanding of their biology. Comparisons with social bees will allow for a preliminary assessment of the applicability of findings in social bees to their solitary relatives.

By generating genomic datasets, reproducible code and pipelines, this project will also provide resources for further studies on solitary bees. Ultimately, these efforts will help aid the development of mitigation strategies and conservation schemes to protect this valuable, but vulnerable group of wild pollinators, thus contributing to the healthy functioning of both wild and anthropogenic ecosystems.