Epsilon Archive for Student Projects

Abstract

In the last decades, studies have shown a global decrease in pollinators. This is of great concern given the essential role that bees play in pollinating numerous crops, which is crucial for human sustenance. Habitat loss emerges as the primary threat to bees across Europe. Within this context, the Iberian Peninsula stands out in importance for pollinator research. It is a bee hotspot, comprising more than half of Europe’s total bee species, but at the same time lacking basic ecological knowledge for many species. The problem is not a lack of data but rather the lack of digitization and compilation of existing datasets.
As for this, three years ago, researchers at CSIC, Spain, launched an initiative with the aim of combining available observations on bees across the peninsula and creating a large open-source database. Initial data retrieval and data cleaning were carried out in 2022 (Bartomeus et al. 2022). The subject of this bachelor’s work was to tap in on this work. The objectives were to: 1) incorporate more datasets into the database using a reproducible workflow, 2) clean and process the data, 3) combine it with EU data on CORINE land cover, 4) calculate habitat preferences for a selection of wild common bee species, and 5) examine if habitat preferences could be explained by a species phenological or latitude breadth, or by its sociality.
With this bachelor’s work, the database grew in size from 87,684 records to 93,803, with the incorporation of new datasets, containing bee observations from as far back as 1830 up until year 2022. Habitat preferences were calculated for the 61 most common wild bee species using null models based on the observation data.
The most preferred habitat was found to be agricultural land; arable land and pastures and dehesas, particularly, suggesting that agricultural land in the Iberian Peninsula can support biodiversity alongside crop production. Andrena spp. was shown to have high preferences on pastures and dehesas, highlighting this habitat importance. Natural habitats were also highly preferred, and urban environments were found to be the least preferred. Despite this, urban environments were shown to host some bee species. This wide variety of habitat preferences demonstrates the importance of maintaining high-quality landscapes with a variety of habitats to effectively support bee populations.
Correlation analyses indicated no significant relationships between habitat preferences and phenological or latitude breadth, or sociality, suggesting other traits such as floral preferences, nesting behavior, and abiotic conditions may influence habitat choice.
The large database on Iberian bees makes it possible to conduct all kinds of analyses. Future research can delve deeper into understanding the underlying traits driving habitat preferences of Iberian bee species or explore other aspects such as population trends over time.