Unraveling the habitat preferences of two closely related bumble bee species in Eastern Europe. Issue 11 (15th April 2020)

• Record Type: Journal Article
• Authors: Geue, Julia C.; Thomassen, Henri A.
• Is Part Of: Ecology and evolution. Volume 10:Issue 11(2020)
• Page Start: 4773
• Page End: 4790
• Publication Date: 2020-04-15
• Subjects: Bombus lucorum -- Bombus terrestris -- Eastern Europe -- pollinators -- random forests -- relative abundance -- species distribution; Ecology -- Periodicals; Evolution -- Periodicals; 577.05
• DOI: 10.1002/ece3.6232
• Languages: English
• ISSNs: 2045-7758

Abstract

Abstract: Co‐occurrence of closely related species is often explained through resource partitioning, where key morphological or life‐history traits evolve under strong divergent selection. In bumble bees (genus Bombus ), differences in tongue lengths, nest sites, and several life‐history traits are the principal factors in resource partitioning. However, the buff‐tailed and white‐tailed bumble bee ( Bombus terrestris and B. lucorum respectively) are very similar in morphology and life history, but their ranges nevertheless partly overlap, raising the question how they are ecologically divergent. What little is known about the environmental factors determining their distributions stems from studies in Central and Western Europe, but even less information is available about their distributions in Eastern Europe, where different subspecies occur. Here, we aimed to disentangle the broad habitat requirements and associated distributions of these species in Romania and Bulgaria. First, we genetically identified sampled individuals from many sites across the study area. We then not only computed species distributions based on presence‐only data, but also expanded on these models using relative abundance data. We found that B. terrestris is a more generalist species than previously thought, but that B. lucorum is restricted to forested areas with colder and wetter climates, which in our study area are primarily found at higher elevations. Both vegetation parameters such as annual mean Leaf Area Index and canopy height, as well as climatic conditions, were important in explaining their distributions. Although our models based on presence‐only data suggest a large overlap in their respective distributions, results on their relative abundance suggest that the two species replace one another across an environmental gradient correlated to elevation. The inclusion of abundance enhances our understanding of the distribution of these species, supporting the emerging recognition of the importance of abundance data in species distribution modeling. Abstract : We used genetic barcoding and species distribution models to disentangle the habitat requirements of two closely related bumble bee species in Romania and Bulgaria. We found that Bombus terrestris is a more generalist species than previously thought, but that B. lucorum is restricted to forested areas with colder and wetter climates. Models based on presence‐only data suggest a large overlap in their respective distributions, but results on their relative abundance suggest that the two species replace one another across an environmental gradient correlated to elevation.