Building eco-evolutionary hypotheses for Chalepogenus oil-collecting bees

Species abiotic and biotic ecological preferences and the interaction of these choices can shape biodiversity’s ecology and evolution. Specifically, abiotic gradients in climatic preferences and geographic ranges, as well as biotic specialized interspecific relationships could act as drivers of species diversification. Understanding these factors helps to define and later testing evolutionary hypotheses of diversification.

The South American oil-collecting bee genus Chalepogenus (Apidae: Tapinotaspidini) includes taxa specialized on different oil-host plants, and with diverse ranges and climatic preferences. The combination of the highly specialized biotic interactions and diverse abiotic gradients mean this genus is ideal to observe the effects of drivers of diversification in evolution. However, these bees are understudied, and their ecology and evolution are both poorly known. Here, we investigate the ecological preferences of these species to build eco-evolutionary hypotheses to be tested in a phylogenetic framework.

With a thorough literature and museum collection review, we collected information on species occurrences, floral-oil hosts, and climatic preferences. We then used the current taxonomic definitions to identify patterns in their ecological preferences and analyzed these patterns to define testable evolutionary hypotheses on the effect of these preferences as drivers of diversification of the genus.

Our results allow us to formulate a series of non-exclusive hypotheses related to the effect of floral-oil host choice, the uplift of the Andes, and the establishment of South-American grasslands, and the combination of climatic preferences, range, and host-plants as driving the evolution of the group.