Habitat Associations of Coexisting Carrion Beetles (Subfamilies Nicrophorinae and Silphinae) in Southeastern Ontario

Abstract

The coexistence of closely related species is thought to play an important role in shaping and maintaining local diversity and community organization. However, competition for shared limiting resources can inhibit coexistence unless species can reduce overlap in resource requirements or minimize differences in competitive ability. Many co-occurring species avoid the costs of coexistence by diverging in habitat use through a process known as habitat partitioning, allowing them to spatially avoid potential competitors. Habitat partitioning appears common among coexisting species and is thought to have important consequences for the evolution of species and traits, and community structure. Yet, despite the commonness of habitat partitioning, little is known about how and when habitat partitioning occurs and its role in facilitating species coexistence. Here, we take the first steps to understanding the role habitat partitioning plays in facilitating coexistence between seven species of burying beetles (genus: Nicrophorus) by examining their habitat associations where they co-occur. We test the hypothesis that co-occurring Nicrophorus species in southeastern Ontario partition resources by associating with different habitat characteristics or distinct habitat types, potentially to facilitate coexistence. To test this idea, we conducted a large-scale survey of carrion beetle abundance and 54 quantitative habitat characteristics at 100 randomly generated sites spanning an environmentally diverse and heterogenous region of southeastern Ontario. We identified the habitat associations of six co-occurring Nicrophorus species and three other carrion beetle species in the subfamily Silphinae. Our findings indicate that co-occurring Nicrophorus species do differ in their habitat use in a pattern consistent with habitat partitioning. Specifically, three Nicrophorus species (Nicrophorus pustulatus, N. hebes, and N. marginatus) were found to be habitat specialists for the forest canopy, wetlands, and open fields, respectively. Three other Nicrophorus species (N. orbicollis, N. sayi, and N. tomentosus) were found to be habitat generalists with wider breadths of habitat use and high overlap in habitat use with some other species. Our findings suggest that habitat may be an important resource axis along which some Nicrophorus species partition, however, divergence along other resource axes is likely also important for facilitating Nicrophorus coexistence.