Splendid Hybrids: The Effects of a Tiger Beetle Hybrid Zone onApparent Species Diversity

Nonexpert citizen groups are being used to monitor species to track ecosystem changes; however, challenges remain for proper identification, especially among diverse groups such as beetles. Tiger beetles, Cicindela spp., have been used for biological diversity monitoring because of their diversity and the ease of recognition. The finding of an apparent hybrid zone among Cicindela denverensis Casey, Cicindela limbalis Klug, and Cicindela splendida Hentz in central Nebraska prompted a detailed study of the biogeography of this species group within Nebraska, a test of characteristics that could be used by citizen scientists, and limited breeding experiments. This study suggests that while C. denverensis appears to hybridize with both C. limbalis and C. splendida within the hybrid zone, all three species maintain their integrity across most of their ranges, largely occupy unique geographic regions, and at least C. denverensis and C. splendida cooccur in many areas with no evidence of hybridization. Evidence of hybridization between C. limbalis and C. splendida was found at only two sites. Furthermore, breeding experiments with virgin C. splendida and C. denverensis showed that they are capable of producing hybrid larvae in the laboratory. The presence of morphological intergrades serves as a cautionary note when using biological indicator species.