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

Abstract

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,Cicindelaspp., have been used for biological diversity monitoring because of their diversity and the ease of recognition. The finding of an apparent hybrid zone amongCicindela denverensisCasey,Cicindela limbalisKlug, andCicindela splendidaHentz 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 whileC. denverensisappears to hybridize with bothC. limbalisandC. splendidawithin the hybrid zone, all three species maintain their integrity across most of their ranges, largely occupy unique geographic regions, and at leastC. denverensisandC. splendidacooccur in many areas with no evidence of hybridization. Evidence of hybridization betweenC. limbalisandC. splendidawas found at only two sites. Furthermore, breeding experiments with virginC. splendidaandC. denverensisshowed 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.