Species delimitation, discovery and conservation in a tiger beetle species complex despite discordant genetic data.

In an age of species declines, delineating and discovering biodiversity is critical for both taxonomic accuracy and conservation. In recent years, there has been a movement away from using exclusively morphological characters to delineate and describe taxa and an increase in the use of molecular markers to describe diversity or through integrative taxonomy, which employs traditional morphological characters, as well as genetic or other data. Tiger beetles are charismatic, of conservation concern, and much work has been done on the morphological delineation of species and subspecies, but few of these taxa have been tested with genetic analyses. In this study, we tested morphologically based taxonomic hypotheses of polymorphic tiger beetles in the Eunota circumpicta (LaFerté-Sénectère, 1841) species complex using multilocus genomic and mtDNA analyses. We find multiple cryptic species within the previous taxonomic concept of Eunota circumpicta, some of which were historically recognized as subspecies. We found that the mtDNA and genomic datasets did not identify the same taxonomic units and that the mtDNA was most at odds with all other genetic and morphological patterns. Overall, we describe new cryptic diversity, which raises important conservation concerns, and provide a working example for testing species and subspecies validity despite discordant data.

A genomic test of subspecies in the Eunota togata species group (Coleoptera: Cicindelidae): Morphology masks evolutionary relationships and taxonomy.

Most of the world's biodiversity is described primarily or exclusively using morphological traits that may not always reflect the true evolutionary units. Accurate taxonomy is critical for conservation efforts and re-evaluation of traditional taxonomy may often be warranted since species and subspecies are frequently the focus of conservation and faunistic studies. Here, we test comprehensive taxonomic hypotheses of morphologically defined subspecies in the tiger beetle, Eunota togata (LaFerté-Sénectère, 1841). The four recognized subspecies were delineated based mainly on the dorsal coloration and extent of white markings termed maculations. We combine inferences from mtDNA genealogies and genome-wide multilocus data to elucidate the evolutionary relationships within the group and assess the taxonomic implications. Three of the four subspecific taxa delineated by morphology were not supported by the genomic or mtDNA data. In fact, the species-level diversity in this group was underestimated, as E. togata was found to represent three well-supported distinct species in all genetic analyses. Emerging from these analyses, we also document an intriguing example of convergent evolution in lighter colored E. togata adapting to similar white saline backgrounds. Our collective work underscores the importance of using molecular methods to reevaluate morphological based taxonomy for species and subspecies delimitation and conservation.

Geographic Life History Differences Predict Genomic Divergence Better than Mitochondrial Barcodes or Phenotype.

Species diversity can be inferred using multiple data types, however, results based on genetic data can be at odds with patterns of phenotypic variation. Tiger beetles of the Cicindelidiapolitula (LeConte, 1875) species complex have been taxonomically problematic due to extreme phenotypic variation within and between populations. To better understand the biology and taxonomy of this group, we used mtDNA genealogies and multilocus nuclear analyses of 34,921 SNPs to elucidate its evolutionary history and evaluate the validity of phenotypically circumscribed species and subspecies. Genetic analyses recovered two divergent species that are also ecologically distinct, based on adult life history. These patterns are incongruous with the phenotypic variation that informed prior taxonomy, and most subspecies were not supported as distinct evolutionary lineages. One of the nominal subspecies was found to be a cryptic species; consequently, we elevate C. p.laetipennis (Horn, 1913) to a full species. Although nuclear and mtDNA datasets recovered broadly similar evolutionary units, mito-nuclear discordance was more common than expected, being observed between nearly all geographically overlapping taxonomic pairs. Additionally, a pattern of 'mitochondrial displacement' was observed, where mitochondria from one species unidirectionally displace others. Overall, we found that geographically associated life history factors better predict genomic divergence than phenotype and mitochondrial genealogies, and consequently taxon identifications based on mtDNA (e.g., DNA barcodes) may be misleading.