Abstract
The last Xerces blue butterfly was seen in the early 1940s, and its extinction is credited to human urban development. This butterfly has become a North American icon for insect conservation, but some have questioned whether it was truly a distinct species, or simply an isolated population of another living species. To address this question, we leveraged next-generation sequencing using a 93-year-old museum specimen. We applied a genome skimming strategy that aimed for the organellar genome and high-copy fractions of the nuclear genome by a shallow sequencing approach. From these data, we were able to recover over 200 million nucleotides, which assembled into several phylogenetically informative markers and the near-complete mitochondrial genome. From our phylogenetic analyses and haplotype network analysis we conclude that the Xerces blue butterfly was a distinct species driven to extinction.
Highlights
Understanding human impacts on biodiversity are essential for conservation
The results of our haplotype network generated from the CO1 barcode alignment containing 197 Glaucopsyche sequences show higher mitogenomic divergence in the network separating G. xerces and G. australis/pseudoxerces from all other G. lygdamus
Pairwise distances calculation of these sequences resulted in an average intraspecific mitogenomic divergence for G. lygdamus of 0.15% and for individuals of the xerces and australis/pseudoxerces clade 0.32 and 0.71%, respectively
Summary
Determining how insect species and populations are being affected by pesticide use, land-use modification and climate change are all active areas of research (reviewed in [1]), but we still understand relatively little about how insects are affected overall [2]. Urban development and disturbance of sandy soils caused the local loss of several species of Lupinus and Lotus, Lo. scoparius (Deerweed), its preferred larval host plant, and the resulting habitat change is thought to have brought about its extinction [3]. Its decline coincided with the introduction of Linepithema humile, the Argentine ant, into the region, and it has been proposed that this invasive ant may have contributed to species loss by outcompeting native ant species that tend and protect the caterpillars of G. xerces. L. humile is known to tend lycaenid larvae in other cases, and several studies have suggested that they may function to other ant symbionts of lycaenid larvae (e.g. [4,5])
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