Wolbachia Infections Mimic Cryptic Speciation in Two Parasitic Butterfly Species, Phengaris teleius and P. nausithous (Lepidoptera: Lycaenidae)

Abstract

Deep mitochondrial divergence within species may result from cryptic speciation, from phylogeographic isolation or from endosymbiotic bacteria like Wolbachia that manipulate host reproduction. Phengaris butterflies are social parasites that spend most of their life in close relationship with ants. Previously, cryptic speciation has been hypothesised for two Phengaris species based on divergent mtDNA sequences. Since Phengaris species are highly endangered, the existence of cryptic species would have drastic consequences for conservation and management. We tested for cryptic speciation and alternative scenarios in P. teleius and P. nausithous based on a comprehensive sample across their Palaearctic ranges using COI gene sequences, nuclear microsatellites and tests for Wolbachia. In both species a deep mitochondrial split occurring 0.65–1.97 myrs ago was observed that did not correspond with microsatellite data but was concordant with Wolbachia infection. Haplotypes previously attributed to cryptic species were part of the Wolbachia-infected clades. In both species remaining phylogeographic structure was largely consistent between mitochondrial and nuclear genomes. In P. teleius several mitochondrial and nuclear groups were observed in East Asia while a single haplogroup and nuclear cluster prevailed across continental Eurasia. Neutrality tests suggested rapid demographic expansion into that area. In contrast, P. nausithous had several mitochondrial and nuclear groups in Europe, suggesting a complex phylogeographic history in the western part of the species range. We conclude that deep intraspecific divergences found in DNA barcode studies do not necessarily need to represent cryptic speciation but instead can be due to both infection by Wolbachia and phylogeographic structure.

Controversial patterns of Wolbachia infestation in the social parasitic Maculinea butterflies (Lepidoptera: Lycaenidae)

“…Ritter et al (2013) tested the theory of cryptic speciation on a comprehensive sample across the Palaearctic ranges and revealed that deep mitochondrial divergence did not correspond with microsatellite data but was concordant with Wolbachia infection in both species. Haplotypes previously attributed to cryptic species were part of Wolbachia- nausithous.…”

“…The mitochondrial haplotype network which included also the sequences of Ritter et al (2013) (Fig. 1b).…”

“…At the same time, inflated diversity and deep splits in mitochondrial sequences proved to be in correspondence with different Wolbachia strains in M. nausithous (Bergsträsser, 1779) and M. teleius (Bergsträsser, 1779) (Ritter et al 2013), i.e. Wolbachia seems to have an influence on the mitochondrial DNA pattern of Maculinea hosts in different ways.…”

“…Wolbachia are also present in the social parasitic Maculinea butterflies (Sielezniew et al 2012;Patricelli et al 2013;Ritter et al 2013;Bereczki et al 2014). Reduced mitochondrial diversity refers to Wolbachia-induced selective sweeps in M. alcon ([Denis & Schiffermüller], 1775) and M. arion (Linnaeus, 1758) (Bereczki et al 2014;Patricelli et al 2013;Sielezniew et al 2012).…”

The taxonomic status of Cossus cossus afghanistanus (Lepidoptera, Cossidae) from Afghanistan: insights from molecular and morphological data

“…Nevertheless, several authors have pointed out that the phylogenetic studies, or species identification based on mtDNA alone, can be misleading as trees inferred from single markers sometimes display relationships that reflect the evolutionary history of individual genes rather than the species being studied (Ballard & Whitlock, 2004;Bensch et al, 2006). Moreover, mitochondrial introgression (Zakharov et al, 2009) and Wolbachia infection (Ritter et al, 2013) also can lead to erroneous phylogenetic reconstructions and species misidentification. Despite these limitations, level of genetic distances can provide indirect evidence for conspecifity/non-conspecifity of species being studied.…”