Mitonuclear discordance in wolf spiders: Genomic evidence for species integrity and introgression

Abstract

Systematists and taxonomists have benefited greatly from the emergence of molecular methods. Species identification has become straightforward through DNA barcoding and the rapid build-up of massive DNA barcode reference libraries. In animals, mitonuclear discordance can significantly complicate the process of species identification and delimitation. The causes of mitonuclear discordance are either biological (e.g., introgression, incomplete lineage sorting, horizontal gene transfer androgenesis) or induced by operational factors (e.g., human error with specimen misidentification or incorrect species delimitation). Moreover, endosymbionts may play an important role in promoting fixation of mitochondrial genomes. Here, we study the mitonuclear discordance of wolf spiders species (Lycosidae) (independent cases from Alopecosa aculeata and Pardosa pullata groups) that share identical COI DNA barcodes. We approached the case utilizing double-digest restriction site-associated DNA sequencing (ddRADseq) to obtain and analyse genomic-scale data. Our results suggest that the observed cases of mitonuclear discordance are not due to operational reasons but result from biological processes. Further analysis indicated introgression and that incomplete lineage sorting is unlikely to have been responsible for the observed discrepancy. Additional survey of endosymbionts provided ideas on further research and their role in shaping mitochondrial DNA distribution patterns. Thus, ddRADseq grants an efficient way to study the taxonomy of problematic groups with insight into underlying evolutionary processes.

Genome-scale data reveal the role of hybridization in lichen-forming fungi

“…open Scientific RepoRtS | (2020) 10:1497 | https://doi.org/10.1038/s41598-020-58279-x www.nature.com/scientificreports www.nature.com/scientificreports/ nuclear markers, which in turn can influence the genome in both adaptive and maladaptive ways 5,[19][20][21][22] . Adaptive introgression of mitochondrial DNA may play an important role in speciation and phylogeography 23,24 .While hybridization has been well-documented among pathogenic fungi 21,[25][26][27][28][29][30] , the role of hybridization on the process of speciation of fungal lineages with different life histories and ecological functions is not well understood, including among lichen-forming fungi. The role of gene flow and hybridization in lichen-forming fungal evolution has been a long-standing question [31][32][33][34][35] .…”

“…open Scientific RepoRtS | (2020) 10:1497 | https://doi.org/10.1038/s41598-020-58279-x www.nature.com/scientificreports www.nature.com/scientificreports/ nuclear markers, which in turn can influence the genome in both adaptive and maladaptive ways 5,[19][20][21][22] . Adaptive introgression of mitochondrial DNA may play an important role in speciation and phylogeography 23,24 .…”

Cryptic diversity in ant‐mimic Micaria spiders (Araneae, Gnaphosidae) and a tribute to early naturalists

“…Introgression through occasional hybridization needs certainly to be considered in morphologically and ecologically similar congeners that occur in sympatry. Recent genomic studies have shown that it may be more prevalent in spiders than previously assumed (Ivanov, Lee, & Mutanen, ; Leduc‐Robert & Maddison, ). However, we observed no single case of disagreement between morphology and mtDNA (i.e.…”

Evidence of hybridization, mitochondrial introgression and biparental inheritance of the kDNA minicircles in Trypanosoma cruzi I

“…Another question related to the mechanisms of genetic exchange in T. cruzi is the mitonuclear discordance observed in some DTUs. This phenomenon can be described as a significant difference in levels of differentiation between nuclear and mitochondrial markers, where nuclear phylogeny is more structured (higher number of and longer branches) than mitochondrial phylogeny (kDNA phylogeny in this case) [37]. In T. cruzi, mito-nuclear discordance is clearly observed in TcIII.…”