Ecology and Evolution (Dec 2020)
The genetic differentiation of a cricket (Velarifictorus micado) with two modes of life cycle in East Asia after the middle Pleistocene and the invasion origin of the United States of America
Abstract
Abstract The cricket Velarifictorus micado is widely distributed in East Asia and colonized the United States of America (the USA) in 1959. It has two life cycles: one having egg diapause and the other having nymphal diapause. We aimed to investigate the biogeographic boundary between them and determine when and why V. micado diverged. Mitochondrial fragments including COI and CytB were used for haplotype network, demographic analysis, and divergence time estimation in individuals of East Asia. We selected several samples from the USA to find out the colonization origin. The haplotype network indicated there were three lineages based on COI, NE lineage (having egg diapause and mainly distributed in the northern regions), SE lineage (having egg diapause and mainly distributed in the south central regions), and SN lineage (the nymph diapause and mainly distributed in the deep south regions). The molecular chronograms indicated that the first divergence of V. micado into two main lineages, NE and southern lineages (SE and SN), was essentially bounded by the Yangtze River. It occurred around ~0.79 Ma (95% HPD: 1.13–0.46 Ma) in the Middle Pleistocene Transition. This was followed by the divergence of the southern lineage into two sublineages, SE and SN lineage, occurred around ~0.50 Ma (95% HPD: 0.71–0.25 Ma), corresponding to the time of development of glaciers in various parts of the Qinghai–Tibet Plateau (QTP) (0.73–0.46 Ma). SE lineage might originate from southwestern China based on the comparison between the haplotype network based on COI and CytB. Our study suggested that divergences of lineages have twice co‐occurred with the tendency of cooling climate in Asia after the Mid‐Pleistocene, and the life‐history strategy may play an important role in lineage diversification. The results suggest that US populations are originally established twice by independent colonization from the SE and NE. [Correction added on 02 June 2021 after first publication: the sixth sentence has been updated to clarify the distributions of the SE and SN lineages, which were originally described as being in the “southern regions”; the last sentence of the abstract has been rewritten for clarity.]
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