1. Introduction
The extant species in the planet have evolved for hundreds of millions
of years. Evidence of climatic and environmental changes could be found
through the adaptation of species and the historical development of the
population within the species (Emerson et al ., 2001). Lucky
individuals survived when the environment had changed dramatically. They
migrated to the new habitat, and they settled, adapted and reproduced
there. In the process of adaptation, new behavioral, physiological and
genetic structure occurred (Avise et al ., 1998). Speciation
duration is about 1-2 Myr, but morphological, physiological and
behavioral changes may produce subspecies and species at almost any time
(Hewitt et al. , 2000). The current distribution and the
differentiation of species are compatible with the local geographical
and climatic environment (Udvardy, 1981). Insects have the relatively
rapid divergence rate (Orr et al ., 1998). Velarifictorus
micado , selected in our study, is widely distributed in Asia, included
China, Russia, Japan, Korea, Cambodia, Vietnam, Indonesia and nearby
islands, covering the Palearctic and Oriental realm, and the
distribution range of this cricket has gradually expanded since the
introduction of V. micado to the United States in 1959 (Alexander
and Walker, 1962; Bowles, 2018). Velarifictorus micado (Saussure,
1877) has been found to have two modes of life cycle. In a population
that diapause as eggs, adults sing from August to October, and their
eggs hatch after getting through the winter. In the other population
that diapause as nymphs, adults sing in May-July, hatch quickly after
mating and get through the winter as nymphs. Different adaptation types
of V. micado lead to differentiation of reproductive modes and
stimulate speciation among populations with different life cycle
patterns (He and Takeda, 2013). Aimed to find out which gene markers can
distinguish the two groups and the biogeographic boundary between them,
figure out why V. micado differentiate into two modes of life
cycle, mitochondrial fragments were extracted from the large sampling
specimens and used in phylogenetic analysis, time estimation and
demographic analysis.