Abstract
The plant bug, Nesidiocoris tenuis (Hemiptera: Miridae), is one of the most thermophilous dicyphines in agroecosystems and is widely distributed in China. Little is known regarding the genetic structure of N. tenuis and the effect of historical climatic fluctuations on N. tenuis populations. We analyzed partial sequences of three mitochondrial protein-coding genes (COI, ND2 and CytB) and nuclear genes (5.8S, ITS2 and 28S) for 516 specimens collected from 37 localities across China. Analyses of the combined mitochondrial dataset indicated that the Southwestern China group (SWC) was significantly differentiated from the remaining populations, other Chinese group (OC). Asymmetric migration and high level of gene flow across a long distance within the OC group was detected. The long-distance dispersal of N. tenuis might be affected by air currents and human interference. Both the neutrality tests and mismatch distributions revealed the occurrence of historical population expansion. Bayesian skyline plot analyses with two different substitution rates indicated that N. tenuis might follow the post-LGM (the Last Glacial Maximum) expansion pattern for temperate species. Pleistocene climatic fluctuation, complicated topography and anthropogenic factors, along with other ecological factors (e.g. temperature and air current) might have accounted for the current population structure of N. tenuis.
Highlights
N. tenuis is a model organism of biological control potential, and knowledge of its population genetics and associated factors is fundamentally crucial for species management and conservation strategies
According to Hebert[13], more than 98% of species pairs exceed 2% sequence divergence, but divergences of coding regions (COI) sequence in our study are much less than 2%, suggesting that our result is in the context of divergences within species
Our analyses based on the combined mitochondrial dataset suggested that SWC group was significantly differentiated from OC group, while the analyses of nuclear data showed an extensive level of shared haplotypes between groups
Summary
N. tenuis is a model organism of biological control potential, and knowledge of its population genetics and associated factors is fundamentally crucial for species management and conservation strategies. Multiple factors can influence population dynamics, genetic diversity and population structure[7]. Strong dispersal ability and human interference promote frequent gene flow between populations, which can decrease genetic subdivision within populations. The Quaternary Period has played an important role in shaping current distribution and genetic diversity of organisms on earth[10]. We investigated its genetic diversity, population structure and demographic history using sequences of mitochondrial and nuclear data. The objectives of this study were to (1) reveal the genetic distribution of N. tenuis related to current factors (geographical barriers, ecological factors and human interference); and (2) investigate demographic history of N. tenuis affected by Pleistocene climate fluctuation in China
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