The center–periphery hypothesis (CPH) states that the genetic diversity, genetic flow and population abundance of a species are highest at the center of the species’geographic distribution. However, most CPH studies have focused on geographic distance and have ignored ecological and historical effects. Studies using niche models to define the center and periphery of a distribution and the interactions among geographical, ecological and historical gradients have rarely been done in the framework of the CPH, especially in biogeographical studies of animal species. Here, we examined the CPH for a widely distributed arthropod, Tetranychus truncatus (Acari: Tetranychidae), in eastern China using three measurements: geographic distance to the center of the distribution (geography), ecological suitability based on current climate data  (ecology), and historical climate data from the last glacial maximum (history). We found that the relative abundances of different populations were more strongly related to ecology than to geography and history. Genetic diversity within populations and genetic differentiation among populations based on mitochondrial marker were only significantly related to history. However, the genetic diversity and population differentiation based on microsatellites were significantly related to all three CPH measurements. Overall, population abundance and genetic pattern cannot be explained very well by geography alone. Our results show that ecological gradients explain the variation in population abundance better than geographic gradients and historical factors, and that current and historical factors strongly influence the spatial patterns of genetic variation. This study highlights the importance of examining more than just geography when assessing the CPH.

In each location, spider mite samples for genetic analysis were collected and soaked in 95% ethanol for DNA extraction in the lab. DNA was extracted using Qiagen DNeasy Blood and Tissue Kits following the standard protocol (Qiagen Valencia, CA, USA). Microsatellite variation was genotyped at 14 loci developed by Ge et al. (2013) (TUFG6, TUFG12, TUFG33, TUFG18, TUFG169, TUFG130N) and Zhang et al. (2016) (TUGZ155, TUFZ4, TUFZ3, TUFZ 34, TUFZ30, TUFZ60, TUFZ23). PCR was performed using the protocol described by Zhang et al. (2016). Fragment lengths were sequenced in an ABI 3170 automated sequencer using LIZ-500 size standard. All allele scores were manually checked for quality and consistency.

Microsatellite type of Tetranychus truncatus populations from China using 14 loci