Population Genetics And Skull Morphology Of Midday Gerbil (Meriones Meridianus)

Midday gerbil (Meriones meridianus Pallas,1773) belongs to Rodentia, Crietidae, Meriones. They are polyphagous and widely scattered in areas of desert or semi-desert in Inner Mongolia, Sinkiang, Qinghai, Gansu province and other places. Adaptive evolution of Midday gerbils, as a land desertification indicator, is closely related to the change of living environment.Taking the skull and Cyt b of mtDNA of Midday gerbil as the research objects, the morphological differences between-and within-population and molecular genetic variation were studied. And the systematic relationship, which conclude from morphological differences and molecular genetic variation of midday gerbil, were discussed.Morphology of skull:The results of data processing (coefficient of variation, correlation analysis and hierarchical clustering) about 32 skull measurements of 342 samples from 20 sampling points. The results are as follows. (1) Measurements are varies most inter-population (RZB (CV= 6.41%～13.93%), RLBBO (CV= 5.24%-14.15%), LSAB (CV= 5.66%～8.99%) and LTD (CV=2.78%～10.49%)) and inter-measurement (SAB (CV= 17.79%), SS (CV= 15.65%), LLCR (CV=9.60%) and GLN (CV= 8.13%)), all of above measurements in different population are significant difference (p< 0.05); (2) SAB, SS and LLCR exhibit a positive correlation (p<0.01) with altitude and latitude, wereas GLN exhibits a negative correlation (p <0.01) with altitude and latitude. (3)A11 populations gathered to two clusters:the first cluster (A) include 16 populations (LH, SGH, HTG, DSBY, YL, AX, SPT, ALR, JT, QM, MG, CS, YZ, NMH, MQ and GT), and the second cluster (B) include 4 populations (GRT, HC, ML and TLF).Molecular genetic analyses:To analyse genetic diversity and phylogeny of Midday gerbils, Cyt b gene (755 bp) of 292 samples collected from 23 sample points was sequenced and analysed. The results are as follows. (1) A high genetic diversity (S=103, h=93, Hdtottl= 0.966±0.005, Pitotal=0.0400±0.00234, ktotal= 30.220) were found in midday gerbil populations; (2) The genetic variation mainly benefited from interpopulational variation (75.47%) and intrapopulation (24.53%); (3) 23 populations were differentiated into two branchs:Mount Tianshan-Xinjiang cluster (ALR, GRT, HC, ML and TLF) and south Tianshan cluster (ALR, AX, CS, DSBY, EJN, GT, HM, HTG, JT, MG, MQ, NEG, QM, SGH, SPT, YL, WL, YW and YZ).Comprehensive analysis:(1) There are great differences in morphology and genetic diversity; (2) Based on the phylogeny produced by morphological differences and molecular genetic analyses, all Midday gerbils populations in China can be divided into two clusters (Mount Tianshan-Xinjiang cluster and South Mount Tianshan cluster); (3) The genetic variation cause may be the geographical isolation of Mount Tianshan; (4) The change of environmental factors of habitat has a effect on variation of adaptation of Midday gerbil. The research provides scientific basis for further study on phylogeography and adaptive mechanism.