Studies On Molecular Ecology And Evolution Of Conandron Ramondioides (Gesneriaceae) Populations

Based on materials of 11 populations of Conandron ramondioides collected from SE China, we have carried out a study on the genetic variation of populations in C. ramondioides by analyzing on single nucleotide polymorphisms of the floral developmental gene Gcycl controlling the floral symmetry. This study aims to explore the molecular evolution of Gcycl gene and formation of the genetic diversity and structure of populations within C. ramondioides. And we have also discussed the potential implication of SNP marker in non-model organisms.The main conclusions are as follow:1. The populations of C. ramondioides are distributed in valley of mountain shady slope, and they are usually found on granite rock at the headstream under evergreen broadleaf forest. The investigated populations all lie in the similar native habitat, and the populations are small and fragmented. Individuals in populations are clumped and the number of individuals is correlative with the moisture degree. Seeds are dispersalmainly by water, and the force of the dehiscencing capsular fruit. Morphological observation shows that there are many unicellular glandular hairs on the petiole and leaf vena, and dense multi-cellular epidermal hairs on the sepal, bract and peduncle in some individuals of the QSh21 and JL04 populations. In other populations, the petiole, leaf vena, sepal, bract and peduncle are smooth. Therefore, we suggest that the populations of C. ramondioides from SE China belong to two ecotypes.2. 18 SNPs are detected within the analyzed 774bp of Gcycl gene of C. ramondioides, in which 11 SNPs are non-synonymous. Morphogenetic observation has shown that there is no obvious variation in the floral symmetry. This result suggests that these non-synonymous substitutions do not the secondary structure of coded protein. Therefore, we can conclude that the evolution of Gcycl gene at population level is in accord with the Neutral Theory.3. C. ramondioides processes a lower genetic diversity. Average heterozygosity, expected heterozygosity and observed heterozygosity are 0.041(±0.0318), 0.0952 (±0.1300), 0.0089(±0.0118), respectively. The most genetic diversity is due to variation between populations (Gst=0.546), and the genetic variation within population is small (Ht=0.097, Hs=0.042). The lower level genetic diversity within each population and higher genetic differentiation between populations were owing to the fragmented and isolated populations which frequent inbreeding and limited gene flow.4. The pair of genetic distance UPGMA cluster analysis between populations shows that the genetic distance among populations is not fully correlated with thegeographic distribution of the 11 populations in SE China. According to the ecology environment, reproductive pattern and paleogeography of C. ramondioides, we suggest that this species might be existed in present area during pre-glacial even in Tertiary before the separation of Taiwan, Ryukyu, Japan archipelago from Eurasia. Continuous distribution area might be fragmented into isolated populations both due to the climate change during ice age and human activity. The results of the pair of genetic distance UPGMA cluster analysis between populations support the conclusion that the populations of C. ramondioides from SE China belong to two ecotypes.5. Our results have shown that SNP is a useful molecular marker for the study on the population history in non-model organisms.