Clonal diversity and spatial genetic structure in the long-lived herb, Prairie trillium

Correcting for Replicated Genotypes May Introduce More Problems Than it Solves

Across the tree of life, many organisms are able to reproduce clonally, via vegetative spread, budding or parthenogenesis. In population genetic analyses of clonally reproducing organisms, it is common practice to retain only a single representative per multilocus genotype. Though this practice of clone correction is widespread, the theoretical justification behind it has been very little studied. Here, I use individual-based simulations to study the effect of clone correction on the estimation of the genetic summary statistics HO, HS, FIS, FST, F''ST and Dest. The simulations follow the standard finite island model, consisting of a set of populations connected by gene flow, but with a variable rate of sexual versus asexual reproduction. The results of the simulations show that by itself, the inclusion of replicated genotypes does not lead to a deviation in the values of the summary statistics, except when the rate of sexual reproduction is less than about one in thousand. However, clone correction can introduce a strong deviation in the values of most of the statistics, when compared to a scenario of full sexual reproduction. For HS and FIS, this deviation can be informative about the process of asexual reproduction, but for FST, F''ST and Dest, clone correction can lead to incorrect conclusions. I therefore argue that clone correction is not strictly necessary, but can in some cases be insightful. However, when clone correction is applied, it is imperative that results for both the corrected and uncorrected data are presented.

Genetic diversity assessment of clonal plant Rosa persica in China

Rosa persica is considered a clonal plant because it is mainly propagated by clonal growth. Due to environmental degradation and habitat devastation, R. persica has been listed as a national second-class protected plant in China. However, the absence of research on wild populations of R. persica has impeded progress in formulating efficient conservation strategies. In this study, we investigated the clonal dispersal distance of R. persica to accurately determine the genetic diversity and population structure of the wild population in Xinjiang. We suggested that 20 m was the threshold distance with which to distinguish between different genets of plants. Based on this, we collated sequencing data from a total of 70 different genets of plants from 117 test samples. Eight populations of R. persica were primarily categorized into three subgroups: BL (Bole), TC (Tacheng) and CG (Changji). Of these, the CG subgroup exhibited the most genetic diversity. This research is the first to illustrates the clonal dispersal distance of R. persica, thus providing valuable reference guidelines for understanding the reproductive characteristics of clonal plants. In addition, the genetic diversity of R. persica provides a theoretical foundation for the formulation of conservation policies.

Clonal growth characteristics and diversity patterns of different Clintonia udensis (Liliaceae) diploid and tetraploid cytotypes in the Hualongshan Mountains

Polyploidization plays an important role in plant evolution and biodiversity. However, intraspecific polyploidy compared to interspecific polyploidy received less attention. Clintonia udensis (Liliaceae) possess diploid (2n = 2x = 14) and autotetraploid (2n = 4x = 28) cytotypes. In the Hualongshan Mountains, the autotetraploids grew on the northern slope, while the diploids grew on the southern slopes. The clonal growth characteristics and clonal architecture were measured and analyzed by field observations and morphological methods. The diversity level and differentiation patterns for two different cytotypes were investigated using SSR markers. The results showed that the clonal growth parameters, such as the bud numbers of each rhizome node and the ratio of rhizome branches in the autotetraploids were higher than those in the diploids. Both the diploids and autotetraploids appeared phalanx clonal architectures with short internodes between ramets. However, the ramets or genets of the diploids had a relatively scattered distribution, while those of the autotetraploids were relatively clumping. The diploids and autotetraploids all allocated more biomass to their vegetative growth. The diploids had a higher allocation to reproductive organs than that of autotetraploids, which indicated that the tetraploids invested more resources in clonal reproduction than diploids. The clone diversity and genetic diversity of the autotetraploids were higher than that of the diploids. Significant genetic differentiation between two different cytotypes was observed (P < 0.01). During establishment and evolution, C. udensis autotetraploids employed more clumping phalanx clonal architecture and exhibited more genetic variation than the diploids.