Abstract
All multicellular organisms are genetic mosaics owing to somatic mutations. The accumulation of somatic genetic variation in clonal species undergoing asexual (or clonal) reproduction may lead to phenotypic heterogeneity among autonomous modules (termed ramets). However, the abundance and dynamics of somatic genetic variation under clonal reproduction remain poorly understood. Here we show that branching events in a seagrass (Zostera marina) clone or genet lead to population bottlenecks of tissue that result in the evolution of genetically differentiated ramets in a process of somatic genetic drift. By studying inter-ramet somatic genetic variation, we uncovered thousands of single nucleotide polymorphisms that segregated among ramets. Ultra-deep resequencing of single ramets revealed that the strength of purifying selection on mosaic genetic variation was greater within than among ramets. Our study provides evidence for multiple levels of selection during the evolution of seagrass genets. Somatic genetic drift during clonal propagation leads to the emergence of genetically unique modules that constitute an elementary level of selection and individuality in long-lived clonal species.
| Original language | English |
|---|---|
| Pages (from-to) | 952-962 |
| Number of pages | 11 |
| Journal | Nature Ecology and Evolution |
| Volume | 4 |
| Issue number | 7 |
| DOIs | |
| Publication status | Published - 2020 |
| MoE publication type | A1 Journal article-refereed |
Funding
This study was supported by a four-year PhD scholarship from the China Scholarship Council to L.Y. and by a fellowship from the Åbo Akademi University Foundation to C.B. We thank J. L. Olsen and B. Werner for helpful comments on earlier versions of the manuscript and in particular I. Baums for discussing methods for sequencing-independent SNP verification via restriction enzyme digestion. We thank the Archipelago Centre Korpoström (Finland) for excellent working facilities, K. Gagnon for field assistance and S. Landis for creating some of the illustrations. Sampling permit no. MH 5448/2015 was granted through Parks and Wildlife Finland (Metsähallitus).