Low dispersal and ploidy differences in a grass maintain photosynthetic diversity despite gene flow and habitat overlap
| Autor: | Patrik Nosil, Vanja Milenkovic, Colin P. Osborne, Emma V. Curran, Graciela Sotelo, Jill K. Olofsson, Pascal-Antoine Christin, Oriane Hidalgo, Florence Nyirenda, Luke T. Dunning, Marjorie R. Lundgren, Ilia J. Leitch, Matheus E. Bianconi, Robyn F. Powell |
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| Přispěvatelé: | European Research Council, Natural Environment Research Council (UK), Royal Society (UK) |
| Rok vydání: | 2021 |
| Předmět: |
Gene Flow
0106 biological sciences 0301 basic medicine C4 photosynthesis Introgression Biology Poaceae 010603 evolutionary biology 01 natural sciences Intraspecific competition Molecular ecology Gene flow Polyploidy Population genomics 03 medical and health sciences Genetics Photosynthesis Hybridization Selection Ecosystem Ecology Evolution Behavior and Systematics Isolation by distance 2. Zero hunger Reproductive isolation 15. Life on land 030104 developmental biology Evolutionary biology Africa Biological dispersal Secondary contact |
| Zdroj: | Digital.CSIC: Repositorio Institucional del CSIC Consejo Superior de Investigaciones Científicas (CSIC) Digital.CSIC. Repositorio Institucional del CSIC instname |
| Popis: | Geographical isolation facilitates the emergence of distinct phenotypes within a single species, but reproductive barriers or selection are needed to maintain the polymorphism after secondary contact. Here, we explore the processes that maintain intraspecific variation of C4 photosynthesis, a complex trait that results from the combined action of multiple genes. The grass Alloteropsis semialata includes C4 and non-C4 populations, which have coexisted as a polyploid series for more than 1 million years in the miombo woodlands of Africa. Using population genomics, we show that there is genome-wide divergence for the photosynthetic types, but the current geographical distribution does not reflect a simple habitat displacement scenario as the genetic clusters overlap, being occasionally mixed within a given habitat. Despite evidence of recurrent introgression between non-C4 and C4 groups, in both diploids and polyploids, the distinct genetic lineages retain their identity, potentially because of selection against hybrids. Coupled with strong isolation by distance within each genetic group, this selection created a geographical mosaic of photosynthetic types. Diploid C4 and non-C4 types never grew together, and the C4 type from mixed populations constantly belonged to the hexaploid lineage. By limiting reproductive interactions between photosynthetic types, the ploidy difference probably allows their co-occurrence, reinforcing the functional diversity within this species. Together, these factors enabled the persistence of divergent physiological traits of ecological importance within a single species despite gene flow and habitat overlap. This work was funded by the European Research Council (grant ERC-2014-STG-638333) and the Natural Environment Research Council (grant NE/M00208X/1). M.E.B. is supported by the Royal Society (RGF\EA\181050) and P.A.C. is funded by a Royal Society University Research Fellowship (grant URF\R\180022). 1 INTRODUCTION 2 MATERIAL AND METHODS 2.1 Population sampling and determination of photosynthetic types 2.2 Estimation of genome sizes 2.3 Population-level RAD sequencing and genotyping 2.4 Phylogenetic analyses, population structure and tests for isolation by distance 2.5 Tests for introgression 2.6 Genome scans 3 RESULTS 3.1 Different photosynthetic types can co-occur in the same location 3.2 C4 and non-C4 types correspond to different genetic groups 3.3 In mixed populations, photosynthetic types are associated with distinct ploidy levels 3.4 Distinct genetic groups are maintained despite gene flow 3.5 Genetic differentiation is widespread across the genome 4 DISCUSSION 4.1 Photosynthetic types can share the same habitat 4.2 Low dispersal probably prevents the homogenization of photosynthetic types among diploids 4.3 Polyploidization enables co-occurrence of different photosynthetic types 5 CONCLUSIONS ACKNOWLEDGEMENTS AUTHOR CONTRIBUTIONS |
| Databáze: | OpenAIRE |
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