Variation, sex, and social cooperation: molecular population genetics of the social amoeba Dictyostelium discoideum
| Autor: | Michael D. Purugganan, David C. Queller, Elizabeth A. Ostrowski, Gerda Saxer, Jonathan M. Flowers, Joan E. Strassmann, Si. I. Li, Angela Stathos |
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| Jazyk: | angličtina |
| Rok vydání: | 2010 |
| Předmět: |
0106 biological sciences
Cancer Research Linkage disequilibrium lcsh:QH426-470 Population Molecular Sequence Data Population genetics Single-nucleotide polymorphism 010603 evolutionary biology 01 natural sciences Polymorphism Single Nucleotide Dictyostelium discoideum Linkage Disequilibrium Nucleotide diversity Evolution Molecular 03 medical and health sciences Species Specificity Genetics Ecology/Behavioral Ecology Dictyostelium 10. No inequality education Molecular Biology Genetics (clinical) Ecology Evolution Behavior and Systematics Phylogeny 030304 developmental biology 0303 health sciences education.field_of_study Evolutionary Biology biology Base Sequence Human evolutionary genetics Genetic Variation biology.organism_classification lcsh:Genetics Evolutionary Biology/Microbial Evolution and Genomics North America Social evolution Research Article |
| Zdroj: | PLoS Genetics, Vol 6, Iss 7, p e1001013 (2010) PLoS Genetics |
| ISSN: | 1553-7404 1553-7390 |
| Popis: | Dictyostelium discoideum is a eukaryotic microbial model system for multicellular development, cell–cell signaling, and social behavior. Key models of social evolution require an understanding of genetic relationships between individuals across the genome or possibly at specific genes, but the nature of variation within D. discoideum is largely unknown. We re-sequenced 137 gene fragments in wild North American strains of D. discoideum and examined the levels and patterns of nucleotide variation in this social microbial species. We observe surprisingly low levels of nucleotide variation in D. discoideum across these strains, with a mean nucleotide diversity (π) of 0.08%, and no strong population stratification among North American strains. We also do not find any clear relationship between nucleotide divergence between strains and levels of social dominance and kin discrimination. Kin discrimination experiments, however, show that strains collected from the same location show greater ability to distinguish self from non-self than do strains from different geographic areas. This suggests that a greater ability to recognize self versus non-self may arise among strains that are more likely to encounter each other in nature, which would lead to preferential formation of fruiting bodies with clonemates and may prevent the evolution of cheating behaviors within D. discoideum populations. Finally, despite the fact that sex has rarely been observed in this species, we document a rapid decay of linkage disequilibrium between SNPs, the presence of recombinant genotypes among natural strains, and high estimates of the population recombination parameter ρ. The SNP data indicate that recombination is widespread within D. discoideum and that sex as a form of social interaction is likely to be an important aspect of the life cycle. Author Summary Theories on the evolution of cooperation sometimes hinge on knowledge of genetic relatedness between individuals. Dictyostelium discoideum has been a model for the study of key biological phenomena, including the evolution and ecology of social cooperation, but the nature of genetic variation within this species is largely unknown. We determine the levels and patterns of molecular variation in this social species. We find a preference of genetically identical cells to cooperate with each other in forming fruiting bodies, a phenomenon known as kin discrimination. Kin discrimination, however, does not appear to be correlated with overall DNA divergence of the strains. Instead, familiarity appears to breed contempt, as strains from the same geographic location (which possibly encounter each other) show higher levels of kin discrimination than strains found further apart. We also show that sex, which is rarely observed in the laboratory, appears to be widespread in the wild—an interesting finding given that sex in D. discoideum is also associated with cooperation between numerous single cells to feed the developing cannibalistic zygote. The finding that sex may occur more frequently in the wild opens the possibility of conducting controlled laboratory matings and developing D. discoideum as a genetic model system. |
| Databáze: | OpenAIRE |
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