D'Andrea Rafael, Ostling Annette
Am Nat. 2016 Jan;187(1):130-5. doi: 10.1086/684116.
Community ecology lacks the success enjoyed by population genetics to quantify the relative roles played by deterministic and stochastic processes. It has been proposed that clustered patterns of abundance in genotype space provide evidence of selection in microbial communities, since no such clustering would arise in the absence of selection. We critique this test for its unrealistic null hypothesis. We show mathematically and with simulations that point mutations alone lead to clustering in genotype space by causing correlations between abundances of similar genotypes. We also show potential deviations from the mutation-only pattern caused by immigration from a source pool. Clustered patterns in genotype space may still be revealing of selection if analyzed quantitatively but only if neutral and selective regimes can be distinguished once mutation and immigration are included in the null model.
群落生态学不像种群遗传学那样成功地量化了确定性过程和随机过程所起的相对作用。有人提出，基因型空间中丰度的聚集模式为微生物群落中的选择提供了证据，因为在没有选择的情况下不会出现这种聚集。我们批评这种检验方法，因为它的零假设不现实。我们通过数学方法和模拟表明，仅点突变就会通过引起相似基因型丰度之间的相关性而导致基因型空间中的聚集。我们还展示了源库移民导致的与仅突变模式的潜在偏差。如果进行定量分析，基因型空间中的聚集模式可能仍然揭示了选择，但前提是在零模型中纳入突变和移民后，中性和选择机制能够被区分开来。
