Department of Ecology Evolution and Marine Biology, University of California Santa Barbara, Santa Barbara, CA, USA.
Programa Educativo de Licenciado en Ecología, Universidad Estatal de Sonora, Hermosillo, Sonora, Mexico.
Heredity (Edinb). 2023 Apr;130(4):251-258. doi: 10.1038/s41437-023-00597-7. Epub 2023 Feb 14.
Seed size affects individual fitness in wild plant populations, but its ability to evolve may be limited by low narrow-sense heritability (h). h is estimated as the proportion of total phenotypic variance (σ) attributable to additive genetic variance (σ), so low values of h may be due to low σ (potentially eroded by natural selection) or to high values of the other factors that contribute to σ, such as extranuclear maternal effects (m) and environmental variance effects (e). Here, we reviewed the published literature and performed a meta-analysis to determine whether h of seed size is routinely low in wild populations and, if so, which components of σ contribute most strongly to total phenotypic variance. We analyzed available estimates of narrow-sense heritability (h) of seed size, as well as the variance components contributing to these parameters. Maternal and environmental components of σ were significantly greater than σ, dominance, paternal, and epistatic components. These results suggest that low h of seed size in wild populations (the mean value observed in this study was 0.13) is due to both high values of maternally derived and environmental (residual) σ, and low values of σ in seed size. The type of breeding design used to estimate h and m also influenced their values, with studies using diallel designs generating lower variance ratios than nested and other designs. e was not influenced by breeding design. For some breeding designs, the number of genotypes included in a study also influenced the resulting h and e estimates, but not m. Our data support the view that a diallel design is better suited than the alternatives for the accurate estimation of σ in seed size due to its factorial design and the inclusion of reciprocal crosses, which allows the independent estimation of both additive and non-additive components of variance.
种子大小会影响野生植物种群中个体的适应性，但它的进化能力可能受到狭义遗传力（h）低的限制。h 被估计为总表型方差（σ）归因于加性遗传方差（σ）的比例，因此 h 值低可能是由于 σ 值低（可能被自然选择侵蚀）或其他导致 σ 值高的因素，例如核外母体效应（m）和环境方差效应（e）。在这里，我们回顾了已发表的文献，并进行了荟萃分析，以确定种子大小的 h 是否在野生种群中通常较低，如果是这样，哪些 σ 成分对总表型方差的贡献最大。我们分析了种子大小的狭义遗传力（h）的可用估计值，以及对这些参数有贡献的 σ 方差成分。σ 的母体和环境成分明显大于 σ、显性、父本和上位性成分。这些结果表明，野生种群中种子大小的 h 值较低（本研究中观察到的平均值为 0.13）是由于母体来源和环境（剩余）σ 值高，以及种子大小的 σ 值低所致。用于估计 h 和 m 的杂种设计类型也会影响它们的值，使用完全双列设计产生的方差比嵌套设计和其他设计低。e 不受杂种设计的影响。对于某些杂种设计，研究中包含的基因型数量也会影响最终的 h 和 e 估计值，但不会影响 m。我们的数据支持这样一种观点，即与替代方案相比，完全双列设计更适合于准确估计种子大小的 σ，因为它具有析因设计和包括互交，可以独立估计方差的加性和非加性成分。
