Instituto de Botánica del Nordeste (IBONE-CONICET-UNNE), Facultad de Ciencias Agrarias, Universidad Nacional del Nordeste (FCA-UNNE), 3400, Corrientes, Argentina.
Programa de Estudios Florísticos y Genética Vegetal, Instituto de Biología Subtropical (PEFyGV, IBS-UNaM-CONICET), 3300, Posadas, Argentina.
Plant Reprod. 2024 Mar;37(1):15-32. doi: 10.1007/s00497-023-00478-3. Epub 2023 Aug 11.
Interspecific comparison of two Paspalum species has demonstrated that mating systems (selfing and outcrossing) contribute to variation (genetically and morphologically) within species through similar but mutually exclusive processes. Mating systems play a key role in the genetic dynamics of populations. Studies show that populations of selfing plants have less genetic diversity than outcrossing plants. Yet, many such studies have ignored morphological diversity. Here, we compared the morphological and molecular diversity patterns in populations of two phylogenetically-related sexual diploids that differ in their mating system: self-sterile Paspalum indecorum and self-fertile P. pumilum. We assessed the morphological variation using 16 morpho-phenological characters and the molecular diversity using three combinations of AFLPs. We compared the morphological and molecular diversity within and among populations in each mating system. Contrary to expectations, selfers showed higher morphological variation within populations, mainly in vegetative and phenological traits, compared to outcrossers. The high morphological variation within populations of selfers led to a low differentiation among populations. At molecular level, selfing populations showed lower levels of genotypic and genetic diversity than outcrossing populations. As expected, selfers showed higher population structure than outcrossers (Phi = 0.301 and Phi = 0.108, respectively). Increased homozygous combinations for the same trait/locus enhance morphological variation and reduce molecular variation within populations in selfing P. pumilum. Thus, selfing outcomes are opposite when comparing morphological and molecular variation in P. pumilum. Meanwhile, pollen flow in obligate outcrossing populations of P. indecorum increases within-population molecular variation, but tends to homogenize phenotypes within-population. Pollen flow in obligate outcrossers tends to merge geographically closer populations; but isolation by distance can lead to a weak differentiation among distant populations of P. indecorum.
两种雀稗属物种的种间比较表明，交配系统（自交和异交）通过相似但相互排斥的过程，导致种内的变异（遗传和形态上）。交配系统在种群的遗传动态中起着关键作用。研究表明，自交植物的种群遗传多样性低于异交植物。然而，许多此类研究忽视了形态多样性。在这里，我们比较了两种在交配系统上不同的系统发育相关的有性二倍体植物的种群的形态和分子多样性模式：自交不育的雀稗 Paspalum indecorum 和自交可育的雀稗 P. pumilum。我们使用 16 个形态表型特征评估形态变异性，使用三种 AFLP 组合评估分子多样性。我们比较了每种交配系统中种群内和种群间的形态和分子多样性。与预期相反，自交种在种群内的形态变异较高，主要表现在营养和物候特征上，与异交种相比。自交种在种群内的高形态变异导致种群间的分化较低。在分子水平上，自交种群的基因型和遗传多样性水平低于异交种群。正如预期的那样，自交种的种群结构高于异交种（Phi=0.301 和 Phi=0.108）。相同性状/基因座的纯合组合增加会增加自交雀稗 P. pumilum 种群内的形态变异，减少分子变异。因此，当比较 P. pumilum 的形态和分子变异时，自交的结果是相反的。同时，在 P. indecorum 中，强制性异交种群的花粉流增加了种群内的分子变异，但往往使种群内的表型同质化。强制性异交种群中的花粉流倾向于合并地理上更近的种群；但距离隔离可能导致 P. indecorum 的远距离种群之间的分化较弱。
