为了避免近亲繁殖抑郁症,植物已经进化出多样化的育种系统来支持异交,比如自我不兼容。然而,生物和非生物条件的变化会导致选择性压力,从而导致自我不相容性的破坏。向增加自交的转变通常与减少的花卉特征有关,对传粉者的吸引力较低,增加近亲繁殖。我们检验了一个假设,即自我不相容性的丧失,向自我受精(自体受精)的转变,自交综合征的伴随进化(与杂交相关的花性状减少)将导致Oenotherapriveris的近亲繁殖和种群分化增加。在它的范围内,该物种的育种系统和花卉性状发生了转变,从具有大花的自亲和种群到具有小花的自亲和种群。
我们进行了育种系统评估,在野外和受控条件下评估花卉性状,并使用RADseq数据测量种群遗传参数。
我们的结果揭示了从O.primiveris范围的西到东向自交综合征的双峰过渡。这种转变包括繁殖系统和交配系统的变化,花卉性状的减少(花直径,herkogamy,和气味产生),向更大的自体婚姻转变,减少遗传多样性,增加近亲繁殖。
观察到的变异强调了广泛研究的重要性,以了解种群和物种内的育种系统变异和自交综合征的进化。
To avoid inbreeding depression, plants have evolved diverse breeding systems to favor outcrossing, such as self-incompatibility. However, changes in biotic and abiotic conditions can result in selective pressures that lead to a breakdown in self-incompatibility. The shift to increased selfing is commonly associated with reduced floral features, lower attractiveness to pollinators, and increased inbreeding. We tested the hypothesis that the loss of self-incompatibility, a shift to self-fertilization (autogamy), and concomitant evolution of the selfing syndrome (reduction in floral traits associated with cross-fertilization) will lead to increased inbreeding and population differentiation in Oenothera primiveris. Across its range, this species exhibits a shift in its breeding system and floral traits from a self-incompatible population with large flowers to self-compatible populations with smaller flowers.
We conducted a breeding system assessment, evaluated floral traits in the field and under controlled conditions, and measured population genetic parameters using RADseq data.
Our results reveal a bimodal transition to the selfing syndrome from the west to the east of the range of O. primiveris. This shift includes variation in the breeding system and the mating system, a reduction in floral traits (flower diameter, herkogamy, and scent production), a shift to greater autogamy, reduced genetic diversity, and increased inbreeding.
The observed variation highlights the importance of range-wide studies to understand breeding system variation and the evolution of the selfing syndrome within populations and species.