Could the reproductive system explain the stability and long-term persistence in a natural hybrid zone of Petunia (Solanaceae)?

ABSTRACT The long-term success of populations is dependent on individual reproductive success, and in general, increased population size and genetic diversity contribute to population maintenance, reducing the risk of local extinction. Interspecific hybridization has consequences that can vary according to the hybrids' fate, which can be strongly influenced by the reproductive capacity of hybrids and canonical individuals from the contact zone. We examined the reproductive biology and morphology of two closely related Petunia (Solanaceae) species and their interspecific hybrids from Serra do Sudeste, Southern Brazil, and we measured their reproductive success under controlled conditions based on seed production and germination from five pollination treatments. We found differences in self-compatibility degree among individuals, lineages, and pollination treatments based on high total seed production (> 204,000 seeds) and germination (630 seedlings evaluated). No correlation was observed between corolla colour and reproductive success or between floral morphological traits and compatibility. High self-compatibility and inter-lineage compatibility can explain the hybrid populations' maintenance and origin, favouring the two analysed species' introgression.

摘要 种群的长期存续依赖于个体繁殖成功，总体而言，种群规模扩大与遗传多样性提升有助于种群维持，降低局域灭绝风险。种间杂交的后果会因杂交后代的命运而异，而这一命运很大程度上受杂交个体与接触带内亲本个体的繁殖能力影响。本研究以巴西南部塞拉杜苏德塞（Serra do Sudeste）地区的两个近缘矮牵牛属（Petunia）（茄科Solanaceae）物种及其种间杂交后代为研究材料，探究了其繁殖生物学与形态学特征，并设置五种授粉处理，在可控实验条件下以种子产量与发芽率为指标评估了各材料的繁殖成功情况。基于总计超过204000粒种子的产量以及对630株幼苗的发芽评估结果，本研究发现不同个体、谱系以及授粉处理间的自交亲和性存在差异。未观测到花冠颜色与繁殖成功之间存在相关性，花部形态性状与亲和性之间亦无显著关联。较高的自交亲和性与种间谱系亲和性能够解释杂交种群的维持与起源，进而促进所研究的两个物种间的遗传渐渗。