Department of Botany, Swedish Museum of Natural History, Box 50007, SE-104 05 Stockholm, Sweden.
Department of Ecology, Environment and Plant Sciences, Stockholm University, SE-106 91 Stockholm, Sweden.
Ann Bot. 2023 Oct 4;132(1):29-42. doi: 10.1093/aob/mcad045.
Plants have evolved an unrivalled diversity of reproductive strategies, including variation in the degree of sexual vs. clonal reproduction. This variation has important effects on the dynamics and genetic structure of populations. We examined the association between large-scale variation in reproductive patterns and intraspecific genetic diversity in two moss species where sex is manifested in the dominant haploid generation and sex expression is irregular. We predicted that in regions with more frequent realized sexual reproduction, populations should display less skewed sex ratios, should more often express sex and should have higher genetic diversity than in regions with largely clonal reproduction.
We assessed reproductive status and phenotypic sex in the dioicous long-lived Drepanocladus trifarius and D. turgescens, in 248 and 438 samples across two regions in Scandinavia with frequent or rare realized sexual reproduction, respectively. In subsets of the samples, we analysed genetic diversity using nuclear and plastid sequence information and identified sex with a sex-specific molecular marker in non-reproductive samples.
Contrary to our predictions, sex ratios did not differ between regions; genetic diversity did not differ in D. trifarius and it was higher in the region with rare sexual reproduction in D. turgescens. Supporting our predictions, relatively more samples expressed sex in D. trifarius in the region with frequent sexual reproduction. Overall, samples were mostly female. The degree of sex expression and genetic diversity differed between sexes.
Sex expression levels, regional sex ratios and genetic diversity were not directly associated with the regional frequency of realized sexual reproduction, and relationships and variation patterns differed between species. We conclude that a combination of species-specific life histories, such as longevity, overall degree of successful sexual reproduction and recruitment, and historical factors are important to explain this variation. Our data on haploid-dominated plants significantly complement plant reproductive biology.
植物进化出了无与伦比的生殖策略多样性，包括有性繁殖和无性繁殖程度的变化。这种变化对种群的动态和遗传结构有重要影响。我们研究了两种藓类植物中生殖模式的大范围变化与种内遗传多样性之间的关系，这两种植物的有性生殖在占优势的单倍体世代中表现出来，且性别表现不规则。我们预测，在有更多实现有性生殖的地区，种群的性别比例应该不那么偏斜，表现出性别的频率应该更高，遗传多样性应该比以无性繁殖为主的地区更高。
我们评估了在两个区域的 248 个和 438 个样本中的二形长寿命藓类植物 Drepanocladus trifarius 和 D. turgescens 的生殖状态和表型性别，这两个区域分别具有频繁或罕见的有性生殖。在样本的子集中，我们使用核和质体序列信息分析了遗传多样性，并在非生殖样本中使用性别特异性分子标记识别了性别。
与我们的预测相反，性别比例在两个区域之间没有差异；在 D. trifarius 中遗传多样性没有差异，而在 D. turgescens 中则在有性生殖罕见的区域更高。支持我们的预测，在有性生殖频繁的区域，D. trifarius 中更多的样本表现出了性别。总体而言，样本主要是雌性。性表达水平、区域性别比例和遗传多样性与区域有性生殖的频率没有直接相关，而且物种之间的关系和变化模式也不同。我们得出结论，特定物种的生活史，如长寿、总体有性生殖成功率和繁殖，以及历史因素的综合作用，对解释这种变化很重要。我们对以单倍体为主的植物的数据极大地补充了植物生殖生物学。
