Centre for Applied Ecology "Prof. Baeta Neves"/INBIO, Instituto Superior of Agronomy, University of Lisbon, Lisbon, Portugal.
Departamento de Ecología Integrativa, Estación Biológica de Doñana (EBD), Consejo Superior de Investigaciones Científicas (CSIC), Sevilla, Spain.
Plant Biol (Stuttg). 2019 Jul;21(4):695-705. doi: 10.1111/plb.12982. Epub 2019 Apr 4.
Investigating spatial variation in the relative importance of sexual reproduction and clonal propagation is critical to obtain more accurate estimates of future effective population sizes and genetic diversity, as well as to identify ecological correlates of clonality. We combined a stratified sampling scheme with microsatellite genetic analyses to estimate variation in the proportion of sexual versus clonal recruits among saplings in five populations of the tree Pyrus bourgaeana. Using a likelihood framework, we identified clones among the genotypes analysed and examined variation among populations regarding the proportion of saplings coming from clonal propagation. We also examined the relationship between the relative abundance of clonal shoots across the studied populations and their herbivory levels. Our results revealed that one third of the saplings examined (N = 225 saplings) had a probability above 0.9 of being clones of nearby (<10 m) trees, with the ratio between clonal propagation and sexual recruitment varying up to eight-fold among populations. A small portion of these putative clonal shoots reached sexual maturity. Relative abundance of clonal shoots did not significantly relate to the herbivory by ungulates. Our results call into question optimistic expectations of previous studies reporting sufficient levels of recruitment under parental trees without animal seed dispersal services. Nevertheless, given that some of these clonal shoots reach sexual maturity, clonal propagation can ultimately facilitate the long-term persistence of populations during adverse periods (e.g. environmental stress, impoverished pollinator communities, seed dispersal limitation).
调查有性繁殖和克隆繁殖的相对重要性的空间变化对于获得更准确的未来有效种群大小和遗传多样性估计，以及识别克隆的生态相关性至关重要。我们结合分层抽样方案和微卫星遗传分析，估计了五个梨属（Pyrus bourgaeana）种群中小树苗中性繁殖与克隆繁殖后代的比例变化。我们使用似然框架识别了分析基因型中的克隆，并研究了种群之间来自克隆繁殖的树苗比例的变化。我们还研究了研究种群中克隆芽的相对丰度与它们的食草水平之间的关系。我们的研究结果表明，三分之一的受检树苗（N=225 棵树苗）有超过 0.9 的可能性是附近（<10 米）树木的克隆，克隆繁殖和有性繁殖的比例在种群之间变化高达八倍。这些假定的克隆芽中只有一小部分达到了性成熟。克隆芽的相对丰度与食草动物的食草行为没有显著关系。我们的研究结果对以前的研究报告中没有动物种子传播服务的情况下，在亲本树下有足够的繁殖水平的乐观预期提出了质疑。然而，考虑到其中一些克隆芽达到了性成熟，克隆繁殖最终可以在不利时期（例如环境压力、贫乏的传粉者群落、种子传播限制）促进种群的长期生存。
