Clonal Diversity and Fine-Scale Genetic Structure of a Keystone Species: Ilex aquifolium

Abstract

Resprouting species, such as English holly (Ilex aquifolium L.), can be severely affected by long-lasting forest management. In the present study, the clonal and fine-scale spatial genetic structure (FSGS) of English holly are evaluated in a sub-Mediterranean mixed forest of Central Spain, where this species was subjected to different and intense human interventions for centuries, including coppicing in dense structures and in open woody pastures. Using seven microsatellite loci, we assessed the contribution of clonal and sexual reproduction to the diversity of holly in both areas and the fine-scale genetic structure was evaluated. For the dense coppiced area, the results showed high clonal diversity derived mainly from stem resprouting. Stems were separated an average of 3 m and up to 10 m, and dense aggregations of stems sometimes included various genotypes. The results also showed recent seed recruitment leading to small unique and isolated genotypes. Furthermore, FSGS was detected at close distances as being stronger in the coppiced area than in the open woody pasture area, especially for individuals of greater diameter at breast height. The results obtained suggest that current management strategies are not negatively affecting the genetic diversity of this species.