Canopy closure shapes clonal diversity and fine‐scale genetic structure in the dioecious understorey perennial Mercurialis perennis

Abstract

Summary 1.The degree of canopy closure can shape the dynamics of understorey plant populations that rely on clonal and sexual recruitment. Populations are expected to undergo declines in clonal diversity under conditions where recruitment from seed is temporally and spatially restricted. Localized seedling recruitment in clonal populations may also affect spatial genetic structure due to the clumping of genetically related genets. 2. Our major objective was to determine the effect of the degree of canopy closure on clonal diversity and spatial genetic structure in the rhizomatous, dioecious forest perennial Mercurialis perennis . As the distribution of the male and female shoots has been shown to be influenced by canopy openings, we paid special attention to the mediating role of the varying sex ratio. 3. We used genome-wide AFLP markers to fingerprint six populations of M. perennis along a light penetration gradient. 4. The proportion of male shoots in a population increased from 0.51 to 0.81 and male genet diversity decreased from 0.72 to 0.21 with increasing site illumination, in agreement with earlier reports of superior male growth in canopy openings. The most illuminated population, with the highest proportion of male shoots, was dominated by a few outsized, largely aggregated male clones (largest clone spreading over 10 m). 5. Overall clonal diversity (G/N: 0.31-0.74; mean: 0.52) and evenness strongly declined in well-lit sites, suggesting reduced sexual recruitment and the vast vegetative spread of a few locally welladapted male genets under canopy gaps. 6. Fine-scale genetic structure among genets was significant within all populations, but its degree tended to increase with an increased proportion of male shoots and reduced clonal diversity. Very localized recruitment due to a low seed dispersal capacity combined with the aggregated distribution of large gender-specific clones likely incurred this pattern. 7. Synthesis. Forest management practices such as the cutting and removal of trees and the establishment of paths decreased the degree of canopy closure. Many understorey herb populations flourish in these canopy gaps, reflected in a higher clonal diversity. We demonstrated, however, that increased illumination negatively affects genotypic and genetic diversity in the dioecious understorey herb M. perennis .

Use of Molecular Marker Information in the Construction of Polycrosses to Enhance Yield in a Lolium perenne Breeding Programme

“…Leaf material of all 30 parental plants was harvested for DNA extraction in March 2007. The AFLP marker information was generated according to Vandepitte et al (2009). Each individual was profiled with six primer combinations to generate polymorphic bands.…”

Clonality as a driver of spatial genetic structure in populations of clonal tree species

“…Clonal reproduction may increase geitonogamy (pollination among flowers within the same clone), affecting the outcrossing rate in the population (Carrillo-Angeles et al 2011). Prolonged clonal growth along with selection and/or inter-clonal competition may eliminate less adapted clones, leading to monoclonal patches (Vandepitte et al 2009) and/ or genetic impoverishment of a population (Silvertown 2008). Also, clonal reproduction may enhance SGS in natural plant populations which may have profound genetic consequences (Chung et al 2005;Chenault et al 2011;Binks et al 2015) On the other hand, clonality confers important ecological advantages, such as the foraging response of plants (Louâpre et al 2012), reallocation of resources between ramets enabling avoidance from environmental stochasticity, and withstanding environmental perturbations or division of labour between connected ramets (Fischer and Kleunen 2001).…”

Sex-specific pattern of spatial genetic structure in dioecious and clonal tree species, Populus alba L.

“…Spatial analysis also detected the non-random distribution of individuals (ramets) of both sexes in space (Table 2). This kind of clonal architecture is frequently reported in populations with significant SGS, which suggests that it may be one of the important factors supporting SGS (Vandepitte et al 2009;Mizuki et al 2010;Dodd et al 2013).…”