Genetic structure in patchy populations of a candidate foundation plant: a case study of Leymus chinensis using genetic and clonal diversity

PREMISE: The distribution of genetic diversity on the landscape has
critical ecological and evolutionary implications. This may be especially
the case on a local scale for foundation plant species since they create
and define ecological communities, contributing disproportionately to
ecosystem function. METHODS: We examined the distribution of genetic
diversity and clones, which we defined first as unique multilocus
genotypes (MLG), and then by grouping similar MLGs into multilocus
lineages (MLL). We used 186 markers from inter-simple sequence repeats
(ISSR) across 358 ramets from 13 patches of the foundation grass Leymus
chinensis. We examined the relationship between genetic and clonal
diversities, their variation with patch-size, and the effect of the number
of markers used to evaluate genetic diversity and structure in this
species. RESULTS: Every ramet had a unique MLG. Almost all patches
consisted of individuals belonging to a single MLL. We confirmed this with
a clustering algorithm to group related genotypes. The predominance of a
single lineage within each patch could be the result of the accumulation
of somatic mutations, limited dispersal, some sexual reproduction with
partners mainly restricted to the same patch, or a combination of all
three. CONCLUSIONS: We found strong genetic structure among patches of L.
chinensis. Consistent with previous work on the species, the clustering of
similar genotypes within patches suggests that clonal reproduction
combined with somatic mutation, limited dispersal, and some degree
of sexual reproduction among neighbors causes individuals within
a patch to be more closely related than among patches.