Abstract
Spatial genetic structure (SGS) of plants mainly depends on the effective population size and gene dispersal. Maternally inherited loci are expected to have higher genetic differentiation between populations and more intensive SGS within populations than biparentally inherited loci because of smaller effective population sizes and fewer opportunities of gene dispersal in the maternally inherited loci. We investigated biparentally inherited nuclear genotypes and maternally inherited chloroplast haplotypes of microsatellites in 17 tree populations of three wild cherry species under different conditions of tree distribution and seed dispersal. As expected, interpopulation genetic differentiation was 6–9 times higher in chloroplast haplotypes than in nuclear genotypes. This difference indicated that pollen flow 4–7 times exceeded seed flow between populations. However, no difference between nuclear and chloroplast loci was detected in within‐population SGS intensity due to their substantial variation among the populations. The SGS intensity tended to increase as trees became more aggregated, suggesting that tree aggregation biased pollen and seed dispersal distances toward shorter. The loss of effective seed dispersers, Asian black bears, did not affect the SGS intensity probably because of mitigation of the bear loss by other vertebrate dispersers and too few tree generations after the bear loss to alter SGS. The findings suggest that SGS is more variable in smaller spatial scales due to various ecological factors in local populations.
Highlights
Gene flow mediated by pollen and seed dispersal affects the ge‐ netic structure in plant populations
To study the expected higher interpopulation genetic differen‐ tiation and higher within‐population Spatial genetic structure (SGS) intensity in chloroplast haplotypes than in nuclear genotypes, we investigated 17 tree pop‐ ulations of three wild cherry species, Cerasus jamasakura (Koidz.) H
We examined chloroplast haplotypes in maternally inherited loci and nuclear genotypes in biparentally inherited loci
Summary
Gene flow mediated by pollen and seed dispersal affects the ge‐ netic structure in plant populations. To study the expected higher interpopulation genetic differen‐ tiation and higher within‐population SGS intensity in chloroplast haplotypes than in nuclear genotypes, we investigated 17 tree pop‐ ulations of three wild cherry species, Cerasus jamasakura (Koidz.) H. Interpopulation genetic differentiation parameters in nuclear genotypes FST(b)/(1 + FIS) (1 − FST(b)) and chloroplast haplotypes FST(m)/(1 − FST(m)) were obtained for every population pair in each species (Appendix S1). Sp in nuclear genotypes, Sp in chlo‐ roplast haplotypes, and the slope ratio bm/bb(1 + FIS), among the 17 populations under different conditions of tree distribution and seed dispersal. TA B L E 2 Indices of fine‐scale spatial genetic structure in nuclear genotypes and chloroplast haplotypes in tree populations of wild cherry species. A model selected to predict the slope ratio with the lowest AIC included no effects (Table S2)
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