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S-allele diversity suggests no mate limitation in small populations of a self-incompatible plant

journal contribution
posted on 2021-02-10, 22:51 authored by R Holderegger, R Häner, D Csencsics, S Angelone, Susan HoebeeSusan Hoebee
Small populations of self-incompatible plants are assumed to be threatened by a limitation of compatible mating partners due to low genetic diversity at the self-incompatibility (S) locus. In contrast, we show by using a PCR-RFLP approach for S-genotype identification that 15 small populations (N = 8-88) of the rare wild pear (Pyrus pyraster) displayed no mate limitation. S-allele diversity within populations was high (N = 9-21) as was mate availability (92.9-100%). Although population size and S-allele diversity were strongly related, no relationship was found between population size and mate availability, gene diversity (He), or fixation index (F IS), based on five neutral microsatellite loci. As we determined the principal mate availability within populations based on the S-genotypes observed, the realized mate availability under natural conditions may differ from our estimates, for example, due to spatially limited pollen dispersal. We therefore urge studies on self-incompatible plants to proceed from the simple assessment of principal mate availability to the determination of realized mate availability in natural populations. © 2008 The Author(s).


We thank F. Gugerli, J. Kohn, U. Landergott, and two anonymous referees for constructive comments on the manuscript, and the private owners, forest authorities, and conservation organizations for the permission to work on their land. Financial support was provided by the Swiss Agency for the Environment (BAFU; project "Protection and Use of Forest Genetic Resources").


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(p. 2922-2928)





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