Selection on floral traits through male fertility in a natural plant population |
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Authors: | Mark van Kleunen Jaroslaw Burczyk |
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Institution: | (1) Centre for Invasion Biology, School of Biological and Conservation Sciences, University of KwaZulu-Natal, P. Bag X01, Scottsville, Pietermaritzburg, 3209, South Africa;(2) Department of Genetics, Institute of Biology and Environmental Protection, University of Bydgoszcz, ul. Chodkiewicza 30, 85-064 Bydgoszcz, Poland |
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Abstract: | Most studies on selection in plants estimate female fitness components and neglect male mating success, although the latter
might also be fundamental to understand adaptive evolution. Information from molecular genetic markers can be used to assess
determinants of male mating success through parentage analyses. We estimated paternal selection gradients on floral traits
in a large natural population of the herb Mimulus guttatus using a paternity probability model and maximum likelihood methods. This analysis revealed more significant selection gradients
than a previous analysis based on regression of estimated male fertilities on floral traits. There were differences between
results of univariate and multivariate analyses most likely due to the underlying covariance structure of the traits. Multivariate
analysis, which corrects for the covariance structure of the traits, indicated that male mating success declined with distance
from and depended on the direction to the mother plants. Moreover, there was directional selection for plants with fewer open
flowers which have smaller corollas, a smaller anther–stigma separation, more red dots on the corolla and a larger fluctuating
asymmetry therein. For most of these traits, however, there was also stabilizing selection indicating that there are intermediate
optima for these traits. The large number of significant selection gradients in this study shows that even in relatively large
natural populations where not all males can be sampled, it is possible to detect significant paternal selection gradients,
and that such studies can give us valuable information required to better understand adaptive plant evolution.
Second affiliation for Mark Van Kleunen is temporary until February 2007. |
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Keywords: | Isozymes Natural selection Mating system Paternity Pollen dispersal Reproduction |
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