Table of Contents
Journal of Botany
Volume 2010, Article ID 612017, 7 pages
http://dx.doi.org/10.1155/2010/612017
Research Article

On the Relationship between Pollen Size and Genome Size

1Department of Biological Sciences, California Polytechnic State University, San Luis Obispo, CA, USA
2Department of Botany, Institute of Ecology and Earth Science, University of Tartu, Tartu, Estonia
3Robinson College, Cambridge, CB3 9AN, UK
4Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, USA

Received 22 December 2009; Accepted 2 April 2010

Academic Editor: Ilia Judith Leitch

Copyright © 2010 Charles A. Knight et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Here we test whether genome size is a predictor of pollen size. If it were, inferences of ancient genome size would be possible using the abundant paleo-palynolgical record. We performed regression analyses across 464 species of pollen width and genome size. We found a significant positive trend. However, regression analysis using phylogentically independent contrasts did not support the correlated evolution of these traits. Instead, a large split between angiosperms and gymnosperms for both pollen width and genome size was revealed. Sister taxa were not more likely to show a positive contrast when compared to deeper nodes. However, significantly more congeneric species had a positive trend than expected by chance. These results may reflect the strong selection pressure for pollen to be small. Also, because pollen grains are not metabolically active when measured, their biology is different than other cells which have been shown to be strongly related to genome size, such as guard cells. Our findings contrast with previously published research. It was our hope that pollen size could be used as a proxy for inferring the genome size of ancient species. However, our results suggest pollen is not a good candidate for such endeavors.