ARE RELATIONSHIPS BETWEEN POLLEN–OVULE RATIO AND POLLEN AND SEED SIZE EXPLAINED BY SEX ALLOCATION?
Article first published online: 25 MAY 2011
© 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.
Volume 65, Issue 10, pages 3002–3005, October 2011
How to Cite
Burd, M. (2011), ARE RELATIONSHIPS BETWEEN POLLEN–OVULE RATIO AND POLLEN AND SEED SIZE EXPLAINED BY SEX ALLOCATION?. Evolution, 65: 3002–3005. doi: 10.1111/j.1558-5646.2011.01338.x
- Issue published online: 3 OCT 2011
- Article first published online: 25 MAY 2011
- Accepted manuscript online: 5 MAY 2011 09:41AM EST
- Received January 14, 2011, Accepted April 22, 2011
- Mating system;
- ovule number;
- pollen number;
- sex ratio;
Positive correlations between pollen–ovule ratio and seed size, and negative correlations between pollen–ovule ratio and pollen grain size have been noted frequently in a wide variety of angiosperm taxa. These relationships are commonly explained as a consequence of sex allocation on the basis of a simple model proposed by Charnov. Indeed, the theoretical expectation from the model has been the basis for interest in the empirical pattern. However, the predicted relationship is a necessary consequence of the mathematics of the model, which therefore has little explanatory power, even though its predictions are consistent with empirical results. The evolution of pollen–ovule ratios is likely to depend on selective factors affecting mating system, pollen presentation and dispensing, patterns of pollen receipt, pollen tube competition, female mate choice through embryo abortion, as well as genetic covariances among pollen, ovule, and seed size and other reproductive traits. To the extent the empirical correlations involving pollen–ovule ratios are interesting, they will need explanation in terms of a suite of selective factors. They are not explained simply by sex allocation trade-offs.