Biology Reference
In-Depth Information
Figure 6.
Mean (SE) flower longevity for selfing and outcrossing species within each of 4 genus pairs. For each
species, n = 4 or 5. P - values are from ANOVA.
Discussion
There is a rich body of theory and empirical work on the evolution of selfing
in flowering plants [e.g. [1,2,4-7,9,10]], but practically none of it involves an
explicit role of selection involving time-limitation. The present paper is only the
second to explore the implications of the time-limitation hypothesis and contrib-
ute to the maturation of this idea. According to the time-limitation hypothesis,
selfing in annuals has evolved as a consequence of strong r-selection in ephemeral
habitats, resulting either as an indirect consequence (trade-off) of selection for
shorter time to reproductive maturity (Figure 1a), or as a direct consequence of
selection for shorter pollination time, i.e., the time between flower maturation
and ovule fertilization (Figure 1b), or both [11]. Consistent with the predictions
of this hypothesis, we found, using phylogenetically-independent contrasts, that
(compared with outcrossing annuals) selfing annuals in general had significantly
shorter plant heights, smaller flowers, shorter bud development time, shorter
flower longevity and smaller seed sizes.
