EEB440H1 Chapter Notes - Chapter N/A: Dioecy, Pollinium, Outcrossing
27 Apr 2016
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Document Summary
Sexual selection has 2 components: competition among members of one sex for access to the other, and some preferences for traits that have certain characteristics permitting them to win intersexual competition. Most plants produce both pollen and ovules. Pollen is the fatherly investment, and ovules (with the later development of endosperm and fruit) are maternal. A plant can more easily produce pollen than ovules. To increase pollen production, can either increase number of pollen grains per anther, increase number of anthers, or increase the number of male flowers. Male flowers tend to outnumber female ones in unisexual plants. Argues that evolution into separate male and female individuals occurred. May need to look at a reason for dioecy as not just being the value of outcrossing. Proposed that the evolution of separate male/female functions may be viewed in terms of sexual selection, including competition for mates and differential fitness of mates. Their contribution to future generations is equal.
