PARENT SESSION
Oral Session # 46: Evolutionary Ecology I: Plants.
Presiding: P Minchin
Wednesday, August 6. 8:00 AM to 11:30 AM, SITCC Meeting Room 201.
Patterns of multiple paternity in fruits of Mimulus ringens.
Mitchell, Randall1, Karron, Jeffrey 2, Holmquist, Karsten2, Bell, John2, 1 University of Akron, Akron, OH, USA2 University of Wisconsin-Milwaukee, Milwaukee, WI, USA
ABSTRACT- Multiple paternity within fruits arises when pollen from more than one donor successfully fertilizes ovules in a single fruit. This can occur in two different ways. 1) A single probe by a pollinator may deposit a mixture of pollen from several donors. 2) A sequence of several separate probes may deposit pollen from different donors. These alternatives have distinct consequences for pollen competition and mate choice. However, there is as yet little evidence on the relative importance of these two mechanisms, and few studies on the overall rate of multiple paternity. We report on patterns of multiple paternity in Mimulus ringens, and use observations of pollinator behavior to infer the mechanisms generating multiply sired fruits. Multiple paternity was very common for M. ringens, with over 95% of 204 fruits having two or more outcross pollen donors in progeny arrays of ten genotyped seeds. The number of sires per fruit averaged 4.63 + 0.10 (mean + SE), including selfs. From our detailed observations of pollinator behavior, and the limited pollen carryover for this species, we infer that the observed levels of multiple paternity could not have been solely the result of single probes that delivered mixed pollen loads. Multiple probes to flowers, each delivering pollen from one to three different sires is more likely to have caused the observed patterns, This suggests that both mixed pollen loads and sequential visitation contribute to multiple paternity in this species.
Key words: Self-pollination, Pollination, Scrophulariaceae, Bombus