H.S., Arathi .
Influence of multiple mating on intra-fruit resource allocation in Collinsia heterophylla.
One of the primary mechanisms resulting in varying patterns of seedset is that of maternal resource allocation that is economized by packing as many seeds as possible into each fruit. Individual seeds however aim to increase their fitness by siphoning larger than fair share of resources resulting in the classic case of parent-offspring conflict and sibling rivalry over resource allocation. Variation in resource sequestration among seeds is determined by pollen donor and hence depending on the breeding system and number of mates one could see complex variations in seed number and size patterns. Collinsia heterophylla is an annual with high seed abortion rates as 1 to 6 seeds mature out of 14 to 16 ovules per flower. To determine whether resource sequestration plays a role in seed number and size variations, I performed hand-pollination experiments creating singly and multiply mated flowers and naturally selfed flowers being controls. Analyses of fruitset, seed number and mass indicated that there was a significant effect of mating type and mate numbers. As expected, fruit set was highest in cross-pollinated flowers and multiply mated fruits had significantly higher seed number/fruit and higher average seed mass as compared to singly mated and selfed fruits. Interestingly, the coefficient of variation (CV) for seed mass was lowest in multiply mated fruits implying uniform resource distribution. Although multiple mating has been suggested as an unfavorable maternal plant strategy due to increased intra-fruit sibling rivalry and drop in fecundity, my results indicate that multiple mating may indeed be beneficial for the maternal parent by increasing offspring number and variability. Increased sibling competition in fruits could create a stronger resource sink than those with lower levels of competition. Fruits that demand more from the maternal plant would therefore contain more uniform sized seeds with higher genetic variability.
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1 - Colorado State University, Biology, 1878 Biology, Fort Collins, CO, 80523, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Wasatch A/Cliff Lodge - Level C
Date: Monday, July 27th, 2009
Time: 1:30 PM