To test the idea, the researchers planted more than 1000 monkeyflowers of the species Mimulus guttatus in a greenhouse at the University of Guelph in Ontario, Canada. Monkeyflowers are common wildflowers found in western North America, from the Sonoran desert to western Alaska.
Some Mimulus guttatus plants produce many flowers, and others produce few. To boost the variation in overall plant size, half the plants in the greenhouse experiment got fertilizer, and the other half went without.
The researchers measured the correlation between flower size and flower number, and at the end of the season they harvested and weighed each plant.
They found that larger plants made bigger, more plentiful blooms, just as they suspected. But when they accounted for differences in overall plant size, the underlying tradeoff between flower size and flower number still held true.
In a second experiment they compiled data for 83 plant genera found in California to test for other possible factors, such as whether a species lives to breed for multiple seasons or just one. But no other factor explained why flower size-number tradeoffs are so hard to spot.
"If you don't account for overall size differences between the species you're comparing, the flower size-number tradeoff is likely to be masked," Maherali said.
The findings appear in the International Journal of Plant Sciences.
|Contact: Robin Ann Smith|
National Evolutionary Synthesis Center (NESCent)