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Pollinator response to male floral display size in two S agittaria (Alismataceae) species
Author(s) -
Muenchow Gayle,
Delesalle Veronique
Publication year - 1994
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1994.tb15486.x
Subject(s) - plant reproductive morphology , biology , pollinator , generalist and specialist species , display size , pollination , population , pollen , dioecy , hermaphrodite , botany , ecology , demography , habitat , display device , sociology , computer science , operating system
One hypothesis for the evolution of maleness in plants postulates the following: male plants appear that have re‐allocated resources from female parts into a larger number of male flowers, creating a larger floral display. Pollinators respond “dramatically” to the increased display, driving the spread of males in the population (Bawa, K. S., 1980, Annual Review of Ecology and Systematics 11:15–40). To test this, we measured the total number of flowers and the size of male displays in dioecious Sagittaria latifolia and monoecious S. australis. We also measured how fast visitors arrived at “target” flowers in the displays. Then we used the Cox Model, a failure time analysis procedure, to analyze the relationship between visitor arrival and display size. We found that male display sizes were somewhat larger in the dioecious than the monoecious plants, but this was due to more compressed blooming rather than to a larger total number of flowers. The visitors to both plants were similar arrays of generalist bees. Visitors did not show the predicted “dramatic” response, however, but rather a plateauing response to larger display sizes, so our results do not support the hypothesis. Reviewing the literature, we found no reports of the “dramatic” response the hypothesis asserts. Instead, relative insensitivity to display size is the rule.