Abstract Detail

Reproductive Processes

Smith, Claire [1], Friedman, Jannice [2].

Stochasticity and pollen capture efficiency in wind-pollinated angiosperms.

Wind pollination has long been considered an inefficient and stochastic process, dependent on multiple environmental factors and resulting in extensive pollen loss. In wind-pollinated angiosperms, patterns of male and female investment are thought to reflect this apparent inefficiency and low probability of successful pollen transfer: while pollen production tends to be high, many species produce only a single ovule per flower. Nonetheless wind pollination has evolved repeatedly in diverse lineages, suggesting that it is an effective means of pollen transfer under some conditions. The few studies that quantify pollen transfer efficiency—the ratio of pollen capture to pollen production within a flower—in wind-pollinated species report values within the same order of magnitude as animal-pollinated species. These measures of efficiency challenge the assumption that wind pollination is inefficient, but do not capture a fundamental aspect of wind pollination: its stochasticity. In addition to measuring pollen transfer efficiency, examining the distribution of pollen loads received within and among individual plants may provide a more comprehensive picture of pollination efficiency by capturing the inherent variance in pollen receipt. To this end, we measured pollen capture and production for 26 wind-pollinated species in Alberta and Ontario, Canada, sampled between 2001-2005 and 2021. To determine pollen loads, we collected stigma-bearing flowers and counted pollen loads on squashed, fuschin-stained stigmas under light microscopy. We accounted for local density by recording the distance from each stigma-bearing plant to its five nearest pollen-producing neighbours. To estimate pollen production, we collected and counted pollen from undehisced anthers. Additionally, to determine whether the ability to self pollinate affects pollen load, we compared dioecious, monoecious, and hermaphroditic species. Pollen capture was highly variable within species and within individual plants and followed a highly leptokurtic distribution, with mean pollen loads per plant per species ranging from 2.6-57.8 grains/flower. Pollen loads tended to be higher in hermaphroditic and monoecious species, suggesting frequent transfer of self-pollen. In wind-pollinated species, high pollen production may represent a balance between selection to maximize mating and reproductive success through pollen dispersal and subsequent pollen competition for fertilization, while low ovule numbers may be driven by a combination of resource allocation and packaging strategies that favour few ovules distributed in multiple flowers.

1 - Queen's University, Biology, 116 Barrie St, Kingston, ON, K7L3N6, Canada
2 - Queen's University, Biology Department, 116 Barrie Street, Kingston, ON, K7L 3N6, Canada

wind pollination
plant ecology.

Presentation Type: Oral Paper
Number: RP5001
Abstract ID:755
Candidate for Awards:None

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