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Seasonal decline in male‐phase duration in a protandrous plant: a response to increased mating opportunities?
Author(s) -
Sargent R. D.,
Roitberg B. D.
Publication year - 2000
Publication title -
functional ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.272
H-Index - 154
eISSN - 1365-2435
pISSN - 0269-8463
DOI - 10.1046/j.1365-2435.2000.00453.x
Subject(s) - biology , onagraceae , pollinator , mating , pollination , duration (music) , ecology , population , seasonal breeder , growing season , mating system , zoology , demography , pollen , art , literature , sociology
1. We examined the effects of pollinator visitation and time of season on male‐ and female‐phase duration, using experimental manipulation and survey data from naturally occurring populations of Chamerion (= Epilobium ) angustifolium (L.) J. Holub (Onagraceae). 2. Based on the observation that male mating opportunity (numbers of female flowers/numbers of male flowers) increases seasonally, we predicted that individual flowers should spend more time in the male phase early in the season when mating opportunity is low. We predicted that if seasonal changes in mating opportunity select for phase duration, male‐phase duration should decline when pollinator effects are experimentally controlled. 3. A comparison of phase duration in naturally pollinated and pollinator‐excluded plants supported this prediction: male‐phase duration in the pollinator‐exclusion treatment was longer and declined faster than in the naturally pollinated group. 4. A population survey revealed that once the effects of temperature were controlled for, male‐phase duration was negatively correlated with date, while female‐phase duration was positively correlated with date. 5. These findings suggest that seasonal variation in mating opportunity, and not just pollination rate or temperature, may play a significant role in phase duration in dichogamous plants.