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Evolution

Title:		Pollinators Discriminate among Floral Heights of a Sexually Deceptive Orchid: Implications for Selection
Author(s):		Peakall R; Handel SN;
Address:		"School of Biological Sciences, Macquarie University, NSW, 2109, Australia. Department of Biological Sciences, Rutgers University, Piscataway, New Jersey, 08855-1059"
Journal Title:		Evolution
Year:		1993
Volume:		47
Issue:		6
Page Number:		1681 - 1687
DOI:		10.1111/j.1558-5646.1993.tb01260.x
ISSN/ISBN:		1558-5646 (Electronic) 0014-3820 (Linking)
Abstract:		"Pollinators have influenced the evolution of many morphological floral traits, although few studies have shown that pollinators have influenced plant height. Chiloglottis trilabra is one of many Australian orchids that deceive and attract male pollinators by mimicking the sex pheromones and morphology of females insects. Orchids in this genus have unusually short flowers whose peduncle elongates dramatically after pollination to approximately twice the original height. In a series of choice experiments in the field, we show that pollinators of C. trilabra strongly discriminate among floral heights, preferring flowers presented at 15 cm-20 cm over flowers presented at lower and higher positions (ranging from 2 cm-100 cm). Our results suggested pollinators have the potential to mediate stabilizing selection for floral height when pollination is limiting. However, the natural height range of the orchid (mean = 10 cm, range 5 cm-15 cm) was lower than the experimentally determined optimum for visitation frequency. This difference may indicate that pollinator-mediated selection does not occur in this species, perhaps because seed set is not sufficiently limited. Alternatively, other life-history factors may counteract pollinator-mediated selection, yielding an evolutionary compromise in height"
Keywords:		Chiloglottis trilabra floral evolution floral height orchid plant-animal interaction pollination pollinator limitation pseudocopulation selection sexual deception thynnine wasp;
Notes:		"PubMed-not-MEDLINEPeakall, Rod Handel, Steven N eng 1993/12/01 Evolution. 1993 Dec; 47(6):1681-1687. doi: 10.1111/j.1558-5646.1993.tb01260.x"