New Zealand Journal of Botany abstracts
Does competition-dependent incompatibility provide
reproductive assurance in Phormium tenax?
Linley K. Jesson*
Lesley D. Milicich
Sarah C. Newman
School of Biological Sciences
Victoria University of Wellington
PO Box 600
Wellington 6140, New Zealand
*Present address: Department of Biology, University of New Brunswick,
PO Bag Service 45111, Fredericton, New Brunswick, Canada E3B 6E1.
jesson@unb.ca
Abstract New Zealand
flax (Phormium tenax) has a reproductive system in
which the early abscission of selfed flowers is determined by the
degree of competition with crossed fruits on the same plant. It has
been suggested that this functions as a form of reproductive assurance,
allowing for high levels of outcrossing when pollinators are abundant,
while ensuring seedset when pollinators are scarce. We performed
experimental crosses and mating system estimation in natural
populations to determine whether P. tenax can set
seed in the absence of pollinators, and how pure and mixed pollen loads
influence reproductive success and population-level selfing rates. Phormium
tenax can set seed autonomously, although if other flowers on
the plant are available for outcrossing, resources are preferentially
allocated to maturing those fruits. Experimental crosses suggest that
flowers pollinated with mixtures of selfed and outcrossed pollen can
result in fruitset, although fruitset is reduced if flowers pollinated
with mixed pollen loads compete with cross-pollinated flowers. Despite
the potential for geitonogamy in P. tenax,
outcrossing rates from five populations showed that these populations
were universally outcrossing (t = 0.83–1.06). In P.
tenax, self-compatibility in the absence of competition from
outcrossed pollen can provide some reproductive assurance, but in large
populations, selfing and mixed mating rarely occur.
Keywords cryptic
incompatibility; inbreeding depression; Phormium tenax;
reproductive assurance; outcrossing rates
B06004; Received 16 February 2006; accepted 25 May 2006; Online
publication date 7 September 2006
New Zealand Journal of Botany, 2006, Vol. 44:
249–259
0028–825X/06/4403–0249 © The Royal Society of
New Zealand 2006
PDF file of entire paper: Print-quality
(365K) | screen-quality
(426K)
This year's abstracts
|
Journal home page |
All abstracts |
Publishing home page
