New Zealand Journal of Botany abstract
Inbreeding depression in the gynodioecious shrub Hebe subalpina
(Scrophulariaceae)
LYNDA F. DELPH*
Department of Biology
Indiana University
Bloomington
Indiana 47405, USA
DAVID G. LLOYD
Department of Plant and Microbial Sciences
University of Canterbury
Private Bag 4800
Christchurch, New Zealand
* Author for correspondence
Abstract Inbreeding depression caused by self-fertilisation
was examined in the gynodioecious shrub Hebe subalpina under two
planting regimens, non-competitive and competitive. We found differences among
families in the magnitude of inbreeding depression, ranging from 0.31 to 0.63.
On average, outcrossed progeny grew nearly twice as large as selfed progeny,
and the coefficients of variation (CVs) for dry mass were lower for outcrossed
progeny than selfed progeny within the non-competitive regimen. Planting regime
had a highly significant effect on dry mass, such that plants grown in the
competitive regimen were an order of magnitude smaller than those in the
non-competitive regimen, and they also had higher CVs. However, planting
regimen did not significantly affect the magnitude of inbreeding depression.
Our results suggest that intrinsic differences exist in the growth rate of
selfed and outcrossed individuals, and that inbreeding depression helps to
maintain females at a high frequency in the population. We suggest that
among-family variation in the magnitude of inbreeding depression is likely in
gynodioecious species because of differences in inbreeding caused by gender.
Keywords gynodioecious; Hebe subalpina; inbreeding
depression; male-sterility
B95026
Received 23 June 1995; accepted 16 November 1995
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