Pollination and breeding systems of alien invasive plants in KwaZulu - Natal in South Africa.
Date
2001
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
According to Baker (1955), success of plant invasions can be attributed to autogamous breeding
systems and generalist pollination systems. A test of Baker's rule was carried out on 19 invasive
alien plant species in KwaZulu-Natal, South Africa. Natural levels of fruit set in these plants was
high (median= 71.5% fruit set per plant). Breeding system experiments for 18 species showed that
17% of the species are allogamous, 72 % are autogamous and 11% are apomictic. This contrasts
markedly with a general flora of 1472 species in which 65% are allogamous, only 14% are
autogamous, and 21% are apomictic. Because the breeding systems of the alien species were largely
autogamous, pollinators make only a small contribution to the overall reproductive success. Seventy
one percent of the 14 alien species for which pollinators were obtained were pollinated by
honeybees, which are super-generalists and ubiquitous in a generalist pollination systems. However,
some species showed pre-adaptation to relatively specialized pollination systems, involving
hawkmoths, butterflies and Xylocopa bees respectively. Thus, alien plants were not visited by a wide
range of insects, but rather showed pre-adaption to one or more pre-existing guilds in the new
habitat. Pollen limitation experiments showed no evidence that reproductive success in populations
of the species is limited by pollen availability.
Description
Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001.
Keywords
Plant invasions--KwaZulu-Natal., Invasive plants--KwaZulu-Natal., Alien plants--KwaZulu-Natal., Pollination., Theses--Botany.