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. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ukzn/oai:http://researchspace.ukzn.ac.za:10413/10375 |
| Date | 04 February 2014 |
| Creators | Rambuda, Tendani Dennis. |
| Contributors | Johnson, Steven D. |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
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