| Summary: | Thesis (PhD)--University of Stellenbosch, 2005. ENGLISH ABSTRACT: Climate sets range limits in many taxa, and as climate changes, the ranges that plants and animals occupy are altered. The responses of species to climate change involve either migration or local adaptation. An investigation of the local physiological adaptation shown by indigenous and alien arthropods to temperature acclimation formed the primary focus of this study. Increased environmental temperatures favour the establishment of alien species on Southern Ocean Islands. The first records of Porce/lio scaber Latreille, 1804 (Isopoda, Porcellionidae) and an Aphidius wasp species from Marion Island were documented here. The alien wasp was discovered in 2003 and had a current known distribution along the east coast of Marion Island. Both isopods and wasps were reproducing successfully on Marion Island. The wasp species is an aphid parasitoid and had been found mummifying the alien aphid Rhopalosiphum padi. These introductions highlighted the ongoing conflict between use and conservation on the Southern Ocean Islands. Despite considerable work on the upper and lower lethal limits of insects, several major taxa have received little attention. Here this issue was addressed and the lower and upper thermal tolerances and cold hardiness strategy of Antarciopsocus jeanneli Badonnel (Psocoptera: Elipsocidae) from sub-Antarctic Marion Island was investigated. A. jeanneli is freeze intolerant, and more specifically, moderately chill tolerant. Field fresh A. jeanne li had a mean supercooling point (SCP) of -11.1oC, whereas LTSO was -7.7°C, indicating pre-freeze mortality. A. jeanneli responded to acclimation: mean SCP increased from -IS.8°C at a treatment temperature ofO°C, to -7.3°C at ISOC. Investigations of the responses to acclimation of upper and lower lethal limits and limits to activity in insects have focussed primarily on Drosophila. Halmaeusa atriceps (Staphylinidae) was examined for thermal tolerance responses to acclimation, and seasonal ...
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