| Summary: | Thesis (PhD)--Stellenbosch University, 2014. ENGLISH ABSTRACT: Recent work has shown that on sub-Antarctic Marion Island, caterpillars of the flightless tineid moth, Pringleophaga marioni, have much higher and considerably less variable populations in recently abandoned nests of the wandering albatross, Diomedea exulans, compared to old nests and other plant communities. Since no evidence for nutrient input was provided, it was hypothesised that wandering albatrosses serve as thermal ecosystem engineers by providing a warm microhabitat in which caterpillar growth and survival are improved. In this thesis, I used a multidisciplinary approach integrating physiology, ecology and behaviour, to better understand the reason for the high caterpillar biomass in nests, and explore the hypothesis of thermal ecosystem engineering. My first objective was to provide a more quantitative life-cycle estimate for P. marioni by rearing caterpillars at different temperature regimes, and in so doing estimate the effects of temperature on development and survival (Chapter 2). Contrary to previous estimates of 2-5 years, a year-long life cycle estimate was found, and although development was fastest at high temperatures of 15°C, caterpillars had low survival. Development time was similar at the fluctuating temperatures of 5-15°C and 10°C, with a longer duration at 5°C. By conducting a more extensive sampling effort of caterpillar biomass and temperature in nests (Chapter 3), I showed that recently abandoned nests had a significantly higher abundance of caterpillars compared to nests from which chicks had recently fledged, as well as older nests. Temperature data collected over a c. one year period showed that temperature in occupied nests remained high during the entire year of occupancy and events at which P. marioni experience chill coma were substantially reduced. Consequently, the effects of thermal acclimation on the physiological and behavioural responses of P. marioni caterpillars were explored. First, how temperature ...
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