| Summary: | 碩士 === 國立臺灣大學 === 生態學與演化生物學研究所 === 106 === Climate change (e.g., elevated temperature and CO2) can affect species growth and development, subsequently shaping trophic interactions and community structure. However, less is known about how elevated temperature and CO2 individually and collectively influence species performance across spatial gradients (e.g., altitudes). To help fill the knowledge gap, we studied the performance of Pieris canidia (herbivore) on Rorippa indica (host plant) by conducting a 3×2×2 factorial experiment: temperature (ambient, +3 °C, +6 °C) × CO2 (500, 1000 ppm) × altitude (species collected from low [100m] and medium [1000m] altitudes). The degree of elevated temperature and CO2 was based on IPCC prediction for 2100. The factorial design allowed us to examine the individual and collective effects of temperature and CO2 on species across altitude (i.e., intraspecific variation). The results showed that temperature (but not CO2) alone, strongly affected P. canidia performance (e.g., reduced larval weight, adult weight, larval period and pupal period under warming). Furthermore, altitudinal origin affected P. canidia performance, either alone or via its interaction with temperature and CO2. For example, P. canidia with a medium-altitude origin had a shorter developmental time, larger larval, pupal and adult weight, and longer longevity than those with a low-altitude origin; there were interaction effects (temperature×CO2, temperature×CO2×altitude) on adult performance. Our study highlights a strong impact of elevated temperature on herbivore performance, which, however, is also mediated by CO2 and altitude. Our attempt to untangle the complexity of individual and collective effects of climate change components across spatial gradients should facilitate new ecological models that will better predict community response to climate change.
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