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Size-temperature responses of organisms and metabolic response to climate change S.K. Morgan Ernest 1 , Kristina Anderson-Teixeira 2 , Felisa A. Smith 3 , Ethan P. White 1 1 Department of Biology and the Ecology Center, Utah State University, 2 Energy Bioscience Institute, University of Illinois Urbana-Champaign, 3 Department of Biology, University of New Mexico Metabolic rate is related to size and temperature Temperature also impacts ectotherm body size Temperature impacts metabolic rate and body size in opposing ways Large size decreases could offset temperature effect on metabolic rate Data Small impact on metabolic rate of size response to temperature Forster et al (2011): •Generally, as temperature increases, body size decreases •80% of ectotherms examined exhibit significant size-temperature relationship •On average, adult body size decreases 2.5% per degree C Drosophila melanogaster Data from Forster et al (2011) Hypothetical responses of metabolic rate to temperature change and body size shifts • Lab results of body size response to temperature • 109 species from nine taxonomic Classes • 85 spp. from Forster et al (2011), 24 spp. from other sources Metabolic Rate But does it? •Estimated metabolic rate (B) using Gillooly et al (2001): R=r 0 M b e -E/kT M mass, b scaling exponent, E activation energy •Class specific b &E unless noted: Quantifying metabolic response to size and temperature changes • Q10 measures magnitude of physiological responses to 10 C change in temperature • Q4: magnitude of response over 4 C Q 4 = (R 2 /R 1 ) 4/(T2-T1) Compare Q4 when size constant vs. varying Generating Q4s for size constant vs. varying scenarios Mean Q4 for size constant Mean Q4 for size response Calculate % difference Class b E Actinopery gii # 0.7 8 0.35 Amphibia 0.8 5 0.58 Branchiopo da 0.7 9 0.31 Entognatha * 0.7 5 0.63 Eurotatori a * 0.7 5 0.63 Gastropoda * 0.7 5 0.63 Insecta 0.7 5 0.62 Malacostra ca 0.7 5 0.51 Maxillopod a 0.6 9 0.68 * Theoretical values, # all fish Less increase in metabolic Rate w/ increasing T More increase in metabolic rate w/ increasing T • Generally, size-temperature response dampens response of metabolic rate to temperature increases • Magnitude of response is small • Response consistent across taxonomic classes • Except stronger response in Amphibia (but sample size small) Rana pipiens. Data from White et al (2006) Mass corrected metabolic rate (Metabolic rate * M -b ) Temperature corrected metabolic rate (Metabolic rate *e E/kT ) Warm Cold Hirst, D. Atkinson. 2011. How do organisms change size with changing temperature? The importance of reproductive enetic timing. Functional Ecology 25:1024-1031 H. Brown, G.B. West, V.M. Savage, E.L. Charnov. 2001. Effects of size and temperature on metabolic rate. Science 293 2248-2251 Phillips, R.S. Seymour. 2006. The scaling of temperature dependence of vertebrate metabolism. Biology Letters 2:125-127. Acknowledgements SKME thanks USU for the post-tenure freedom to explore new ideas and start learning to Photo of Rana pipiens is copyrighted to Joyce Gross and obtained via Amphibiaweb.org Percent change in metabolic rate Mass (grams) Initial size 30 grams No Size change Decreasing size weecology.org
