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Figure 1 | BMC Evolutionary Biology

Figure 1

From: Effect of temperature and glia in brain size enlargement and origin of allometric body-brain size scaling in vertebrates

Figure 1

Allometric relationships of the brain and body weights of vertebrate animals on a log-log plot. A. Endothermic animals included 678 mammal species [3],[16],[22],[61] (red open circle), 600 bird species [10] (cyan triangle) and 33 insectivore species [16] (purple cross). Ectothermic animals included 110 fish species [44] (black open circle), 71 reptilian species [11] (black open diamond), and 86 amphibian species [11] (black open triangle). The fitting functions are W = 0.078P0.717 (adjusted- R2 = 0.95, p < 0.01) for endotherms and W = 0.014P0.578 (adjusted- R2 = 0.91, p < 0.01) for ectotherms. All these datasets are provided in Additional file 1: Table S1. B. The relationship of the brains and bodies of randomly selected fish. Data from 30 polar-water fish species (blue, temperature ~1°C), 70 temperate species (green, 10–20°C), 88 tropical species (red, temperature 20–30°C) and 17 shark species that live in sub-tropical waters (red, core body temperature range 20–30°C [26],[27]) were randomly selected from a fish database (http://fishbase.org) [44]. The fitting functions are W = 0.0036P0.59 (adjusted- R2 = 0.82, p < 0.01) for polar-water fish, W = 0.0078P0.64 (adjusted- R2 = 0.92, p < 0.01) for temperate-water fish, and W = 0.0118P0.7 (adjusted- R2 = 0.94, p < 0.01) for tropical-water fish and the sharks. All these datasets are provided in Additional file 2: Table S2. C. Brain size as a function of temperature for fixed body masses, i.e., 10 grams and 1000 grams respectively. The open triangles represent the averaged data from 29 fish species with body masses of 5–15 grams, and the open squares represent the average of 33 species with body masses of 500–1500 grams from three temperature conditions. The data for 38°C are from 46 endotherms with body masses of 5–15 grams (solid square) and 52 endotherms with body masses of 500–1500 grams (solid triangle). The fitting equations are log10W = 0.205P0.0323 for P = 1000 g (adjusted- R2 = 0.98, p < 0.01 for only fish data) and log10W = 0.0095P0.0343 for 1000 g (adjusted- R2 = 0.91, p < 0.01, only for the fish data). D. The brain size ratios as a function of body sizes: Brainendotherm/Brainectotherm (black line), Braintropic fish/Brainpolar fish (black dashed line) and Brainprimate/Brainmammal (black dotted line).

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