Dinosaurs, dragons, and dwarfs: The evolution of maximal body size
Dinosaurs, dragons, and dwarfs: The evolution of maximal body size
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DOI：
10.1073/pnas.251548698
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发表时间：
2001-12-04
影响因子：
11.1
通讯作者：
Flannery, T
中科院分区：
文献类型：
--
作者：
Burness, GP;Diamond, J;Flannery, T
在当地动物群中，最大的陆生脊椎动物的最大体型和分类归属差异很大。这种差异是否反映了营养水平（食草动物与食肉动物）之间以及分类从属关系（哺乳动物和鸟类与爬行动物）之间的食物需求差异？我们收集了过去65，000年来来自海洋岛屿和大陆的顶级陆地食草动物和食肉动物的体型和食物需求的数据。顶级物种的身体质量被发现增加与土地面积的增加，与身体质量和家域面积之间的关系的斜率类似，这表明最大的身体大小是由家域的数量，可以适应到一个给定的土地面积。在一定的陆地面积上，优势种的体型大小顺序为：变温食草动物>吸热食草动物>变温食肉动物>吸热食肉动物。当我们将体重转换为食物需求时，顶级草食动物的食物消耗量约为顶级食肉动物的8倍，与营养金字塔的预期因子雅阁。虽然在给定的营养水平上，顶级外温动物比顶级内温动物重，但外温动物每克体重的代谢率较低，导致内温动物和外温动物具有相同的食物消耗。这些模式解释了有史以来最大的灭绝哺乳动物的大小，但最大的恐龙的大小超过了陆地面积的预测，仍然无法解释。
Among local faunas, the maximum body size and taxonomic affiliation of the top terrestrial vertebrate vary greatly. Does this variation reflect how food requirements differ between trophic levels (herbivores vs. carnivores) and with taxonomic affiliation (mammals and birds vs. reptiles)? We gathered data on the body size and food requirements of the top terrestrial herbivores and carnivores, over the past 65,000 years, from oceanic islands and continents. The body mass of the top species was found to increase with increasing land area, with a slope similar to that of the relation between body mass and home range area, suggesting that maximum body size is determined by the number of home ranges that can fit into a given land area. For a given land area, the body size of the top species decreased in the sequence: ectothermic herbivore > endothermic herbivore > ectothermic carnivore > endothermic carnivore. When we converted body mass to food requirements, the food consumption of a top herbivore was about 8 times that of a top carnivore, in accord with the factor expected from the trophic pyramid. Although top ectotherms were heavier than top endotherms at a given trophic level, lower metabolic rates per gram of body mass in ectotherms resulted in endotherms and ectotherms having the same food consumption. These patterns explain the size of the largest-ever extinct mammal, but the size of the largest dinosaurs exceeds that predicted from land areas and remains unexplained.