Extended Data Table 1 Theoretical mechanisms of body size constraints in vertebrates by trophic guild from the primary literature
From: Anthropogenic disruptions to longstanding patterns of trophic-size structure in vertebrates
Trophic Guild | Type of Constraint | Mechanism | References |
|---|---|---|---|
Herbivores | Minimum Size | Physiology: Need to be big enough to have digestive systems efficient (large) enough to extract enough energy; smallest herbivores are eating fruit or seeds which are energy dense | |
Promotes Smaller Size | High quality plant resources (fruit/seeds) are lower in abundance and seasonal | ||
Higher population sizes and lower extinction risk | |||
Promotes Larger Size | Jarman-Bell principle (larger species can survive on lower quality forage) | ||
Able to travel farther (and migrate) | |||
Large size is a generally effective strategy for protection against predators | |||
Maximum Size | Lower quality resource availability | ||
Biomechanical (bone density/structure, heart size/circulation, overheating) | |||
Plant fermentation efficiency limit | |||
Omnivores | Minimum Size | Physiology: High mass-specific metabolism, need very high protein food source | |
Promotes Smaller Size | Higher population sizes and lower extinction risk | ||
Promotes Larger Size | Larger size leads to lower mass-specific metabolic rate, higher efficiency | ||
Maximum Size | Resource availability: Larger than max size of carnivores (for example, bears) because they can rely on plants when animals are unavailable; smaller than max size of herbivores because they lack the digestive systems required to process bulk energy-poor foods | ||
Invertivores | Minimum Size | Physiology: High mass-specific metabolism, need very high protein food source | |
Need to be larger than their prey | |||
Promotes Smaller Size | Higher population sizes and lower extinction risk | ||
Promotes Larger Size | Larger size leads to lower mass-specific metabolic rate, higher efficiency | ||
Maximum Size | For terrestrial mammalian invertivores, the abundance, distribution and energy content of terrestrial invertebrates are not sufficient to support body masses above 20 kg | ||
Carnivores | Minimum Size | Need to be larger than their prey (at least at these sizes) | |
Promotes Smaller Size | Higher population sizes and lower extinction risk | ||
Promotes Larger Size | Patchiness of food favors fasting and starvation resistance afforded by larger sizes | ||
Larger size leads to lower mass-specific metabolic rate, higher efficiency | |||
Maximum Size | 1,100 kg limit due to tradeoff of high hunting costs versus payoff |
