Mammal

"...y-efficient per unit of mass. Let's make this concrete: A shrew weighs about 5 grams. It has one of the highest metabolic rates per gram of any mammal. It must eat 150-200% of its body weight daily (1.5-2 times its mass) - eating almost constantly - because its metabolism is so ferociously fast."

"But even they face annual trade-offs. A bird sitting on eggs isn't flying around gaining weight. A pregnant mammal is directing calories to the fetus, not building muscle. :::share{variant="slate" label="Energy Trade-offs"} You can't optimize everything simultane..."

"Iterate fast, see what survives. Most lineages went extinct. The survivors became modern phyla. During the Cenozoic era (last 66 million years), mammals radiated into niches left empty after dinosaurs died. But this time, environments were stable. Competition was fierce. K-selection."

"Salmon → predators → nutrient dispersal → tree growth → forest canopy → understory shade → berry abundance → small mammal populations → predator diversity. One species removal collapses multiple dependent relationships. In Yellowstone National Park, wolves were extirpat..."

"...ports it. And remember: the safest time is dormancy. The riskiest time is waking up. --- References Barnes, B.M. (1989). Freeze avoidance in a mammal: body temperatures below 0°C in an Arctic hibernator. Science, 244(4912), 1593-1595. Buck, C.L., & Barnes, B.M. (2000)."