Net Energy Gain
The difference between energy acquired from food and energy expended to obtain it. Net energy gain = energy intake − (search costs + handling costs + metabolic costs). This is the biological equivalent of profit margin.
Biological Context
Optimal foraging theory predicts animals maximize net energy gain per unit time. A lion chasing a mouse expends more calories than the mouse provides—negative net energy gain. Darwin's finches with large beaks gain high net energy from large seeds (like 11mm Tribulus seeds) but poor returns from tiny seeds, while small-beaked finches show the reverse pattern. During the 1977 Galápagos drought, large seeds became the only option—finches with beaks that couldn't crack them efficiently had negative energy margins and died. The currency of evolution is net energy gain, not gross intake.
Business Application
Net energy gain is the biological term for what business calls 'margin.' Revenue minus costs equals net gain. Like finches selecting seeds, companies should pursue opportunities where their capabilities yield positive margins. A company poorly suited to a market segment may have negative unit economics—spending more to acquire and serve customers than they return. High gross revenue with negative net gain is evolutionary suicide. The finch that chases every seed regardless of return goes extinct; the business that chases every customer regardless of margin follows the same path.