The Mechanism

Tzu-jan. Fitness times the change
In a trait equals
The covariance between

Subpopulation values
For the trait and fitness, plus
The expected change

In the amount of the trait
Due to carriers’ fitness,
The environment’s effects.

All sets all on fire,
Selves appearing of themselves,
As all will and as all must,

Brooking no interference
Because nothing arises
Outside the mechanism.