The all-or-nothing principle means that

a. all the nerve impulses go to the brain
b. an entire neuron depolarizes to its maximum strength
c. all the potassium ions on one side of the cell membrane move to the other side of the cell membrane
d. all the sodium ions on one side of the cell membrane move to the other side of the cell membrane

they each offer a fresh glut of resources to the organisms that can arrive and exploit them. as individuals and new species continue to appear, they actively and passively alter the environment. competition for shared resources increases, local abiotic and biotic conditions shift, and the relative abundances of species change accordingly. the process is called ecological succession, and it is one of the earliest and most well-known concepts in ecology.