Figure 1.5 Evolution by natural selection. In this example, the caterpillar population is initially quite variable in color (a). Individuals that better match the twig are less obvious to the bird hunting for food and therefore more likely to survive. If color is genetically inherited, the next generation (b) of the caterpillar population will be better matched to resemble twigs. As this natural selection continues over many generations, the color of the caterpillar population will closely match the twigs (c). At this stage, the color of the caterpillar represents an adaptation against predation.