Passage V

Nemoria caterpillars that hatch in the spring mature into a yellow, ridged morph (body type); those that hatch in the summer mature into a gray, smooth morph. A researcher hypothesized that caterpillar morphology is influenced by 3 environmental factors: temperature, photoperiod (hours [hr] of sunlight per day), and diet. He performed 3 studies on Nemoria.

Study 1

Treatment groups (groups exposed to different experimental conditions) of equal numbers were created by varying 3 factors: temperature (15°C or 25°C), photoperiod (12.5 hr or 14 hr), and diet (catkins [oak flower clusters] or oak leaves). The percent of caterpillars that developed into each morph appears in Table 1.

Study 2

Caterpillars were raised at 25°C, with a 14 hr photo-period, and on 1 of 5 diets: catkins, catkins and oak leaves, catkins and tannins (a compound found in oak leaves, but not found in catkins), oak leaves, or oak leaves without tannins. The percent that developed into each morph appears in Table 2.

Study 3

Female caterpillars were raised at 25°C with a 14 hr photoperiod on either catkins or oak leaves. Pupation time in days (d), pupal weight (g),and number of offspring produced by female moths were recorded (see Figure 1).

Tables and figure adapted from Erick Greene, "A Diet-Induced Developmental Polymorphism in a Caterpillar." ©1989 by the American Association for the Advancement of Science.