Complete the last column. The differences in phenotypic plasticity between the clones of Daphnia from lakes with vs. without fish must be due to genetic differences, since the researchers raised and tested the clones of Daphnia in the laboratory under identical conditions (except that half of each clone of Daphnia were exposed to UV light as they developed and half were not). 8. Based on this evidence, scientists believe that, after a lake was stocked with fish, natural selection acted against Daphnia that had phenotypic plasticity in melanin production and instead favored Daphnia that had consistently low levels of melanin production. Propose a hypothesis to explain why, in lakes with fish, natural selection favored consistently low production of melanin instead of phenotypic plasticity in melanin production. How could phenotypic plasticity in pigmentation decrease fitness for Daphnia in lakes with fish? D. Natural selection can increase phenotypic plasticity in Daphnia behavior. In this section we will discuss a When there are no fish in a pond Daphnia benefit from different species of Daphnia that lives swimming closer to the surface where there is more food in ponds in Europe. These Daphnia and more warmth, both of which promote more rapid have a different way of avoiding fish growth. predation. Since the fish that eat these Phenotypic Plasticity in Swimming Depth of Daphnia Daphnia swim near the surface of the When There Are No Fish When There Are Fish vs. water, the Daphnia can reduce fish predation by swimming lower in the water when fish are present. 9. Complete the following table to predict where Daphnia will swim, depending on the amount of fish predation. Optimum Amount and Why would this swimming depth (or change in swimming swimming pattern of fish depth) increase the fitness of the Daphnia under these depth of predation conditions? Daphnia* No fish predation at any time of year Fish predation varies in different seasons (e.g. higher in the summer)
Complete the last column. The differences in phenotypic plasticity between the clones of Daphnia from lakes with vs. without fish must be due to genetic differences, since the researchers raised and tested the clones of Daphnia in the laboratory under identical conditions (except that half of each clone of Daphnia were exposed to UV light as they developed and half were not). 8. Based on this evidence, scientists believe that, after a lake was stocked with fish, natural selection acted against Daphnia that had phenotypic plasticity in melanin production and instead favored Daphnia that had consistently low levels of melanin production. Propose a hypothesis to explain why, in lakes with fish, natural selection favored consistently low production of melanin instead of phenotypic plasticity in melanin production. How could phenotypic plasticity in pigmentation decrease fitness for Daphnia in lakes with fish? D. Natural selection can increase phenotypic plasticity in Daphnia behavior. In this section we will discuss a different species of Daphnia that lives in ponds in Europe. These Daphnia have a different way of avoiding fish predation. Since the fish that eat these Daphnia swim near the surface of the water, the Daphnia can reduce fish predation by swimming lower in the water when fish are present. When there are no fish in a pond Daphnia benefit from swimming closer to the surface where there is more food and more warmth, both of which promote more rapid growth. Phenotypic Plasticity in Swimming Depth of Daphnia When There Are No Fish vs. When There Are Fish 9. Complete the following table to predict where Daphnia will swim, depending on the amount of fish predation. Amount and pattern of fish predation Optimum swimming depth of Daphnia* Why would this swimming depth (or change in swimming depth) increase the fitness of the Daphnia under these conditions? No fish predation at any time of year Fish predation varies in different seasons (e.g. higher in the summer)
evol%20adapt%20SHO.docx