A researcher studied the relationship between the phenotypes of snakes and their

Question

A researcher studied the relationship between the phenotypes of snakes and their fitness. First, he measured the color patterns and escape behavior of hundreds of snakes. For color pattern, snakes were scored as being either checkered or striped (see photos below). For escape behavior, snakes were chased by simulating a predator attack; some snakes moved in a straight line while fleeing, but others tended to turn frequently. After recording these phenotypes, the researcher released the snakes in their natural environment. A year later, he returned to see which snakes had survived. The survival of snakes was used as a proxy of fitness. The figure below shows the relationships between color pattern and relative fitness for snakes that flee straight and snakes that flee by turning.

Figure 1. Both the color pattern and escape behavior of a garter snake affects its fitness relative to other snakes. Photos of a checkered snake (top) and a stripe snake (bottom) are shown.

Use this information to answer questions 1-6.

True/False:

1.Regardless of its color pattern, a snake that flees a predator by turning would likely survive.

2.A snake with stripes would be more likely to survive by fleeing predators in a straight line.

3.Regardless of escape behavior, the color pattern of snakes will be influenced by directional selection.

4.Over many generations, the population of snakes should evolve toward striped snakes that flee by turning or checkered snakes that flee straight.

5. The strength of selection for color pattern is greater in snakes that flee by turning than in snakes that flee straight.

6.Although the researcher estimated fitness by survival, he could have also used another proxy for fitness, such as mating success.

Explanation / Answer

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