Figure 25.2
Use the following information when answering the corresponding question(s)
Martin Wikelski and L.Michael Romero (Body size,performance and fitness in Galápagos marine iguanas,Integrative and Comparative Biology 43 [2003]:376-86)measured the snout-to-vent (anus)length of Galápagos marine iguanas and observed the percent survival of different-sized animals,all of the same age.Figure 25.2 shows the log snout-vent length (SVL,a measure of overall body size)plotted against the percent survival of these different size classes for males and females.

-Examine Figure 25.2.What type of selection for body size appears to be occurring in these marine iguanas?
A)directional selection
B)stabilizing selection
C)disruptive selection
D)You cannot determine the type of selection from the above information.

Question

Figure 25.2
Use the following information when answering the corresponding question(s)
Martin Wikelski and L.Michael Romero (Body size,performance and fitness in Galápagos marine iguanas,Integrative and Comparative Biology 43 [2003]:376-86)measured the snout-to-vent (anus)length of Galápagos marine iguanas and observed the percent survival of different-sized animals,all of the same age.Figure 25.2 shows the log snout-vent length (SVL,a measure of overall body size)plotted against the percent survival of these different size classes for males and females.
 
-Examine Figure 25.2.What type of selection for body size appears to be occurring in these marine iguanas?
A)directional selection 
B)stabilizing selection 
C)disruptive selection 
D)You cannot determine the type of selection from the above information.

Quizplus · Accepted Answer

Stabilizing selection appears to be occurring in these marine iguanas as there is a higher percent survival for intermediate-sized individuals and lower percent survival for both smaller and larger individuals. This suggests that there is selective pressure against extreme body sizes and a preference for individuals with intermediate body sizes.

Figure 25.2 Use the Following Information When Answering the Corresponding Question(s)