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. 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.

Figure 25.2
-Examine the figure above.What type of selection for body size appears to be occurring in these marine iguanas?

Question

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. 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.
  
Figure 25.2
-Examine the figure above.What type of selection for body size appears to be occurring in these marine iguanas?

Quizplus · Accepted Answer

Stabilizing selection appears to be occurring in these marine iguanas, as intermediate body size individuals have the highest percent survival. This means that individuals with extreme body sizes (either very large or very small) have reduced survival, while individuals with intermediate body sizes have higher survival rates.