Two researchers measured the snout-to-vent (anus) length of…
Two researchers measured the snout-to-vent (anus) length of Galápagos marine iguanas (lizards) and observed the percent survival of different-sized animals, all of the same age. The graph 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.(Data from M. Wikelski and L. Michael Romero. Body size, performance and fitness in Galapagos marine iguanas. Integrative and Comparative Biology 43:376-386 .)Based on the data in the figure, what type of selection for body size appears to be occurring in these marine iguanas?