Scientists marked and released 100 lizards on 4 islands. Each island is home to predators. After a month they trapped and counted all surviving marked lizards. They then repeated the experiment, but after removing all predators from each island. Their results are summarised below. Which of the following inferences can you make from this plot?
a. Predators have no impact on lizard survival
b. Predators have a bigger impact on female survival than male survival
c. Some islands did not have any predators to begin with
d. Females survival is twice that of males, but only in the presence of predators
