Currently the only predators of Galápagos marine iguanas are Galápagos hawks.Iguana body size is not correlated with risk of hawk predation,although small iguanas can sprint faster than large iguanas.If predators (e.g.,cats)that preferably catch and eat slower iguanas are introduced to the island,iguana body size is likely to ________ in the absence of other factors;the iguanas would then be under ________ selection.

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Quizplus · Accepted Answer

If slower-iguanas-predators are introduced on the island, smaller iguanas that can sprint faster are likely to survive and reproduce more successfully than their larger counterparts. Over time, this would lead to a decrease in iguana body size, as smaller individuals would have a better chance of escaping predation than larger ones. This is an example of directional selection, as the selection pressure favors one extreme of the trait distribution (i.e., smaller body size).

Currently the Only Predators of Galápagos Marine Iguanas Are Galápagos