Changes to ecosystems

Marine iguanas are found only on the Galápagos Islands, which are located off the coast of Ecuador. These lizards are unique in that they forage for food in the ocean.

Compared to land iguanas, marine iguanas have certain adaptations that allow them to survive in their coastal habitat. These adaptations include a long, flattened tail used for swimming and dense leg bones that give the iguanas stability underwater.

Scientists believe the land-dwelling ancestors of the marine iguana floated on vegetative debris from Central America to the Galápagos Islands about 4.5 million years ago.

Based on the information given above, which of the following is most likely true about the ancestry of the marine iguana?

(Choice A)
The iguanas needed to survive in an ocean environment when they arrived on the Galápagos Islands, so they developed adaptive characteristics over time.
(Choice B)
The ancestral iguana population had many more individuals with adaptations for swimming than individuals without these adaptations.
(Choice C)
Iguanas with characteristics that were better suited for swimming were able to exploit a novel food source, so they left more surviving offspring over time.

Macleod, Amy, Ariel Rodríguez, Miguel Vences, Pablo Orozco-ter Wengel, Carolina García, Fritz Trillmich, Gabriele Gentile, Adalgisa Caccone, Galo Quezada and Sebastian Steinfartz. 2015. “Hybridization Masks Speciation in the Evolutionary History of the Galápagos Marine Iguana” Proceedings of the Royal Society B: Biological Sciences 282(1809). https://doi.org/10.1098/rspb.2015.0425.

Hugi, Jasmina, and Marcelo R. Sánchez-Villagra. “Life History and Skeletal Adaptations in the Galapagos Marine Iguana (Amblyrhynchus cristatus) as Reconstructed with Bone Histological Data—A Comparative Study of Iguanines” Journal of Herpetology 46(3):312-324. https://doi.org/10.1670/11-071.

AP®︎/College Environmental science

Course: AP®︎/College Environmental science > Unit 1

Problem