A new study confirmed Charles Darwin's initial observation about animals in islands; they are tamer than their mainland counterparts.
Researchers from the University of California, Riverside, Indiana University, Purdue University, Fort Wayne and George Washington University have gathered evidence showing that lizards living on islands are indeed tamer than those living in the mainland.
"Our study confirms Darwin's observations and numerous anecdotal reports of island tameness," said professor of biology at UC Riverside Theodore Garland on a press release. "His insights have once again proven to be correct, and remain an important source of inspiration for present-day biologists."
More than 150 years ago, Darwin surveyed the Galapagos Island to observe the animals living there. His observations later became his inspiration for his natural selection theory which suggests that as the environment change, animals develop new functions to help them improve their chances of surviving. He also noted that this genetic evolution will discard structures and behaviors which are no longer needed when circumstances have changed.
Darwin also observed that the animals living on the island are often tamer and postulated that this may be due to the lack of predators in the same environment.
"When prey are very small relative to predators, predators do not attack isolated individual prey," Garland explained. "This results in the absence of fleeing or very short flight initiation distance."
To conduct the study, the researchers analyzed the connections of flight initiation distance or the distance between the predator and the prey with which the latter starts to run away. They gathered data from mainland and island lizard species, noting the variations in predator approach speed and prey size. The lizard species involved in the study were from five continents and island territories from the Pacific Oceans, Caribbean, Atlantic, and Mediterranean Seas.
The results of the study reflected that there is a decrease of flight initiation distance the farther the lizard is from the mainland. The researchers concluded that island tameness does exist and island lizards are more accessible than those living in the mainland.
The study was published in the online journal Proceedings of the Royal Society B.
