Lizards have tails that break off when predators are trying to capture them. The tails continue to move as a distraction to the predator. This allows the lizard to escape predators better. What best describes the trait?
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Answer:
Tail-shedding, known to scientists as caudal autotomy, is a common anti-predator defense among lizards. When attacked, many lizards jettison the wriggling appendage and flee. The predator often feasts on the tail while the lucky lizard scurries to safety. Later, the lizard simply grows a new tail.
Mainland Greece and the thousands of offshore islands of the Aegean are an ideal place to study how evolution shapes isolated animal populations, with each group adapting to conditions peculiar to its home island. The situation is reminiscent of Darwin's study of finch-beak variation on the Galapagos Islands.
Millions of years ago, when sea levels were lower than they are today, the islands of the Aegean were part of the mainland, and the entire region shared a similar variety of lizard predators. Today, those predators include mammals such as foxes and jackals, as well as vipers and birds such as hawks, falcons, shrikes, crows and ravens.
Over the millennia, sea levels rose and thousands of Aegean islands formed. Gradually, the diversity of the predator populations on those islands declined. Today, some of the Aegean islands are viper-free.
The U-M-led team looked for correlations between autotomy rates and the presence or absence of various types of lizard predators at the study's 10 collecting sites. The autotomy rate is a measure of the ease with which lizards shed their tails. The higher the rate, the easier the tail separates from the body.
The only strong signal that emerged from the study was the link to vipers.
The team found that viper-free islands are home to lizards that have largely lost the ability to shed their tails. Conversely, all the locations where vipers have survived are inhabited by lizards with high autotomy rates.
The study involved more than 200 insect-eating lizards from 15 species, most measuring 5 to 8 inches from snout to tail-tip.
In the laboratory, researchers used calipers to gently pinch lizards' tails with a standardized level of pressure for 15 seconds. Laboratory autotomy rates for each species were expressed as the fraction of lizards that shed their tails during this procedure. Understanding the distribution of tail autotomic ability among different lizard populations has important practical applications for conservation biologists. Because of the central importance of tail-shedding as a defense against predators, the expression of this ability can help predict which lizard populations are most vulnerable to the accidental introduction of non-native predators.
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