![]() The mean age at death was only 5months (reviewed in Price 2002). For example, Blus (1971) established abreeding colony of short-tailed shrews in captivity and found thatonly 11% of his wild-caught shrews, and 9% of his captive-bornshrews, survived for 12 months. ![]() Mortality of wild animals in captivity can be severe during thosefirst few generations. Wild animals can be extremely stressed by the captive environment.Compared to the wild, the captive environment is extremely confined,provides few hiding places, is full of bright lights, and issurrounded by human "predators" who approach and handle the animal.These stressful conditions frequently lead to death or reproductivefailure in captive wild animals. Wild animals, including rats, are more active and reactive thananimals that have been domesticated for many generations. Lastly, animals are not passive subjects of natural selection.They can act on and respond to their environment, and many of themmay learn and adjust individually to their changed circumstances. ![]() Relaxed selection (removal of natural selection oncertain traits) also plays a role in both environments, andartificial selection (preferential breeding of animals with certaintraits by their human managers) plays a role in captivity. Natural selection isn't the only force acting on animals in newenvironments. The second generation, and all subsequentgenerations, will pass through the same seive, and only those whosurvive and breed will pass on their traits to the next generations.After generations, the new population may look and act quitedifferently from the original population. The survivors form the basis of the next generation of animals inthe new environment. The criteria for success have changed,and most of the animals, well-adapted to their former environment,find themselves poorly adapted to their new one. It is the same with wild animals in the domestic environment ordomestic animals in the wild. ![]() A few of these linguistsmay happen to have superb sporting ability, but most will fail. The reverse situation is true too: place a group of linguists whospeak four languages in a room and tell them the only way out is todemonstrate world-class mastery of a sport. A small number of them may happen to speakfour languages, and they'll survive. Now transport themto a new environment: put them all in a room and tell them that theonly way out is for them to demonstrate fluency in four languages.All of a sudden, these sports stars find themselves poorly adapted totheir new environment. Ifthey weren't, they'd be eliminated from the team. Consider a national sports team of your choice.The players are extremely good at what they do: playing the sport.Some are better than others, but all the members are very good. The survivorsare those that happen to have the traits that are compatible withthese new circumstances. Hence,mortality and reproductive failure are high in wild rats moved tocaptivity, and on domestic rats released in the wild. Natural selection is severe in the early generations after theswitch from the wild to captivity or from captivity to the wild.Natural selection acts on populations: individuals that are poorlyadapted to their new environment die or fail to breed. In the domestic environment, the successful rat isone who is passive to changes, tolerates humans, breeds willinglywith whatever members of the opposite sex are provided, toleratesconfinement, bright lights, poor hiding places, a simple environment,and handling by human "predators."Ĭhange their places, and many rats will have a lot of troublemaking the switch. In the wild environment, a successful rat is one who isreactive to changes, flees humans, finds rats of the opposite sex tobreed with, finds food and shelter in a complex environment andavoids predators. The criteria for success are dramaticallychanged. In both cases, ananimal adapted to a particular environment is placed in a drasticallydifferent environment. These two situations are actually very similar. What about the reverse - releasing a domestic animal in the wild?Is it helpless, a soft urbanite released into the harsh naturalworld? Does it revert to its wild roots? What happens if you bring a wild animal into captivity? Because ofits "hardy" constitution, is it actually more fit than its"degenerate" domestic cousins? What happens to wild animals that arekept for generations in captivity? Interactions between wild and domestic rats.Wild Rats in Captivity and Domestic Ratsin the Wild Home: Wild Rats: Wild rats in captivity, domestic rats in the wild
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