Chapter 19 Endangered Species 471 Copyright Goodheart-Willcox Co., Inc. High Specialization An organism that is highly specialized eats a particular food and lives in a limited or exclusive area. (A species is referred to as generalized when it can exist in a wide range of conditions.) These animals are more vulnerable to extinction because they cannot adapt to sud- den and extreme changes of their environment. The koala (Phascolarctos cinereus), for example, is a marsupial herbivore that is native to Australia. The koala feeds selectively on the leaves of cer- tain eucalyptus trees that grow in the eucalypt forests and woodlands, Figure 19-7. Each koala has a home range that consists of multiple trees, or its home trees. Koalas typically do not stray into other home ranges unless they are breeding. When eucalyptus trees are felled or consumed by forest fi re, koalas lose their home range. As koa- las do not share home ranges, homeless koalas will perish unless they fi nd an area with unin- habited trees. Koalas forced to live near humans are often attacked by dogs or hit by vehicles. With such a limited diet and range, any changes to the koala’s habitat will affect the species. The koala is listed as vulnerable on the IUCN Red List and may soon become endangered with the high rate of deforestation occurring in Australia. Disease All living organisms are vulnerable to disease that can result in problems ranging from stunted growth and development to reproductive failures or death. An individual occurrence of a disease, such as canine distemper, may be limited to one animal or it may be the indication of a wide- spread problem, Figure 19-8. Canine distemper is a highly con- tagious viral disease that causes breathing diffi culty, diarrhea leading to dehydration, and neurological impairments leading to death. Young or unhealthy animals will likely die if they con- tract the disease. Canine distemper is rare in pets due to vaccinations how- ever, a wild animal with the disease can easily spread it to other wild animals. In addition, canine distemper is not limited to canines and can infect other species, including raccoons, kinka- jous, red pandas, black bear, skunks, ferrets, mink, lions, tigers, and many other animals susceptible to this type of distemper virus. Diseases that infect wildlife include rabies, chronic wast- ing disease in deer, and bacterial wilt in plants. Note that some wildlife diseases can be transferred to humans. Wildlife dis- eases that can infect human beings are referred to as zoonotic diseases. Diseases that have spread or are spreading to large areas and other continents are referred to as pandemic diseases. unselfishly/Shutterstock.com Figure 19-7. Koalas eat eucalyptus leaves as the main component of their diet. Their teeth and stomachs are highly specialized to digest this leaf matter which is poisonous to most animals. Koalas sleep for extended periods to conserve energy as their bodies digest the eucalyptus leaves that contain little nutritive value. Meeh/Shutterstock.com Figure 19-8. This grey fox is in the final throws of canine distemper, a disease which is transmissible among many species of animals.