Chapter 11 Review Sheet
I. Central Case: Saving the Siberian Tiger
A. Up until the past 200 years, tigers roamed widely across the Asian continent from Turkey to northeast Russia to Indonesia.
B. Of the tigers that still survive in small pockets of their former range, those in the subspecies known as the Siberian tiger are the largest cats in the world.
C. For thousands of years, the Siberian tiger coexisted with the native people of what is today the Russian Far East, who equated the tiger with royalty and viewed it as a guardian.
D. The Russians who moved into and exerted control over the region in the early to mid-20th century had no cultural traditions that expressed respect for the animal, leading to the decline of the species.
E. International conservation groups began to get involved, working with Russian biologists to try to save the dwindling tiger population.
F. Today, the Siberian tiger population is up to roughly 330 to 370, and 600 more survive in zoos around the world. However, 40% of the tiger’s habitat has disappeared in the last decade.
II. Our Planet of Life
A. What is biodiversity?
1. Biological diversity, or biodiversity, is the sum total of all organisms in an area.
2. Biodiversity takes into account the diversity of species, their genes, their populations, and their communities.
B. Biodiversity encompasses several levels of life’s organization.
1. Species diversity is expressed in terms of the number or variety of species in the world or in a particular region.
a.Taxonomists, the scientists who classify species, use an organism’s physical appearance and genetic makeup to determine to which species it belongs.
b.Speciation, the generation of new species, adds to species diversity, while extinction decrease species diversity.
c. Biodiversity exists below the species level in the form of subspecies.
2. Genetic diversity encompasses the differences in DNA composition among individuals within a given species.
a. Whether genetic diversity is extremely minor or great enough to warrant subspecies status, such diversity has repercussions for the well-being of a species in at least two major ways.
b. First, as a species becomes adapted to local environmental conditions, its genetic diversity may decrease.
c. In the long term, species with more genetic diversity have better chances of persisting, because their built-in variation better enables them to cope with environmental change.
3. Ecosystem diversity, community diversity, habitat diversity, and landscape diversity are all ways to view biodiversity.
C.Measuring biodiversity is not easy.
D.You may be able to help measure biodiversity where you live.
E.Global biodiversity is not distributed evenly.
III. Biodiversity Loss and Species Extinction
A. Extinction occurs when the last member of a species dies and the species ceases to exist; in contrast, the extinction of a certain population from a given area, but not the entire species globally, is called extirpation.
B. Extinction is a natural process.
1. Most extinctions preceding the appearance of humans have occurred one by one, at a rate that paleontologists refer to as the background rate of extinction.
C. Earth has experienced five previous mass extinction episodes.
D. Humans set the sixth mass extinction in motion years ago.
E. Current extinction rates are much higher than normal.
1. To keep track of the current status of endangered species, the World Conservation Union (IUCN) maintains the Red List.
F. Biodiversity loss involves more than extinction.
G. There are several major causes of biodiversity loss:
1. Habitat alteration
2. Invasive species
5. Climate change
H. Causes of biodiversity loss can be difficult to determine.
IV. Benefits of Biodiversity
A. Biodiversity provides ecosystem...