Chp 15 Flashcards
How many mass extinctions were experienced on a global scale before the alarming mass extinction that’s now occurring?
five
North America is currently experiencing an unprecedented and rapid loss of species. What is believed to be the main trigger of such events, either directly or indirectly?
increased human population
Life on Earth has experienced several mass extinctions. What likely caused one or more of these extinctions?
an asteroid impact
Which of the following would be most threatened by habitat fragmentation?
mountain lions
What is the role a species plays in an ecosystem?
ecological niche
Which organism can be considered a predator?
wood warbler
During the 1980s, wolves were reintroduced to Yellowstone National Park after decades of absence due to attempted extermination in the early part of the twentieth century. Within 20 years, not only had the wolf population increased, but there was also a dramatic increase in other species, such as aspen, cottonwood, and willow trees, beavers, warblers, insects, and fish. These changes in Yellowstone Park are examples of how important a(n) ________ can be to an ecosystem.
keystone species
What would a species that has a high number of alleles for many genes that are distributed throughout the population have?
high genetic variability
What describes the greater fitness of individuals who carry one copy of the sickle-cell allele in areas where malaria is common?
heterozygote advantage
What is the best strategy for preserving biodiversity?
to prevent species from becoming endangered in the first place
