Ch. 5 Objectives

• Differentiate between extinct, extirpated and endangered

• Extinction is the complete elimination of an entire species.
• Extirpation is when a species disappears from one location but survives in another.
• Endangered is when a species is at risk of going extinct in the near future.

2. Compare and contrast the causes of previous mass extinctions with those of modern-day.

• Likely causes of previous mass extinctions include the following abiotic forces: falling sea levels, climate change, asteroid collisions, shifting continents or volcanic eruptions
• Ice ages
• Extinctions of today are more likely a result of biotic forces—specifically, human actions.

3. Identify human activities that threaten species with extinction

• Destruction of habitat and fragmentation
• Introduction of non-native species
• Over-harvesting a population
• Burning fossil fuels contributes to climate change

4. Describe traits that increase a species’ risk of extinction.

• Specialized niche
• Small population size
• Inbreeding
• Allee effect
• Restricted geographic range

5. Explain how the extinction of a species affects other species, including humans.

• Saving species from extinction is a moral issue for many people.
• We were put here to take care of organisms
• Species provide economic benefits.
• Money from hunting, lumber, cost of pollution, medicine...
• Species provide recreational opportunities.
• Hunting, hiking, gardening...
• Species maintain balance within the community
• Predator/prey, biodiversity...

6. Predict the effect on the biological community from environmental change.

• If a keystone predator is extirpated, prey populations can skyrocket which will affect other organisms within the community.
• Keystone species is one that greatly affects the other species in the community.
• When one species is extirpated and other species have similar niches and roles, there may be little effect on the community.

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6. cont.

• However, if too many species become extinct or extirpated, other species that rely on them may also disappear.

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7. Explain why grassland bird populations are declining at an alarming rate.

• Loss of North American grassland habitat and grassland plant diversity
• Increased use of herbicide and pesticide
• Feral animals
• Loss of wintering habitat in Central and South America

8. Explain what resource managers are doing to increase grassland bird populations.

• Restoring native prairies
• Encouraging farmers to leave weedy borders around the edges of fields
• Encouraging farmers to convert pastures to native grasses
• Creating natural disturbances by mowing, disking and setting prescribed fires

9. Describe the threat posed by invasive species.

• Non-native invasive species grow quickly, reproduce often and bear many offspring.
• Limiting factors may not be present to control their populations.
• Native species are often displaced or go extinct, disrupting the existing ecosystem.
• They can damage agricultural crops and spread disease to native and domesticated plants and animals.

10. Explain the strategies resource managers use to slow the spread of invasive species.

• Eradicating non-native vegetation by using a combination of burning, mowing and herbicide
• Surveying areas to detect outbreaks of invasive species such as emerald ash borer and setting up quarantines for infested areas
• Encouraging boaters to use hot water to wash boats, motors and trailers and to let them dry in the sun for five days to kill attached zebra mussels