chapter 7 population ecology the wolf...

22
CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERS Endangered gray wolves return to the American West

Upload: lemien

Post on 30-Jul-2018

232 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERSvuearth101.weebly.com/uploads/9/8/2/9/98290512/chapter_9_ppt... · CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERS Endangered gray wolves

CHAPTER 7 POPULATION ECOLOGY

THE WOLF WATCHERSEndangered gray wolves return to the American West

Page 2: CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERSvuearth101.weebly.com/uploads/9/8/2/9/98290512/chapter_9_ppt... · CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERS Endangered gray wolves

Population size and makeup can fluctuate or remain stable. Population stability is often dependent on predators. When human impact results in reduced predation, we may need to manage the system ourselves.

Main

concept

7 THE WOLF WATCHERSEndangered gray wolves return to the American West

Case StudyYellowstone Gray Wolf

Restoration Project

Page 3: CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERSvuearth101.weebly.com/uploads/9/8/2/9/98290512/chapter_9_ppt... · CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERS Endangered gray wolves

7 THE WOLF WATCHERSEndangered gray wolves return to the American West

Case Study – Yellowstone Gray Wolf Restoration ProjectHistory of decline – Humans hunted wolves, destroyed habitat by conversion for agriculture, and hunted wolves’ food sources—elk, deer, and bison.

Wolf populations in Yellowstone had also declined as a result of predator control programs.Protected under the Endangered Species Act of 1973

In 1987, 41 wolves were reintroduced and outfitted with radio collars allowing researchers to track the size of wolf packs, their food sources, and movement patterns.

Page 4: CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERSvuearth101.weebly.com/uploads/9/8/2/9/98290512/chapter_9_ppt... · CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERS Endangered gray wolves

Yellowstone– retunr of the wolf

https://www.youtube.com/watch?v=dMGJ9oThHbc

Page 5: CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERSvuearth101.weebly.com/uploads/9/8/2/9/98290512/chapter_9_ppt... · CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERS Endangered gray wolves

7 THE WOLF WATCHERSEndangered gray wolves return to the American West

Populations, all the individuals of a species living together in the same area, fluctuate naturally over time.

Populations increase with birth and immigration and decrease with death and emigration.

Response is often based on access to food, water, nesting sites, and predation.

Population dynamics can be predictable or more random.

Information from tracking helps aid recovery and plan conservation strategies for wolves and for many other threatened plants and animals.

Page 6: CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERSvuearth101.weebly.com/uploads/9/8/2/9/98290512/chapter_9_ppt... · CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERS Endangered gray wolves

Populations fluctuate in size and have varied distributions

TERMS TO KNOW:PopulationPopulation dynamicsMinimum viable population

7

Below a minimum number of individuals, a species may not be viable long term.

Courtship rituals,flocking, schooling, foraging, and genetic variability are often dependent on population size.

Doug Smith, Population

Biologist

Page 7: CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERSvuearth101.weebly.com/uploads/9/8/2/9/98290512/chapter_9_ppt... · CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERS Endangered gray wolves

Populations fluctuate in size and have varied distributions7Successful population density varies by species. Too low and individuals may not be able to find mates or only mates that are closely related.

In a population that is too dense, competition, fighting, and disease can become problems.

Location and spacing of individuals within a population may be influenced by a variety of factors.

Page 8: CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERSvuearth101.weebly.com/uploads/9/8/2/9/98290512/chapter_9_ppt... · CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERS Endangered gray wolves

Populations fluctuate in size and have varied distributions7

Social species such as wolves, elk, and prairie dogs provide examples of clumped distribution.

Individuals are found in groups within the habitat.

Page 9: CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERSvuearth101.weebly.com/uploads/9/8/2/9/98290512/chapter_9_ppt... · CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERS Endangered gray wolves

Populations fluctuate in size and have varied distributions7

Random distribution –Species that disperse randomly in an environment like wind-blown seeds that germinate where they land

Individuals are spread out irregularly.

Page 10: CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERSvuearth101.weebly.com/uploads/9/8/2/9/98290512/chapter_9_ppt... · CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERS Endangered gray wolves

Populations fluctuate in size and have varied distributions7Individuals spaced evenly possibly due to territorial behavior or something that suppresses growth.

Creosote bushes in the desert are an example of uniform distribution.

Page 11: CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERSvuearth101.weebly.com/uploads/9/8/2/9/98290512/chapter_9_ppt... · CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERS Endangered gray wolves

A variety of factors affect population growth7TERMS TO KNOW:Population growth rateBirth rateDeath rateBiotic potential (r)Exponential growthLogistic growthCarrying capacity

Limiting factors are resources needed for survival but that may be in short supply. This scarcity will determine carrying capacity.

Resistance factors, such as predation, competition, and disease, will also contribute to controlling population size and growth.

These factors are density-dependent, but other factors such as natural disaster are density-independent since they would occur regardless of the population size.

Page 12: CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERSvuearth101.weebly.com/uploads/9/8/2/9/98290512/chapter_9_ppt... · CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERS Endangered gray wolves

A variety of factors affect population growth7

TERMS TO KNOW:Density dependentDensity independentReproductive strategiesr-selected speciesK-selected species

Effects of density-dependent factors increase as populations grow. Disease Competition Predation

Page 13: CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERSvuearth101.weebly.com/uploads/9/8/2/9/98290512/chapter_9_ppt... · CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERS Endangered gray wolves

A variety of factors affect population growth7

TERMS TO KNOW:Density dependentDensity independentReproductive strategiesr-selected speciesK-selected species

Effects of density independent factors affect a population, regardless of its size, but can serve to decrease the population. Storm Fire/Flood Avalanche

Page 14: CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERSvuearth101.weebly.com/uploads/9/8/2/9/98290512/chapter_9_ppt... · CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERS Endangered gray wolves

A variety of factors affect population growth7High rate of population increase and well adapted to exploit unpredictable environments

Will increase quickly as resources become available

P. 168

Page 15: CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERSvuearth101.weebly.com/uploads/9/8/2/9/98290512/chapter_9_ppt... · CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERS Endangered gray wolves

A variety of factors affect population growth7Low reproductive rates and very responsive to environmental conditions

Decrease or increase slowly as resource availability changes

Page 16: CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERSvuearth101.weebly.com/uploads/9/8/2/9/98290512/chapter_9_ppt... · CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERS Endangered gray wolves

A variety of factors affect population growth7K-selected species tend to be stable in undisturbed areas.Slow increases and decreases in response to the environment.

TERMS TO KNO

r-selected species with rapid reproductive potential sometimes have sudden population growth with high peaks which may overshoot carrying capacity followed by sudden crashes. Some populations will level off near carrying capacity while others will continue to overshoot and crash.

Page 17: CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERSvuearth101.weebly.com/uploads/9/8/2/9/98290512/chapter_9_ppt... · CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERS Endangered gray wolves

A variety of factors affect population growth7Some populations

overshoot carrying capacity, drop below it, and increase and overshoot it again until

they settle down close to carrying capacity.

Page 18: CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERSvuearth101.weebly.com/uploads/9/8/2/9/98290512/chapter_9_ppt... · CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERS Endangered gray wolves

A variety of factors affect population growth7Example – Isle Royale, MichiganWolves preyed upon moose and the moose population dropped, followed by a drop in the wolf population. As moose populations recovered, so did the wolves’ until a Parvoepidemic reduced wolves to their lowest point.

Page 19: CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERSvuearth101.weebly.com/uploads/9/8/2/9/98290512/chapter_9_ppt... · CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERS Endangered gray wolves

The loss of the wolf emphasized the importance of an

ecosystem’s top predator7Black line shows winter browse line from herbivores

Populations do not exist in isolation. Like the Yellowstone example demonstrates, the addition of a keystone species like the wolf can result in observable changes in the behavior of its prey. Cascading effects on other community level processes may follow.

Page 20: CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERSvuearth101.weebly.com/uploads/9/8/2/9/98290512/chapter_9_ppt... · CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERS Endangered gray wolves

The loss of the wolf emphasized the importance of an

ecosystem’s top predator7

Without wolves, beavers thrive and build dams that create lakes and ponds. Elk stay in the willow thickets and overgraze willow needed by the beavers.

Page 21: CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERSvuearth101.weebly.com/uploads/9/8/2/9/98290512/chapter_9_ppt... · CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERS Endangered gray wolves

The loss of the wolf emphasized the importance of an

ecosystem’s top predator7With wolves, willows regrow because elk feed in the meadows, where they can watch for wolves rather than in the willow thickets. With more willows, beavers return and the wildlife populations recover.

Page 22: CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERSvuearth101.weebly.com/uploads/9/8/2/9/98290512/chapter_9_ppt... · CHAPTER 7 POPULATION ECOLOGY THE WOLF WATCHERS Endangered gray wolves

How wolves change rivers

https://www.youtube.com/watch?v=ysa5OBhXz-Q