5.1 How Populations Grow. Population density is the number of individuals that live in a defined area.

Transcription

1 5.1 How Populations Grow Population density is the number of individuals that live in a defined area.

2 5.1 How Populations Grow KEY CONCEPT Populations grow in predictable patterns.

3 5.1 How Populations Grow Four factors affect the size of a population. immigration births emigration deaths

4 5.1 How Populations Grow Exponential Growth vs. Logistic Growth Exponential growth is a rapid population increase due to an abundance of resources. Shown as a J shaped curve

5 5.1 How Populations Grow Exponential Growth vs. Logistic Growth Exponential growth is a rapid population increase due to an abundance of resources. Exponential Growth Phase = period of rapid growth when population repeatedly increases in size; does not continue forever Lag Phase = initial period of slow growth

6 5.1 How Populations Grow Logistic growth is due to a population facing limited resources. Shown as a S shaped curve

7 5.1 How Populations Grow Carrying capacity is the maximum number of individuals in a population that the environment can support. 4) Leveling Off 3) Reaching Carrying Capacity 2) Exponential Growth Phase 1) Lag Phase

8 5.1 How Populations Grow Human Population Growth humans are in the exponential phase of growth Projections for the future estimate 8.9 billion people by 2050

9 5.2 Limits of Growth Ecological factors limit population growth. A limiting factor is something that keeps the size of a population down. 1) Density-dependent limiting factors - affected by the number of individuals in a given area - ex: predation, competition, parasitism and disease

10 5.2 Limits of Growth 2) Density independent limiting factors limit a population s growth regardless of the density. ex: unusual weather, natural disasters, human activities

11 KEY CONCEPT The impact of a growing human population threatens biodiversity.

12 Which is more diverse? A B

13 Which is more diverse? A B

14 Which has more diversity? A B

15 Which has more biodiversity? A B

16 biodiversity = the variety life forms on Earth

17 Importance of Biodiversity Every organism has its own niche (ex: producers, decomposers) All organisms depend on each other (ex: symbiosis, food chain/food web) Provide a variety of resources: food clean water medicine recycled nutrients

18 Loss of Biodiversity Causes: 1) Habitat loss 2) Pollution 3) Overharvesting 4) Global climate change 5) Introduced or Invasive new species (non native species)

19 Introduced species can disrupt stable relationships in an ecosystem. An introduced species is one that is brought to an ecosystem by humans. accidental purposeful Invasive species can have an environmental and economic impact.

20 Introduced species can disrupt stable relationships in an ecosystem. Non native species may introduce parasites, plants, and animal species that are not native to a particular area. Many non native species compete against native species for the resources (food, shelter) and disrupt the balance of the environment. Non native species flourish because they have few natural predators or parasites to slow down their population growth.

21 Invasive species often push out native species. Burmese python Origin: Southeast Asia Current Habitat: Florida Everglades Method of Arrival: came to U.S. as a pet species Problem: threats to endangered bird species in the Everglades

22 Invasive species often push out native species. mice Origin: Europe Current Habitat: Australia Method of Arrival: British Cargo ship in late 1700s Problem: major pest species and caused economic damage of crops

23 Invasive species often push out native species. Kudzu plant Origin: Southeast Asia Current Habitat: Eastern United States Method of Arrival: came to U.S. as an ornamental house plant in 1876 Problem: classified as a problematic weed species because of its rapid growth

24 Loss of Biodiversity Result: 1) Ecosystem Breakdown 2) More Endangered Species 3) Extinction