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Populations

Populations. A PRS introduction. A ‘population’ refers to…. A group of organisms of one species that interbreed and live in the same place at the same time A group of organisms of different species living in the same place at the same time.

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Populations

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  1. Populations A PRS introduction

  2. A ‘population’ refers to… • A group of organisms of one species that interbreed and live in the same place at the same time • A group of organisms of different species living in the same place at the same time. • All living organisms living together in the same place at the same time AND their non-living environment that they interact with.

  3. A population is… A group of organisms of one species that interbreed and live in the same place at the same time. Human Population specifically refers to people living in the same territory at the same time. (Ex. Population of the USA)

  4. Which of the following does NOT directly affect the size of a human population? • The number of births • The number of deaths • The number of immigrants • All of these do directly affect the size of a human population • None of these directly affect the size of a human population

  5. Formula for Human Population Change: New population size = Initial Population + Births – Deaths + Immigrants – Emigrants

  6. The RATE of change (in %)… • Is calculated by: (Births – Deaths + Immigrants – Emigrants) * 100 Initial Population

  7. What is a country’s rate of population change if… • Initial Population = 3,060,000 • Births = 60,000 • Deaths = 50,000 • Immigrants = 10,000 • Emigrants = 3,000 Click in your answer in % rounded to the nearest 100ths place.

  8. Answer: Births – Deaths = 10,000 Immigrants – Emigrants = 7,000 17,000 / 3,060,000 = 0.005555 x 100 = 0.56%

  9. Consider this non-human example… Suppose a lake exists for years without any lily pads. Then one day, a person introduces a lily pad from a different part of the world. This lily pad has no predators in this new pond and abundant nutrients, sunlight, etc. Given these conditions, the lily pad will divide and produce two lily pads each day. In other words, by the end of day one, there would be two lily pads, at then end of day two there would be four…etc.

  10. How many lily pads are in the pond after just two weeks (14 days)? Click in your numerical answer.

  11. After just two weeks… • The pond would have 16,384 lily pads. This is an example of exponential growth. X = 1*214/1 214 = 16,384

  12. If you plot exponential growth on a graph, the line will appear shaped like what letter of the alphabet? • A • X • S • J

  13. This is referred to as a “J-shaped” curve

  14. TRUE or FALSE • Exponential growth of a population on earth can continue infinitely.

  15. Many things in reality cause exponential growth to be limited. These things are referred to as… LIMITING FACTORS The limiting factors of a population define the maximum number of individuals that can live for an extended time period. This is known as the CARRYING CAPACITY

  16. Possible examples of limiting factors include…. • Sunlight (for plants) • Temperature • Water • Nutrients/Food • Habitat Space • Predation • Disease

  17. Types of population growth

  18. Types of population growth The living conditions for the average individual are not as good when the population is near the carrying capacity. WHY?

  19. So how can we analyze real populations? • Population pyramid • Why break it down this way?

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