1 / 20

Chapter 4

Chapter 4. Population Biology. What is a population?. Group of organisms, all of the same species that live a specific area. How fast do populations grow?. Increase slow at first, then faster because there are more reproducing individuals Populations do not increase forever

chelsea-burns
Download Presentation

Chapter 4

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 4 Population Biology

  2. What is a population? • Group of organisms, all of the same species that live a specific area

  3. How fast do populations grow? • Increase slow at first, then faster because there are more reproducing individuals • Populations do not increase forever • Populations will level out due to limited factors • Examples of limited factors: predation, disease, lack of space, food supply

  4. Exponential Population Growth

  5. Let's look at the graph in your book on pg. 94

  6. Population Growth Graph J-shaped curve showing exponential growth of a population This population has not yet reached its carrying capacity. S-shaped curve shows how a population becomes limitied by environmental factors Carrying Capacity: the maximum size of a population that an area can support

  7. Population Growth Steady State Carrying Capacity Exponential Phase Lag Phase

  8. Carrying Capacity • The number of organisms of one species that an environment can support indefinitely • Developing environment: more births than deaths and the population increases until it reaches its carrying capacity • When it reaches carrying capacity, more deaths than births due to limited resource • Population fall below carrying capacity again

  9. Limiting Factors • Any biotic or abiotic factors that restricts the existence, numbers, reproduction or distribution of organisms. • Ex. Soil, food, organism, strong winds, temperatures, high elevations, water

  10. Tolerance • Ability of an organism to withstand fluctuations in biotic and abiotic environmental factors • Example: too much water or too little water on corn plants

  11. Ranges of Tolerance • Range over which a population or organism can successfully survive and grow • Too much or too little of an environmental factor can be limiting

  12. What affects population density?Population density: number of individuals in a given area • Density-dependent factors: affect the size of a population and depend on the size of that population • Examples: disease, predation, parasites, limited resources, competition, stress from overcrowding • Density-Independent Factors: affect the size of a population but do not depend on the size of that population • Examples: volcanic eruptions, temperature, storms, floods, droughts, chemical pesticides

  13. Organism interactions limit populations size Population size are not limited only by abiotic factors Examples: Predator-Prey Relationships, Competition

  14. Predator-Prey Relationships • Predation can be a limiting factor on population size • Predator-Prey relationships show a predictable cycle of population increases and decreases over time

  15. Competition within a Population • What happens when organisms within the same population compete for resources?

  16. DEMOGRAPHY • The study of human population size, density, and distribution, movement, and its birth and death rates • Factors that have lead to human population living longer and producing offspring that live long enough to produce offspring • Vaccines • Producing more food • Technology to supply clean water • Infant mortality rate decrease

  17. Calculating growth rate • Birthrate: number of live births per 1000 • Death rate: number of deaths per 1000 • Immigration: movement of individuals into a population • Emigration: movement of individuals out of a population • Birthrate – Death rate = Population Growth Rate (PGR) • PGR above zero population is growing • PGR below zero, fewer individuals are enter than leaving

  18. Age Structure Graph

  19. Age Structure Graph

  20. Ways To Estimate Populations1. Random Sample 2. Mark & Recapture

More Related