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Natural science: Week 14 Chapter 14: Population Ecology

Natural science: Week 14 Chapter 14: Population Ecology . Monday, April 14 th , 2014. POPULATION ECOLOGY. Population. What is a population? What types of populations are there? Human Population? What is the planet’s limit for human population?. 2010: World population = 6.9 billion

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Natural science: Week 14 Chapter 14: Population Ecology

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  1. Natural science: Week 14Chapter 14: Population Ecology Monday, April 14th, 2014

  2. POPULATION ECOLOGY

  3. Population What is a population? What types of populations are there? Human Population? What is the planet’s limit for human population? 2010: World population = 6.9 billion Predicted to ‘level out’ at 9.1 billion ~2050

  4. Population Ecology Ecology: the field of biology that focuses on the interactions among and between populations and their environment(s). Population: all of the individuals of a particular species within a given area. Structure of populations: • What level of the population? • Distribution? • Abundance? • Dynamics?

  5. Population Structure • Size? • Dispersion? • Uniform or random distribution? • Changing through time? • Birth rates/Death rates • Infant Mortality

  6. Levels of Population • Individual • Populations of same species • Communities of interacting species • Effect of biological activities on the biological environment

  7. Population Structure • How do we determine population size and structure? • Mark-capture method: capture individuals, tag them, and then release them; then, capture again, and determine what proportion of the population are tagged.

  8. Population Distrubution • Dispersion of a population: how they are distributed in space • Clumped: high densities of individuals in certain resource-rich areas, low densities elsewhere • Uniform: densities dispersed in a uniform manner across a habitat • Random: there is no compelling factor that is actively bringing individuals together or pushing them apart.

  9. Exponential Population Growth • Exponential growth: growth that occurs in proportion to the current total • Results in a J-shaped growth curve

  10. Population Growth

  11. Limits to Population Growth Populations have the capacity to grow exponentially; however, there are limitations • Resources – food, water, shelter, space carrying capacity: the maximum population that can be supported indefinitely in a given environment Resource-limited population have an S-shaped growth curve. (logistic growth curve – page 345) Density-dependent vs. Density Independent Factors

  12. Carrying Capacity for Humans • Is our population reaching its carrying capacity on Earth? • Look at the logistic growth curve: • Our needs: • Food • Clean water • Clean air • Energy for essentials Renewable vs. nonrenewable resources!

  13. Future of the Human Population • Managing population growth is essential. • If a population overshoots the carrying capacity, a severe decline in population with occur. • This pattern of ‘boom & crash’ can happen over and over again in a population. • Look at another way of tracking populations: the population pyramid. • Changing/growing populations resembles a true pyramid • Stable populations look like a column

  14. Population Pyramids

  15. Ways to Slow Population Growth Improve conditions for women – increase access to: • Education • Healthcare • Job market • Tools and information to regulate fertility • Slowing grow rates has other benefits: • Better quality of life • Less human impact on nature

  16. Human Populations http://www.learner.org/courses/envsci/interactives/demographics/

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