Natural science week 14 chapter 14 population ecology
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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

Natural science: Week 14Chapter 14: Population Ecology

Monday, April 14th, 2014


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

Population ecology1
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?

Population structure
Population Structure

  • Size?

  • Dispersion?

  • Uniform or random distribution?

  • Changing through time?

  • Birth rates/Death rates

  • Infant Mortality

Levels of population
Levels of Population

  • Individual

  • Populations of same species

  • Communities of interacting species

  • Effect of biological activities on the biological environment

Population structure1
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.

Population distrubution
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.

Exponential population growth
Exponential Population Growth

  • Exponential growth: growth that occurs in proportion to the current total

    • Results in a J-shaped growth curve

Limits to population growth
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

Carrying capacity for humans
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!

Future of the human population
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

Ways to slow population growth
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

Human populations
Human Populations