Chapter 18 – Introduction to Ecology Section 1: Introduction to Ecology

Ecology Ecology is the study of the interactions between organisms and the biotic and abiotic components of their environment Biotic = living Abiotic = nonliving

Today’s Environment The Exploding Human Population The world’s human population has tripled from 2 billion people in 1930 to 6 billion people in 1999 Causes severe crowding Requires an increasing amount of food, energy and space for disposing waste

Today’s Environment The 6th Mass Extinction Species are disappearing faster than at any other time since the last mass extinction About 20% of the species of birds have become extinct in the last 2000 years Caused by: Habitat destruction Over-hunting New diseases and predators being introduced to non-native areas

Today’s Environment The Thinning Ozone Layer The ozone layer protects Earth’s living organisms by absorbing UV radiation from the sun Industrial chemicals called chlorofluorocarbons (CFCs) react with the ozone and are destroying the ozone later In 1992 a ban was established on using CFCs and related chemicals In 1996, the ozone level over Antarctica was about 50% of the maximum density This allows in extra UV radiation that can lead to sunburn and skin cancer

Today’s Environment Climatic Changes Greenhouse Effect: the ability of carbon dioxide and water vapor to trap the reflected heat from the sun and direct it back towards the Earth Protects the Earth from the deep-freeze of space Human use of fossil fuels has increased the amount of carbon dioxide in the atmosphere by 25% in the last 100 years The increase of greenhouse gases are trapping excess heat in our atmosphere, causing global temperatures to rise Scientists warn that if the problem is not corrected in the next 10 years, the condition of our Earth will not be able to be reversed

A Key Theme in Ecology No single organism is isolated!! The interconnectedness or interdependence of all organisms is central to the study of ecology The survival of organisms depends on their interactions with their surrounding environment Ex: Humans cannot live without the plants that produce food and oxygen

Levels of Organization

The Biosphere Biosphere: the broadest and most inclusive level of organization The Earth and its atmosphere make up our biosphere Extends from 8 to 10 km (5-6 miles) above the Earth’s surface to the deepest parts of the ocean

Ecosystems The biosphere is comprised of smaller units called ecosystems Includes all of the organisms and the abiotic environment found in a specific place Ex: Pond Ecosystem Abiotic components: water temperature, amount of dissolved oxygen and carbon dioxide, the pH level Biotic components: insects, fish, algae, aquatic plants, turtles

Ecosystem Chapter 18

Communities, Populations and Organisms A community is all of the interacting organisms living in an area Ex: All of the fish, turtles, insects, plants and algae make up the community of a pond A population includes all of the members of a species that live in one place at one time Ex: All of the humans in Vernon Hills An organism is a single, living thing. Ecologists study organisms for their adaptations that allow them to overcome the challenges of their environment

Chapter 18 Community

There are none! Brain Break Try to count the number of black dots on the image below... There are none!

Chapter 18 – Introduction to Ecology Section 2: Ecology of Organisms

Biotic and Abiotic Factors Environmental factors found in an organisms habitat are broken into two classes: Biotic = living components of the environment Abiotic = nonliving components of the environment Includes: Temperature Humidity pH Salinity Oxygen concentration Amount of sunlight Availability of nitrogen Precipitation

Biotic and Abiotic Factors Visual

The Changing Environment Abiotic factors are NOT constant Ex: Temperature Varies from hour to hour, day to day, season to season, and year to year Varies from place to place: Phoenix will be hotter than Chicago Can vary within a habitat Different in temperature between being in the shade of a tree vs. out in direct sunlight

Responses to a Changing Environment Organisms are adapted to function within a specific range of an abiotic factor Ex: Temperature All organisms have a range of temperature in which they can function To determine the range in which an organism can live, you can measure how efficiently it performs at specific temperatures A tolerance curve is a graph of performance vs. values of an environmental variable Performance is usually reduced when the values are outside of the optimal range Organisms cannot survive in areas where they are exposed to conditions that fall outside of their tolerance range

Tolerance Curve Zones of Physiological Intolerance (no performance) Zones of physiological stress (reduced performance) Swimming Speed Temperature

Acclimation Acclimation is the process by which organisms can adjust their tolerance to abiotic factors Ex: Going to the mountains If you spend a few weeks in the mountains, your body will acclimate to the lower oxygen levels by producing more red blood cells in your body This will allow your blood to carry more oxygen Acclimation IS NOT adaptation!! Adaptation is a genetic change in a species that occurs over many generations – acclimation occurs within the lifetime of a species

Control of Internal Conditions The abiotic factors within an environment can fluctuate Two ways to deal with the changes: Conformers: do not regulate internal conditions; they change as their environment changes Ex: Desert lizards’ rises and falls with the temperature of their environment Regulators: use energy to control some of their internal conditions Ex: humans maintain a constant internal body temperature

Escape from Unsuitable Conditions Organisms have developed strategies for surviving unfavorable environmental conditions: Dormancy: a state of reduced activity during which an organism’s metabolism slows down Ex: Reptiles and amphibians “hide” underground and become dormant during the winter to survive the cold temperatures Migration: when organisms move to a more favorable environment Ex: Seasonal movements of birds

Resources Resources: the energy and materials that an organism needs to survive Ex: Food, water, shelter and sunlight The resources essential for survival vary between different species Ex: The resources plants require are different from those humans need

The Niche A specie’s niche is the role an organism plays in its environment Includes: Range of conditions the organism can tolerate Methods by which it obtains resources Interactions with its environment such as reproduction A fundamental niche is the range of conditions that a species can potentially tolerate and the range of resources it can potentially use A realized niche is the range of resources an organism actually uses

The Niche Visual

Niche Differences Generalists are species with broad niches Can tolerate a range of conditions and use a variety of resources Ex: Virginia opossum  found all over the US and can eat a wide range of food Specialists are species that have narrow niches Ex: koalas  only feed on leaves from a few species of eucalyptus trees