An Introduction to Ecology

Lecture Outline

Overview: The Scope of Ecology

·         Ecology is the scientific study of the interactions between organisms and their environment.

·         What ecology is not!

1. A philosophical viewpoint or a religious bias
2. A political orientation (environmentalism)
3. A commitment to save the earth
4. An attitude in opposition to change

·         What ecologists do?

·         Ecologists ask questions about factors affecting the distribution and abundance of organisms.

·         Ecologists might study how interactions between organisms and the environment affect the number of species living in an area, the cycling of nutrients, or the growth of populations.

·         Design experiments to test basic assumptions and concepts

·         Describe the composition of different types of ecosystems

·         Look at interactions among organisms

·         Evaluate the impacts of human activities on ecosystems

·         Study biodiversity and the survival/extinction rates of different organisms

·         Focus on different aspects of ecosystems

How do ecologists approach the study of ecosystems?

·         Levels (organisms, populations, communities)

Levels of Organization

Atom

Molecule

Macromolecule/Compound

Cells/Cell Organelles

Tissues

Organs

Organ Systems

Organisms   (What is a species?)

Population

Community

Ecosystem

Biosphere

·         Interactions (predation, parasitism, competition)

·         Processes (photosynthesis, respiration, transpiration)

·         Pathways (food chains, biogeochemical cycles, succession)

·         Locations (aquatic, marine and terrestrial ecosystems; biomes

Interrelatedness in the Ecosphere - where to look? 

·         Sequential processes (biomagnification, developmental disorders)

·         Geographic transfers (terrestrial to aquatic; watershed to airshed)

·         Habitat alteration and loss of biodiversity (bleaching of coral reefs; deforestation; desertification)

·         Biotic potential and carrying capacity; ecological sustainability; optimization

·         Homeostasis (intricate balance between living creatures and their habitats)

  What are some trends in current ecological research? 

·         Characterization of biodiversity in the world's ecosystems

·         Exploring uncharted regions and unique ecosystems

·         Studying the impacts of "exotic" species that "invade" local environments

·         Assessing the ecological sustainability of human activities (e.g., The Great Warming)

·         Linking evolution and ecology

·         Movement of toxics through environmental pathways

·         Impact of toxic substances on human health

 Ecology and evolutionary biology are closely related sciences.

·         Ecology has a long history as a descriptive science.

·         Modern ecology is also a rigorous experimental science.

·         Ecology and evolutionary biology are closely related sciences.

·         Events that occur over ecological time (minutes to years) translate into effects over evolutionary time (decades to millennia).

°         For example, hawks feeding on field mice kill certain individuals (over ecological time), reducing population size (an ecological effect), altering the gene pool (an evolutionary effect), and selecting for mice with fur color that camouflages them in their environment (over evolutionary time).

 Ecological research ranges from the adaptations of individual organisms to the dynamics of the biosphere.

·         The environment of any organism includes the following components:

°         Abiotic components: nonliving chemical and physical factors such as temperature, light, water, and nutrients.

°         Biotic components: all living organisms in the individual’s environment.

·         Ecology can be divided into a number of areas of study.

·         Organismal ecology is concerned with the behavioral, physiological, and morphological ways individuals interact with the environment.

·         A population is a group of individuals of the same species living in a particular geographic area. Population ecology examines factors that affect population size and composition.

·         A community consists of all the organisms of all the species that inhabit a particular area. Community ecology examines the interactions between species and considers how factors such as predation, competition, disease, and disturbance affect community structure and organization.

·         An ecosystem consists of all the abiotic factors in addition to the entire community of species that exist in a certain area. Ecosystem ecology studies energy flow and cycling of chemicals among the various abiotic and biotic components.

·         Ecosystems are biotic communities which include: 3 major layers

1. Atmosphere: The atmosphere is the body of air which surrounds our planet. Most of our atmosphere is located close to the earth's surface where it is most dense. The air of our planet is 79% nitrogen and just under 21% oxygen; the small amount remaining is composed of carbon dioxide and other gasses.

2. Hydrosphere: The hydrosphere is composed of all of the water on or near the earth. This includes the oceans, rivers, lakes, and even the moisture in the air. Ninety-seven percent of the earth's water is in the oceans. The remaining three percent is fresh water; three-quarters of the fresh water is solid and exists in ice sheets

3. Lithosphere: The lithosphere is the solid, rocky crust covering entire planet. This crust is inorganic and is composed of minerals. It covers the entire surface of the earth from the top of Mount Everest to the bottom of the Mariana Trench.

·         A landscape or seascape consists of several different ecosystems linked by exchanges of energy, materials, and organisms. Landscape ecology deals with arrays of ecosystems and their arrangement in a geographic region.

°         Each landscape or seascape consists of a mosaic of different types of patches, an environmental characteristic ecologists refer to as patchiness. Landscape ecological research focuses on the factors controlling exchanges of energy, materials, and organisms among ecosystem patches.

·         The biosphere is the global ecosystem, the sum of all of the planet’s ecosystems. The biosphere includes the entire portion of Earth inhabited by life, The biosphere is composed of all living organisms. Plants, animals, and one-celled organisms are all part of the biosphere. Most of the planet's life is found from three meters below the ground to thirty meters above it and in the top 200 meters of the oceans and seas.

 Ecology provides a scientific context for evaluating environmental issues.

·         It is important to clarify the difference between ecology, the scientific study of the distribution and abundance of organisms, and environmentalism, advocacy for the protection or preservation of the natural environment.

·         To address environmental problems, we need to understand the interactions of organisms and the environment.

°         The science of ecology provides that understanding.

·         In 1962, Rachel Carson’s book Silent Spring warned that the use of pesticides such as DDT was causing population declines in many nontarget organisms.

·         Today, acid precipitation, land misuse, toxic wastes, habitat destruction, and the growing list of endangered or extinct species are just a few of the problems that threaten the Earth.

·         Many influential ecologists feel a responsibility to educate legislators and the general public about decisions that affect the environment.

°         It is important to communicate the scientific complexity of environmental issues.

·         Our ecological information is always incomplete. The precautionary principle (essentially “an ounce of prevention is worth a pound of cure”) can guide decision making on environmental issues.