Lecture 01Ecology

Ecology as a Science

• What is ecology?

• Characteristics of living things

• Levels of organization of living things

• Levels of organization of ecosystems

• Basic relationships within ecosystems – terminology

• Scientific logic – how we know (what we think) we know

• Ecology: – From Greek – oikos logos = knowledge of or

study of one’s home– Study of distribution and abundance of living

things and their interactions with each other and with their environment

– Ecology as a Branch of Biology – study of living things

What are the Characteristics of Living Things?

All living organisms share five basic properties:

1. Cellular Organization – cell is basic unit of life

2. Metabolism – use energy

3. Homeostasis - maintain stable internal conditions

4. Growth and reproduction

5. Heredity

living things come from living things

Information for traits coded in DNA (deoxyribonucleic acid)

Living things are organized as organisms:

Atoms compounds cells tissues

organs and organ systems organisms

All living things composed of cells

Not all organisms show all these levels of organization!

Populations – single organisms – basic unit in ecology - fill a niche (‘job’ or function)

communities - populations of many

types of organisms

ecosystems: All organisms living in an area, and the physical environment (habitat) with which these organisms interact.

Organisms in an Ecosystem are Interrelated with Each Other and Their Environment

• Every organism in an ecosystem has its niche

• "When we try to pick out anything by itself, we find it hitched to everything in the universe.“ John Muir

• Review of Ecological levels of organization

• Individual/organism

• Population

• Community

• Ecosystems

• Bioshphere

• The Organism

• Functioning together with great precision, the organ systems make up the complex multicellular organism. Organisms interact to form still more complex levels of biological organization.

• Populations

• All the members of one species that live in the same area make up a population.

• Community

• The population of organisms that inhabit a particular area and interact with one another form a community.

• Thus a community can be comprised of hundreds of different types of life forms. The study of how organisms of a community relate to one another and with their non-living environment is called "ecology".

• Community

• A community, together with its non-living environment is referred to as an "ecosystem".

• Pond Tundra

• Largest Ecosystem is the Biosphere

Ecology vs. Environmentalism

Environmentalist:

• Save the world!– An emotion, a cause

Ecologist:

• Understand the world!– How does it work – uses scientific method– Poses specific questions in the form of

hypothesis– Involves controlled experiments and detailed

study

Observation: Hydrangeas of the same variety but growing in different parts of the garden have different colors.

Hypothesis: Something about the soil is different; perhaps acidity (pH).

• Set up experiment to test hypothesis:– Grow one group of Hydrangeas in acid pH – Grow second group of hydrangeas in soil with

basic pH– Keep everything else the same– Observe:

Acid pH

Alkaline pH

Scientific Theory

• Hypotheses are tentative explanations– phenomenon in a particular situation

• Theories are widely accepted explanations– Support from many lines of evidence– Basis of understanding– May be revised or modified– Theory of Evolution

20

Warbler Feeding Zones

Observation Studies in Ecology

• Investigates questions concerning (for example)– Species distribution– What species are present– Populations, reproductive success– How species interact– Changes in species make-up of a habitat– Migratory patterns and routes

• Answers may – lead to more questions– Management decisions …

Organisms Require Resources

• Energy flows through ecosystems– Trophic levels = ‘feeding’ levels– Some energy is lost during transfer to each

higher trophic level

• Materials cycle– Carbon, phosphorus, nitrogen, water cycle

through biotic and abiotic aspects of ecosystems

– Global in scale

Biotic cycling

Biotic and Abiotic

Nutrients Cycle

• Include things like carbon, nitrogen, phosphorus– Some required in greater concentrations than

others– Excesses may be toxic

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Birds of prey

Birds

BirdsMammalsMammals

Arthropods

Fish

Algae

Mollusks

Annelids

Meiofauna

Bacteria and fungi

Inorganicnutrients

Humans

Top carnivores

Carnivores

Herbivores

Photosynthesizers

Decomposers

Inorganicnutrients

Inorganicnutrients

Summary

• Ecology is an investigative science that relies on the scientific method

• The scientific method requires observation, creation of a hypothesis, and data collection to refute or support the hypothesis.

• Ecology and evolution are two separate disciplines that overlap in their investigation of the natural world.

• An understanding of ecology may lead us to sound environmental decisions