Introduction to Ecology cont’d

Introduction to Ecology

• How do you know you are talking to a real ecologist? They always answer any question the same way.

Rob Colwell

Introduction to Ecology

• How do you know you are talking to a real ecologist? They always answer any question the same way.

• “Well it depends…”

Rob Colwell

Ecology is:

• A science of dependency

• A probabilistic science

Intermediate Number Systems

The first ecologists?

Two Founders of Ecology

Ernst Haeckel Eugene Warming

Definitions of Ecology

• Haeckel – 1870 – By ecology we mean the body of knowledge concerning the economy of nature – the investigation of the total relations of the animal both to its inorganic and organic environment.

• Tansley – 1904 – (Ecology is) Those relations of plants, with their surroundings and with one another, which depend directly upon differences of habitat among plants.

• Elton – 1927 – Ecology is the new name for a very old subject. It simply means scientific natural history.

Definitions of Ecology cont’d

• Andrewartha – 1961 – Ecology is the scientific study of the distribution and abundance of organisms.

• Krebs – 1972, 2008 – Ecology is the scientific study of the interactions that determine the distribution and abundance of organisms.

• Townsend et al. 2003 – Ecology is the scientific study of the distribution and abundance of organisms and the interactions that determine distribution and abundance.

We study these interactions via:

• Descriptive studies

• Modeling – verbal, graphical or mathematical

• Experiments in nature

The Fundamental Equation of Ecology – Harper 1977

Δ N = B – D + I – E

Change in Number = Births – Deaths + Immigration - Emigration

John L. Harper – 1925-2009

Some Definitions of Terms• environment - biotic and abiotic factors that

influence organisms

• organism - individual living thing

• population - many individuals of one species living close enough to each other to potentially interbreed

• community - all interacting populations in a particular habitat - includes plants, animals, decomposer microbes - pond or forest community. - in practice often used when 2 or more species discussed

Some Definitions of Terms• ecosystem - community plus abiotic factors - nutrients,

water, soil, climate, etc. - pond ecosystem

• habitat - place where microbe, plant or animal lives

• biosphere - the earth and all its ecological systems

• autecology - relation of individual organism to environment

• synecology - relation of populations or species to other populations or species

How to study ecology?

Initial Observation

Hypothesis

reasoning?

Experiment

Observation/Data Analysis

Interpretation

Hypothesis not Supported

NewHypothesis

NewExperiment

NewObservation

Final Hypothesis Supported

Theory

Scientific methodis a repetitiveprocess that leadsto the buildingof theories

Creosote and sage brush desert

Diagram of desert plant root growth

Statistics - a powerful tool for analyzing data

1. Descriptive Statistics - provide an overview of the attributes of a data set. These include measurements of central tendency (frequency histograms, mean, median, & mode) and dispersion (range, variance & standard deviation)

2. Inferential Statistics - provide measures of how well your data support your hypothesis and if your data are generalizable beyond what was tested (significance tests)

Differences Between Means

Asks whether samples come from populations with different means

Null Hypothesis Alternative Hypothesis

A

Y

B CA

Y

B C

Observational Studies

pubs.usgs.gov/circ/circ1209/studyunit_design.htm

Watering Hole showing Piosphere

Piosphere is an area of land degraded by many animals gathering around a watering hole

Model of Piosphere

Lab Experiments

Field Experiments

Pelvetiopsis

Rothamsted, England – Broadbalk Wheat Experiment

Rothamsted,England – Park GrassExperiment

Natural snapshot experiment

Succession following avalanches at different times

Natural trajectory experiment

Eruption of Krakatau – 1883