Introduction to Ecology cont’d. Introduction to Ecology How do you know you are talking to a real...
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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