Transcript Why and how to study ecology - Powerpoint for Sept. 14.

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 – 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
ΔN=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?
Scientific method Initial Observation
reasoning?
is a repetitive
process that leads Hypothesis
to the building
of theories
New
Hypothesis
Experiment
New
Experiment
Observation/
Data Analysis
New
Observation
Hypothesis not Supported
Interpretation
Final Hypothesis Supported
Theory
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
Y
Alternative Hypothesis
Y
A
B
C
A
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 Grass
Experiment
Natural snapshot experiment
Succession following avalanches at different times
Natural trajectory experiment
Eruption of Krakatau – 1883