Lecture 2

Question 1

Ecology as Science

How does the scientific method work?

Answer 1

“The Happy Bear”

Observation
Question
Research
Guess (Hypothesis - an educated guess)
Experiment
Analyze Data (commonly use stats to infer significant results)
Conclusion (repeatable) OR back to Question

Question 2

Ecologists evaluate competing hypotheses about natural systems with… (3 things)

Answer 2

experiments, observations, and models

Question 3

Methods to answer questions about the natural world: (4)

Answer 3

1. Observational Studies
2. Experiments in the field (only so much you can control)
   - i.e. barnacles exposed/unexposed to predators; leaves labelled with isotope of carbon (which acts as a dye)
3. Controlled lab experiments (greenhouse)
4. Quantitative Models

Question 4

Ecological Experiments (hierarchy)

Answer 4

lab experiments, small scale field experiments, large scale ecosystem experiments (to largest spatial scale and longest temporal scale)

i.e. ancient stores of carbon ‘burped’ into the atmosphere

Question 5

Experimental Design (3 steps)

Answer 5

1. Replicate—perform each treatment
   more than once.
2. Assign treatments at random.
3. Statistical analysis is used to determine
   significant effects.

Question 6

The Two Key Rs

Answer 6

Replicate and Randomize

Question 7

Critical C

Answer 7

Control

i.e. injecting poison and water into pike muscle tissue (ensures the injection, the needle itself does not effect the results)

Question 8

Purpose for an experimental control

Answer 8

Controls are used to account for anything that may potentially affect results

Question 9

Experiments have 3 attributes: No experiment can capture all three

Answer 9

*Hint: GRP

1. Generality (large-scale studies)
2. Realism (field experiments)
3. Precision (lab experiments)

Question 10

Case Study: Deformity and Decline in Amphibian Populations

Answer 10

High incidence of
deformities in
amphibians

Declining populations
of amphibians
worldwide

Question 11

Case Study: Why Amphibians?

Answer 11

• live on land and water
• permeable skin

*making it a sensitive species = good bio indicators (like fungus and lichen)

Question 12

Case Study:

A controlled experiment:

Answer 12

Tree frog eggs were exposed to Ribeiroia
parasites in the lab.

Four treatments: 0 (the control group), 16,
32, or 48 Ribeiroia parasites.

Question 13

Case Study:

A field experiment:

Answer 13

Six ponds, three with pesticide
contamination.

Six cages in each pond, three with mesh
size that allowed parasite to enter.

Question 14

Case Study:

Hypothesis: Pesticides decrease the
ability of frogs to resist infection by
parasites.

Answer 14

Studies have suggested that no single
factor can explain decline of amphibian
populations.

The declines seem to be caused by
complex factors that often act together
and may vary from place to place.

Complex Causation

Question 15

Hatch and Blaustein (2003) studied the
effects of UV light and nitrate on Pacific
tree frog tadpoles.

Answer 15

UV: higher at high elevations

Nitrate: from farms

Question 16

Case Study: Cysts

Answer 16

Cysts mess up formation of limbs

• become easy prey
• passed out in bird feces

Glass bead mimicked the effect of a cyst