Lectures 1-2: How do we study ecology

Question 1

What is the definition of ecology?

Answer 1

> the scientific study of the distribution and abundance of organisms and the interactions (between organisms and with the chemical and physical environment) that determine distribution and abundance

Question 2

what are the three concepts of ecology?

Answer 2

1) events in the natural world are interconnected
2) ecology is the scientific study of interactions between organisms and their environment
3) ecologists evaluate competing hypotheses about natural systems with observations, experiments and models

Question 3

describe ecology in terms of scale, diversity and rigour

Answer 3

> ecological processes occur over different scales
ecological evidence comes from a variety of sources
ecology relies upon scientific rigour and application of statistics

Question 4

What are the different ecological scales?

Answer 4

> time scales - expensive, require commitment
spatial scales - large to microscopic
biological scales

Question 5

describe the levels within biological scales

Answer 5

> organism
- interactions between individuals and their environment
population
- presence/absence of a particular species
- abundance/ rarity
community
- composition/ structure ecological communities
ecosystem
- community and physical enviroment

Question 6

describe the diversity of ecological evidence

Answer 6

> observations: descriptive, allow hypothesis formation
manipulative field experiments: allow hypothesis testing
- major approach to test hypothesis, change system to see the effect
laboratory experiments: field systems may be too complex/ expensive to study, laboratory experiments can complement and help design field experiments
simple laboratory systems: basic understanding of simple systems within an ecosystem; build understanding of more complex systems
models: constructed mathematical models can provide insight, manipulations tested etc.

Question 7

what are four important points when it comes to scientific rigour and statistics?

Answer 7

1) you can’t prove anything with statistics
2) in ecology, we are not searching fro proof, rather we are looking for conclusions in which we can be confident
3) must carefully plan experiments (including statistical treatment of data collected) before conducting work in order to collect appropriate data to answer questions
4) representative samples, to provide estimates

Question 8

how can you interpret a p value?

Answer 8

> p-value = probability that an event occurred by chance
P=0.05
- level arbitrarily decided upon
- 95% certainty that data not generated by chance
- null hypothesis: there is no effect of A upon B

Question 9

what is standard error?

Answer 9

> attaches confidence to results
Standard error of the mean (SE)
SE = sample standard deviation/sqrt(#samples)
95% confidence interval = 95% probability that true mean lies within 2 standard errors of the estimated mean

Question 10

What must you ensure in any sampling program?

Answer 10

> estimation is accurate and unbiased (representative)
the estimate is a precise as possible (i.e., narrow CI, small SE)
effort/expense is used effectively (these are always limited)

Question 11

what are ome differences between random sampling and stratified random sampling?

Answer 11

> random sampling just randomly allocates plots to sample
stratified random sampling breaks the area into quadrants then randomly samples
- this reduces the sample mean but increases the variability
however, by increasing the amount of samples taken, with stratified random sampling you can get a sample mean much closer to the true mean with lower variability

Question 12

look at the example of the DBM

Answer 12

refer to lecture notes