Spatial Patterns

Question 1

Explain the 3 types of spatial patterns

Answer 1

1. clumped = individuals having shorter inter-individual distances
2. dispersed = more space between
3. random = somewhere in between, some closer and some further

Question 2

What are some causes of clumped and dispersed spatial patterns

Answer 2

clumped = location of resources, dispersal limitation, geography, social behaviours
dispersed = competition, geography, social behaviours (territorial)

Question 3

Which spatial pattern has the highest variance/mean ratio

Answer 3

clumped because some quadrants with 0, some with 9.
the higher the ratio, the higher the clumpiness
(whereas if dispersed was perfect, would have ratio of 0)

Question 4

Poisson Distribution

Answer 4

can be used to give the expected frequency distribution of events in space or time, if the null hypothesis of random distribution is true
(number of independent events occurring in a fixed time)

Question 5

Aside from the poisson distribution, how can spatial patterns be tested/calculated

Answer 5

compare observed and expected frequencies using a goodness of fit test (chi-squared)

Question 6

When comparing data of clumped and randomly dispersed species to the Poisson distribution, how would they look

Answer 6

randomly dispersed species would have a 1>lambda and when graphing observed and expected, would see, not uniform decrease, but displays decreasing distribution
in clumped, would see empty and densely population quadrants so see some over and under represented in poisson

Question 7

Explain the 3 special properties of the Poisson distribution in terms of number to determine if clumped

Answer 7

mean = variance = lambda
if variance/mean >1 = clumped
if variance/mean < 1 = dispersed

Question 8

What is the MAIN importance when talking about spatial patterns

Answer 8

it is important that you know what scale it is being viewed at. could be clumped on one scale and dispersed on another
(could use point pattern analysis)