lab 8 - spatial relations
TRANSCRIPT
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Spatial Relations
BSC 2011L
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Distribute yourselves!
• Plant in the desert – need to have your roots
reach water.
• Poison arrow tree
• Algae in deep ocean
• Mushrooms on a rotting log
• Mayfly mating frenzy
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Spatial relations• Distribution of individuals within a population
– how individuals are arranged in space
Random
Not random
---Even/Uniform
---Clumped 1. Clumped
2. Even/Uniform
3. RandomWhich is most common?
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Non-random – Clumped
“Patchy” Physical, chemical, and
environmental conditions
Hiding places (prey or predators)
Limited dispersal of juveniles,
seeds, larvae, baby birds
Social Factors
Selfish herd
Family groups
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Non-random -- Uniform• Distances between individuals
are maximized
• strong competition for a resource
– Ex. Allelopathy
– Other examples?
nest distribution of blue
tilapia in sewage treatment
ponds
creosote bushes in southwest
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Random
• The location of one individual bears no relationship to the locations of other individuals
• Usually found:
– in homogeneous environments
– individuals neither attract nor repel one another
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• Distributions may change:
– seasons as resources change
– spatial scale is very important
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Collect data for 3 tests.
2 tests of species distribution (clumped,
even, or random)
-- Clark-Evans nearest neighbor
method
-- Variance/Mean ratio
1 test of Interspecific Association
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Clark-Evans nearest neighbor
method – Ant Lions
Measure to 4 nearest neighbors
Estimate area in cm2
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Clark-Evans nearest neighbor
method – ant lions
• Measure distance to „nearest neighbor‟
• Calculate RATIO of measured / expected
R = 1 RANDOM
R > 1 EVEN
R < 1 CLUMPED
Do t test to test if the R value is „significantly different
that 1 (at alpha level of 0.05)
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Variance/mean ratio method
50 hoop tosses
(for our class)
COUNT
NUMBER OF
PLANTS
Colocasia esculenta
(Araceae)
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Variance/mean ratio method
• If v/m near 1 random
• If v/m <1 even distribution
• If v/m >1 clumped
• TEST for significance using t test
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Interspecific association
At same time as above, record presence or absence of species B in quadrant.
For each hoop
toss, record
presence or
absence of each
species
Justicia americana(Acanthaceae) 50 hoop tosses
(for our class)
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Interspecific Association
Record number of hoop tosses in each category (W,X, Y, Z)
N = number of total hoop tosses
If W x Z > X x Y, positive association
If W x Z < X x Y, negative association
Do Chi-squared test
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You will be doing this
worksheet at home.
*Remember this sheet is
worth 15 points
• Pgs. 147-148 in the lab manual
• Do not do computer version on
bioviewer!
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Due Wednesday
• 1. Spatial Relations datasheet (pgs 147-148
using data collected in lab Saturday) (15
pts).
• 2. Quiz 4 -- Do quiz bank questions OR
improve one of the WIKI articles (turn in
paragraph explaining briefly what you did)
OR take quiz at end of lab on Spatial
Relations. (5 pts)
• 3. Population Ecology PRE-LAB (pgs 129-
130) (5 pts)