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Lab 8 - Spatial Relations


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Lab 8 - Spatial Relations

  1. 1. Spatial RelationsBSC 2011L<br />
  2. 2. Distribute yourselves!<br />Plant in the desert – need to have your roots reach water.<br />Poison arrow tree<br />Algae in deep ocean<br />Mushrooms on a rotting log<br />Mayfly mating frenzy<br />
  3. 3. Spatial relations<br />1. Clumped<br />3. Random<br />2. Even/Uniform<br />Distribution of individuals within a population<br />how individuals are arranged in space<br />Random<br />Not random<br /> ---Even/Uniform<br /> ---Clumped<br />Which is most common?<br />
  4. 4. Non-random – Clumped<br /> “Patchy” Physical, chemical, and environmental conditions<br />Hiding places (prey or predators)<br />Limited dispersal of juveniles, <br />seeds, larvae, baby birds<br />Social Factors<br /> Selfish herd<br /> Family groups<br />
  5. 5. Non-random -- Uniform<br />Distances between individuals are maximized<br />strong competition for a resource<br />Ex. Allelopathy<br />Other examples?<br />nest distribution of blue tilapia in sewage treatment ponds<br />creosote bushes in southwest <br />
  6. 6. Random<br />The location of one individual bears no relationship to the locations of other individuals<br />Usually found:<br />in homogeneous environments <br />individuals neither attract nor repel one another<br />
  7. 7. Distributions may change:<br />seasons as resources change<br />spatial scale is very important<br />
  8. 8.
  9. 9.
  10. 10. Collect data for 3 tests.<br />2 tests of species distribution (clumped, even, or random) <br /> -- Clark-Evans nearest neighbor method<br /> -- Variance/Mean ratio<br />1 test of Interspecific Association<br />
  11. 11. Clark-Evans nearest neighbor method – Ant Lions<br />Measure to 4 nearest neighbors<br />Estimate area in cm2<br />
  12. 12. Clark-Evans nearest neighbor method – ant lions<br />Measure distance to ‘nearest neighbor’<br />Calculate RATIO of measured / expected<br /><ul><li>R = 1  RANDOM
  13. 13. R > 1  EVEN
  14. 14. R < 1  CLUMPED
  15. 15. Do t test to test if the R value is ‘significantly different that 1 (at alpha level of 0.05)</li></li></ul><li>Variance/mean ratio method<br />Colocasia esculenta<br />(Araceae)<br />50 hoop tosses (for our class)<br />COUNT NUMBER OF PLANTS<br />
  16. 16. Variance/mean ratio method<br />If v/m near 1  random<br />If v/m &lt;1  even distribution<br />If v/m &gt;1  clumped<br />TEST for significance using t test<br />
  17. 17. Interspecific association<br />At same time as above, record presence or absence of species B in quadrant.<br />Justicia americana<br />(Acanthaceae) <br />50 hoop tosses (for our class)<br />For each hoop toss, record presence or absence of each species<br />
  18. 18. Interspecific Association<br />Record number of hoop tosses in each category (W,X, Y, Z)<br />N = number of total hoop tosses<br />If W x Z &gt; X x Y, positive association<br />If W x Z &lt; X x Y, negative association<br />Do Chi-squared test <br />
  19. 19. You will be doing this worksheet at home. *Remember this sheet is worth 15 points<br />Pgs. 147-148 in the lab manual<br />Do not do computer version on bioviewer!<br />
  20. 20. Due Wednesday<br />1. Spatial Relations datasheet (pgs 147-148 using data collected in lab Saturday) (15 pts). <br />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) <br />3. Population Ecology PRE-LAB (pgs 129-130) (5 pts)<br />