Download Final notes on populations and communities.

V. Communities
A. Terminology
1. habitat: the physical location where an organism lives
2. competition: two (or more) species rely on the same limited resource
3. predation: an animal species (the predator) eats another animal species
(the prey)
Figure 17. Population growth cycles of predator and prey (lynx and snowshoe hare).
http://kentsimmons.uwinnipeg.ca/16cm05/cm16ppt06/Population%20Ecology_files/
v3_document.htm
4. herbivory: an animal species eats a plant species
5. symbiosis: an interspecific interaction where the two species maintain a
close association with each other (often one species lives on/in the host
species)
a. mutualism: both species benefit from the relationship (+,+)
i. the clownfish and the sea anemone: the clownfish eats scraps from
the sea anemone and keeps it clean while the sea anemone provides
protection from predators to the clownfish
ii. the large blue butterfly of the UK and a certain species of ant: the
larvae of the large blue butterfly secrete a substance that the ant
drinks and then the ant carries the larvae to their nests where the
larvae eat ant larvae, then pupate (this butterfly went extinct in the
UK but was reintroduced from Sweden in 2009)
*note that there are many relationships of this type where one animal “farms”
another
http://www.telegraph.co.uk/earth/wildlife/5542084/Large-Blue-butterfly-fluttersback-from-extinction-thanks-to-a-tiny-ant.html
iii. ants and acacia trees:
Figure 18. An investigation into the type of relationship between Acacia trees and
ants.
http://content.bfwpub.com/webroot_pubcontent/Content/BCS_3/Sadava_9e/Interac
tive%20Summaries/5610.html
b. parasitism: one species benefits from the relationship while the other is
harmed (+,-)
c. commensalism*: one species benefits from the relationship while the
other is unaffected (+,0)
*not in IB syllabus
d. amensalism*: one species is unaffected but the other is harmed (0,-)
6. niche: the role of the organism in its habitat; encompasses its relationships
with other organisms, feeding activities and spatial habitat
a. fundamental niche: the potential niche of an organism when
competition is not severe
b. realized niche: the actual niche occupied by an organism when
competition is severe
Figure 19. Fundamental and real niches of two species of barnacles.
http://kentsimmons.uwinnipeg.ca/16cm05/1116/16comeco.htm
In this example, the fundamental niches of the two species overlap. This was
discovered by allowing each species to grow without the other and determining what
part of the habitat was utilized.
Q: Which of the two species outcompetes the other one?
7. competitive exclusion: two species that require exactly the same resources
(including physical habitat, food/nutrients etc.) cannot be found in the same
community
a. the species that uses the resources better will reproduce more quickly
and pushes out the other species
Figures 20, 21 and 22. A classic example of competitive exclusion by Gause
involving Paramecium caudatum and Paramecium aurelia.
http://www.emc.maricopa.edu/faculty/farabee/biobk/biobookpopecol.html
What is K?
What is K?
What happened?
7. Niche differentiation: species that have similar niches (and are thus
competitors) utilize the same niche but in slightly different ways
a. note that this implies that natural selection has influenced the
development of the structures and behaviours of the species
b. Resource partitioning: species that have similar niches behave in such
as was as to reduce competition
i. the competing species may use the resource at different times
ii. the competing species may use the same resource but in different
parts of the habitat
iii. the competing species may use slightly different parts of the same
food source because they have morphological/physical differences
that make them better able to make use of one part of the
resource than another
Figure 23. Resource partitioning among bumblebees in Colorado. The bumblebees
with longer proboscides/proboscises utilize flowers with longer corollas. They reduce
competition by being found at different altitudes. The bumblebees with shorter
proboscides/proboscises utilize flowers with shorter corollas. They, too, reduce
competition by being found at different altitudes.
http://www.nature.com/scitable/knowledge/library/resource-partitioning-and-whyit-matters-17362658
Figure 24. Resource partitioning among warblers.
http://www.citruscollege.edu/lc/archive/biology/Pages/Chapter43-Rabitoy.aspx
C. Succession: the changes in a community over time as some species enter the
area and some species become locally extinct or leave the area
1. the presence of a species often changes the community both in terms of
biotic and abiotic factors so that it becomes more or less ideal for other
species (known as facilitation)
2. Primary succession: occurs in an area that is devoid of life such as new
volcanic islands or glacial moraines
a. the first species to colonize an area are called pioneer species
i. usually small plants such as mosses or lichens
a. able to grow on bare rock
b. can help to break down the rock into soil (some mosses produce
acid) and also become part of the soil when they die
b. followed by small, fast-growing species such as grasses
i. do not require deep soil
c. next are shrubs and small trees
d. followed by larger trees
e. eventually there will be a stable community known as the climax
community
f. the whole process may take hundreds of years
A brief description of primary succession in the Hawaiian island can be found here:
http://hvo.wr.usgs.gov/volcanowatch/1999/99_01_21.html
Animation:
http://bcs.whfreeman.com/thelifewire9e/default.asp#542578__591727__
Figure 25. Primary succession on a glacial moraine.
http://content.bfwpub.com/webroot_pubcontent/Content/BCS_3/Sadava_9e/Interac
tive%20Summaries/5710.html
Figure 26. Succession in a temperate deciduous forest.
http://content.bfwpub.com/webroot_pubcontent/Content/BCS_3/Sadava_9e/Interac
tive%20Summaries/5710.html
3. Secondary succession: occurs in an area that has undergone severe
disruption of the community such as a fire or volcanic eruption
a. the time to reach a climax community is less because there is already
soil and because seeds and spores of plants may already be present
4. The final climax community is dependent on the same factors that affect
plant and animal distributions as well as the history of the area
5. As succession continues:
a. net productivity increases
b. the biomass of the community increases
c. species diversity increases
d. the climax community is occurs when the aforementioned values reach
a plateau
i. heterotrophs in the community balance out the increase in
autotrophs’ efficiency
For a graph, go to
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/S/Succession.html
because the graph did not copy over properly.
Q: Why do the descriptions of succession omit description/discussion of animals?
References:
1. http://www.emc.maricopa.edu/faculty/farabee/biobk/biobookcommecosys.htm
l
2. Biomes of the world website:
http://www.marietta.edu/~biol/biomes/biome_main.htm
3. http://www.mycozynook.com/101RGCh1OH.htm
4. Information about terrestrial biomes:
http://www.nature.com/scitable/knowledge/library/terrestrial-biomes13236757
5. A nice powerpoint with coverage of many basic concepts and useful images.
https://docs.google.com/present/view?id=dfh23k67_2452gjf8bfdp
6. This page is part of a site that chronicles a deep-sea mission in 2000:
http://www.ceoe.udel.edu/deepsea/level-2/chemistry/chemo.html
7. http://www.deltacollege.edu/emp/jdebow/energytransfer.html
8. http://kentsimmons.uwinnipeg.ca/16cm05/1116/16comeco.htm#Interspecific
%20Competition
9. http://www.mansfield.ohio-state.edu/~sabedon/campbl52.htm
10.
http://www.nature.com/scitable/knowledge/library/resourcepartitioning-and-why-it-matters-17362658
11.
http://bcs.whfreeman.com/thelifewire9e/default.asp#542578__591730_
_
12.
http://www.citruscollege.edu/lc/archive/biology/Pages/Chapter43Rabitoy.aspx
13.
For practice and review: There are other chapters associated with each book that
might be useful.
1. http://highered.mcgrawhill.com/sites/0073031208/student_view0/chapter25/multiple_choice.html
2. http://highered.mcgrawhill.com/sites/007340344x/student_view0/chapter33/post-test.html
3. http://wps.prenhall.com/esm_audesirk_bloe_7/17/4463/1142621.cw/index.ht
ml