BIOL 2300 Lecture Notes - Lecture 8: Dynamic Equilibrium, Behavioral Ecology, Net Energy Gain

19 views6 pages

sangriakoala177

22 Jun 2018

School

University of Manitoba

Department

Biological Sciences

Course

BIOL 2300

Professor

Paul G.Messing

For unlimited access to Class Notes, a Class+ subscription is required.

LECTURE 8 ORGANISMS AND COMPETITION

Individuals do not live in isolation…

Intraspecific Competition

How does competition arise?

Types of Competition

What is the Result of Competition?

Ideal Free Distribution

Generalized Experimental Design

Example – Harper 1982

Summary

Unlock document

This preview shows pages 1-2 of the document.
Unlock all 6 pages and 3 million more documents.

Already have an account? Log in

Individuals do not live in isolation…

• Individuals of the same species have similar requirements for survival,

growth, reproduction

• Demand for resource may exceed supply

• Individuals may compete for resources

Intraspecific Competition

• An interaction between individuals of the same species (intra) brought about

by a shared requirement for a resource in limited supply

• Limited resources – food and habitats

• Results in:

o Reduced survival, growth, and/or reproduction of some individuals

▪ Possible reduction in fitness

o Competition: an interaction in which two or more individuals seek out

a common resource that is in limited supply relative to the number

seeking it

▪ Acts as a selective pressure in nature

• Intraspecific interactions exhibit density-dependence.

o Their effect varies with population size, intensifying as a population

nears its carrying capacity.

o Allows intraspecific interactions to regulate populations

How does competition arise?

• Resources are not evenly distributed

(distributed in patches)

o Environmental heterogeneity

Unlock document

This preview shows pages 1-2 of the document.
Unlock all 6 pages and 3 million more documents.

Already have an account? Log in

Document Summary

Individuals of the same species have similar requirements for survival, growth, reproduction: demand for resource may exceed supply. Intraspecific interactions exhibit density-dependence: their effect varies with population size, intensifying as a population nears its carrying capacity, allows intraspecific interactions to regulate populations. How does competition arise: resources are not evenly distributed (distributed in patches, environmental heterogeneity. Types of competition: exploitation (scramble) competition: an individual responds to a decreased level of a limited resource remaining after it has been exploited by other individuals, individuals do not interact directly, e. g. , grazing herbivores. Interference (contest) competition: an individual actually prevents another from exploiting a limited resource within a portion of the habitat: individuals interact directly, e. g. , territoriality. Individuals in an area reach an equilibrium distribution, where: all patches occupied, more individuals in higher quality patches, at the equilibrium distribution, the consumption rates of individuals are equal for all competitors in all patches.

Related Questions

Plant competition lab:

Objectives

In this lab, we will conduct an experiment to test both interspecific competition (between radish and collards plants) and intraspecific competition (radishes competing with radishes, or collards competing with collards). To determine if competition is occurring, we will measure survival, plant height, and aboveground biomass. Once the lab is completed and the data are collated from the entire class, you will then need to make graphs and answer the questions at the end of the lab.

Procedure:

Take 9 pots. Use only pots of the same shape (square or round); do not mix types.

Fill the pots with soil to within Â½ inch of the top.

Thoroughly water the soil (until it runs out the bottom).

Add more soil if necessary to bring up the level to within Â½ inch of the top.

Place the appropriate number of seeds on the soil surface. Be sure the seeds are evenly spaced. In the mixed species pots, intersperse the two species. See the table below for the nine different treatments.

Cover the seeds with a thin layer of soil. DO NOT water the soil again.

Label the pot with your name and the treatment on a piece of tape.

Before harvesting any plants in a pot, collect the following data:

Number of surviving radishes

Number of surviving collards

Average height of surviving radishes (cm)

Average height of surviving collards (cm)

2. After counting and measuring surviving plants, clip each plant where the stem meets the soil. If your pot is a mixed-species treatment, separate radishes from collards.

3a. For single-species treatments:

Weigh all plants within a pot for the total aboveground biomass (g)

Divide the total aboveground biomass by the number of plants that were alive in the pot, to calculate the mean aboveground biomass (g per plant)

3b. For mixed-species treatments:

Weigh all the plants of each species separately, for total aboveground biomass (g) for each species

For each species separately, divide the total aboveground biomass by the number of plants of that species that were alive in the pot, to calculate the mean aboveground biomass (g per plant, within a species)

Experimental Design

Single-species treatments (intraspecific competition tests)

4 collard seeds

16 collard seeds

36 collard seeds

4 radish seeds

16 radish seeds

36 radish seeds

Mixed-species treatments (interspecific competition tests)

2 collard + 2 radish seeds (4 total seeds)

8 collard + 8 radish seeds (16 total seeds)

18 collard + 18 radish seeds (36 total seeds)

Your mixed-species seeds should be arranged in a Latin square design, as shown below (the immediate neighbors of each seed are the other species).

--> Questions to consider about this lab

A. Hypotheses:

B. Which treatments are the controls and which are the experimental treatments?

C. What are the replicates in this experiment? How many are there for each treatment?

D. Do you see any inherent sources of bias in this experimental design?

E. Are there any problems with the experimental design that you can identify which might make interpretation of the data difficult or impossible?

lemonjellyfish99

5. Results of the experiment showed that P. cinereus inhibits survival of P. shenandoah in deep soil, but did not provide any information on how this actually occurs.( Article Below)

a.) Give one example of how competitive exclusion of P. shenandoah by P. cinereus may occur through interference competition. Be sure to thoroughly explain how this would lead to competitive exclusion of P. shenandoah.

b.) Give one example of how competitive exclusion of P. shenandoah by P. cinereus may occur through exploitative competition. Be sure to thoroughly explain how this would lead to competitive exclusion of P. shenandoah.

c.) List the four other factors the researcher considered when trying to explain the distribution patterns of P. shenandoah and briefly state why each factor was rejected as the mechanism responsible for P. shenandoah distribution.

Competitive Exclusion as a Factor Influencing the Distributions of Two Species of Terrestrial Salamanders.

The salamander Plethodon richmondi shenandoah is restricted to areas of talus on Hawksbill Mountain, Shenandoah National Park, Virginia, while P. cinereus inhabits the soil outside the talus. To test the hypothesis that the former species is excluded from the soil by the latter species, three enclosures were constructed in each of four habitats: (i) in talus consisting only of bare rocks, (ii) in talus where soil has infiltrated between but not under rocks, (iii) in isolated pockets of shallow soil within the rocky confines of the talus, and (iv) in deep soil outside the talus. In each habitat one enclosure contained an isolated sample of shenandoah, another an isolated sample of cinereus, and the third a mixture of the two species. The above testes indicated that: (i) neither species survived the extremely dry conditions of the bard rocks for more than a week, (ii) shenandoah expressed a higher survivorship than did cinereus in this relatively dry habitat, (iii) in the shallow soil shenandoah had lower survivorship in the presence of cinereus than it did in isolation, and (iv) in the deep soil shenandoah had poorer survivorship than cinereus in the mixed species enclosure and poorer survivorship than its isolated control. P. cinereus apparently inhibits the presence of shenandoah in areas of soil, while shenandoah survives better under rocky conditions. However, the talus is a suboptimal habitat for shenandoah, since its survivorship in isolated enclosures is significantly better in the presence of soil. It seems unlikely that salamanders other than cinereus could exclude shenandoah from the soil or that other animals exert a strong influence. Predation, diseases, and parasites also do not appear to exclude shenandoah from areas of deep soil. Competitive exclusion by cinereus has probably restricted the distribution of shenandoah to the suboptimal talus refugium.

Climate change is a real and worsening phenomenon. Many people think that the effects of climate change are restricted to the increase in the Earthâs average temperature. As we will see this semester, this is certainly not the case. Even where global warming is the main driving force, it may not be the sole or even primary factor determining whether a species will survive or become extinct. For this weekâs forum, read the blog Falling to the competition: how climate change forces species to collide and answer the questions that follow.

1. How do plants generally respond to global warming?

2. Elevated temperature associated with climate change is not the sole factor affecting plant survival. What other factor(s) may be involved?

3. If a plant fails to move to a higher elevation to adapt to warming, its chances for survival are much less than that of a plant that does. How do you explain this finding?

4. In what important way does the design of this study differ from what plants should expect to encounter in a real world scenario? What does this imply will be the strongest detriment to a plantâs survival in a warming world?

limejellyfish620

BIOL 2300 Lecture Notes - Lecture 8: Dynamic Equilibrium, Behavioral Ecology, Net Energy Gain

Document Summary

Get access

Related Documents

BISC302 Lecture Notes - Lecture 15: Lamprey, Logistic Function, Allelopathy

BIOL 2060 Lecture Notes - Lecture 10: Intraspecific Competition, Interspecific Competition, Logistic Function

BIOL 4150 Lecture Notes - Dn2

Related Questions