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Ecology > Chapter 14: Interspecific Competition > Flashcards

Chapter 14: Interspecific Competition Flashcards

1
Q

Interspecific competition?

A
  • competition between two different species for a common resource in short supply
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2
Q

Interspecific competition is probably a major force behind?

A
  • species divergence and specialization
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3
Q

Competition ?

A
  • any relationship in which populations of two or more species negatively affected
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4
Q

What are six types of competition?

A
  1. Consumption of shared resources
  2. Preemption of space(primarily between sessile organisms aka since I’m taking u[ this space its not available to anyone else)
  3. Overgrowth: growing on top of another species etc like lichens
  4. Chemical interaction: toxins or growth inhibitors (common in forests where a tree lays dead needles on ground)
  5. Territorial: behavioural exclusion from space defended as territory
  6. Encounter: non territorial meetings e.g. scavengers fighting over carcass
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5
Q

Competition models?

A
  • mathematical models used to build hypotheses about species interactions
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6
Q

Classic competition model?

A
  • Lotka-Volterra Model based on the logistic equation from chapter 11
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7
Q

Logistic equation?

A

dN/dt= rN( K-N/K)

*k= carrying capacity

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8
Q

Lotka-volterra model formula?

A
  • term added for competitive effect of one species on the population growth of another
    Species 1: dN1/dt= r1N1(K1-N1- alphaN2/K1)

Species2: dN2/dt= r2N2( K2-N2-betaN1/K2)

*alpha is the competitive effect of species 2 on species 1; beta is the competitive effect of species 1 on species 2

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9
Q

Lotka-volterra model:

-Amount of resource used by two species is not/ or is usually the same

A
  • is not
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10
Q

Lotka-volterra model:

-convert from one species to another?

A
  • alpha N2 is the number of equivalents of species 1
  • beta N1 is the number of equivalents of species 2
  • can convert between species suing coefficient
  • can confer that epopulation density of one species to the equivalent of another
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11
Q

Lotka-volterra model:

- explain the alpha value system

A
  • alpha= 0 species 2 has no competitive effect on species 1

- alpha 1, species 2 individual more effect than a species 1 individual

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12
Q

Lotka-volterra model:

- without interspecific competition whats going on with K?

A
  • without interspecific competition (if alpha or N2= 0 or beta or N1 = 0), population of each species grows logistically to K
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13
Q

Lotka-volterra model:

- with interspecific competition what occurs?

A
  • either one species out competes the other or they coexist
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14
Q

Lotka-volterra model:

- how many situations does it predict?

A

4

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15
Q

Lotka-volterra model:

- graphical models?

A
  • Zero growth isoclines points at which population growths 0 (dN1/dt and dN2/dt= 0_
  • two diagonal lines are plotted one for each species
  • populations always come back to zero growth isocline
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16
Q

Lotka-volterra model:
- outcomes?
L>winning?

A
  • Species 1 wins: even when species 2 is at its carrying capacity, it can’t stop species 1 from increasing ( K2<K1/alpha)
  • Species 2: reverse situation
    • when species 2 wins its isocline is now higher than species 1
17
Q

Lotka-volterra model:

- equilibrium outcomes?

A
  1. Unstable equilibrium: determined by initial densities. Interspecific competition limits growth more than infraspecific (outcome can go either way via one winning)
  2. Stable equilibrium: intraspecific competition limits population growth more than interspecific
    ( coexistence?)
18
Q
  1. 4 Competitive Exclusion Principle:

- explain this principle

A
  • complex competitors cannot coexist
  • when two species have same ecological requirements and live in the same space, the species with faster population growth expected to dried the other to extinction
19
Q
  1. 4 Competitive Exclusion Principle:

- explain assumptions

A
  • assumes same resource requirements and environment is constant
  • not likely in nature (aka not likely they will have the exact same resources) **resources are not the only regulation of a population
20
Q

14.5 Effect of Factors other than resources ?

A
  • e.g. plant growth also affected by temperature, pH, rekatuve humidity, salinity
  • *biotic and abioitc interactions influencing whether species A over Species B occurs as well not just the two species interaction.
21
Q

14.6 Temporal Variation in environment??

A
  • ex: shift in grass species in grasslands in zimbabwe
  • associated with changes in annual rainuful
  • you should factor in different seasons
  • when rainfall was low the green species dominant but as soon as it increased another species displaced it
  • whole environmental conditions can change and affect a species
22
Q
  1. 7 Competition Occurs for Multiple Resources:

- Example via Groves and Williams 1975

A
  • competition between clover and skelton weed
  • clover better competitor for both above and below structural resources
  • one species does not do well when just the roots are completing
  • when just the shoots are in comp each other the same species does not do well
  • when fully exposed to each other the same species did not do well at well.
23
Q

14.8 Relative competitive abilities change along environmental gradients ?

A
  • due to changes in carrying capacities of species related to changing resources base or form changes in the physics environment that interact with resource availability
  • *competition changes as you go along the gradient
    ex: salt marsh zonation
  • combo of both biological and environmental factors
24
Q

14.10 Resource petitioning also important in coexistence ??

A

-animals use different kinds and sizes of food at different times or forage in different areas
ex: size of canine teeth (and prey) of cats..
*one species forages in morning and the another light.
example : size of canine teeth which relates to different types of prey they can exploit…therefore coexisting cat species presumedly are not competing for the same resources

25
Q
  1. 10 Resource petitioning also important in coexistence ??

- plants species vary in?

A
  • proportions of nutrients required, tolerance for light and shade.
  • two plants side by side may have different root systems one allowing them to grow deeper down and another to grow deep down.
26
Q

Demonstrating the importance of competition in the field?

A
  • competition is difficult to demonstrate in the field.

* *you cannot control a lot of factors in the field…lots of confounding variables due to environment changes..

27
Q

Demonstrating the importance of competition in the field?

-techniques?

A
  • cage animals in our out separating predators
    L> still simplistic bc what is the affect the changes has on everything else
    **its hard to tie in alb results in nature for exploiting

Ecology (24 decks)

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