Community ecology

Question 1

Community

Answer 1

Interacting species within a defined area
Interactions

Question 2

Species interactions

types

Answer 2

Competition (-/-)
Consumption (+/-)
Mutualism (+/+)
Commensalism (+/0)

Labels
Can be either a + or a –
A + or a – to fitness leads to a + or a – to population number

Studies of species interactions focus on the interaction’s influence on the fitness of the organisms

Question 3

Species interactions

Answer 3

Can affect the distribution and abundance of a particular species
Can lead to natural selection
Coevolutionary arms race
The outcome of each interaction is dynamic and conditional

Question 4

Competition

intraspecific

Answer 4

within species
Space, food, light, mates
Density dependent intensity
Is a major cause of density dependent growth

Question 5

competition

interspecific

Answer 5

different species encounter an overlap in their niches

Question 6

Niche

Answer 6

A range of resources the organism can use

A range of conditions it can tolerate

Question 7

Niche overlap leads

Answer 7

to competition

Question 8

Complete niche overlap

Answer 8

Species in the same niche can not coexist
Called the competitive exclusion principle
G. F. Gause

If there is asymmetric competition then one will outcompete the other and cause the other to go extinct

Question 9

Niche differentiation

Answer 9

No one wants to compete forever

Also called resource partitioning

Leads to character displacement

Question 10

Competition on a community level

Answer 10

influenced the population

Question 11

How does studying competition help in conservation studies?

Answer 11

Invasive species
Maintaining current interactions

If an ecosystem is highly diverse then invasive species have less of an impact because of the number and amount of competitive interactions

Question 12

Prey steps versus predator steps

Answer 12

Detect predator
Avoid detection
Avoid capture
Get back at the predator

• Detect prey while avoiding detection
• Catch prey
• Consume prey

Question 13

Herbivory

Answer 13

Consumption of plant tissues

Question 14

Parasitism

Answer 14

Consumption of a host by a parasite
Long period of time
Piece by piece
Isn’t the only type of parasitism

Question 15

Predation

Answer 15

When a predator kills and consumes most or all of another individual

Question 16

Constitutive defenses

Answer 16

Escape
Hiding
Poison
Bad taste or bad coloration
Schooling
Flocking
Weaponry: spines, hooves etc
Natural selection favors the prey that can not get eaten

Question 17

consumption

Answer 17

Causes the prey to lose fitness
Prey put up a fight

One organism eats the other

Herbivory
Parasitism
Predation

Question 18

Mimicry

Answer 18

1 species closely resembles another

Question 19

Mullerian mimicry

Answer 19

both species are harmful and they look like each other

Question 20

Batesian mimicry

Answer 20

one is harmful, but they still look alike

Question 21

Inducible defenses

Answer 21

Constitutive defenses are expensive

only occur in the presence of a predator

Efficient energetically but slow and necessary to produce

They decrease with the decrease in the predator population

Question 22

Why don’t prey die out?

Answer 22

Prey are naturally selected to survive
Smaller
Larger clutch sizes
Reproduce younger
Large intrinsic growth rates

Predators do decrease the population significantly however
Exp: wolves in alaska

Question 23

Why don’t herbivores eat everything?

Answer 23

Limiting impacts on herbivory include, nitrogen limitations, predation or top down control, and defenses by the plants

Well defended but offer better nutrition
Won’t survive well if they are not preyed on

Question 24

Predator prey arms race

Answer 24

Since prey are selected to escape
predators are selected to capture
Two species co evolve
increase their fitness

Consider malaria and humans

Question 25

Conservation

Answer 25

Predator and parasite studies have lead to biocontrol mechanisms

Integrated pest management

Question 26

Mutualism

Answer 26

Pollinators
Fungi and roots
Nitrogen fixing bacteria and plants
Farmer ants and fungi

dynamic
One change in the ecosystem can lead to the relationship being irrelevant and unnecessary

Question 27

Natural selection and mutualism

Answer 27

The species are not being nice
Nature is selfish
If one stops paying out the other will stop too
Reciprocal parasitism

Question 28

Commensalism

Answer 28

Not well studied
Difficult to identify

Remoras and sharks
Barnacles and whales

Question 29

Answer 29

Each relationship is fluid and dynamic
Dependent on stable conditions and variables