3-Community ecology

Question 1

community

Answer 1

all the species that interact with one another within a defined area

Question 2

what kind of interactions do community ecologists primarily think about

Answer 2

• biotic interactions
  
  • how do species interact with each other
  • what are the fitness consequences of these interactions?
  • how do these interactions change with time and location?

Question 3

Amenalism

Answer 3

occur when an organism inflicts harm to another without any fitness cost/benefit to itself

• / 0

Question 4

Commensalism

Answer 4

occurs when one species benefits from the interaction, but the other species is unaffected

+ / 0

Question 5

Mutualism

Answer 5

when two species interact in a way that confers fitness benefits to both

+ / +

Question 6

Consumption

Answer 6

when one organism eats (or absorbs the nutrients) from another
positive fitness effect for the consumer, and a negative fitness effect on the prey

+ / -

Question 7

Competition

Answer 7

when individuals use the same limited resources
there are negative fitness consequences for both individuals

• / -

Question 8

types of consumption

Answer 8

1. predation
2. parasitism
3. herbivory

Question 9

predation

Answer 9

one organism kills and consumes another organism

1. can also affect the distribution of their prey
2. can positively affect biodiversity of the community (number of species in an area and their relative abundance)

Question 10

parasitism

Answer 10

one organism lives on/in another and steals its nutrients/resources, usually does not kill host

Question 11

herbivory

Answer 11

one organism consumes all or part of a plant

Question 12

COMPETITION

Answer 12

organisms use common resources that are in limited supply

Question 13

types of competition

Answer 13

• intraspecific competition—between same species
• interspecific competition—between different species

Question 14

NICHE

Answer 14

the resources used by a species (where it lives, the food it eats) and its relationship with other species (their role in ecosystem)

Question 15

fundamental niche

Answer 15

based on physiological tolerance, the range of resources an organism is able to use in the absence of biotic interactions

Question 16

realized niche

Answer 16

range of resources able to be used in the presence of biotic interactions

Question 17

INTERSPECIES COMPETITION HAS TWO POSSIBLE OUTCOMES

Answer 17

1. competitive exclusion
   
   1. one competing species is eliminated from part or all of the site/habitat by a superior competitor
2. stable coexistence
   
   1. through niche partitioning!!
   2. species are able to coexist
      
      1. both remain in the site/habitat

outcome depends on the strength of competitors and degree of niche overlap

Question 18

WHAT HAPPENS IF ONE COMPETITOR IS COMPLETELY SUPERIOR?

Answer 18

if niches only partially overlap:
- both species can co-occur!!
- weaker competitor experiences reduction from its fundamental niche
- competitively excluded from part of niche
- superior competitor experiences no reduction

if niches fully overlap:
- species cannot co-occur
- weaker is competitively excluded from entire niche!

Question 19

COMPETITION ON EVEN MORE FOOTING CAN LEAD TO NICHE PARTITIONING :O

Answer 19

• competition in the overlap is costly, so species reduce their niche overlap by using area not used by the other species
• realized niche becomes smaller than fundamental niche for both species
• if one competitor were removed, the other species could immediately capitalize on the full range of resources (change was not heritable)

Question 20

what can competition over time lead to?

Answer 20

EVOLUTIONARY CHANGE

Question 21

character displacement

Answer 21

heritable change in species’ traits that allow individuals to avoid competition by specializing on different resources

niche partitioning can lead to this!!

traits become more divergent in sympatric populations as compared to allopatric populations

Question 22

ECOLOGICAL SUCCESSION

Answer 22

a process by which the mix of species in an area changes over time (years to centuries)

Question 23

Primary Succession

Answer 23

occurs when a new patch of land is created or follows a disturbance that removed all the soil and all living organisms

Question 24

PIONEEERING SPECIES

Answer 24

Early colonizes that do not require much soil

Question 25

progression after primary succession

Answer 25

• nothing remains but bare rock/gravel
• organisms need to start from scratch and when they die, their remains will slowly contribute to the fomration of soil
• as the soil deepens, larger plans can colonize the site
• larger plants provide cover and shade, which will restrict the growth of shade-intolerant plants
• eventually a climax community is reached, unless a disturbance occurs to stop succession

Question 26

Secondary succession

Answer 26

follows a disturbance that has removed some or all living organisms but soil and nutrients remain

Question 27

what can influence the pattern of succession?

Answer 27

plant traits!