Competition

Question 1

populations grow exponentially when

Answer 1

resources are unlimited

Question 2

intrinsic growth rate (r) depends on

Answer 2

life history traits

Question 3

species interactions (3)

Answer 3

species interconnected through chain of resources

• 2 species might compete for them (comp)
• one species might serve as a resource for another (predation)
• 2 species might collaborate to increase their resources (mutualism)

Question 4

Liebig’s law of the minimum

Answer 4

Each pop should incr until the supply of the most limiting resource constrains further growth
Suggests resource limiting growth is the most scarce

According to the law, each pop grows until the supply of the limiting resource no longer satisfies the pop’s need for it

Question 5

2 types of competition

Answer 5

intra and inter specific

Question 6

Intraspecific is

Answer 6

one of the density dependent factors

Question 7

indirect competition

Answer 7

through shared resources

Exploitative competition eg in plants for sunlight

Question 8

Direct competition

Answer 8

through defending resources
interference comp
eg physical combat

Question 9

If 2 populations share same resource..

Answer 9

carrying capacity of 1 pop reduced by conspecifics (N1 organisms belonging to same species) and competitors (N2 ie hoe many of species 2 is present

have to modify logistic model if 2 species sharing same resources

Question 10

Looks- Volterra model for inter specific competition

Answer 10

when 2 pops of different species compete for the same resource, they reduce each other’s growth
Most common stable equilibrium is when either pop drives other to extinction
Stable coexistence reached when each pop limits its own growth more than growth of competitor ie when interspecies smaller than intraspecies competition

Question 11

competitive exclusion

Answer 11

if 2 species use same resource and share same habitat, then one competing species will eventually exclude the other

If 2 competing species seem to coexist in a stable environment, must be using different resources

Question 12

fundamental niche

Answer 12

entire set of conditions under which an species can survive and reproduce itself

Question 13

realised niche

Answer 13

set of conditions used by given species, after interactions with other species (predation and comp) have been taken into account

Question 14

niche overlap

Answer 14

similarity in how 2 species use resources

intensity of comp when resources are limiting

Question 15

what does evolution predict for the species not competing (niche overlap)

Answer 15

will separate and can avoid comp and coexist in he same place

Question 16

does competitive exclusion explain geographic distribution?

Answer 16

likely explanation for differential use of resources in nature- resource partitioning in response to comp

but

• differences may be due to separate evol - allows these species to live together
• or differences among species may be irrelevant to comp- resources not limiting or comp not related to differences
• need experiment to test comp exclusion hypothesis

Question 17

evolutionary consequences

Answer 17

if there’s genetic variation in a pop for incr competitivity, competitiveness can evolve

also if variation in resource use exists, selection within a pop may favour avoidance of comp with other species by evolving different traits

Question 18

character displacement

Answer 18

when 2 species utilise same resource and have overlapping geographic distribution, their morphology may shift to avoid competition

Question 19

overall does diversification of resources affect

a) species distribution
b) species characters

Answer 19

yes

and yes

Question 20

negative outcome of competition due to use of same resources

Answer 20

resources often limited, because all populations will grow