topic 7 - comp in experiments

Question 1

describe guase 1932

Answer 1

comp of two yeast species

1st in isolation then mixed

Question 2

gause initial results

Answer 2

stable coexistence

Question 3

set up for comp exclusion experiments

Answer 3

• gause (1930’s) – paramecium (LEFT)
• Birch’s (1950s) grain beetle experiments (RIGHT)
• Simple homogeneous environments & similar resource requirements
○ Other grain beetles & paramecium can co-exist in lab studies
○ Beetles: one eats the outside of wheat grain, the other the eats the inside
○ Paramecium: one feeds test tube bottom, the other at the top

Question 4

competition exclusion define

Answer 4

• Two species cannot co-exist on a single limiting resource exploited the exact same way (i.e., niches cannot completely overlap)

Question 5

describe coexist

Answer 5

Occupy different niches -resource partitioning - reduces interspecific
competition- more limited by intraspecific than interspecific competition-
CO-EXISTENCE

Question 6

describe niche concept

Answer 6

Biotic & abiotic requirements & limitations of a species

warbler tree observations

Question 7

• Niche as an “n-dimensional hypervolume”? look at graphs

Answer 7

• Niche as a multi-dimensional space
○ n = # factors important to a species survival & reproduction
Biotic and abiotic dimensions

Question 8

define fundamental niche

Answer 8

• Fundamental niche
• Range of conditions under which a species can
persist/survive
• All resources that an organism can exploit- in the absence of other biotic interactions

Question 9

describe realized niche

Answer 9

• Realized niche
Portion of the FN that a sp. actually exploits
• Considers interactions with other species (e.g.,
competition may restrict environment in which
a species can persist)

Question 10

• Why is niche concept useful?

Answer 10

• if there is niche overlap, competition should be suspected

Question 11

what is competition exclusion principle

Answer 11

• No two species can co-exist indefinitely while occupying the exact
same niche at the exact same time
superior competitor outcompetes

Question 12

types of niche differentiation? results?

Answer 12

Competition common throughout evolutionary history
• Resulted in adaptations that minimize competitive effects (niche
differentiation)
– Resource partitioning
– Character displacement
• Resource partitioning

Question 13

describing resource partitioning look at grwaph

Answer 13

• Occurs when natural selection drives competing species into
different patterns of resource use
• Weakens interspecific competition via niche differentiation
(promotes co-existence)

Question 14

how is resource partitioning determined

Answer 14

Resource usage patterns often determined by morphology of predators & prey
• Larger predators tend to eat larger prey
• E.g., salamanders: prey size limited by size of mouth (gape-limited predation)

Question 15

describe character displacement.

Answer 15

volutionary consequence of interspecific competition; traits evolve in responseto selection to reduce competition between species.

Question 16

character displacement sympatric vs allopatric? look at graphs

Answer 16

Evolutionary consequence of interspecific competition; traits evolve in responseto selection to reduce competition between species.
• Where sympatric -> divergence of traits that determine resource utilization patterns (e.g., beak length)
• Where allopatric -> differences minimized or lost
•

Question 17

competitive ability?

Answer 17

• Can’t always avoid competition - competitive ability also
important
• Competitive ability: one element of the evolution of life
history strategies

Question 18

define life history. what is it shaped by

Answer 18

• The schedule & characteristics of an organisms growth, development, reproduction & survival
  
  • Shaped by genetics & environment

Question 19

life history traits? 9

Answer 19

Lifespan
	– Age at 1st reproduction
	– Reproductive rates
	– Growth rates
	– Mortality rates
	– # offspring
	– # reproductive events
	– Offspring size
	– Competitive ability

Question 20

describe life history theory 3 points. what does it assume?

Answer 20

• Evolution of life histories involve trade-offs – resources are finite!
• Limited amount of resources that can be allocated to different
functions (competitive ability, reproduction, defense)
– Beneficial change in one trait often leads
to a negative affect on another

• Assumes LH traits are shaped by natural selection in a manner
that maximizes fitness
•