EE Lecture 28: Interspec Competition

Question 1

deine interspecific compeition

Answer 1

when individuals of one species suffers a reduction in fecundity/growth rate/survuval due to resource exploitation or interference by individuals of another species

Question 2

what is amensalism

Answer 2

type of interspec comp where one species is inhibited but the other is not

Question 3

why care about interspec comp

Answer 3

helps direct evoln

shapes community composition

Question 4

what is interference comp

Answer 4

type of contest comp. visible compeition = hard to test if it reduces fecundity

Question 5

give an example of resource comp

Answer 5

diatoms use silica to construct cell wall
examined competition for silica (SiO2) in 2 diatoms - S.ulna and A.formosa alone, and in comp with eachother
they measured vhange in diatom pop density and silica conc in water over time
when grown alone, each species reduced silica to low + constant conc - each species also reached a stable pop size
S. had lower stable pop size than A, and it reduced silica to lower levels than A.
when 2 competed, S drove A to extinction, apparently because it reduce SiO2 levels so low that A couldnt survive

Question 6

what is exploitative comp

Answer 6

when individuals reduce the supply of resource as they use it

Question 7

what is the ghost of competition past

Answer 7

species A B and C dont compete now - but this may be because evoln has shaped their resource ecploitation in response to compeition in the past

Question 8

when studying competition - if we dont see compeition, what could this be a result of

Answer 8

ghost of comps past or PARALLEL evoln

Question 9

what is logistic growth model which adds inTRAspec comp

Answer 9

dN/dt = rN [ 1 - (N/K) ]

Question 10

what is Lotka Volterra Comp model

Answer 10

model interspec competition by using the logistic growth model

Question 11

write Lotka-Volterra Comp model

Answer 11

dX/dt = rX [ 1 - (X + aY / K) ]
dY/dt = rY [ 1 - (Y + bX / K) ]

a = comp effect of Y on X
b = comp effect of X on Y
a > 1 means Y hurts X more than X hurts X
b > 1 means X hurts Y more than Y hurts Y

Question 12

in Lotka - Volterra comp model, what does a mean?

what if a > 1

Answer 12

a shows comp effect of Y on X

if a > 1 , it means Y hurts X more than X hurts X

Question 13

in the Lotka-Volterra comp model what does b mean?

what if b > 1 ?

Answer 13

b shows comp effect of X on Y

if b>1 means that X hurts Y more than Y hurts Y

Question 14

what is result of intraspec > interspec comp

Answer 14

coexistance

Question 15

if intraspec

Answer 15

get compeititive exclusion

Question 16

what is the competitive exclusion principle

Answer 16

if two competing species coezist in a stable enviro, they do so as a result of niche differentiation

Question 17

what does aggregation promote

Answer 17

coexistence because more intraspec then interspec comp

Question 18

name a paper which outlined how aggregation promotes coexistance

Answer 18

highly aggregated species - much less comp than expected

a kind of random or spatial niche differentiation

Question 19

what is aggregation wrt.niche

Answer 19

a kind of random or spatial niche differentiation

Question 20

what are the effects of anthropogenic homogenization of enviro

Answer 20

simplifying enviro so reduces the enviro heterogeneity = may lead to comp exclusion through removal og refuges