species interactions, coexistence and ecosystem function Flashcards
(53 cards)
1
Q
why is predation important
A
-Ecology: determines structure and dynamics of communities
-Evolution: selects for morphology, physiology and behaviour – strong selection pressure
-Agriculture: pest control and pesticides
-Conservation: predator control vs reintroductions (of apex predators) and, pesticides – remove a predatory to protect their prey
-Biodiversity: richness, evenness, diversity and gradients
2
Q
what is a predator
A
any individual that consumes another individual or abiotic thing
3
Q
effect of competition on population density
A
detrimental to both species
4
Q
effect of predation on population density
A
beneficial to one and detrimental to the other
5
Q
effect of mutualism on population density
A
beneficial to both species
6
Q
effect of commensalism on population density
A
one species benefits and the other is unaffected
7
Q
traits of predators
A
- mobility
- camouflage
- trickery
- morphology
8
Q
behaviour traits of predators
A
- sit and wait
- sit and dangle
- set and pursue
- pursue
- stalk
9
Q
traits of prey
A
- mobility
- camouflage
- aposematism
- mimicry
- trickery
- defensive structures
- autotomy
- chemical defence
10
Q
behaviour of prey
A
- warning signals
- playing dead
- staring or distraction
11
Q
safety in numbers for prey
A
- dilution effect
- predator confusion
- predator satiation
- improved vigilance
12
Q
how does predation impact biodiversity
A
- keystone predation targeting the domain predator can increase diversity
- keystone predation targeting the weakest competitors can lower diversity
- generalist predation lowers biodiversity
- however is very context dependant due to competitive hierarchy’s and prey traits
13
Q
prey and predator population
A
P growth function - P death function
14
Q
type I - functional response
A
- direct relationship
- as prey density increases consumption rate increases proportionally
- gradient = 0.5
- constant mortality rate
15
Q
type II - functional response
A
- predator eats as much as it can until it is full
- therefore has a max capacity - where line goes flat
- more common response
- predators do not regulate their prey so destabilise the population
- as density increases death rate increases
16
Q
type III - functional response
A
- competition is high when there is little prey so low consumption rate
- creates a stabilising population
- very rate
- mortality rate increases then decreases with density
17
Q
optimal foraging theory
A
- organisms ability to choose the right foods
- enables it to pass on these genes and instincts to its offspring
18
Q
concept of profitability
A
- predators want to maximise probability using less energy, spending less time and gain as much energy as possible from prey
- they do this by being choosy with their diet
19
Q
equation for profit
A
= E (energy/calories) / h (handling time)
20
Q
what is a trophic cascade
A
- predation over many different levels
- indirect interatcions between nonadhacent trophic levels
21
Q
sea otter trophic cascade
A
look at lecture slides
22
Q
agal bloom trophic cascade
A
a. Largemouth bass predator decreases (was deliberately removed from lake in experiment)
b. The population of small fish increased
c. Zooplankton population decreases as they are the main prey for small fish
d. This caused anoxia and loss of diversity and change in co2 flux (is a carbon sink as algae hold co2)
23
Q
effect of loss of predators on trophic levels
A
- loss of plant diversity
- loss of plant biomass
- loss of plant community
- loss of herbivore density
24
Q
the ecology of fear
A
- the fear of being eaten can have a cascading effect
- the presence of a predator has the effect as the prey is too scared to go out that they do not hunt
- this causes the preys population to decrease anyways as they stare and its preys to increase
25
maximum sustainable yield
- done to get the most money worth from crops sustainably
- at a point half of K
26
what is the harvesting theory
high yields are obtained from populations held below their carrying capacity
27
what is the inflection point
where the population rapidly increases below negative feedback and density dependence sets in
28
caveats of maximum sustainable yield
- ignores population structure (age, size, sex ratios)
- assumes environment does not vary
- impossible to reliably obtain as hard to accurately harvest
29
fixed quota harvesting
- constant harvesting rate
- same % of population always taken no matter the population size
- if this is above the recruitment line the population will deplete = unsustainable
- underharvesting = harvest rate is pushed back to the (divergent) equilibrium point - not stable
30
anchovies harvesting quota failing
- a certain amount of anchovies were allowed to be collected in a year then fishing was closed
- led to overfishing in the beginning of the year as people wanted to catch as much as possible before quota was reached for money
- in an el nino year the population naturally decreased but the quota was not changed = population at breaking point and crashed
31
fixed effort harvesting letters
H = yield
q = efficiency
E = effort
N = population size
32
what is fixed effort harvesting
constant efficiency rate reached
- only when effort is massively overprescribed in risk of extinction high
33
when do individuals compete
- when resources are limited
34
exploitative competition
- when resources are shrinking but do not completely disappear
- leads to density dependence effect slowing population growth
35
how do individuals compete - indirect
- exploitative/scramble - depleting resources
- pre-emptive - using space
- cost - loss of resource/access
36
how do individuals compete - interference
- overgrowth - species grow over one another to deprive the other of light
- chemical - produce toxins
- territorial - fighting in defence space
- encounter - transient interaction directly over a specific resource
- cost - loss of resource of well of the cost of fighting (energy)
37
what is a resource
- food
- shelter
- climate
- nutrients
- territory
- mates
38
effect of competition on carrying capacity
- K decreases with increased competition
- is it because of inter or intra specific competition?
- K usually lower with inter than intra
39
competitive exclusion principle
- no two species can share the same resource
- no two species can occupy the same niche
- no two species can coexist when they have identical needs of a limited resources
40
when do competitors exist
- intraspecific comp >> inter comp
- intra density dependence>> inter interaction
41
evolution and niches
- evolution favours separate niches minimising interspecific competition and promoting coexistence
- if there is exclusion there is a very strong selection pressure
42
character displacement
- where species are on separate islands and not competing against each other they are very similar
- but if on the same island due to strong selection pressure they evolve to be different to avoid competition
43
what does biogeochemical activity determine
- soil fertility
- air and water quality
- habitability of ecosystems
- earths climate
- existence of humans
44
biodiversity function theories
- species add function due to complementarity - each species has a specific role in the ecosystem so they can coexist
- species are primarily redundant - most function is achieved with a smaller number of species - can afford to lose a bit of biodiversity without a drop in ecosystem function
- species are primarily singular (linear and keystone)
45
grimes humpback curve
- very low and high biomass has low biodiversity
- low b = harsh environment where only a few niche species can survive
- high b = very productive environment made of a few well adapted dominant species
- intermediate biomass has greatest biodiversity
46
biodiversity for multifunctionality
- as ecosystems perform multiple functions does having one extra species have a beneficial effect on each function
- the more functions considered the more positive effects found
- cautionary theory
47
mass ratio hypothesis
plants with greater biomass influence ecosystem properties more
48
ecosystem stability
- ability of an ecosystem to not fluctuate in respinse to changes in teh enrvionment and keep the same level of ecosystem function
- biodiveristy is very important for this
49
ecosystem stability of higher diveristy - greater negative convarience effect
- as one species biomass' declines another species biomass will increase by the same amount - remain in equilibrium state
50
ecosystem stability of higher diversity - portfolio effect / statistical averaging
- if you have a large number of species you cannot have some species with a very high level of biomass
- high species richness in needed as lots of small biomass accumulate to make up biomass
- as small numbers cannot fluctuate that much the ecosystem is stable
51
climate and stability relationship
- wetter areas with more sunlight (tropics) were more stable
- warmer areas have lower stability
- has a very large effect at a global scale
52
composition vs biodiversity
- ecosystem composition should be just as focused on in conservation
- explained 67% of improvement in water quality
53
