Anne Bjorkman - Community ecology

Question 1

Species interaction categories

Answer 1

Positive or negative or neutral. Trophic or not.

Question 2

Symbiosis

Answer 2

One species live in or on another organism. Can be positive or negative. They live together.

Question 3

Ammensalism

Answer 3

Hurting one, neutral for the other.

Question 4

Commensalism

Answer 4

Neutral for one, positive for one.

Question 5

Mutualism

Answer 5

Positive for both parts. E.g. plants and mykorrhizal fungi.

Question 6

Parasitism

Answer 6

A sort of predation. Positive for one, negative for one.

Question 7

Predation

Answer 7

Carnivory, herbivory and parasitism. Trophic. Predator kills and eats prey. Influence evolution and population dynamics. Predators can have big effects on communities (arctic fox, jaguar/cougar). Can benefit biodiversity, as it stops one species from taking over.

Question 8

Carnivory

Answer 8

Predator and prey are both animals.

Question 9

Carnivores energy

Answer 9

They must balance cost of pursue vs consumation.

Question 10

Active pursuit

Answer 10

Be stronger and faster than prey.

Question 11

Stealthy ambush

Answer 11

Look harmless and wait for prey. Predator.

Question 12

Warning signals in prey

Answer 12

Toxic animals can show that with bright colours. Predators must learn to recognize them. Prey must survive a brief encounter with them.

Question 13

Batesian mimikry

Answer 13

Non-toxic animal looks like a toxic animal, predator confuses them.

Question 14

Mullerian mimikry

Answer 14

Two toxic species look similar to avoid predation. Gives stronger recognition signals to predators.

Question 15

Group behavior to avoid predator

Answer 15

Flocking, alarm calls can create protection.

Question 16

Herbivory

Answer 16

Animals eating plants or algae. Usually, the plant doesn’t die, but it can affect its fitness. Most insect herbivores are specialists. Vertebrate herbivores are usually generealists.

Question 17

Plant defenses

Answer 17

Secondary metabolites, spines, thorns, waxy leaves…

Question 18

Parasitism

Answer 18

Predator lives in or on its prey. Feeds on specific tissue. Many of these relationships are symbiotic. Parasites specialize on host species, but host can have many parasites on them. There can be parasites on parasites. About 50% of species on earth have parasites. Parasites can be pathogenic (not bacteria and viruses).

Question 19

Endoparasites

Answer 19

Live inside the hosts body, like botflies that lay eggs under the skin, the larva then emerge.

Question 20

Ectoparasites

Answer 20

Live outside the host. Stuff to prevent the host from brushing them away, like claws.

Question 21

Grooming

Answer 21

Removing ectoparasites. Usually mutualistic, the one grooming eats the bug.

Question 22

Keystone species

Answer 22

A very important species. A predator that has a disproportionately large effect on its environment relative to its abundance. (Plants and herbivores are often much more abundant than predators, and are therefore not keystone species)

Question 23

Competition

Answer 23

Non-trophic. Two or more species overlap in the use of limiting resources, like nitrogen for plants, food, water, space, and so on. Affects them negatively, affecting growth, reproduction and/or survival. Can occur between predators, herbivores or pathogens.

Question 24

Competitive exclusion

Answer 24

One species prevents the other from using the resource. The second species goes extinct. Not very common.

Question 25

Competitive coexistance

Answer 25

The ability for species to coexist despite sharing limited resources.

Question 26

Resource partitioning

Answer 26

Species use limited resources in different ways, reduces competition. Competitive coexistance.

Question 27

Avoiding predation defenses

Answer 27

Running or flying away, morphological defenses like shells, tough skin, spines, and crypsis (camouflage).

Question 28

Chemical defenses

Answer 28

To avoid predation. Common in small or weak prey and sessile organisms.

Question 29

Character displacement

Answer 29

Individuals within a species may evolve different behaviors or morphologies if they are competing with another species.

Question 30

Competition: physical environment

Answer 30

Competition outcomes change depending on the physical environment and processes such as disturbance and predation. Leads to different species being excluded from certain places.

Question 31

Positive interactions types

Answer 31

Facilitations.
Mutualism: Both species benefit, sometimes highly dependant, symbiotic.
Commensalism: one part benefits, the other is unaffected.

Question 32

Positive species interactions

Answer 32

Quite common, like plants and polinators, mykorrhiza. Some are obligate, others optional. Some are symbiotic.

Question 33

Frugivores

Answer 33

Animals that eat fruits and disperse the seeds. Mutualistic relationship.

Question 34

Mutualism environment

Answer 34

More likely in stressfull than benign environments. They need each other to survive, neighbour helps protect from stress. In benign environments, neighbour creates competition. More common on high altitudes than low for example.

Question 35

Ammensalism

Answer 35

One part is unaffected, the other is harmed. E.g. big vertebrates crushing insects.

Question 36

Consequences of species interaction

Answer 36

Influence evoltion. Adaptation in one species may lead to evolution of an adaptation in a species it interacts with; coevolution. An introduced species can decimate prey population in a new location, because the prey have not co-evolved with the predator - invasive species.

Question 37

Co-evolution

Answer 37

Escalating adaptations and counter-adaptations against each other (in interacting species).

Question 38

Interactions most likely to lead to co-evolution

Answer 38

Interactions that happen regularly and with high frequency, and has a strong effect.
Commensal and ammensal interactions are less likely to lead to co-evolution. Pressure on both parts are needed.

Question 39

What grows where, and why?

Answer 39

Filter from all possible species, the regional species pool, to the local community.
Three filters: dispersal, environmental filtering, and biotic interactions.

Question 40

Dispersal

Answer 40

What species can reach the location? Plants: consider gravity, transport by animal, wind and water, ballistic mechanisms. Average vs rare long-distance events, both matter. Barriers, like mountains or oceans, must also be considered.

Question 41

Environmental filtering

Answer 41

Can an individual establish and survive in the abiotic conditions? Temperature, water, nutrients in soil, photoperiod cues, environmental variability, and so on.
Each species is able to exist and reproduce within a range of values for a particular environmental factor, and has an optimum level with maximum performance. Outside that, only growth, then only survival, then death.

Question 42

Biotic interactions

Answer 42

Can an individual establish and survive in the biotic conditions at a location? Competition, predation, beneficial interactions.

Question 43

Environmental filtering vs competition

Answer 43

Species are as different as they can, but are more similar in harsh environment, due to the difficulty to survive. More competition in benign environments, and therefore more different species.

Question 44

Environmental vs biotic filter

Answer 44

Environmental filter leads to species more similar to each other, biotic filters lead to species more different to each other. This way, you can tell if environment or competition is the most important factor in this place.

Question 45

Niche differentiation

Answer 45

Pressure on species to differentiate to use different niches, to live in different ways and eat different food.

Question 46

Experiments to see if it’s a dispersal problem

Answer 46

Seed traps, good if you don’t want to introduce a new species, but not completely accurate.
Seed addition, more accurate.
Transplant experiments.

Question 47

Is abiotic or biotic filtering the problem?

Answer 47

Are the species different or similar?

A relationship between species composition and environmental variable X might indicate environmental filtering, but there might also be another limiting variable that is not measured.

Random selection: compare to a null model, you randomly select species, that are put in the null model, and then you compare the null model to the observed place. Less similar values in observed place = competitive exclusion

Question 48

Filter depends on scale

Answer 48

Bigger area might lead to more different species and competitive exclusion, but a smaller area might lead to more similar species, showing an environmental filter.

Question 49

Why do communities change over time?

Answer 49

There is change in the filters; dispersal, abiotic and biotic. Example: climate change leading to warmer temperatures.

Question 50

Succession

Answer 50

The gradual, and often predictable change in a community, often after a disturbance.

Question 51

Primary succession

Answer 51

The community starts from zero, like after a glacier. Change through time where no community existed before.

Question 52

Secondary succession

Answer 52

Community change through time in places that experienced disturbance. Something is left, it doesn’t start from scratch.

Question 53

Climate change affects successional trajectories

Answer 53

Drier, warmer conditions causes more frequent fires, which affects the composition of species.

Question 54

Practical use community assembly

Answer 54

Conservation/restoration of rare or degraded habitats.
Understanding the factors that promote invasive species success.
Predicting range shifts under climate change.

Question 55

Advancing treelines experiment

Answer 55

Dispersal: maybe the seeds can’t reach higher altitudes.
Temperature is just one abiotic factor, something else might be hindering them, like soil type.
Biotic interactions, competition, could stop them.
Mutualistic interactions that can’t or take long time to get to higher altitudes.
Global warming is not happening at the same rate everywhere.

Experiment:
Seed addition to remove dispersal limitation.
Herbivore exclosure to remove predation.
Plot scarification to remove competition.