Struggle for Existence pt. 7

Question 1

ecological community

Answer 1

all organisms or biotic entities in some spatially defined locality

Question 2

ecosystem

Answer 2

biotic + abiotic (atmosphere, weather, mineral nutrients) elements

Question 3

Community study

Answer 3

Considers only a subset of the species in a local ecosystem. Subsets might be taxonomically-defined or functionally-defined.

Question 4

What does it mean for organisms to share a guild?

Answer 4

Have similar functional niches.

Question 5

Community ecology is concerned with

Answer 5

species richness

Question 6

dominants

Answer 6

species that are very common in a community

Question 7

species diversity

Answer 7

distribution of abundance and rarity
ex. a community with ten equally abundant bird species is considered more diverse than one with one common bird species and 9 rare ones

Question 8

What does the brake term in logistic model represent?

Answer 8

intraspecific competition

Question 9

What does the second braking term in Lotka-Volterra competition model represent

Answer 9

interspecific competition exerted by a second species

Question 10

What is the alpha parameter and what does it represent?

Answer 10

competition coefficient, effect on 1 by 2

ON-BY

Question 11

Four possible outcomes according to Lotka-Volterra model

Answer 11

• species 1 can outcompete 2 making it go extinct and it will reach carrying capacity OR VICE VERSA
• two species can stably coexist
• competition is unstable but winner depends on starting numbers, whichever one gets initial advantage will outcompete other

Question 12

Condition for stable existence…

Answer 12

that each species inhibit its own population growth more than it inhibits the growth of the other species’ population.

Question 13

G. F. Gause

Answer 13

investigated competition with various species of protozoan genus Paramecium (showed behaviour that resembled LV predictions)

Question 14

Thomas Park

Answer 14

Flour beetle experiments. Showed importance of abiotic factors in determining outcome of biotic interactions. Confirmed that it was unlikely of difficult for two competing species to coexist.

Question 15

Principle of Competitive Exclusion

Answer 15

Two species that compete for the same resources cannot coexist for long

Question 16

Robert MacArthur

Answer 16

Warbler study
niche overlap=alpha competition coefficient
(later this was proven to be an incorrect assumption except in specific environment with to K species)
however it was found later on that OVERLAP DOES NOT MEASURE COMP.

Question 17

Limiting similarity

Answer 17

max amount of niche overlap that would allow two species to coexist (out of date idea)

Question 18

What community structure arises from a “resource-partitioning” viewpoint?

Answer 18

Equilibrial, because it says coexistence depends on patterns of resource use and that competitive exclusion will sort out organisms until only ones with different niches remain

Question 19

What does it mean when a cycle damps out or becomes amplified?

Answer 19

damp out
- predator and prey level off asymptotically at stable values and coexist indefinitely

Amplified
- mutual extinction

Question 20

Do predator prey lagged cycles actually exist in the lab

Answer 20

not really, and if they do, it doesn’t persist for long.

Question 21

How prey persists

Answer 21

• finding refuge (nooks and crannies)

- multiple prey species

Question 22

Predator-prey cycles are most pronounced in….

Answer 22

1. simple communities with low species richness where predators have little choice
2. predators are obligate specialists that can successfully consume only one species of prey

Question 23

Where can we see pronounced long-lived predator-prey cycles in real life?

Answer 23

• Arctic
• with herbivorous insects (frequently eat only one kind of plant because they’ve adapted to the chemical defences of that plant)

Question 24

How does predation affect interspecific competition?

Answer 24

It can stop superior competitors from outcompeting inferior competitors. It keeps competition for resources from reaching an equilibrium state.

Question 25

Robert Paine

Answer 25

sea star experiments

• when the starfish were removed biodiversity went down because mussels proliferated (biotic factors)
• in calm waters, mussels survived better because they weren’t being scraped off by debris slammed against rock from turbulent water (abiotic factors)

Question 26

Why are predators, parasites, and diseases especially effective mechanisms for driving populations below their carrying capacity?

Answer 26

Because they are density-dependent control factors. The more abundant the prey, the more efficient the natural enemy.

Question 27

metapopulation

Answer 27

collection of numerous smaller subpopulations spread across space (regions contain numerous discrete patches of habitat)

Question 28

equilibrium proportion of patches occupied (equation)

Answer 28

p = 1 - (e/c)

Question 29

source-sink dichotomy

Answer 29

• source patch maintains a growing subpopulation and is a net exporter of dispersing colonists
• sink patch is lower quality and incapable of maintaining subpop. except through immigration (if dispersal were cut off the sink patch would go extinct, but if it is embedded in a healthy metapop, it can remain occupied indefinitely)

Question 30

emergent properties

Answer 30

Attributes of the whole system that are not inherent in the individual parts of the system (whole is greater than the sum of its parts)

Question 31

coexistence can be…

Answer 31

global but not local. The differences in life histories allows prolonged coexistence at the metapopulation level.