week 3

Question 1

what is an ecosystem

Answer 1

a collection of dynamic communities interacting with the physical environment
*dynamic meaning that there is continuous productivity occurring

Question 2

what is the rank in size of the components of an ecosystem

Answer 2

organism, population, community, ecosystem and biome

Question 3

what is meant by a dynamic ecosystem

Answer 3

that things are continuously changing and/or evolving, driven by the relation and interaction between bitoic and abiotic factors

Question 4

what is ecological succession

Answer 4

the gradual replacement of one community by another
-primary or secondary

Question 5

what is primary succession?

Answer 5

the colonization of an area that had no or little soil previously. Commonly will evolve in serial stages
1)formation of lichens
2)formation of mosses
3) formation of small trees or shrubs with small roots systems

Question 6

what are the three stages in primary succession? what are the benefits?

Answer 6

1) formation of liches directly on the rock surface. this is a mutualistic relationship, where the lichen benefits from the CO2 made by fungi and fungi use O2 from lichen
2) 2) formation of moss. this is a fast growing stage. the small ribzoids of the moss are able to slowly break down the parent rock creating soil
3) formation of small srhubs and trees, stronger root system is able to make soil more efficiently

Question 7

what is a climax community?

Answer 7

where vegetation in an area would reach a stable and hearty stage and remain in equilibrium for the rest of the time.

overall this is not true as succession is commonly a cyclic event due to biotic and abiotic disturbances

Question 8

what is an ecological disturbance?

Answer 8

a punctated event that alters the structure and function of an ecosystem (population ad communities)
*can be either biotic or abiotic
-fires, floods, volcanic eruptions, earthquakes
- viruses, the introduction of an invasive species

Question 9

what is net primary productivity

Answer 9

the GPP minus the cost of cellular respiration (of acquiring energy to survive)

Question 10

what is gross primary productivity

Answer 10

the total amount of biomass(carbon containing compounds) produced by plants in an ecosystem over a given time frame

Question 11

describe the intermediate diversity hypothesis

Answer 11

the notion that there is a limit to the level of biodiversity within a system.
- too much biodiversity causes when competition is high or resources are low (low disturbance)
-too little when disturbances are frequent, not allowing for an adequate establishment of any community or population, or at the very least very few .

Question 12

what is the gia hypothesis

Answer 12

the foundation of the dynamic equilibrium of an ecosystem.
the idea at the levels of prey and predators mimic each other
-low preadtor is a response on decreasing prey count, which in time allows for the prey to increase its size and the predtor population will soon follow

Question 13

inertia

Answer 13

and ecosystems ability to withstand change

Question 14

resilience

Answer 14

an ecosystem’s ability to recover from a disturbance

Question 15

what is an alien spices

Answer 15

a species that is found outside its realized or functional niche, somewhere its not expected
**not always invasive

Question 16

what si an invasive species?

Answer 16

an alien species which outcompetes the native species, commonly causing harm (directly or indirectly)
**greatest threat to biodiversity

Question 17

what is hyperabundance

Answer 17

when a native species population increases to the extent it is pest-like.
*it may impose undesirable stress to its ecosystem
*may be a repose to removing a keystone species (predator)

Question 18

what do feedback loops do and what are the 2 feedback loops?

Answer 18

they work to maintain an ecosystem stability

1) positive, move away from equilibrium (exponential growth effect)
2) negative trends toward equilibrium (cyclical response)

Question 19

density dependant vs independent populations

Answer 19

density dependant populations tend to fluctuate slightly around their carrying capacity. the functionality of therr population relies on the # of orgs in their pop
-commonly limited by resources, competition and disease
independent pop grows exponentially as there lacks a ‘capacity’, though other factor will eventually limit it

Question 20

what are the 2 strategies fro population growth

Answer 20

R - rapid with minimal parental investment. better suited for fluctuating environments and offspring are commonly dispersed
K- slow with increased reproduction energy by a parent (offspring are in a competitive world). more susceptible to being endangered

Question 21

allopatric speciation

Answer 21

speciation by the physical separation of a population by a geographical barrier. 2 new species are formed suited for different environments

Question 22

peripatric speciation

Answer 22

speciation from the isolation of a small group of a population. the original species still exists, but a small group of the population is separated (not geographically). this group tends to remain small and may exhibit what was considered rare in the original population frequently.

Question 23

parapatric speciation

Answer 23

this is a large population that is spread out over a large area, often merging into adjacent niches than what was considered to be original. The ‘new’ species may only mate with those in their residing area

Question 24

sympatric speciation

Answer 24

will arise spontaneously where no barriers exist between the old and new populations. may be due to genetic polymorphism due to individuals utilizing different components of the environment to fulfill similar purposes.

Question 25

what is a mass extinction?

Answer 25

the rapid decline in biodiversity on a global level. COmmonly around 80% of biodiversity is lost in a very short time frame.