Topic 7 - Ecology

Question 1

Define population?

Answer 1

All members of a particular species w/in an ecosystem, found in the same time & place, & actually or potentially breeding

Question 2

Define community?

Answer 2

All the interacting populations w/in an ecosystem

Question 3

Define ecosystem?

Answer 3

All organisms & their nonliving environment w/in a defined area

Question 4

Define Biosphere?

Answer 4

That part of the earth inhabited by living organisms; includes both living/nonliving components

Question 5

Population dynamics is…? Contributing factors are…?

Answer 5

Changes in population size over time. 4 contributing factors: 
births
deaths
immigration (migration into an area)
emigration (migration out of an area)

Question 6

Population growth rate =? Results in?

Answer 6

Change in population size per individual per unit time (rate of natural increase)

r=birth rate - death rate
Population growth =r X N

Results in exponential growth (J shaped growth curve)

Question 7

Exponential growth is?

Answer 7

Boom n bustttt (think awkward dance moves) growth curve

Often observed w/ invasive species invasions
Natural mortality is limited e.g. Cane toad

Question 8

Logistic growth is?

Answer 8

Pop is maintained at steady level => CARRYING CAPACITY

Limits to growth ( e.g. lack of food) slowly decreases the pop. growth rate

Question 9

Mortality Factors (2 kinds!)

Answer 9

Density-INdependant

Density-DEpendant

Question 10

What are density INdependent factors? What do they do?

Answer 10

Are independent of pop. => physical conditions that affects all individuals regardless of pop. size e.g. natural disaster

Question 11

What are density DEpendent factors? What do they do?

Answer 11

Limit pop. growth in proportion to size of pop. Increase in magnitude as pop. increases e.g. predation, competition

Question 12

What is an ecological niche? Includes?

Answer 12

All aspects of an organism's way of life.
Includes:
-food source
-nesting requirements
-temp, pH, sunlight tolerances
-water requirements etc

Note: Competition is fiercest b/w organisms w/ similar niche requirements

Question 13

Define competition? What purpose does competition serve?

Answer 13

Interactions b/w organisms attempting to use the same limited resource e.g. food, hiding places, mates etc

Coz resources are finite, comp. serves to limit pop. growth

Question 14

What is INTRAspecific competition?

Answer 14

competition b/w members of the SAME species

Question 15

What is INTERspecific competition?

Answer 15

competition b/w members of DIFFERENT species

Question 16

What is the competitive exclusion principle?

Answer 16

No two species can occupy the same ecological niche simultaneously.
If attempted => one will be forced out.

Question 17

What is resource partitioning?

Answer 17

Evolutionary adaptation that reduces niche overlap
Niche breadth is narrowed compared to species that do not have to compete.

THINK BUG TREE EXAMPLE.
RP is an example of coevolution=> two interacting species acting as forces of natural selection on each other

Question 18

State 2 types of species interactions & give example!

Answer 18

1. Antagonistic e.g. predation, parasitism

2. Mutualistic e.g. mutualism (reallllllyyy?!)

Question 19

In predation…?

Answer 19

predator is generally larger than prey. more than 1 prey is consumed during life of predator

Question 20

In parasitism…?

Answer 20

Consumer is usually smaller than host. One host usually consumed during development
Death of host is typically gradual

Question 21

In mutualism…?

Answer 21

both organisms benefit from the interaction

Question 22

What is a trophic level?

Answer 22

Literally ‘feeding level’. categories of organisms in a community, & the position of an organism in a food chain, defined by the organism’s source of energy

(think energy pyramid example)

Question 23

Energy flows….?

Answer 23

from one trophic level to the next, w/ maximum energy at base (primary consumers) & steadily diminishing at higher levels
producers=>primary consumers=>secondary consumers=>tertiary consumers

• energy pyramid
• but dont forget about the decomposers/detritus feeders!

Question 24

Nutrient cycling is where…

Answer 24

nutrients pass from one trophic level to the next, as demonstrated in a food chain or food web

Question 25

Detritus feeders & decomposers do what?

Answer 25

Detritus feed on debris
Decomposers feed on similar matter by secreting digestive enzymes externally

Both return nutrients to ecosystems in the form of simple molecules => make nutrients available to other individuals

Question 26

Define biomass

Answer 26

Total weight of all living material w/in a defined area

Question 27

Define biomagnification

Answer 27

Increasing accumulation of a toxic substance in progressively higher trophic levels

Question 28

Description of food web

Answer 28

A representation of the complex feeding relationships w/in a community, incl. many organisms at various trophic levels, w/ many consumers occupying more than one level simultaneously

Question 29

Description of food chain

Answer 29

A linear feeding relationship in a community, using a single representative from each trophic level