lecture 16 and 17 community and population ecology

Question 1

what is an ecological niche

niche theory

Answer 1

the multidimensional environment in which a species can exist

Question 2

what is the space a species can occupy called?

Answer 2

fundamental niche

Question 3

what is the space a species actually lives in

Answer 3

realised niche

Question 4

what determines where a species will live within it niche?

Answer 4

competition, disease, predation

Question 5

what are the 4 community level processes and what do they mean

Answer 5

4 categories of community level processes that drive the dynamics of a community:

1. environment-species relationship
   - is based on the species / niche requirements. a species will be more likely to survive in a certain environment that suits their needs i.e. hot environment
2. dispersal
   - this occurs when a species is good at breeding, lots of species will disperse across the landscape impacting community composition
3. ecological drift
   - when a species is lost from an environment, this is due to randomness and chance
4. evolutionary diversification
   - occurs when a new lineage is made. will create more diversity in the population

Question 6

how are the different ways you can measure ecological communities?

Answer 6

can measure

• species richness - no. of species in a community
• alpha diversity - the diversity within a community
• beta diversity - the change in community composition between sites
• gamma diversity - the diversity of an entire landscape

Question 7

what is the competitive exclusion principle

Answer 7

states that two species that rely on the same ecological requirements cannot co-exist. one will outcompete the other

Question 8

what does population ecology consider?

Answer 8

all the single species that occur together in space and time

Question 9

what are the vital rates of population ecology

Answer 9

births deaths immigration and emigration

Question 10

what is R

Answer 10

population growth rate

Question 11

what happens if R is over 1
what happens if R is less than 1
what happens if R is 0

Answer 11

if R is over one population will increase
if R is less than 1 population will decrease
if R is 0 population will remain the same

Question 12

what are the 4 factors that influence R? and what do they mean

Answer 12

1. density dependence
   - generally if R will decrease when population density increases as there will be more people competing for resources etc
   (however there can be allee affects where R decreases when population density decreases)
2. demographic stochasticity
   - there are random variations in births and deaths. a growth or decline in R will not always look steady due to this. it will look more variant
3. environmental stochasticity
   - there can be random variations in environmental conditions that affect birth and death rates such as rainfall patterns etc.
4. catastrophes
   - is a type of environmental stochasticity - an extreme variation in the environment that may cause a dramatic decline in R

Question 13

what are the different ways you can measure a population?

Answer 13

• direct observation of a species
• mark and recapture studies - for hard to catch species
• modelling populations

Question 14

what can population ecology be used for?

Answer 14

conservation of threatened species
control or eradication of a species
management of a harvested species

Question 15

what is the difference between realised and fundamental niche

Answer 15

fundamental niche is the space in which a species can occupy
the part of the niche that they actually live in is called the realised niche