Unit 10 #2 - Population ecology

Question 1

Name 3 types of population dispersal with an example for each

Answer 1

1. Clumped spacing (Cariboo’s all together)
2. uniform spacing (trees uniform in forest b/c light also uniform and all trees need it)
3. Random spacing (dandelion’s on lawn b/c can grow anywhere or Lichen)

Question 2

Why is lichen in a symbiotic relationship

Answer 2

Lichen is in a symbiotic (mutualistic) relationship with cyanobacteria b/c they both benefit from one another. Lichen provides shelter, water and minerals to cyanobacteria which in return provides sugar and nitrates.

Question 3

What is metapopulation

Answer 3

The fact that a population does not occupy all the rage at the same time eg. caribou move

Type of metapopulation: source-sink metapopulation (source=where they breed, sink=where they die)

Question 4

Dispersal

Answer 4

mechanism to spread out b/c some species cannot move eg, coconut near water fall and float away to island eg parasites have complex dispersal mechanisms

Question 5

What is responsible for population demography

Answer 5

Input: birth and immigration
Output: deaths and emigration

Question 6

Why can we say that fruit flies have shorter generations than humans

Answer 6

Usually, smaller organisms have smaller generations

*humans are an exception

Question 7

Does a type 3 survivor ship have greater change to live another day at the beginning or end of its life

Answer 7

at end of its life

Question 8

What is the link between survival and reproduction

Answer 8

More children = less likely to survive another year

Question 9

WHat is carrying capacity

Answer 9

average population size in a habitat

Question 10

What is biotic potential in Exponential growth

Answer 10

How fast a population can increase if there is no limits to growth (= (births-deaths)+(immigration-emigration))

Question 11

Which type of growth is density independant

Answer 11

Exponential growth

Question 12

Which type of growth is density dependant

Answer 12

Logistical growth

*it also has a carrying capacity

Question 13

What is Semelparity in life history with an example

Answer 13

One reproductive event in lifetime. Many small off spring. ie Mayfly will be larva and adult in 1 day, they will lay many eggs and die (they make lots of babies but no investment/parental attention)

Question 14

What is Iteroparity in life history with an example

Answer 14

Several reproductive events in a life time. Few large offsprings. ie us we will have some babies and give a lot of parental effort

Question 15

what are the characteristics of an r selected population with an example

Answer 15

age 1st reproduction (eary
life span (short)
Maturation time (short)
Mortality rate (high)
Number offsprings per reproductive episode (often high)
Number reproductions per lifetime (few)
Parental care (none 
Size offspring (small)

ie us bc population growth is exponential and slowed down with pandemics, climate change…

Question 16

An example of K selected population

Answer 16

Elephants

Question 17

What is eutrophication and its link with phosporus

Answer 17

algal bloom is caused by blue-green algae (cyanobacteria) which produces toxins. This is because at night it consumes O2 bc it cannot perform photosynthesis and therefore fish lack o2 and die. These algae can fix N2 and transform it into NH3/NO3-

Phosphorus causes algal bloom and it contaminates waters through fertilizers used by farmers.

Question 18

How is the age structure (population pyramids ) different for western and poorer countries

Answer 18

Western situation: more older than younger and it is overall stabilized

Poor: more young than old (pear shape) because often people die young.

Question 19

What are the 2 things that affect population growth

Answer 19

generation time and sex ratio (number of females affect population growth because they give birth)

These concepts are related to fecundity (birth/reproduction) and mortality (death/survival)

Question 20

Name density-independant effects on populations

Answer 20

cold and drought

Question 21

Name density-dependant effects

Answer 21

competition, toxic wastes, predation, intrinsic factors (stress hormones = lower fertility), territoriality, disease (more dense=more disease)

Question 22

Visualize the graph of density effects that affects birth and death rates

Answer 22

cross of density-dependant birth rate (diminishes with density bc more pop=less ressource) and density-dependant death rate (increase bc disease and more ressource), with the cross point being the equilibrium population density

Question 23

Explain the boom-bust cycles

Answer 23

As population of lynx increases, hare population diminishes, so lynx population diminishes because no more food them , so hare population increases because no predation, so lynx population increases because lots of food for them