Chapter 5 - Population Dynamics

Question 1

R-selected species

Answer 1

Characterised by:

• short life span
• rapid reproduction
• fats growing
• little parental care

Eg) weeds, mosses, lichens, small animals

Question 2

K-selected species

Answer 2

Characterised by:

• long life span
• slow growing
• breed later in life
• fewer offspring

Eg) trees, large animals,

Question 3

distribution

Answer 3

The places in the ecosystem where individuals of species are found; usually this is not evenly spread

Question 4

Measuring distribution

Clumped

Answer 4

Clumped: describes the situation in which individuals in a population are grouped together where biotic/abiotic factors are favourable; can be social (Eg) schools of fish) or clumping of vegetation

Question 5

Measuring distribution

Random

Answer 5

Organisms are spaced irregularly; the location of an organism does not affect the location of another. This Is more common with plants than for animals

Question 6

Measuring distribution

Uniform

Answer 6

Organisms are spaced evenly; the presence of one organism determines how close or distant another will be. Common in high-density populations of some animals that set up for breeding territories.
Eg) penguins

Question 7

Measuring growth

Answer 7

Growth: when populations number increase

Formula to measure population growth:
=(birth rates+immigration rates)-(death rates+emigration rates)

The use of population pyramids useful to know the structure of a population significant for predicating future growth trends

Question 8

Abundance

Answer 8

How many; the number of a species in a population

Abundance is the same as density. Ie no of species per square metre

Question 9

Measuring abundance

Quadrat

Answer 9

A square or rectangular plot of land used to mark off at random a physical area to isolate a sample and determine the percentage of vegetation and animals occurring within the marked area

• most often used for small insects and/or plants
• useful for stationary organisms

Question 10

Measuring abundance

3 options for measuring inside a quadrat

Answer 10

1. Counting each individual quadrat
2. Percentage cover is estimated then the quadrants are averaged and applied to a larger area
3. Number are estimated using an abundance range; 3=abundant, 0=absent

Question 11

Measuring abundance

Transect

Answer 11

• A line across a community to determine the distribution of species
• information gathered is used to measure the distribution of organisms
• most often used for species that are fixed in place like mosses, plants

Placing quadrats along a transect line can be used to measure the density

Question 12

Measuring abundance

Direct observation

Answer 12

• visually observing and counting animals or plants
• most effective for large animals or plants of which there are no many to count and are mobile
• can take a sample and then apply that to a larger area to estimate population for a large area
• this is considered time consuming and dangerous

Question 13

Measuring abundance

Capture-mark-recapture

Answer 13

-commonly used to sample mobile species

Step 1: capture- animals are caught randomly
Step 2: mark and release - each captured animal is tagged and returned to their habitat
Step 3: recapture - later, a random sample is taken and the number of tagged animals is counted

Question 14

Measuring abundance

Remote tracking

Answer 14

Mobile/,argue species are tracked using GPS in an attempt to predict future needs and management using computer technology

Question 15

Carrying capacity

Answer 15

The maximum population size of a species that can be supported in a given environment.

Populations rely on balanced relationships between their biotic and abiotic components

Question 16

Density dependent factors

Answer 16

These are biotic (living)

• competition
• disease
• parasites
• predation
• food supply

Question 17

Density independent factors

Answer 17

These are abiotic 
Physical factors
-acidity 
-rainfall
-humidity
-temperature
-salinity 

Catastrophic events

• volcanic eruption
• tsunami
• fire
• drought
• earthquake
• flood

Question 18

Chemical control

Answer 18

• A quick and effective method of getting rid of pests using pesticides
• chemical controls can be ecologically damaging and costly

Question 19

Biological control

Answer 19

• known as integrated pest management
• uses biological measures to control pests
• Limits the use of chemicals to target specific species
• exploit relationships between organisms

Question 20

Biological control

4 kinds of biological control

Answer 20

1. General predators: organisms that consume a great variety of pest species
   Eg) ladybirds target aphids

2.specialised predators: organisms that target one pest species
Eg) dragonflies target all life stages of mosquitoes

3. Parasites: organisms such wasps or flies that lay eggs in the bodies of hosts. When they hatch, the larvae feed on the body of the host causing the hosts death.
4. Microbial diseases: caused by bacteria, fungi, and viruses that target species and cause death through illness
   Eg) myxomatosis which was released to control rabbit populations