Natural Selection

Question 1

What is Evolution?

Answer 1

Just means change over time

Natural Selection is one mechanism for it

Question 2

What is needed for Natural Selection?

Answer 2

Pre-Existing Variation
Pressure - not everyone is successful
Differential success
  Some survive, some don’t 
Heritability
    Some code accounts for different
    traits & different success

Question 3

Pre-Existing Variation

Answer 3

Within a species, individuals differ slightly in terms of their outwardly visible traits or Chemistry

Ex. In a population of mice, some have light fur, medium brown fur, or dark fur

Question 4

Selective Pressure

Answer 4

Organisms must contend with challenges, like finding food, mates, avoiding predators, or evading thermal stress, or bad weather

Ex. Mice need to go out & forage for food, but they need to avoid being eaten by birds of prey

Law of Tolerance

Question 5

Differential Success

Answer 5

Not all organisms will be successful & live to reproduce… related to trait variation

Ex. Some colours of coat provide better camouflage
Better camouflage = not getting
by predators, so the survivors live to
reproduce

Question 6

Heritability

Answer 6

Traits can be passed from parents to offspring

Ex. Genes (DNA) codes to Colour

Question 7

What is Adaption?

Answer 7

Any feature of Characteristic of an organism that helps for make that species more successful in their environment or their role in it (niche)

Question 8

How does Natural Selection work?

Answer 8

It “picks” Beneficial traits from the already existing variations, these traits increase in the population
It also selects against harmful traits,
Those decrease in the population

Question 9

What are the two types of Selective pressures?

Answer 9

Abiotic

Biotic

Question 10

Abiotic pressures

What are Density Independent factors?

Answer 10

Non-Living
Weather (temp, precipitation)
What conditions are tolerable

Density Independent factors will:
    affect organisms the same way
    regardless of how many organisms
    there are
        Eg. Hurricanes

Question 11

Biotic pressures

What are Density Dependent factors?

Answer 11

Living stuff, (relationships)

Competition
    Fight for limited resources
        Interference Competition
            Direct physical interaction 
        Exploitative Competition
           Indirect (no touching)

Predator - prey interactions
Prey adapt to avoid predators
Predators adapt to catch/kill prey

Symiosis
    Mutualism
        Everybody wins
    Commensalism
        One benefits, une unharmed 
    Parasitism
        One benefits, one is harmed

Density Dependent is when:
Intensity of the pressure changes
with the number of organisms

Question 12

How are Variations formed?

Answer 12

DNA must be copied, mistakes called mutations can occur. Mutations can possibly produce different proteins and therefore different traits
If the new trait is beneficial, it gets
selected for
If it’s bad, it’s gets selected against

Question 13

How do Nucleotide/Amino Acid sequences help in analysing how closely related organisms are?

Answer 13

How similar the sequences

=

How closely related the organisms are