week 12, may 2nd - 6th

Question 1

Name and explain second condition for no evolution

Answer 1

No mutations
Mutations are changes in DNA
Singe nucleotide (added, substituted or removed) = usually would change codon on mRNA changing amino acid sequence
Crossing over = homologous chromosomes not exchanging the same amount of genes resulting in having an extra gene or missing a gene
Chromosome fails to separate properly during cell divisions resulting in adding or missing a chromosome

Question 2

Name and explain third condition for no evolution

Answer 2

No migration

New individuals arriving or some individuals leaving would change gene pool

Question 3

Name and explain fourth condition for no evolution

Answer 3

No selection of mates

Selecting a mate would change the frequencies of alleles or individuals in next generation

Question 4

What did Lamarck say

Answer 4

Inheritance of acquired characteristics
Realized that the environment selected/ successful variant favoured
Believed that variations between individuals were acquired during lifetime and were found in offspring (false)

Question 5

What did Darwin (Wallace) say

Answer 5

Theory of evolution = origin of species
Individual variants are inherited by genetics
Environment selects or favours the successful variant
More successful variants reproduce more
Next generation have more of successful phenotype

Question 6

What is Darwin’s fitness

Answer 6

Number of offspring you produce that survive and are fertile

Question 7

Name sources of variation

Answer 7

Mutations
Recombination of existing alleles by meiosis (crossing over and independent assortment), different mating pairs and migration

Question 8

What is divergent evolution

Answer 8

Common ancestor structure evolved for different purposes
Structure called homologous
Different nice: ecological role

Question 9

What is convergent evolution

Answer 9

Different ancestors evolved to form a common structure

Structure called analogous

Question 10

Name the 3 trends of selection

Answer 10

Stabilizing selection
Directional selection
Disruptive selection

Question 11

Explain stabilizing selection

Answer 11

Favours middle variant
Selects against both extreme variants
Ex = weight of baby at birth, clutch size (ideal amount of eggs laid)

Question 12

Explain directional selection

Answer 12

Selecting one extreme
Ex = antibiotic resistance - bacteria
Pesticidic resistance - insects weeds herbicide resistance

Question 13

Explain disruptive selection

Answer 13

Two types of environment
Each environment is selecting one of the extreme variant
Middle variant is selected against (killed)

Question 14

Describe Batesian mimicry

Answer 14

Model is armed (poisonous)
Mimic looks like the model but is unarmed (palatable)
Like coral snake and king snake

Question 15

Describe mullerian mimicry

Answer 15

Both model and mimic are armed
Predator avoids all of them
Like monarch and viceroy butterfly
Like wasps, bees and hornets

Question 16

What are reproductive isolating mechanisms and name the two groups

Answer 16

Preventing two species from reproducing resulting in viable fertile offspring
Prezygotic barriers
Postzygotic barriers

Question 17

Explain prezygotic barriers (5)

Answer 17

Prevents fertilization (zygote formation)
1 - habitat isolation (two species live in different places and therefore never meet (different continents))
2 - temporal isolation (different species, reproductive season is at different times)
3 - behavioural isolation (courtship ritual is species specific and doesnt attract different species
4 - mechanical isolation (different species of animals have different size and shape of genitals)
5 - gametic isolation (sperm of a different species cannot fertilize an ovum of another species because sperm has to bind to a species specific receptor

Question 18

Explain postzygotic barriers (3)

Answer 18

Prevents formation of viable and fertile offspring
1 - reduced hybrid viability miscarriage (embryo or fetus dies before birth)
2 - reduced hybrid fertility (offspring is healthy but infertile like a mule)
3 - hybrid breakdown (offspring is outcompetes bu the two parental species)

Question 19

What is speciation

Answer 19

Forming new species

Question 20

Name the two types of speciation

Answer 20

Allopatric

Sympatric

Question 21

Describe allopatric speciation

Answer 21

New animal species
Geographical barrier that fragments an original population into smaller populations that are prevented to reproduce together because the barrier isolated them from each other
With different mutations make them different species
Ex = Galápagos Islands, different species of tortoises

Question 22

Describe sympatric speciation

Answer 22

New species of plants
New species originates within the two parental species range
Diploid set from both parents —> fertilization —> nondisjunction = new species