Evolution Part 2

Question 1

What did Hardy and Weinberg principale state?

Answer 1

States that allele frequencies of a gene will remain the same in a stable population

Question 2

frequencies of a gene will remain the same in a stable population, as long as…

Answer 2

1. Mutations are not occurring.
2. Mating is random.
3. Natural selection does not occur.
4. No genes enter or leave the population.
5. The population is large.

Question 3

It is impossible to meet these
conditions in nature, so why apply this law?

Answer 3

Because
- it shows that populations tent to remain static without evolution
-provides a standard by which evolution can be measured, because if gene frequencies do change, then it delivers solid evidence of evolution

Question 4

What are the hardy Weinberg equations?

Answer 4

P + q= 1 (or 100%)

And

p^2 + 2pq + q^2 = 1 (or 100%)

Question 5

What does p mean in the HARDY-WEINBERG equations?

Answer 5

p = freq. of dominant allele (B)

Question 6

What does q mean in the HARDY-WEINBERG equations?

Answer 6

q = freq. of recessive allele (b)

Question 7

What does p^2 mean in the HARDY-WEINBERG equations?

Answer 7

p^2 = freq. of BB genotype

Question 8

What does 2pq mean in the HARDY-WEINBERG equations?

Answer 8

2pq = freq. of Bb genotype

Question 9

What does q^2 mean in the HARDY-WEINBERG equations?

Answer 9

q^2 = freq. of bb genotype

Question 10

True or false: Dominant allele doesn’t always have the higher frequency in a population, and vice versa

Answer 10

True (e.g. human blood type O is most common, but the trait is recessive)

Question 11

Practice a question

Answer 11

How did it go?

Question 12

What are Species?

Answer 12

a population whose members can interbreed with one another in nature to produce fertile offspring

Question 13

What is speciation?

Answer 13

-the formation of new species through evolution
-may occur as a result of reproductive isolating mechanisms
There are 2 modes

Question 14

What are the 2 modes of speciation?

Answer 14

1. Allopatric
2. Sympatric

Question 15

What is Allopatric?

Answer 15

1 mode of speciation
-it happens due to geographical barrier
-populations isolated by dam, river, etc
-e.g. Pacific and Caribbean wrasse (fish)

Question 16

What is Sympatric?

Answer 16

1 mode of Speciation
-it is the development of a new species within the original population without being geographically isolated
-usually results from sudden mutation
-common errors in meiosis result in individuals with extra sets of chromosomes—> polyploidy
-e.g. grey tree frogs in Ontario

Question 17

More understanding about polyploids

Answer 17

polyploidy (more than just two sets of chromosomes).
Polyploids produce fertile offspring when mated with each other, but produce sterile offspring when mated with the original species

Question 18

What does reproductive isolating mechanisms do?

Answer 18

• prevent mating between species
  -may lead to formation of new species —>speciation
  -9 types in 2 main categories
  1. Pre-zygotic
  2. Post-zygotic

Question 19

What is Pre-zygotic?

Answer 19

Prevent mating and/or hinder fertilization

Question 20

What is post-zygotic?

Answer 20

Prevent the zygote (formed from union of sperm and egg) from developing

Question 21

How do humans influence speciation?

Answer 21

• human activities that destroy habitats (road construction and agriculture expansion) threaten survival of species
  -causes reduction of gene flow and genetic diversity
  -e.g. giant pandas of china

Question 22

What is divergent evolution?

Answer 22

• a pattern of speciation
• process of developing 2 or more species from a common ancestor over a long time
  -reduces competition between species and increases biodiversity
• e.g. Ontario’s rodents
  -adaptive radiation is a type

Question 23

What is adaptive radiation?

Answer 23

-type of divergent evolution
-diversification of 1 species into many closely related species over a short time to fill different ecological niches
- e.g. Darwins finches of the Galápagos Islands

Question 24

What is convergent evolution?

Answer 24

• a pattern of speciation
• the evolution of similar traits in distantly related species
• natural selection favours evolution of similar adaptations in similar environments
• e.g. sharks and dolphins

Question 25

What is coevolution?

Answer 25

-process by which 1 species evolves in response to the evolutionary changes of another • 1 or both species may become increasingly dependent on the other • therefore, a threat to 1 species might be a threat to the other -4 examples

Question 26

What are the 4 examples of convolution?

Answer 26

1. Poison-arrow frog 2. Flowering plants & pollinators 3. Plants & herbivorous insects 4. Mimicry

Question 27

Poison-arrrow frog

Answer 27

-Warning colouration adaptation in the poison-arrow frog and avoidance behaviour of predators Example of coevolution

Question 28

Flowering plants & pollinators

Answer 28

-have symbiotic relationship → both organisms benefit - pollinator (insect) gets nectar, while plant gets its pollen spread • e.g. hawk moth and Madagascar orchid Example of coevolution

Question 29

Plants & Herbivorous insects

Answer 29

- plants have evolved toxic chemicals to prevent plant-eating insects from feeding on them -natural selection has favoured any variation in insect populations that inactivate or eliminate these poisons -e.g monarch caterpillar Example of coevolution

Question 30

Mimicry

Answer 30

- one species (mimic) resembles another species (model) in order to gain same survival advantage -occurs when evolution of 1 species affects the evolution of another, but NOT v/v -e.g hoverfly and wasp -e.g viceroy and monarch butterflies Example of coevolution

Question 31

What happens in evolution of complex features?

Answer 31

-occurs via *cumulative selection* → evolution of a simple structure into a more complex structure through a series of small adaptations • results in significant and new adaptations that increases chances of survival • e.g. evolution of complex eye

Question 32

What is cumulative selection?

Answer 32

Evolution of a simple structure into a more complex structure through a series of small adaptations

Question 33

What is Phylogeny?

Answer 33

- The study of the evolutionary development of a species

Question 34

What is a phylogenic tree?

Answer 34

-shows evolutionary relationships between different species - created by comparing anatomy, homologous structures, and similarities in DNA and proteins - contains evolutionary branches → called *clades* -backed up by molecular evidence

Question 35

What is a branch point(clade)?

Answer 35

Point where two species diverged from a common ancestor

Question 36

What is cladistics?

Answer 36

- the process of determining the arrangement of branches in a phylogenetic tree - organisms of a clade share homologous structures and similar DNA

Question 37

What is a Cladogram

Answer 37

- *hypothetical* picture of the actual evolutionary history of organisms

Question 38

What is a synapomorphy?

Answer 38

A trait shared between two or more groups