GED More Evidence for Natural Selection

Question 1

Define BIOGEOGRAPHY

Answer 1

Distribution of species around the world

Question 2

How can Marsupials be found in America and Australia which are so far apart and divided by the sea suggesting that marsupials could not have swimmed there?

Answer 2

-This is bacause of the Pangea
-All land was unified
-65 millions years ago you could WALK from South America to Antartica and then AUSTRALIA

Question 3

How is it possible finding MARSUPIALS fossils in antartica?

Answer 3

-It is possible as marsupials which arised in South America 80 mya, slowly moved through the land and dispersed into Antarrtica and eventually Australia as the land was UNIFIED

Question 4

Define CONVERGENT EVOLUTION

Answer 4

UNRELATED/ Distanly related species show similar adaptation due to similar selection pressures but with often DIFFERENT GENETIC FACTORS

Question 5

If two species that showed convergent evolution had a ancestorial track-back would they share the same common ancestors?

Answer 5

No. Converging species adapt to environment but they might/or often come from very different evolutionary routes

Question 6

Name some species that show convergent evolution:

Answer 6

North American Porcupine and Crested Porcupine
- Last ancestor 45 Mya!
- Branched off into many different mammals
- But found the same SOLUTION/ADAPTATION
- Use hairs as quill and they live countries apart

Cactus USA and Euphorbia South Africa (lil bush type of cactus)
- Desertic plants
- Adapted to arid conditions in similar way (small leaves, spines to protect from herbivores, fleshy stems to store water)

Question 7

What does the tree lineage show?
For example, a strawberry (FRUIT) and nettle (PLANT) common ancestor is a TREE
whereas
the common ancestor of a maple TREE and mulberry TREE is not a tree.

Answer 7

This shows how due to EVOLUTION and adaptation species change and adapt to different selections or similar selections ending up being very different or very similar when the common ancestors are not very similar.

Question 8

What is CARCINISATION?

Answer 8

Tendency to turn into crab
Ecological reason poorly understood
Most likely beneficial, increases survival

Question 9

Give an overview of the Peppered Moths and natural selection in Manchester.

Answer 9

Peppered moths turned from white to black
-Due to industrial pollution trees/houses started turning black/darker
-Selection pressure was acting
-Moths overtime changed colour from white to black to CAMOUFLAGE better hence increasing survival

Question 10

Who caused the selection pressure for Peppered moths in Manchester?

Answer 10

Humans

Question 11

Give 2 examples where humans caused selection pressures.

Answer 11

• Green bulbs in china (bulbs turned grey to camouflage with rocky grey environment)
• Tuskless Elephants (tuskless less likely to be poached)

Question 12

What is a main difference between evolution ands Natural selection?

Answer 12

• Evolution is shown in ‘next’/ offspring generation
• Natural selection can act on the present population for example the Lizards in a hurricane EVOLUTION act on the future

Question 13

What did the Lizard in a hurricane highlight?

Answer 13

• Lizard were measured/studied before hurricane Irma hit
• Hurricane Irma hit
• Lizard population studied again, average lizard had now longer arms, bigger toepad etc.
• Natural selection acted on these but this was NOT evolution as evolution is change in allele frequencies in a pop, this was just a change in current lizard pop demographics
• Evolution was strongly suggested by the offspring of these surviving lizard with offspring having bigger toe pads, longer arms/…

Question 14

What carries the GENETIC code in all organisms?

Answer 14

DNA

Question 15

2 characteristics of Molecular genetics

Answer 15

-DNA is the sole and UNIVERSAL carrier of the genetic code
- Genetic Code is universal - all organisms contain the same cellular machinery for decoding and copying genetic information

Question 16

What does the code be universal suggest?

Answer 16

Shows existence of a common ancestor for all creatures (LUCA)

Question 17

How does the molecular clock work?

Answer 17

• Tracks evolution by comparison of DNA sequences bw species (obviously comparing the same proteins)
• difference in DNA sequence indicate how different the species are

Question 18

What does the amount of difference between gene sequences indicate?

Answer 18

• Indicates relatedness
  if two gene have many differences less closely related
  if gene has few differences - more closely related

Question 19

What does the molecular clock use to compare species?

Answer 19

Proteins, genes in the same protein( e.g Haemoglobin) in different organism

Question 20

Do the molecular clock correlate to anything?

Answer 20

It correlates to fossil data record

Question 21

Do genetic differences (using molecular clock) have a rate?

Answer 21

Genetic differences accumulate at Constant rate
As time passes more genetic differences

Question 22

What causes genetic differences between species? (2)

Answer 22

• Mutations
• Errors in egg and sperm cells

Question 23

Evolutionary tree of Cytochrome C gene closely correlates with morphological tree, why is this important?

Answer 23

• It shows evolution by natural selection
• This is because Cytochrome tree closely resemble the predicted morphological tree INSTEAD of showing random correlation
• This is proved by number of differences in base of DNA sequence
  (Look at notes if confused)

Question 24

A hippo is more correlated to a WHALE than to a rhino, how is this possible and why it is important?

Answer 24

• This is due to EVOLUTION
• Whale’s ancestors terrestrials which moved in waters slowly losing limbs and ect.
• Whereas hippo branched into terrestrial environment
  (Another proof of natural selection and evolution, as ancestor adapted to water leading to whales)

Question 25

Why do whales have majority of the olfactory gene disactivated? How does it show natural selection?

Answer 25

• Whales descends from terrestrial that slowly moved into water
• Olfactory system less used in water BECAUSE whales use nose to breathe
• Nose to breathe is used only up in the air out of the ocean
• So inside water nose is not used, hence less olfactory system used
• Unlike other fish which have gills to respire they can use nose so have a good olfactory system
• So ability to smell lost over time in whales
• Natural selection acting

Question 26

Why do whales have 68% of olfactory genes disactivated whereas a dog only 17%?

Answer 26

• Natural selection
• Whale does not use nose a lot, sense of smell lost over time
• Dog uses sense of smell more hence genes are more active

Question 27

How did LACTASE arise?

Answer 27

• People were having milk way before lactose gene, MILK drinking selection pressure led to development of Lactose gene

Question 28

How could the lactose GENE have been advantageous in the past?

Answer 28

• FAMINE occurred in the past
• Lack of LACTASE gene means people cannot have milk products
• Less food for these individual = less likely to survive
• Whereas those with lactase gene, can have lactose more likely to survive and pass on the genes
• Natural, evolution by Natural selection

Question 29

Why can NOT all genetic sequence changes by natural selection be identified?

Answer 29

• This is explained by NEUTRAL theory
• Not all mutation CHANGE the amino acid produced as DNA is degenerate

Question 30

Which part of DNA would provide the best MOLECULAR CLOCKS?

Answer 30

• Noncoding regions
• As these regions are not seen by NATURAL selection
• Hence, they mutate only RANDOMLY and not due selection pressures factors