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Genes, Evolution and Development > Evolution Mathew Cobb II > Flashcards

Evolution Mathew Cobb II Flashcards

1
Q

Define fitness

A

This is a measure of which organisms survive and reproduce better.

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2
Q

Define darwinian fitness

A

This is a measure of the genetic contribution of an individual to the next generations gene pool,compared with the population average. Darwinian fitness is measured by the number of offspring/close kin that survive to reproductive age.

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3
Q

How is darwinian fitness measured

A

By counting the number of offspring produced that survive to reproductive age.

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4
Q

Explain the concept of heterozygote fitness, give an example

A

Situation where individuals with the heterozygous genotype are fitter/ healthier than homozygous genotypes. An example is sickle cell anaemia.

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5
Q

State the 5 different modes of selection

A

1) stabilizing selection
2) directional selection
3) Frequency dependent selection
4) Sexual selection
5) Natural selection

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6
Q

Explain stabilizing selection

A

Acts to decrease the genetic variation in a population

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7
Q

Explain directional selection

A

Mode of natural selection in which a single phenotype is favoured causing the allele frequency to continuously change

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8
Q

Explain diversifying selection

A

increases genetic variation when natural selection selects for two or more extreme phenotypes.

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9
Q

Summarize the selection debate

A

There is debate over who/what is selected. Individuals are selected, not species.

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10
Q

Define and explain kin selection

A

This is an evolutionary strategy that favours the reproductive success of an organisms relatives, at a cost to the organisms own survival and reproduction.

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11
Q

Define altruism

A

This is where an organism will do a behaviour that is at its own expense and of greater benefit to another (related) organism

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12
Q

Define Hamiltons’ Rule

A

rb > c

Relatedness x benefit must exceed the cost to the organism, for that organism to exhibit altruism.

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13
Q

State the criteria for altruism

A

Altruism is likely to take place between two individuals when the relatedness between two individuals is high, like in social insects such as bees and wasps.

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14
Q

What is haplodiploidy? How does it occur in Hymenoptera

A

In this system, the number of chromosome sets determines the sex. This is a sex determining system where males develop from unfertilized eggs and are haploid, and females are diploid. Males can only produce daughters upon fertilization with a queen bee. Males are 100 percent related to daughter, as daugher has all of the dads genes.

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15
Q

What are hymenoptera

A

Bees and wasps.

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16
Q

Summarize Eusociality in hymenoptera

A

In a eusocial colony with a single queen, wasps/bees/ants are more closely related to their sisters than to their offspring or mother. Two sisters are 0.75 related to eachother but a mother and daughter are only related by 0.5. This occurs because the male father passes on 100 percent of his genes to his daughters while a mother only passees on 50 percent.

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17
Q

Define eusociality

A

Mainly observed in hymenoptera.
Queens and reproductive males take the roles of the sole reproducers while workers work together to create a living situation favourable for the brood.

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18
Q

Define inclusive fitness

A

Inclusive fitness is where the survival of a closely related organism is

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19
Q

How much of the human genome codes for protein

A

only 3 percent

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20
Q

How much of the genome codes for regulatory genes

A

10 percent

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21
Q

How much of the genome is junk DNA

A

85 percent (has no effect on fitness if deleted)

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22
Q

Define and explain transposons

A

Known as jumpinh genes, these are sequences of DNA that can move around in the genome. They act as agents of evolution because their migration about the genome can produce mutations.

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23
Q

How do transposons give rise to new genes

A
  • There is a duplication event in a non coding sequence.
  • The duplicated sequence undergoes some base changes and is translocated to a promoter, and is then transcribed.
  • This results in the production of new neutral alleles or new gain of function mutation that is slightly advantageous.
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24
Q

Define and explain horizontal gene transfer

A

Occurs in prokaryotes
This is the movement of genetic material between unicellular organisms in the same generation.

There are 3 mechanisms for HGT,transformation, transduction and conjugation.

25
Q

Horizontal gene transfer has been cited as a driving force for evolution. True or false

A

True.

26
Q

By what percentage are the two human genomes different

A

0.1 percent. This is 3 million bases.

27
Q

State the challenges that horizontal gene transfer presents

A

A key question up for debate is how does horizontal gene transfer fit into the current neo darwinian evolutionary paradigm.

28
Q

when did modern humans appear in africa

A

300,000 years ago modern humans appeared in africa.

29
Q

How did humans leave africa

A

They walked at a rate of just 1km per year.

30
Q

List qualities charactaristic of humans

A

1) ability to co-operate
2) humans work together
3) humans are creative and produce art
4) ability to use tools
5) rapidly found ways of improving tools
6) virtually all the large animals went extinct wherever humans went
7) humans wiped out entire species and caused their extinction

31
Q

Explain the relationship between humans and denisovans

A

Denisovans were cousins of humans.

32
Q

State the assumptions of the hardy weinberg law

A
  • Random mating
  • no migration
  • no mutations
  • large population size
  • no selection pressures
33
Q

List the factors that lead to changes in allele and genotype frequencies

A
  • Genetic drift
  • Non random mating
  • mutations
  • natural selection
  • migration and gene flow
34
Q

State 4 mechanisms that preserve genetic variation in a population

A

Diploid factors of organisms

Balancing factors

Neutral alleles

Different selection pressures in different geographical environments

35
Q

Define sexual selection

A

This is a special form of selection, this is not natural selection, where individuals can have seemingly maladaptive characters, i.e that attract more predators, but are used to attract females.
Here, a selection pressure is created by one sex. Eg is male chimps looking more attractive to females if they groom others or share food.

36
Q

Does hamiltons rule only explain why altruism in haploidiploidy state?

A

NO!! This is just one example. Bill hamilton is trying to explain that altruism will often occur if relatedness is high, and the haplodiploidy sex determination system is one example of a system of where we have very related individuals.

37
Q

Explain the difference between darwinian fitness and inclusive fitness

A

Darwinian fitness = direct fitness of an organism, their own survival and reproduction and passing on their genes to their offspring.

Inclusive fitness is the direct fitness + fitness of closely related individuals.

38
Q

Do inclusive fitness and kin selection state the same thing??

A

Yes!! Kin selection is the same as inclusive fitness.

39
Q

Are all haplodiploid organisms social

A

No!! not all of them are social!! They are

40
Q

Can altruism occur in organisms that are not social? and in organisms that are not haplodiploidy?

A

Yes!!! • Hamilton’s rule is particularly likely to occur when relatedness between individuals is high, an example of this is in social insects!! Therefore social insects are simply just an example of this!!

41
Q

What are transposons

A

sequence of DNA that can move.

42
Q

How much of DNA is junk?

A

85 percent

43
Q

How much of our DNA is made up of repetetive elements

A

45 percent!! 10 percent is Alu

44
Q

Define transposon

A

jumping gene, mobile genetic element.

45
Q

What are retrotransposns

A

Remnants of viral infections. RNA viruses that inserts itself into the host cell that has hijaced the genome and inserted itself into host DNA But has got stuck! so we are walking around with a lot of dead viruses inside us.

46
Q

What is the role of transposons

A
  • agents of evolution - produce mutations
  • may also be involved in some cancers.
  • produce new genes due to gene duplication events, translocation and insertion into a promoter region
47
Q

all mamallian require protein syncitins

A

All the genes that encode

48
Q

How did the placenta arise?

A

Retrovirus inserted into genome, was captured and halted. Now it is an endogenous retrovirus. Was then co-opted to produce syncitins (protein required by placenta)

49
Q

What percentage of the cows genome is from snake?

A

25 percent of a cows genome is from a snake

50
Q

Are insects crusteceans??

A

Yes

51
Q

Explain why a cow is more closey related to a snake than to a sheep?

A

Due to ticks, that acted as a vector, transferring genes from the snake into the genome of the cow upon infection!!

52
Q

Cow sharing 25 percent of snakes genes is due to?

A

Horizontal gene transfer!

53
Q

On average how much do we differ from eachother

A

we differ from each other by 0.1 percent.

54
Q

How many mutations do we have that were not present in our parents

A

on average, 70 new nuclear mutations that were not present in parents.

55
Q

Are humans still evolving

A

YES!! 2 examples

56
Q

Give some examples of natural selection in humans

A

Skin color - melanin production is higher in sunnier regions- provides greater protection against UV radiation.
EPASI 1 gene allows greater oxygen concentration… in Tibetans
Lactose persistence
Protection against malaria

57
Q

Provide evidence for the fact that we all came from africa

A

We are all african origin because the richest genetic variation is found in africa. In any organism, you get the largest genetic variation in the ancestral region.

Heterozygosity (genetic variation) decreases with distance from East africa (walking distance) this is an example of genetic drift/

58
Q

Who left africa before us

A

The Neanderthals

59
Q

What is the relationship between neanderthals and humans

A

Neanderthals are the cousins of humans. We did not descend from neanderthals. We shared a common ancestor.

Genes, Evolution and Development (14 decks)

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