Evolution - Development of the Theory

Question 1

How is evolution measured?

Answer 1

It is measured at the population level

Question 2

What is evolution?

Answer 2

Its a descent with modifications or noticing changes in allele frequencies overtime

Question 3

What did Darwin based his theory of natural selection on?

Answer 3

He based his theories on 1. Over reproduction , 2. Individual variation

Question 4

What is Over reproduction?

Answer 4

When there is an excessive number of off-springs which led to struggles of existence

Question 5

What is individual variation?

Answer 5

When you notice different things in different organisms and notice that all organisms had so much variation and that they are heritable.

Question 6

Define heritable?

Answer 6

When genes are passed from one generation to the next

Question 7

What is modern synthesis?

Answer 7

Fusion of genetics with evolutionary biology (when your interacting genetics with evolution)

Question 8

What are the essentials of evolution?

Answer 8

All organisms vary genetically within a population so if a trait is not heritable than natural selection will not act upon that variation
Traits must also be heritable
Favourable traits with allow organisms to survive and reproduce to pass their genes on to the next generation
Major change in evolution normally takes long periods of times

Question 9

What does misconception of evolution mean?

Answer 9

Its essentially what people think evolution is, but really its not always true

Question 10

Evolution of theory is about the origin of life (miscon)

Answer 10

Evolution mainly focuses on how life changes after its origin and how life branches our and diversify

Question 11

Organisms are always getting better (miscon)

Answer 11

The idea of evolution is not about organisms reaching up to the very top of perfection. NS will just simply weed out individuals who seem to be unfit for a particular environment.

Question 12

Evolution is NS (miscon)

Answer 12

Evolution is not the same as NS, NS is the mechanism focused on surviving on a specific environment

Question 13

Evolution means life chaned by “chance” (miscon)

Answer 13

NS is not random. Mutations is the ultimate source for genetic variation that selection will act upon however, NS itself will simply choose which variant is most fit for the environment so it wont pick by choice. However the idea of mutation may be random

Question 14

Organisms “try” to adapt (miscon)

Answer 14

Organisms do not try to adapt however NS leads to adaptation but the process itself does not involve “trying”

Question 15

NS gives organisms what they need (miscon)

Answer 15

NS does not ever know what a species need they do not have senses. If a population happens to have genetic variation which will allow some to survive better than others, then those individuals will leave behind off-springs which will allow the population to evolve.

Question 16

Selection acts for the “good of species” (miscon)

Answer 16

Selection happens to individuals, not species. The idea of Altruistic is sometimes believed that NS promotes this behaviour, but that’s not true. NS will simply choose individuals from a population they believe is the most fit. The reason why altruistic may happen could be because they will get repaid for that act and that behaviour can be favoured by NS. Kin selection is also involved in this.

Question 17

What is kin selection?

Answer 17

When genes are being passed on whether its directly or indirectly by saving your relatives and warning them of predators so they are able to survive and reproduce

Question 18

Evolution occurs slowly (miscon)

Answer 18

Not necessarily true it can actually occur rapidly depending on factors

Question 19

Selection acts on individuals (miscon)

Answer 19

Does not act on individuals but the change is acted upon population. So you won’t notice evolution in your own lifetime but can be recognized in then entire population

Question 20

NS is not directed (miscon)

Answer 20

Based on the environment the organisms is living in

Question 21

Evolution by natural selection is a random process (miscon)

Answer 21

Mutations themselves might occur randomly in a genome but the natural selection is not random. It selects individuals in a population with a certain trait

Question 22

Traits arise in response to a change in the environment (miscon)

Answer 22

If a certain mutation arises and is promoted, NS will act upon it

Question 23

Selection acts on the genotype because that is what is inherited (miscon)

Answer 23

Selection acts upon the phenotype but phenotype is based on the genotype, so responding change will occur in the genotype

Question 24

Humans have stopped evolving (miscon)

Answer 24

No we did not stop evolving.

Question 25

Define Natural selection

Answer 25

The process by which random evolutionary changes are selected for by nature is a consistent, non-random , orderly way

Question 26

Evidence regarding evolution

Answer 26

There has been debates about how evolution took place, there has been gaps in fossil records which may indicate evolution, Evolution is constantly being refined, Darwinism’s rejection, all his ideas worked under NS even though he had no idea about it

Question 27

What is adaptation?

Answer 27

It is a trait or characteristic of an organism that increases its fitness relative to individuals without the trait

Question 28

What is fitness?

Answer 28

The ability of an individual to survive and reproduce in it’s enviornement

Question 29

What are Darwin’s 4 Postulates?

Answer 29

1. Individuals within populations are variable (because of mutations, shuffling alleles, new combinations, individuals within populations are variable for many traits)
2. The variations among individuals are, at least, in part, passed from parents to offsprings ( individuals pass their alleles on to their offspring intact)
3. In every generation, some individuals are more successful at surviving and reproducing than others
4. Survival and reproduction of individuals is not random (the individuals that survive and reproduce are those with the alleles that best adapt them to their environment)

Question 30

Modern Synthesis

Answer 30

Integrating genetics with Darwin’s 4 postulates-
So gradual evolution results from small genetics changes that are acted upon NS, but he did not know what genetic was
The origin of species and higher taxa (macroevolution) can be explained in terms of NS acting upon individuals (microevolution)
You can have very small phenotypic changes lead up to larger ones

Question 31

What are the road blocks for evolution?

Answer 31

Would ask questions like; How was variability generated in populations? Did not understand how phenotypes were essentials to reproductive success
How were “variations” passed onto the offspring? ; Did not know how genetics worked and how variations passed on
Age of earth; They assumed earth was only a few thousands years old but then with the “Lord Kelvin” calculations, it showed up that the earth was a lot older than we thought

Question 32

What was Darwin’s finches case study?

Answer 32

Darwin would travel around and he started studying Finches. They were a collection of birds who derived from Central or South American common ancestors. He noticed different variation in beak sizes and decided to analyze and study what gene was responsible for variation in beaks.

Question 33

What gene was responsible for variation in beaks of Finches?

Answer 33

(BMP4) Bone Morphogenic Protein 4

Question 34

What did larger beaks signify?

Answer 34

More expression of BMP4

Question 35

What did smaller beaks signify?

Answer 35

Less expression of BMP4

Question 36

Analysis of graphs based on beak size

Answer 36

So in a graph, if you noticed a bunch of markers clustered together, that signify that genetics was relatively strong. If we noticed the markers spread all across the graph, that signifies that the environment is more important and that genetics was not that strong.

Question 37

1976 and 1978 survival rate of finches

Answer 37

In 1976 there was 751 finches. Only 90 out of those 751 survived by 1978. The other 85% did not survive. They noticed the 90 who did survive had an average beak size of 10mm. So the survival and reproduction was not random, it was based on the fittest finches.

Question 38

Did the finches evolved from 1976 and 1978?

Answer 38

Yes the Finches did evolved. In 1976, the average beak size of the finches was about 8.8mm while by 1978, the average beak size was 9.8mm/10.0mm. That means the average phenotype in the offspring did evolve.

Question 39

Was there variations on survival and reproduction for the finches?

Answer 39

Essentially, the variation of survival and reproduction was literally all based on what the environment provided. If it provided a lot of nutrients, food, water, then Finches would be able to survive and later on reproduce.

Question 40

Explain how NS is not forward looking and how it is not random?

Answer 40

NS does not have end end game. As new generation arises and genetic variability has been expressed, NS will act upon the most fit in that specific population and generation. Selection is always evolving with the environment so it is always going to be based on the current environment. Because some generations may still be adapted to previous environments that is not fit for their CURRENT environment. NS is random, the mutations affecting genotype may be, which may express phenotype differently and NS will act upon that but NS in general is never random. NS is also NOT progressive. Newer and newer generations are not always going to be considered better than their previous generations. The population may cope better with their new environment but they are not exactly considered a better fit generation.

Question 41

Explain how fitness is not circular?

Answer 41

Fitness will vary within time. What was considered fit last generation may not be considered fit this generation

Question 42

Explain how selection acts upon individuals

Answer 42

Selection will act about phenotype which is partially by the genotype. Before selection the average beak size was from smaller to bigger, then when the smaller beak birds die, it was based on larger beaks and then the average beak size on the next generation was just slightly bigger

Question 43

Explain how NS is not “perfect”

Answer 43

• Always tradeoffs
• Fish with better reproductive system, swim slower = caught by predators
• Fish was smaller reproductive system, swim faster = escapes predators

There is always a trade off between sexual and reproductive selection you will rarely get that perfect generation that has both