LECTURE 11: EVOLUTION OF COMPLEXITY

Question 1

Lamarck

Answer 1

Individuals have an inherent tendency toward greater complexity

Question 2

Evolution of Complexity Involves Cooperation of Previously Independent Individuals

Answer 2

• The cooperation of previously independent organisms enables them to channel the energy they are using toward a greater complexity

Question 3

The Evolution of Eukaryotes

Answer 3

• A prokaryotic cell underwent an endosymbiotic event in which it took in mitochondria and chloroplast
• Started reproducing these organelles with their own genomes
• All organisms that undergo photosynthesis have the chloroplast

Question 4

What is the Unit of Selection? (GENE)

Answer 4

• Phenotypes that organisms have been selected upon due to their positive effects on the viability and reproduction of the individual
• The phenotype is encoded for my specific alleles that are used to improve the fitness of the organism
• This does not mean, though, that having this gene will benefit the species as a whole but can rather just improve the fitness of the individual

Question 5

When is cooperation adaptive? High relatedness

Answer 5

• Genes that lead to helping relatives via natural selection
• If a sacrifice myself for my brother and sister, there is still a good chance that our genes will be able to make it to future generations

Question 6

When is cooperation adaptive? Reciprocal altruism

Answer 6

• When individuals continuously meet each other and help each other out, they establish a beneficial cycle
• be wary of cheaters

Question 7

Cheater

Answer 7

an individual that receives help from another individual without reciprocating the same gesture

Question 8

Gene is the Unit of Selection

Answer 8

Gene is the unit of inheritance and thus it is the unit of selection
- having ideal genes that improve the fitness of the individual is what enables natural selection to favor the individual

Question 9

Selection of Individuals is a Form of Cooperation

Answer 9

• Natural selection acting upon an individual is a form of cooperation because our genomes are made of genes and alleles from different places - our mom and our dad
• natural selection aims to keep the genes that are good for us while getting rid of the genes that are bad for us
• random mating, independent assortment, and mutation want to make these genes persist randomly, however, natural selection ensures that these genes persist due to their effect on the fitness of the individuals

Question 10

How do genes stay cooperative? Mitosis and Meiosis

Answer 10

• Mitosis and meiosis prevent competition between the cells of our body.
  prevents the left leg from competing with the right

Question 11

How do genes stay cooperative? Development and Multicellularity

Answer 11

• Having genes stem from one place ensures that there is no competition when the individual is beginning to grow and develop
• all the cells in the body come from the same common ancestor and thus do not compete with each other

Question 12

How do genes stay cooperative? Uniparental Inheritance of Organelles

Answer 12

• Mitochondria and chloroplasts are inherited from maternal cells
• without having to regard the paternal ones, it eliminates the competition between which proliferate best through the body, etc.

Question 13

How do genes stay cooperative? Fair Meiosis

Answer 13

Segregation in meiosis helps to ensure that there is the fair transmission of alleles in the future generations and that beneficial alleles are kept and harmful alleles are eliminated

Question 14

To what extent does meiosis stay cooperative? Meiotic Drive

Answer 14

• Transmission bias in the direction of one allele regardless of its effect on fitness
• can increase the frequency of deleterious alleles and thus have detrimental effects on the species as a whole
  RESTORER ALLELES help to control the proliferation of this unfair transmission

Question 15

To what extent does meiosis stay cooperative? Transposable elements

Answer 15

There is an over replication of selfish alleles that duplicate themselves within a chromosome and then insert them elsewhere within the genome. There is an abundance of the number of selfish elements present in the genome

Question 16

How do we control selfish genes?

Answer 16

1. Host Silencing mechanisms: DNA methylation and RNA interference help to prevent the over-proliferation of these elements in the genome
2. Transposon-Selection Balance: There is an overabundance in transposable elements in the genome. If it inserts itself in an essential gene and has detrimental effects on the organisms, natural selection ensure that the element does not make an appearance in future generations

Question 17

Mitochondrial Transmission

Answer 17

Without the presence of mitosis and meiosis in these organelles, there is the increase in the opportunity for the spread of selfish elements

Question 18

How do mitochondria stay cooperative?

Answer 18

Uniparental Inheritance of Organelles: males do not have to compete for females which ensure that there is the absence of competition between these cells in the zygote and individual

Question 19

New conflict because of mitochondria?

Answer 19

• since maternal mitochondria is the one that is transmitted to future generations, mutations are more common in order to maximize the fitness of the female even if it is at the expense of the male

Question 20

Cytoplasmic Sterility in Plants

Answer 20

In hermaphroditic plants, females are preferred due to the fact that they transmit the mitochondria. These mutations can cause the males of the plant to become sterile which decreases the fitness of the males and can even decrease the fitness of the plant

Question 21

How do collections of cells stay cooperative?

Answer 21

1. Mitosis and Mitochondria
2. Cell lineages that spread through the body are controlled by meiosis and thus do not spread to future generations
3. tumor suppressors are designed in order to combat the transmission of these cell lineages and regulate their growth and transmission

Question 22

Cancer: Cell Lineages

Answer 22

• Cancers are cell lineages that are selfish in the sense that the develop and proliferate at the expense of other cells and at the expense of the individuals
• They also evolve resistances to chemotherapies and our immune systems

Question 23

How do genomes stay cooperative?

Answer 23

• There is no competition between cells of an individual
• Genes succeed if they are good for fitness
• We have a lot of methods in order to combat things that are not good for the individual (restorer alleles, host silencing mechanisms, etc.)