Lecture 4 - Competition

Question 1

What causes the difference in reproductive success?

Answer 1

Something in the environment - we say sandy grounds ‘selects for’ being yellow

Question 2

What were the general principles of Malthus’ essay? (2)

Answer 2

1. Populations could potentially grow exponentially, but in practice cannot do so
2. Therefore, populations must by limited by incomplete survival and reproduction

Question 3

What is an example of competition in black and yellow cats?

Answer 3

90 black cats and 10 yellow cats - both have 50% chance to survive.

Now yellow has 51% chance to survive and reproduce, now that yellow have an advantage (in sandy env) so less likely to be killed by predators.

Question 4

What is important to note about the cats example?

Answer 4

• The environmental conditions did not cause the yellow mutation to come about; the environment selects from a reservoir of variation that happens to be in the population
• Individuals do not change colour over their lifetimes
• Black-coloured parents still have black-coloured offspring
• The proportion of cats descended from yellow-coloured parents gradually rises

Question 5

An allele that confers a selective advantage increases in frequency relative to the alternative allele, at what time frequency?

Answer 5

More quickly if it is dominant
more slowly if it recessive

Question 6

What is reproductive success?

Answer 6

The number of descendants an individual leaves

Question 7

Define fitness

Answer 7

strictly a property of an allele, change in frequency of an allele over generations determines fitness

Question 8

The fitness of an allele is dependant on?

Answer 8

the average reproductive success of all the individuals it appears in

Question 9

What determines whether something could evolve?

Answer 9

Whether the alleles coding for it have high fitness or not

Question 10

What is the evolutionarily stable strategy (ESS)?

Answer 10

A behaviour that is once common in a population, it cannot be competed by any alternative behaviour

Once selection finds an ESS, it keeps the close to that point - sort of plateaus

Question 11

Do individuals in the population reproduce to their max potential capacity?

Answer 11

No - there is differential reproductive success, and phenotypic characteristics affecting reproductive success

Question 12

Who is the main person looking at kin selection?

Answer 12

Hamilton - Hamilton’s rule

Question 13

What is Hamilton’s formula?

Answer 13

A behaviour can evolve if on average

c < rb

c = cost
b = benefit
r = relatedness

Question 14

What are applications of kin selection?

Answer 14

Hamilton’s rule has wide applicably - it can be used to understand why and to what extent adults invest in their children/grandchildren

Question 15

What is the study of alarm calling in prairie dogs (Hoogland,1983)?

Answer 15

Hoogland found that prairie dogs were more likely to give alarm calls when close relatives were nearby. This supports kin selection theory, as warning relatives of danger helps pass on shared genes, even at personal risk.

Question 16

What phenomena’s do kin selection explain?

Answer 16

Alloparenting
Kin directed helping
Multicellularity
Eusociality

Question 17

Applications of kin selection at the cellular level

Answer 17

Most body cells (somatic cells) do not reproduce themselves but support the reproductive cells (sperm and egg), which pass on genes. This reflects kin selection: somatic cells “sacrifice” themselves to help related germ cells succeed, enhancing the organism’s inclusive fitnes

Question 18

Applications of kin selection of eusociality

Answer 18

Whole colony of individuals to further the reproduction of one, e.g. the queen bee

Question 19

What are evolutionary transitions?

Answer 19

Points in history of life where several previously pre-living elements come together and start to operate as a collective

Each of these points holds a major evolution transitions, where new bio organisms form.

Question 20

What is intragenomic conflict?

Answer 20

Arises whenever genes favour their own interests above the whole

Question 21

Explain segregation disorders in mice

Answer 21

Abnormal allele distribution during meiosis in mice.

• t haplotype allele present in most males and disables most non t sperm
• harmful to mice as homozygote is lethal in males

Question 22

How is the history of life defined?

Answer 22

Series of transitions where previously competing entities form collectives in which they cooperate

Question 23

covariance

Answer 23

when you do well, your genes do well - strong positive link between how successful phenotype is and how many copies your genes make

Question 24

alloparenting

Answer 24

Investment in siblings’ offspring or younger siblings instead of self-reproduction.

Question 25

what kind of process is competition?

Answer 25

Competition is a multiplicative process because small differences in success lead to exponentially larger outcomes over time, especially in evolution where advantages compound across generations.

Question 26

kin-directed helping

Answer 26

Assisting relatives at personal cost for mutual benefit.

Question 27

Cytoplasmic Male Sterility

Answer 27

Maternal mitochondrial DNA suppresses male gamete production. So only female gametes produced= lower overall reproductive success

Question 28

intraspecific vs interspecific competition

Answer 28

Intraspecific competition: Competition within the same species (e.g., for mates or food). Interspecific competition: Competition between different species (e.g., for shared ecological niches)

Question 28

collective cooperation

Answer 28

transition from competition to cooperation entities in evolution