Lecture 4 - Competition Flashcards
What causes the difference in reproductive success?
Something in the environment - we say sandy grounds ‘selects for’ being yellow
What were the general principles of Malthus’ essay? (2)
- Populations could potentially grow exponentially, but in practice cannot do so
- Therefore, populations must by limited by incomplete survival and reproduction
What is an example of competition in black and yellow cats?
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.
What is important to note about the cats example?
- 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
An allele that confers a selective advantage increases in frequency relative to the alternative allele, at what time frequency?
More quickly if it is dominant
more slowly if it recessive
What is reproductive success?
The number of descendants an individual leaves
Define fitness
strictly a property of an allele, change in frequency of an allele over generations determines fitness
The fitness of an allele is dependant on?
the average reproductive success of all the individuals it appears in
What determines whether something could evolve?
Whether the alleles coding for it have high fitness or not
What is the evolutionarily stable strategy (ESS)?
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
Do individuals in the population reproduce to their max potential capacity?
No - there is differential reproductive success, and phenotypic characteristics affecting reproductive success
Who is the main person looking at kin selection?
Hamilton - Hamilton’s rule
What is Hamilton’s formula?
A behaviour can evolve if on average
c < rb
c = cost
b = benefit
r = relatedness
What are applications of kin selection?
Hamilton’s rule has wide applicably - it can be used to understand why and to what extent adults invest in their children/grandchildren
What is the study of alarm calling in prairie dogs (Hoogland,1983)?
Survival represented by - amount of alarm calls the prairie dogs make in order to alarm others
Dogs with no kin present - calls lower frequency, but higher in males
Dogs with offspring present - highest, similar in both genders
Dogs with siblings present - just less that offspring, similar in gender
What phenomena’s do kin selection explain?
Alloparenting
Kin directed helping
Multicellularity
Eusociality
Applications of kin selection at the cellular level
Most cells have no chance of reproducing in the body
Sperm and egg cells are the opposite, do absolutely nothing until required for reproduction and determine what goes onto the next generation
Applications of kin selection of eusociality
Whole colony of individuals to further the reproduction of one, e.g. the queen bee
What are evolutionary transitions?
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.
What is intragenomic conflict?
Arises whenever genes favour their own interests above the whole
Where are segregation distorters seen?
in mice
How is the history of life defined?
Series of transitions where previously competing entities form collectives in which they cooperate
What can selection favor in relation to higher-level collectives?
Adaptations for the good of higher-level collectives
This occurs when mechanisms abolish differentials in reproductive success among the collective’s constituent elements.
What must evolve for there to be a positive overall covariance between a collective’s functioning and the reproductive success of its elements?
Mechanisms that abolish differentials in reproductive success
These mechanisms ensure that the success of the collective aligns with the success of its individual components.
What are complex organisms considered in the context of selection and collectives?
Coalitions of different genes
They exemplify how selection can operate at higher levels than individual genes.
Is the covariance between the fitness of different genes within an organism always total?
No
This can lead to intra-genomic conflict where some genes benefit at the expense of the whole organism.
What does intra-genomic conflict result from?
The non-total covariance between fitness of different genes
This conflict can create patterns that favor certain genes over the organism as a whole.
