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Flashcards in Selection Deck (19)
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1
Q

what are the prerequisites for selection?

A

variation in fitness between phenotypes. variation needs genetic basis.

2
Q

describe selection

A
  • a non random process
  • acts of differences
  • leads to adaption
3
Q

what is adaptation?

A

consequence of selection. beneficial function becomes prominent

4
Q

what are some factors of fitness?

A

viability of zygotes. mating success of reproductive adults. fecundity of mating pairs. gamete compatibility

5
Q

what is absolute fitness (W)?

A

genotype specific rate of increase that predicts the absolute number of indiviuals

6
Q

what is relative fitness (w)?

A

fitness relative to one genotype, convention is that its relative to the fittest genotype

7
Q

what happens if selections is against recessive phenotype?

A

lower fitness compared to the dominant

8
Q

what is the selection coefficient (s)?

A

difference between relative fitness value and 1

9
Q

describe selection for a dominant advantageous allele

A
  • initially it can be selected for rapidly

- cannot be fixed by selection alone also genetic drift

10
Q

how are deleterious recessive alleles affected by selection?

A

cannot be selected against when its in the heterozygous form

11
Q

describe selection for advantageous recessive alleles

A
  • first in the form of heterozygotes
  • need a few homozygotes
  • low at firs tthen shoots up
  • at the same time selection against a dominant deleterious allele is very low
12
Q

what does the response to selection depend on?

A
  • allele frequencies (p and q)

- relative fitness of the genotypes

13
Q

what are the different factors of response to selection?

A

heritability. strength of selection. allele frequencies. dominance of the allele. population size

14
Q

what is directional selection?

A

one phenotype has a higher fitness - population moves towards this over time

15
Q

what is stabilizing selection?

A

population already at the optimum - intermediates have a higher fitness

16
Q

what is disruptive selection?

A

extreme phenotypes have a higher fitness level

17
Q

what is frequency dependent selection?

A

fitness can depend on other genotypes and is affected by a genotypes frequency in the environment. being rare is an advantage.

18
Q

what does frequency dependent selection lead to?

A

stable equilibrium

19
Q

if the absolute fitness is greater than one what is the result?

A

in the next generation there will be more of that particulr genotype