Introduction to Evolution: Selection

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  • Created by: KayshaN
  • Created on: 04-11-19 21:12
Mean phenotype is the fittest, fitness depends on where phenotype fits...
Stabilising Selection
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Fitter at one of the extremes of the mean, artificial selection- fishing nets, let smaller fish through
Directional Selection
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Fitter at the two extremes, mean less fit
Disruptive Selection
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How is variation maintained? (5)
1)diff selection in diff areas 2)heterozygote is fitter 3)fitness increases if you are rarer 4)immigration 5)mutation
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What are the 3 things a group needs to do to be selected?
1)assesment of food avalibilty 2)communication to others in the group 3)restricition of reproduction
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Group Selection is?
Weak
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What does the 50% cost of males mean in sexual reproduction?
population grow slower because need 1 male per female whereas asexual no need
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What is the Red Queen Hypothesis?
allows you to shuffle pack and bring combonation into contact more quicky than asexual
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Pros of Sexual Reproduction...
elimination of bad mutations, favourable combonations, faster evolution
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Cons of Sexual Reproduction...
50% male cost dont reproduce, recombination breaks up favourable combos, mating is risky
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What is inclusive fitness?
organisms genetic sucess based on alturistic behaviour
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What is alturism?
'apparant' cooperation, carrying for copies of ones genes e.g. ants, bees
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Two types of Kin Recognition?
1)Direct= visual, chemical, vocal cues Indirect= you're near me, you're probably related
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Sexual Selection example, male peacock
enourmous tail, highly coloured, but females prefer longer tails
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Define adaptation.
characteristics that increase fitness, depends on environment
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Outline the following constraint on adaptations: Consequence of Construction
an adaptation may not effect function, sandrels
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Outline the following constraint on adaptations: Physical/Chemical Constraints
e.g. need bigger legs to support biger body, cant have thin legged elephant
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Outline the following constraint on adaptations: Histroical Constraints
environment changes, after time not fitness anymore
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Outline the following constraint on adaptations: Time Lag
not suited to environement not e.g. dodo bird and seeds
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Outline the following constraint on adaptations: Genetic Constraint
mutations, drive of mutations
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Outline the following constraint on adaptations: Trade of Compromise
need to find mate, colour, sexual selection but also need to think about predators e.g. waterboatman
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Describe the uneasy alliance between males and females.
Both pass on 50% of genes to offspring but each want maximise own fitness
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What is sexual selection?
a specific form of natural selection
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Define Intrasexual Selection
Members of one sex compete e.g. male to male
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Define Intersexual Selection
Individual from one sex choose members from other sex to mate with
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Outline Bateman's Principle.
Males fundamentally promiscuous, Females fundmentally selective beacuse females few large gametes and males have many small gametes
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What are secondary sexual characteristics? Outline examples of both direct and indirect.
Features not directly linked to reproductive system. Direct= weapons, size Indirect= ornaments, peacocks tail
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Outline the 3 defensive and 1 offensive tactics of Sperm Competition
Defensive: mate guarding, mating plugs (secretions harden), toxic seminal substances antiaprodisiac Offensive: physical removal of sperm
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Define Cuckoldry
males who unintetionally invest parental effort into offspring that are not their own.
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Why is female mate choice so important?
more to lose, need to make their choice carefully
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What are the four classes of evolutionary models in sexual selection?
1) Direct benefit- food, shelter 2)Good Genes-favourable traits 3)Runaway Sexual Selection-evolution exaggeragerated male ornamentation 4) Sensory Exploitation-pref male traits that elict neurobiological response e.g. red in primates
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Outline Polyandry
1 female, many males! genetic benefits, good gene hyp, material
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Outline Monogamy
1 female, 1 male! shared parental care, reduced genetic variety
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Outline Polygynandry
many feamles, many males! no pair bonds, some choice, more likely in unpredictable environment
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Outline Polygyny
1 male, many feamles! increase reproducitve fitness, best territory, females attracted
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Define Lecks
Males come together to hold territory
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Define Harems
Defended group of males associated with one male e.g.gorillas
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What are the advantages and disadvantages of choosing a mate when in a group?
Pros: less energy, choice, more than one, mate sampling Cons: male-male comp, control by dominace, inbreeding
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Other cards in this set

Card 2

Front

Fitter at one of the extremes of the mean, artificial selection- fishing nets, let smaller fish through

Back

Directional Selection

Card 3

Front

Fitter at the two extremes, mean less fit

Back

Preview of the front of card 3

Card 4

Front

How is variation maintained? (5)

Back

Preview of the front of card 4

Card 5

Front

What are the 3 things a group needs to do to be selected?

Back

Preview of the front of card 5
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