Final

Question 1

Three properties of natural selection

Answer 1

Variation
Heritable - some variation is heritable
Fitness- individuals with some trait have a better chance of surviving to reproduce or leave more offspring.

Question 2

What is good evidence for ongoing selection?

Answer 2

• there is variation
• variation is heritable
• the trait affects function related to the proposed selective mechanism
• there are measurable effects of the triat on survival or reproduction

Question 3

ancestral constraints

Answer 3

traits inherited from an ancesor that are difficult to change and which are suboptimal o limit subsequent adaption

Question 4

Why didn’t selection improve longevity? - Senescence theory

Answer 4

If extrinsic damage tended to kill ancestors when they were old, then intrinsic damage will have evolved to kill you when you are old also, even if you are now protected from extrinsic damage.

Question 5

Two main theories of why we have alleles that make us senesce

Answer 5

Mutation accumulation theory - Random effects
- Late acting mutations can accumulate: they are not selected against because individuals rarely live that long, and therefore there is almost no loss of reproduction

and

Antagonistic pleiotropy theory - Trade- offs
- deleterious mutations that act in old age were selected for because of their beneficial effects earlier in life.

Question 6

Why are females choosier than males in selecting mates

Answer 6

they have more at stake in each mating
- the consequences are hirgher iwth alot more investment
- they also dont compete as much so they can afford to say no

Question 7

intrasexual selection

Answer 7

males compete amongst each another and females mate with the winner

Question 8

intersexual selection

Answer 8

females choose among males according to their qualities

Question 9

honest indicator

Answer 9

if any male can make a trait its not an honest indicator o quality. females should be selected o pay attention only to honest indicators
□ if indicator is costly then only the best males can make it and therefore it will be an honest indicator

Question 10

Sensory bias

Answer 10

females have bodies and nervous systems that are strongly selected in context o finding food, avoiding predators etc and its those systems that males have to “please”
□ ex: guppies with orange attract females as orange pigment comes rom their food and thus females are attuned to seeing orange

Question 11

the mechanism of runaway sexual selection

Answer 11

1. Start: there is variability in male trait & female preference for it. Non-choosy females are agnostic.
2. Agnostic females mate indiscriminately; choosy females mate more with males with the trait, and therefore raise its frequency and generate linkage disequilibrium that associates the ♂ trait and ♀ preference.
3. With each subsequent generation, the linkage disequilibrium gets stronger, the average preference of females increases, and the male trait increases in frequency.

Question 12

homoplasy

Answer 12

convergence or reversal. Often used when talking about misleading traits when reconstructing phylogeny; “extra” steps in evolution

Question 13

adaptive radiation

Answer 13

rapid increase in the number of species with a common ancestor, characterized by great ecological and morphological diversity

Question 14

transposable elements

Answer 14

known as “jumping genes”, are sequences of DNA that move from one location in the genome to another

Question 15

complete coalescence

Answer 15

to unite into a whole

Question 16

pleiotropy

Answer 16

a sing gen having more than one effect

Question 17

The negative Epistasis Hypothesis

Answer 17

selection generates negative genetic association among alleles such that favourable alleles can be found on the same chromosome as unfacourable alleles. Sex and recombination acts to break up these genetic association so the favourable alleles can be on chromosomes wiht ontehr favourable alleles and then get selected for

Question 18

The Red Queeen Hypothesis

Answer 18

condition/interaction with species are constantly changing resulting in changes in the selective pressures. Sex and recombination allows new allele combination to arise rapidly and these allele combinations can then be selected on

Question 19

Selective interference hypothesis

Answer 19

new facourable alleles are just as likely to find themselves on chromosomes wiht other beneficial allesles as they are to find themselves on chromosomes with ungavourable alleles, when thsi happens, sex and recombination is necessary to break up the new benificial alleles and the unfacourable alleles so the new beneficial ones can be selected for