Lecture 7: Mechanisms and rates of speciation 2

Question 1

contributors to speciation:

Answer 1

• chance
• ecology
• reinforcement
• sexual selection

Question 2

sexual selection

Answer 2

the result of the differential reproductive success that arises from competition for mates and access to fertilisation

Question 3

sexual selections which involves natural selection

Answer 3

• direct benefits to females
• good genes hypothesis
• sensory bias

Question 4

sexual selection which don’t involve natural selection

Answer 4

• fisherian runaway selection

- chaseaway selection

Question 5

sexual selection favours

Answer 5

mate acquisition and fertilisation

Question 6

natural selection favours

Answer 6

survival and fecundity

Question 7

___ may build linkage disequilibrium more effectively

Answer 7

sexual selection

-non-random mating reduces recombination

Question 8

sexual selection can generate ___ isolation

Answer 8

prezygotic

Question 9

Ecology and sexual selection: Food resources

Answer 9

Red crossbills

• -> choose mate on more efficient feeder
• -call type & feeder linked example of direct system (‘magic trait’)

Question 10

Ecology and sexual selection: Food resources 2 different environment effects

Answer 10

Harsher environment:

• cape penduline tit
• monogamous, biparental care

Rich environment:

• Eurasion penduline tit
• sexual conflict over investment, 1/3 of broods deserted by both parents

Question 11

Ecology and sexual selection: Predation

Answer 11

Guppies

• males have spots to increase female attraction
• low predation, spot number decreases. less attractive to females
• high predation those with low spots count are more attractive (As she wants young to survive)

Question 12

Ecology and sexual selection: Parasitism

Answer 12

• parasites may exploit Sexual signals of host
• parasite load has effect on host condition
• might lead to co-evolutionary cycle that help maintain honesty in sexual signalling

Question 13

ecology and sexual selection: sensory environment

Answer 13

visual/acoustic/olfactory signals have to navigate an environment

• signal must work with the environment
• -acoustic adaption hypothesis urban vs city birds

Question 14

how to measure level of SS

Answer 14

various proxies

• -genital size
• -mating system
• -dichromatism/dimorphism

Question 15

how to measure speciation

Answer 15

no. of extant spp in a clade

Question 16

does SS actually lead to speciation? correlation between no. spp and level of ss in a clade?

Answer 16

correlated! looks as tho more speciation happens when more SS

Question 17

is there evidence to show SS doesn’t lead to speciation?

Answer 17

YES

Question 18

why is it hard to tell if SS leads to speciation?

Answer 18

• depends when u measure it
• also hard to measure SS
• -so at the mo, we still aren’t sure

Question 19

rates of speciation: booms?

Answer 19

– you can get booms of speciation after things such as glacial refugia

Question 20

rates of speciation: Lake Victoria & Cichlids

Answer 20

• Lake V contains 500 spp. of cichlids
• lake presumed to be 750,000 yrs old
• predicted cichlids are 200,000 yrs old
• Lake dried out 14,700 yrs ago, though all fish must have died and spectated after this but discovered that they used other nearby lakes as refuge

Question 21

effect area size has on rate of speciation

Answer 21

bigger area, greater chance of speciation

Question 22

less gene flow the ___ area needed to speciate

Answer 22

smaller

Question 23

rates of speciation are ___ variable and ___ to estimate

Answer 23

extremely variable and hard to estimate

Question 24

speciation rate depends on __

Answer 24

the area available and level of dispersal and gene flow between 2 population

Question 25

Ecology & sexual selection: Parasitism

Answer 25

• parasites use sexual signals to find and parasitise hosts

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