Sexual selection 2

Question 1

Natterjack toads

Answer 1

• Males call to attract gemales to mating pools
• Pools are usually remporary, without fish to predate the tadpoles
• Large noisy males often get mated first
• Non-calling “Satillite” males intercept females coming to pool
• However satellites only get 20% of matings, dsepite being 40% of the population
• Size and loudness increases with age so it is not a genetic difference

Question 2

Coho salmon

Answer 2

• North american species
• After spawning upstream, both males and females die
• Females mature at 3 years old
• Hooknoses mature at 3 years old, large and bright
• Jacks mature at two years, small and dull
• Hooknoses fight for female access while the jack sneaks in
• Male morph type is genetically determined so we should expect both strategies to have equal payoffs

Question 3

Ruff

Answer 3

• Lek breeding sandpiper
• Males come in three coloours, brown, black and white
• Brown/black - aggressive, 91% of matings
• White - non-aggressive, 9% of matings
• White males tolerated at larger leks as more females are hard to control

Question 4

Soay Sheep

Answer 4

• Found on st.kilda
• Males are either horned or scurred
• Horned are better fighters and get exclusive access to fertile females
• Scurred chase around females but lose them quickly
• Paternity depends on population density
• low density- Horned can monopolise females
• high density -too many females to be controlled so Scurred can have some access
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