Lecture 12- Alternative Reproduction Strategies

Question 1

Explain the mating strategy as natterjack toads(alternate)

Answer 1

Female natterjack toads follow a sound gradient towards the loudest sounding male, as these also sound the closest. Callers are often large makes who produce these sounds to attract a potential mate. Satellite natterjack toads do not produce a sound, but instead hang around the edges of ponds and intercept females travelling towards callers. Satellites get lesser overall matings

Question 2

Why do natter jack toads gather round temporary pools?

Answer 2

They are less likely to contain fish, which predate offspring

Question 3

How are callers and satellites determined in natterjack toads? (Eg. Genetics)

Answer 3

Determined by age. Younger, smaller males are often satellites and mature into callers

Question 4

Why do satellite toads still exist in natterjack toad populations, despite a markedly lesser reproductive duchess rate?

Answer 4

Satellites and callers ave distinguished via age, as satellites are younger moles that mature into callers. As there will always be younger males within populations,satellites will always exist.

Question 6

What is the percentage population and mating success of callers and satellite natterjack toads?

Answer 6

Callers: 60% of population, 80% of matings
Satellites: 40% of population, 20% of matings

Question 7

What are the two morphs of coho salmon? What are the differences in maturity in relation to relates?

Answer 7

Two morphs:

• hook nose salmon, who mature at 3 years. These are large, and mature at the same age/ time as females(3years). Stay and mature in the oceanfor 3 years before travelling to breeding ponds.
• jacks. Mature at 2years and stay small

Question 8

How do the reproductive strategies as jacks and hooknoses differ?

Answer 8

• hooknoses utilise their hooknoses as weapons to fight for access to females and eggs via intrasexual selection
• jacks lack weapons for competition, so manage to fertilise female eggs via sneaking their sperm near the females eggs during spawning

Question 9

What is the difference in reproductive payoff/ success between the two morphs of coho salmon? Why is this the case?

Answer 9

Both strategies have similar reproductive pay off, as both jacks and hooknoses exist in populations. If one was more successful than the other, they would dominate populations and the other would go extinct

Question 10

When are jacks and hooknoses Mose successful in reproduction?

Answer 10

When they are rarer in populations. Eg, a population with less hooknoses means less completion between the males, and subsequently more reproductive success for the rarer individuals

Question 11

Describe the survival fitness of hooknoses and jacks ( give the ratios)

Answer 11

Jacks (0.13) greate survival probability due to returning from the ocean a year early, so less exposure to predators.
Hooknoses (o.o6). Greater size, bright colours and extra year in ocean means a greater risk os predation than jacks, meaning a less survivorship to breeding ratio

Question 12

Give information on the breeding spans of jacks and hooknose salmon (give ratios)

Answer 12

Jacks (8.4 days). Lesser size means less stored resources (they don’t feed during breeding), so lesser breeding period.
Hooknoses (12.7 days). Larger muscle mass and stored fat means they can breed for longer

Question 13

What is the difference in breeding success between jacks and hooknoses?

Answer 13

Jacks: o.66 success
Hooknoses: 1.00 success

Question 14

What is the fitness ratio between jacks and hooknoses? What does this mean?

Answer 14

0.95. As this is extremely close to one, it shows that both strategies have pretty much equal pay offs within the population.

Question 15

What is the reproductive selection between jacks and hooknoses called? What does this reach?

Answer 15

Frequency dependant selection, meaning each does best when rare in the population. The two reach a stable equilibrium

Question 16

What are the mating arenas on ruffs called?

Answer 16

Leks

Question 17

What are the reproductive strategies of ruffs related to?

Answer 17

Plumage polymorphism

Question 18

Describe the two reproductive strategies of the different ruffs

Answer 18

• black/brown ruffed males defined small patches of ground within leks, and engage in intrasexual selection to defend their spots. These make up 77% of males and 91% of matings.
• white ruffs travel between leks and acts as non aggressive satellites. They make up 23% of the population getting 9% of total matings

Question 19

Why are white males tolerated by the more aggressive species in leks?

Answer 19

They attract more females to the lek, and therefore there’s a greater chance of mating for all

Question 20

When are white ruffs able to get mates?

Answer 20

When the mating ground is large, as the more aggressive ruffs basically can’t control the white ones and they are able to acquire mates. In smaller mating grounds the darker ruffs always get mates

Question 21

What type of sexual section occurs in ruff populations?

Answer 21

Intersexual selection with the females picking the males

Question 22

How are the horned morphs in soya sheep determined?

Answer 22

Genetically

Question 23

What are the two types of soya sheep males and what are their reproductive strategies?

Answer 23

Horned males: fight for females and get the most matings. They have exclusive access to females and chase off any other competitors.
Scurred males: seek out females in oestrus (fertile) and try and make with them quickly before horned males realise fertile females are there

Question 24

Explain how genes impact reproductive success in soay sheep

Answer 24

The horn gene is controlled by the dominant H gene. Therefore, scurred sheep only occur when the hh homozygous phoentype is present. However, HH males are more vulnerable to parasite in winter, so heterosygous and hh homozygous individuals have overall greater survival rates and the hh gene is kept in populations by the reporoductive success of hornedHh males

Question 25

How is the making strategy of coho salmon determined?

Answer 25

Genetically determined