1. Colour and predation pressure in guppies Male guppies are brightly coloured. Males with more bright spots are more attractive to spots actually displayed is the result of a trade-off between pressures of predation and females but are also more obvious to predators, and therefore the number (and size) of mating Question 1.1. Female guppies begin to breed as soon as they become mature at about three months old, they then produce clutches of eggs at roughly one-month intervals until they die. Clutches vary in size from one to 40 eggs (average about 10 eggs) if the size of a population of guppies in a certain stream stays more or less stable over several years, how many of a given female's offspring, on average, must survive to reproductive age in this population? (Explain your answer) Endler built several artificial ponds and stocked each with a population of guppies derived from several different localities in Trinidad. At the start of the experiment, there was considerable variation among males in the number of their spots, with a mean of 10 across all the populations (time=0 months). After 6 months, the mean number of spots per male had increased to 11.8 (Figure 1). first sample predatory fish then added to second ponds B and C sample Fig 1 Dard sample B 12 mean number of spois per male 11 TO 16 20 12 time months Having sampled his populations at six months, Endler divided them into three groups (A, B and C). To each group C pond he added one individual of a fish called Crenicichla alta, which is a voracious predator of guppies. To each group B pond he added six individuals of another predatory fish called Rivulus hartii, which does not prey on guppies. No fish were added to the group A ponds. The ponds were then left alone for a further five months at which point he sampled them again and counted the number of spots on the male guppies Q 1.2. The purpose of the group C ponds was to see what the effect would be on the guppy populations of adding a voracious predator after several generations in which there had been no predation. What do you think was the purpose of the group A and B ponds? Q 1.3. Why did the number of spots per male guppy initially increase? Q. 1.4 Explain why the number of spots per guppy decreased in group C but continued to increase in the other two groups Q. 1.5 Why was there more than one pond for each group (A, B and C)? Q.1.6. Why is the information under Q.1.1 (including your answer) relevant to interpreting the results of the experiment? 1. Colour and predation pressure in guppies Male guppies are brightly coloured. Males with more bright spots are more attractive to spots actually displayed is the result of a trade-off between pressures of predation and females but are also more obvious to predators, and therefore the number (and size) of mating Question 1.1. Female guppies begin to breed as soon as they become mature at about three months old, they then produce clutches of eggs at roughly one-month intervals until they die. Clutches vary in size from one to 40 eggs (average about 10 eggs) if the size of a population of guppies in a certain stream stays more or less stable over several years, how many of a given female's offspring, on average, must survive to reproductive age in this population? (Explain your answer) Endler built several artificial ponds and stocked each with a population of guppies derived from several different localities in Trinidad. At the start of the experiment, there was considerable variation among males in the number of their spots, with a mean of 10 across all the populations (time=0 months). After 6 months, the mean number of spots per male had increased to 11.8 (Figure 1). first sample predatory fish then added to second ponds B and C sample Fig 1 Dard sample B 12 mean number of spois per male 11 TO 16 20 12 time months Having sampled his populations at six months, Endler divided them into three groups (A, B and C). To each group C pond he added one individual of a fish called Crenicichla alta, which is a voracious predator of guppies. To each group B pond he added six individuals of another predatory fish called Rivulus hartii, which does not prey on guppies. No fish were added to the group A ponds. The ponds were then left alone for a further five months at which point he sampled them again and counted the number of spots on the male guppies Q 1.2. The purpose of the group C ponds was to see what the effect would be on the guppy populations of adding a voracious predator after several generations in which there had been no predation. What do you think was the purpose of the group A and B ponds? Q 1.3. Why did the number of spots per male guppy initially increase? Q. 1.4 Explain why the number of spots per guppy decreased in group C but continued to increase in the other two groups Q. 1.5 Why was there more than one pond for each group (A, B and C)? Q.1.6. Why is the information under Q.1.1 (including your answer) relevant to interpreting the results of the experiment