Elderflower orchids (picture A) in Europe have a polymorphism for yellow and pur

Question

Elderflower orchids (picture A) in Europe have a polymorphism for yellow and purple flowers. Unlike most other flowers, these orchids do not produce nectar for pollinating bumblebees to eat. Naïve bumblebees looking for a meal end up pollinating the flower without reward. Evolutionary ecologist Luc Gigord and his colleagues set up an experiment to determine the effects of the color of the orchid flower on the plant’s fitness. They examined the fitness of the yellow genotype relative to its frequency in the population. Results are shown in Figures B and C. Figure B shows a measure of male fitness (number of pollen packets removed by bees). Figure C shows a measure of female fitness (number of fertilized seeds).

a) At the lowest frequency of the yellow morph, what was the relative reproductive success of males? Of females?

b) At the highest frequency of the yellow morph, what was the relative reproductive success of males? Of females?

c) What do these results imply for the coexistence of yellow and purple genotypes? Explain your answer.

d) How might the foraging behavior of bumblebees drive this relationship?

0.99-Polinia removal rs Male reproductive success (relative) - 09 08 07 6[0 5 4 03 0:2 :600] Frequency of yellow morph 0.85-Fruit setrs Female reproductive success (relative) 09 8[0 07 06 05 0.4 0:20:3 on 6 Frequency of yellow morph

Explanation / Answer

a)At the lowest frequency the reproductive sucess of males and females are the highest.By examining the graph we can understand that as frequency increases reproducive sucess of both males and females decreases ie it is negative frequency dependent.

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