Females of the yellow dung fly, Scathophaga stercoraria, mate with multiple males, and the sperm of different males “compete” to fertilize her eggs. The last male to mate usually gains a disproportionate number of fertilizations. In a laboratory experiment on male and female dung flies from two populations, one in Switzerland and the other in the United Kingdom (U.K.), Hosken et al. (2002) found that fertilizations by the last male (assessed by DNA fingerprinting) depended on the population of origin of both the male and female. Females were mated to two males in turn, one from each population, and the father of each egg laid was then determined. On average, males from the same population as the female fared worse than foreign males. The following graph, redrawn from Hosken et al. (2002), shows the mean percentage of offspring sired by the second male ±SE.

a. What do we call the type of experimental design that was carried out?

b. Write the statement of a linear model to fit to these data.

c. Based on the graph, which F-ratios are likely to be greater than one?

Transcribed Image Text:

Percentage of offspring sired by second male 100 90 80 70 60- 50 40 T Swiss male Swiss U.K. male U.K. Female's origin