case0602: Mate Preference of Platyfish

In Sleuth2: Data Sets from Ramsey and Schafer's "Statistical Sleuth (2nd Ed)"

Mate Preference of Platyfish

Description

Do female Platyfish prefer male Platyfish with yellow swordtails? A.L. Basolo proposed and tested a selection model in which females have a pre-existing bias for a male trait even before the males possess it. Six pairs of males were surgically given artificial, plastic swordtails—one pair received a bright yellow sword, the other a transparent sword. Females were given the opportunity to engage in courtship activity with either of the males. Of the total time spent by each female engaged in courtship during a 20 minute observation period, the percentages of time spent with the yellow-sword male were recorded.

Usage

case0602

Format

A data frame with 84 observations on the following 3 variables.

Proportion

The proportion of courtship time spent by 84 females with the yellow-sword males

Pair

Factor variable with 6 levels—"Pair 1", "Pair 2", "Pair 3", "Pair 4", "Pair 5" and "Pair 6"

Length

Body size of the males

Source

Ramsey, F.L. and Schafer, D.W. (2002). The Statistical Sleuth: A Course in Methods of Data Analysis (2nd ed), Duxbury.

References

Basolo, A.L. (1990). Female Preference Predates the Evolution of the Sword in Swordtail Fish, Science 250: 808–810.

Examples

str(case0602)
boxplot(Proportion~Pair, case0602, ylab="Proportion")

#as in Display 6.5 
summary(aov(Proportion~Pair, case0602))

n.fish  <- with(case0602, tapply(Proportion, Pair, length))
av.fish <- with(case0602, tapply(Proportion, Pair, mean))
sd.fish <- with(case0602, tapply(Proportion, Pair, sd))
male.body.size <- with(case0602, tapply(Length, Pair, unique))
mean.body <- mean(male.body.size)
table.fish <- data.frame(n.fish, round(av.fish*100,2),
                         round(sd.fish*100,2), male.body.size,
                         2*(male.body.size-mean.body))
names(table.fish) <- c("n", "average", "sd", "male.body.size", "coefficient")
s.pooled <- with(table.fish, round(sqrt(sum(sd^2*(n-1))/sum(n-1)),2))
g <- with(table.fish, sum(average*coefficient))
se.g <- with(table.fish, round(s.pooled*sqrt(sum(coefficient^2/n)),2))
g/se.g

Sleuth2 documentation built on Jan. 25, 2024, 3:02 p.m.