Horn measurements of the rhinoceros beetle Xylotrupes gideon.

Description

A measured sample of 177 males. Pronotum width (body) and pronotal horn length (horn) were measured in mm/10 with a slide micrometer.
This sample of horn lengths is used to illustrate fitting the mixture of two normal probability distributions.

Usage

data(x_gideon)

Format

A data frame with 177 observations on the following 2 variables.

body

Pronotum width (mm/10)

horn

Pronotal horn length (mm/10)

Details

Xylotrupes gideon:
Collection data for the measured sample of the dynastine rhinoceros beetle Xylotrupes gideon:
Lampung Province, Sumatra, Indonesia; 1999;
collected by Agusyanto Hasan.

A measured sample of 177 males was selected from the above total sample of 193. Pronotum width was measured at its greatest width.
Pronotal horn length was measured from the mid-dorsal point of the posterior margin of the pronotum to the anterior apex of the left line of the pronotal horn.

Source

Rowland, J.M. 2003. Male horn dimorphism, phylogeny and systematics of rhinoceros beetles of the genus
Xylotrupes (Scarabaeidae: Coleoptera). Aust. J. Zool., 51: 213-258.

References

Rowland JM, Qualls CR. 2005. Likelihood models for discriminating alternative phenotypes in morphologically dimorphic species.
Evolutionary Ecology Research 7: 421-434.

See Also

mix.mle, o_taurus

Examples

data(x_gideon)
## Scatter plot of horn versus body showing trait scaling
plot(x_gideon$horn, x_gideon$body)

## Plot histogram with overlaid density plot
hist(x_gideon$horn, freq=FALSE)
points( x_gideon$horn, rep(0, nrow(x_gideon)))

## Estimation of mixture of normals
fit.gideon <- mix.mle(x_gideon$horn, method='normal', 
    mix.prob=0.5, dist1.par1=100, dist1.par2=10, dist2.par1=300, dist2.par2=10)

print(fit.gideon)
plot(fit.gideon)

Results