248 
Psyche 
[September-December 
roth, 1969, 1970). In addition to wing reduction, high elevation 
litter beetles are often eyeless or microphthalmous, and less darkly 
pigmented. This generalization was strikingly demonstrated to me 
by the beetles in a litter sample from the highest point in Jamaica, 
forested Blue Mountain Peak at 7400 feet. The sample contained 
beetles with these characters in the families Histeridae, Tenebrioni- 
dae, Curculionidae, Cerylonidae, Pselaphidae, and Carabidae, as 
well as Leiodidae. Most of these beetles were absent or much less 
common at lower elevations. In Aglvptinus dimorphicus there was 
only a very slight indication of reduction in eye size at higher ele- 
vations or in cave populations. 
An explanation for wing reduction in A. dimorphicus is not 
difficult to envision. Selective pressures must favor retention of 
long winged genotypes in the lowlands because the habitats are 
climatically more variable (with wet and dry seasons) and have 
feeding and reproduction resources that last for a short time (dung 
and fungi is consumed or decays quickly). The ability to disperse 
to new and more favorable sites is necessary for populations in 
such lowland circumstances. In contrast, selection for wings is 
relaxed in cave and montane forest populations because the dis- 
persal function of flight is less important. The beetles live in a 
stable climate (with little or no seasonal variation in temperature 
and moisture, especially in deep litter), and feeding and reproduc- 
tion resources are long lasting (guano piles and deep mats of slowly 
decomposing montane vegetation). 
I would reason that the lowland caves were occupied in the past 
by long winged individuals. They could more easily arrive at the 
guano piles deep in the caves, through flight guided by olfaction. 
These winged colonizers also carried the short winged condition in 
their genome, perhaps in a simple recessive condition. Peru and 
Mocho caves now contain long winged members in their popula- 
tions and may thus represent recent colonizations. The other 13 
caves, with only short winged populations, must represent older 
colonizations from which selection has removed the long winged 
condition. This seems to represent an active selective force against 
wings, rather than just a relaxed selection which no longer encour- 
ages their genetic maintenance. I cannot identify the selective force 
that seems to work so well against the winged condition of these 
beetles in caves (but see Barr, 1968, and also Regal, 1977, for a 
discussion of the loss of “useless” features). I also cannot deter- 
