0851996159

relationships and origins remain unresolved. For example, it is unclear

whether xenobiosis or temporary social parasitism ever lead to

inquilinism.

Social parasitism in ants and other social insects appears to be largely

a temperate-zone phenomenon and to be concentrated in particular

phylogenetic lines. Various authors have discussed factors that might be

responsible for these patterns (see Alloway, 1980, 1997; Allowayet al.,

1982; Stuart and Alloway, 1982, 1983; Buschinger, 1986, 1990; Hölldobler

and Wilson, 1990; Stuart, 1990, 1993; Topoff, 1997; and references

therein). Because most known socially parasitic social insects occur in the

temperate regions around the world, it has been suggested that cooler

temperatures might facilitate the acceptance of alien individuals into

colonies. As already discussed, the adoption of young mated queens back

into their parental nests (i.e. secondary polygyny) would seem to be

an important precursor to parasitic colony foundation. It has also been

suggested that the occurrence of closely related sympatric species in large

dense populations, which, to some extent, compete with each other,

would promote the kinds of interactions necessary for the evolution

of social parasitism; and these factors also tend to be characteristic of

temperate regions. The tendency of colonies to fragment into small, often

queenless, nest units, a trait often associated with secondary polygyny

Social Parasitism in Ants 329

Territorial

aggression

Secondary

polygyny

Intraspecific

slavery

Interspecific

slavery

Temporary

social

parasitism

Inquilinism

Xenobiosis

Plesiobiosis

Fig. 15.1. Possible evolutionary pathways for social parasitism in ants (redrawn

with modifications from Hölldobler and Wilson, 1990).