1973] 
Scriber — P apilionidae 
363 
in this and similar cases such as the four species of the P. demodocus 
(Esper) group of swallowtails that have evolved on Madagascar, 
or the three species of the P. nireus (L.) group in West Africa that 
are presumed to have speciated during the Tertiary when the climate 
and vegetation were rapidly changing (Owen, 1971). Furthermore, 
because the author is in this study to a large degree uncertain of 
regional food plant preferences that might distinguish a polymorphic 
population of specialized individuals from a monomorphic population 
of generalized individuals, no attempt has been made to differentiate 
any components of niche breadth as described by Roughgarden 
(1972). 
It is probably fair to assume that neither the latitudinal gradients 
in diversity nor those for trophic niche breadth remain constant for 
any long periods of time. The phylogenetic histories of the Papilioni- 
dae are certainly intertwined with the zoogeographical movement and 
changes in the flora of major continents (Hovanitz, 1958; Carcas- 
son, 1964; and Kostrowicki, 1969), and this paper is merely an 
attempt to look at the present state of these continually changing 
phylogenies. 
Besides regional preferences there can be temporal changes in food- 
plant preferences and these are frequently accentuated by human agri- 
culture. Owen (1971) points out that several species of African 
papilionids have recently expanded their ranges and seasonal abun- 
dance by switching from their wild Rutaceous foodplants onto culti- 
vated varieties of Citrus which, unlike the wild plants, maintain 
their leaves throughout the dry season and are spreading rapidly with 
agricultural development. The extent to which members of the 
Papilionidae have become secondarily polyphagous on completely new 
plant families or else by revitalized usage upon re-exposure to ances- 
tral hostplant families is uncertain. It is very likely that besides the 
general ecological pressures such as competition with more specialized 
herbivores, there may well be both ‘fixed’ and ‘variable’ metabolic 
‘cost’ associated with any extension of the normal range of food 
plants utilized by a species (Feeny, 1974). In Papilvo demoleus for 
example the principal natural foodplants for Papilio demoleus 
stheneles (Macleay) in Australia are Psoralea tenax and P. patens 
which are members of the Leguminosae family (D’Abrera, 1971 ; 
McCubbin, 1971; and Common and Waterhouse, 1972), while in 
Ceylon and India the presumed ancestral P. demoleus demoleus (L.) 
feed primarily upon various Rutaceae, such as Aegle , Clausenia, Gly- 
oosmis, and Citrus (Woodhouse, 1950; and Igarashi, 1966). Al- 
though the females of P. d. stheneles oviposit upon Citrus in Queens- 
