| Abstract: | Jamieson & Craig (1987) have argued that the feeding of nestlings by nonparental birds may simply be an unselected consequence of delayed dispersal in cooperatively breeding birds in which philopatric individuals are responding to the stimulus of begging young in their vicinity (see also Jamieson 1986, 1989). Jamieson & Craig (1990) recently criticized my attempt to examine what they describe as this “unselected” hypothesis of Williams (1966) and several selectionist (or adaptive) hypotheses for the current utility of helping behaviour in the bell miner (Manorina melanophrys) (Clarke 1989). In this paper I address specific issues raised by Jamieson & Craig (1990), especially whether the unselected hypothesis is an adequate explanation of the pattern of helping in the bell miner. I will also attempt to highlight the difficulty of formulating specific predictions from the unselected hypothesis and the apparent ease with which it can be modified to accommodate departures from its general predictions. |
