Hi Tony, Just in case you have not check this one out for a lead:
Bolnick, D.I., Yang, L.H., Fordyce, J.A., Davis, J.M., & Svanbäck, R. (2002) Measuring individual-level resource specialization. Ecology, 83, 2936-2941. Then if you have way more than the frequencies, I'd say you could combine / reduce the info and make yourself your own "impact on prey" index, and use it as a continuous variable as described in the cited paper. Mario Quevedo Unidad de Ecología, Dept. B.O.S., Universidad de Oviedo Campus del Cristo, 33071 Oviedo Spain phone: +34 98 510 48 31 fax: +34 98 510 48 66 [EMAIL PROTECTED] >hi all, > >im currently grappling with the task of getting some measure of the trophic >niche width and niche overlap of an assemblage of consumers and am finding >it difficult to follow the literature. i have a list of consumers and >corresponding consumption frequencies for a series of prey and am chasing a >suitable measure that will highlight the approximate width of the niche of >each consumer along this resource dimension (ie food type), and a separate >measure that will enable me to estimate pair-wise overlap between them (i do >recognize such an approach has limitations - eg that overlap does not >necessarily indicate competition). much recent work seems to simply use >number of prey taxa as an index of niche width, but im keen to try and go >further than this. specifically, i have data on consumption rates of each >consumer on each prey type and prey availability, which i know some previous >work included into both a breadth and overlap index. > >it seems that much work was done in the 70's/80s (eg hurlbert, pianka, >levins, macarthur, slobchikoff & schultz, pielou, colwell & fatuyma, abrams) >on this topic and the result was a mass of different equations - each of >which is apparently more suitable than the next! i was wondering if there >was any solid conclusions from this work (ie is there a best-measure) and if >there is any recent work that summarizes/extends these ideas? > >any help/leads would be much appreciated, > >cheers, > >tony > >__________________________________________ > >tony dell >department of zoology and tropical ecology james cook university townsville, >qld 4811 australia > >ph 07 47814757 or 47814520 >fax 07 47251570 >email [EMAIL PROTECTED] >=========================================================================
