ABSTRACT
Cuticular wax alkane, LCOH, and LCFA patterns differ markedly between plant species (Table 2). The fecal patterns of these markers will therefore closely reflect the combination of plant species consumed by the animal and can be used to estimate this, with one proviso, i.e., while the fecal recovery of wax markers is high, it is incomplete and generally increases with increasing carbon-chain length, especially with alkanes.[4] Before relating fecal marker patterns to those in the dietary components, it is therefore necessary to correct for differential recoveries of individual alkanes, LCOH, or LCFA.[1]
Several mathematical packages are available for calculating diet composition from wax marker patterns in feces and the plant species on study;[1] in controlled comparisons with relatively simple mixtures (less than five species), alkane-based diet compositions have shown excellent agreement with known diet compositions.[1] However, as the number of species to be separated approaches the number of available alkanes, it becomes increasingly difficult to reliably estimate diet composition; the number of dietary components cannot exceed the number of available markers. The use of LCOH and LCFA, in addition to
Table 1 Major components of plant epicuticular wax. Component Remarks Hydrocarbons Saturated straight-chain hydrocarbons (n-alkanes), mainly
odd-numbered carbon chains (C21-C37) Branched-chain alkanes and unsaturated hydrocarbons (alkenes) with similar chain lengths
Wax esters Esters of LCFA and LCOH (mainly even-numbered carbon chains C32-C64)
Free LCOH Mainly even-numbered carbon chains (C20-C34) Free LCFA Mainly even-numbered carbon chains (C20-C34) Long-chain fatty aldehydes, ketones, b-diketones Quantitative analytical procedure not yet established LCFA = long-chain fatty acids; LCOH = long-chain fatty alcohols.
