Baseline differences in d space - AndrewLJackson/SIA-for-Ecologists GitHub Wiki

When using SIBER or similar tools to quantify and compare dispersion (variation) in isotope d-space between groups from different locations or time-points, complications can arise if the underlying inputs to the system are wider or narrower in the primary producers (or in the environmental sources). This issue was discussed in detail in the following papers. The issue remains somewhat unresolved though, and while there are some options, there is no single solution for all situations.

• The original paper: Layman, C.A., Arrington, D.A., Montana, C.G. & Post, D.M. 2007. Can stable isotope ratios provide for community-wide measures of trophic structure? doi
• The associated comment: Hoeinghuas and Zeug, 2008. Can stable isotope ratios provide for community-wide measures of trophic structure? Comment. doi
• The reply: Layman and Post. 2008. Can stable isotope ratios provide for community-wide measures of trophic structure? Reply. doi

A method is provided by Araujo et al for creating a standardised derived metric that might work for some situations. This paper is also nice in that it also compares the isotope variation with gut-contents variation.