Some thoughts about the challenge of inferring ecological interactions from spatial data.

Abstract

Dr. Luis Escobar asked me to provide a joint review of the submissions by Stephens et al. (2019, this issue) and Peterson et al. (2019, this issue).  I pulled thoughts together, but by the time I sent them along, he had received other reviews and made an editorial decision. He felt my perspective might nevertheless warrant publishing as a commentary alongside these two pieces.  My review was of the original submissions, which are now appearing with minor, mainly cosmetic changes.  I have only lightly edited the text of my review, and added a few additional thoughts and pertinent references. Neither group of authors has seen my commentary, and so I am responsible for any omissions or lapses in interpretation.  The protocol developed by Stephens seems to me a potentially valuable exploratory tool in describing patterns of co-occurrence, but I note several potential problems in identifying interactions usingsolely  this protocol.  I also gently disagree with Peterson et al., who state flatly that co-occurrence data can shed no light at all on interspecific interactions.  I suggest there are a number of counter-examples to this claim in the literature.  I argue that spatiotemporal data, when available, iprovide a much more powerful tool for discerning interactions, than do staticspatial data.  Finally, I use a simple thought experiment to point out that biotic drivers could be playing a key  causal role in limitnig distributions, even in equisitlvely accurate SDMs that use only abiotic (scenopoetic) data as input data.