I am, of course, referring to Hurlbert’s 1990 paper in Oikos, Spatial Distribution of the Montane Unicorn.
A longstanding assumption in population ecology was that a variance-to-mean ratio (VMR) of <1 indicated a dispersed population, VMR>1 an aggregated population, and VMR=1 a random distribution. Hurlbert’s point was that this assumption regarding VMR=1 is incorrect: he modeled nonrandom distrubutions with VMR=1. He coined the term “unicornian” to mean a nonrandom distribution with VMR=1.
I asked a generative AI if there are any actual organisms that show such a distribution. It confidently said yas, then cited lots of studies which actually exist, but do not show such populations. So next I searched Google Scholar for the expression VMR=1. It brought up lots of studies – even many published since Hurlbert’s unicorn paper – which stated that they were using that as their assumption of a random distribution. There were a few which referred to Hurlbert’s warning about this assumption, but did not in fact find such a distribution in their study population. I also found papers which cited Hurlbert as their source for using VMR<1 to mean dispersion and VMR>1 to mean aggregation, but did not refer at all to VMR=1.
Finally, I managed to find three which presented model or hypothetical examples of “unicornian” distributions, but none which found an actual population doing this.
So, knowing that there are professional ecologists here who may be more up on this aspect of the literature than I am, I ask those: Do any real organisms show a unicornian distribution?
And if not, is Hurlbert’s point still relevant?