Every living thing needs nutrients. Much previous work has shown that a variety of soil nutrients – in particular Nitrogen (N), Phosphorous (P), and Potassium (K) – greatly impact plant communities. Often, human behaviors, especially agricultural practices like fertilization, have generated significant shifts in these nutrients. When environments become flushed with these nutrients, overall biomass typically increases but biodiversity often decreases. This is expected according to two hypotheses:

  1. Nutrient Limitation Hypothesis: Limitations in nutrients suppress abundance, and therefore increases in nutrients will drive increased abundance.
  2. Community Homogenization Hypothesis: Species that are most efficient at utilizing resources are prevented from completely excluding other species due to resource limitations. Therefore, increases in nutrients will allow these species to competitively exclude other species, decreasing overall diversity.

It may be Friday the 13th, but this article is talking about some lucky ants. Canopy ants, in particular. Ants that forage in trees exhibit a high level of ecological dominance, and ants are usually the most conspicuous organisms running around on tree trunks and branches, especially in tropical forests. This begs the question: Why? Dr. Terry McGlynn and Erica Parra, in a paper published last year, set out to address this question.

polyrhachis
Nest of Polyrhachis ants, a dominant arboreal genus. Photo: Alex Wild