  In 1972, Robert May triggered a worldwide research program studying
ecological communities using random matrix theory. Yet, it remains unclear if
and when we can treat real communities as random ecosystems. Here, we draw on
recent progress in random matrix theory and statistical physics to extend May's
approach to generalized consumer-resource models. We show that in diverse
ecosystems adding even modest amounts of noise to consumer preferences results
in a transition to "typicality" where macroscopic ecological properties of
communities are indistinguishable from those of random ecosystems, even when
resource preferences have prominent designed structures. We test these ideas
using numerical simulations on a wide variety of ecological models. Our work
offers an explanation for the success of random consumer-resource models in
reproducing experimentally observed ecological patterns in microbial
communities and highlights the difficulty of scaling up bottom-up approaches in
synthetic ecology to diverse communities.
