Mathematical Biology Seminar

Date: March 6, 2025

Time: 4:00PM - 4:50PM

Location: BLOC 302

Speaker: Chuliang Song, UCLA

Title: Observer invariance: a meta-law for ecological models

Abstract: The dynamics of an ecological model should remain unchanged if we choose to group identical individuals within a species into subspecies. This fundamental constraint, which we call observer invariance, necessarily holds because individuals interact via their traits and not some abstract notion of ``species identity''. While the principle looks self-evident, we show that many models in common use violate observer invariance. This exposes an implicit assumption of hidden trait differences between species that often leads to strong niche differentiation. We meticulously examine the root causes of these violations across various levels of ecological interaction (intraspecific, pairwise interspecific, and higher-order), and offer corresponding recipes for restoring observer invariance.