Müllerian mimicry in Neotropical butterflies: one mimicry ring to bring them all and in the jungle bind them

Aim  Uncovering the effects of Müllerian mimetic interactions on the evolution of species niches and geographic distributions at a continental scale.  Location  Neotropics and part of Nearctic.   Time Period  19th century to present, with most data collected within the last 30 years.   Major Taxa Studied  Heliconiini (Heliconiinae) and Ithomiini (Danainae) butterfly tribes.   Methods  We leveraged a dataset of 67,563 geolocalized occurrences from fieldwork observations and museum collections to map broad-scale biodiversity patterns of heliconiine butterflies. We tested for congruences and disparities with known Ithomiini biodiversity patterns, a group from which they diverged 86.5 My ago, yet share numerous warning wing colour patterns. We used phylogenetic comparative analyses to test for both the spatial co-occurrence of species with similar aposematic wing patterns and the convergence of their climatic niche within and between tribes.   Results  Both tribes exhibit wide overlap in biodiversity hotspots across the Neotropics, including a high prevalence of rare species and mimetic patterns in the tropical Andes. Ithomiine species dominate Andean communities, while the Amazon basin hosts a higher relative richness of heliconiines. Phenotypically similar species within and between tribes share climatic niches as a result of selection favouring both co-occurrence of look-alike species and convergence of warning signals within local communities.   Main Conclusions  We documented continental-scale spatial and evolutionary associations among species sharing warning signals both within and between tribes separated by 86.5 My of independent evolutionary history. Our results provide empirical evidence for the pervasive effects of mutualistic interactions on biodiversity patterns. Critically, they also emphasise the vulnerability of mimetic communities, bound together by positive interactions, to disassembly induced by climate change.