A switch to feeding on cycads generates parallel accelerated evolution of toxin tolerance in two clades of Eumaeus caterpillars (Lepidoptera: Lycaenidae)

We assembled a complete reference genome of Eumaeus atala, an aposematic cycad-eating hairstreak butterfly that suffered near extinction in the United States in the last century. Based on an analysis of genomic sequences of Eumaeus and 19 representative genera, the closest relatives of Eumaeus are Theorema and Mithras. We report natural history information for Eumaeus, Theorema, and Mithras. Using genomic sequences for each species of Eumaeus, Theorema, and Mithras (and three outgroups), we trace the evolution of cycad feeding, coloration, gregarious behavior, and other traits. The switch to feeding on cycads and to conspicuous coloration was accompanied by little genomic change. Soon after its origin, Eumaeus split into two fast evolving lineages, instead of forming a clump of close relatives in the phylogenetic tree. Significant overlap of the fast evolving proteins in both clades indicates parallel evolution. The functions of the fast evolving proteins suggest that the caterpillars developed tolerance to cycad toxins with a range of mechanisms including autophagy of damaged cells, removal of cell debris by macrophages, and more active cell proliferation.

Atala, Atala Hairstreak, Coontie Hairstreak, Eumaeus atala Röber (Insecta: Lepidoptera: Lycaenidae)

The atala is our largest and most spectacular eastern U.S. hairstreak. Due to decline in abundance of its host plant, coontie, because of over-harvest (as a source of starch) and habitat destruction due to development, the atala was believed to have become extinct. It was not collected in Florida from 1937 until 1959. The atala is now common locally in southeast Florida probably as a result of the popularity of its host plant as a landscape ornamental. In fact, it is now occasionally considered a pest in ornamental plant nurseries. This document is EENY-169, one of the Featured Creatures series of the Entomology and Nematology Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Published: October 2000. EENY-641/IN326: Atala Butterfly, Atala Hairstreak, Coontie Hairstreak, Eumaeus atala Poey 1832 (Insecta: Lepidoptera: Lycaenidae) (ufl.edu)