New paper by Jing

Around the World in 26 Million Years: Diversification and Biogeography of Pantropical Grass-Yellow Eurema Butterflies (Pieridae: Coliadinae)

Catopsilia + Eurema; ​Photo credit and thanks to D.J. Martins. 

Grass-yellow butterflies are a group of pantropical pierid genera (Abaeis, Eurema, Leucidia, Pyrisitia, Teriocolias) distributed throughout the Old and New World tropics. Little is known about its diversification pattern, including the biogeographic mechanisms explaining their global distribution. We present the first densely sampled, time-calibrated phylogeny and biogeographic reconstruction to confirm the monophyly of the genera and widespread species. Additionally, we inferred the biogeographic events attributing to their current, cosmopolitan distribution.

Our phylogenies converged on similar topologies with robust support. We recovered that grass-yellows emerged ca. 26 mya in the New World and a single extant lineage dispersed to Asia in the early Miocene, where they diversified and dispersed to Africa and Australasia. The fastest rates of diversification occurred in the Old World tropics during the late Miocene. Many of the grass-yellow genera were paraphyletic or polyphyletic as traditionally circumscribed. To maintain nomenclatural stability, we place all grass-yellows in Eurema sensu lato and recognize two subgenera: Eurema (Abaeis) and Eurema (Eurema). Our results suggest that grass-yellow butterflies attained their global distribution via dispersal. The Indo-Australian and Caribbean archipelagoes seem to have accelerated the diversification of the group, and movement in and out of these regions was frequent. Although the traditional view of founder-event speciation envisions migrants from large landmasses ("mainland") colonizing smaller landmasses ("islands"), we find that island to mainland dispersal and differentiation were equally or more common.

Leong J., Matos Maravi P. F., Núñez R., Nunes R., Liang W., Braby M.F., Doleck T., Aduse-Poku K., Inayoshi Y., Hsu Y.-F., Wahlberg N., Peggie D., et al., Kawahara A.Y., Pierce N., Lohman D. (2025) Around the World in 26 Million Years: Diversification and Biogeography of Pantropical Grass-Yellow Eurema Butterflies (Pieridae: Coliadinae). Journal of Biogeography Early View : DOI: 10.1111/jbi.15107

Ultrametric chronogram of grass-yellow butterflies inferred with BEAST using secondary calibrations from Kawahara et al. (2019) with a geological time scale along the bottom. Specimen codes of the samples are indicated in Table S1; ISO country codes of collection are provided for Eurema hecabe samples. Coloured blocks under the species names indicate their subgenus. Branch colours correspond to the diversification rate λ scale and indicate diversification rate shifts inferred by a BSD analysis. Coloured circles at the tips indicate the species' range with reference to the map and legend. Geographic areas and combinations of areas are indicated with colour in the inset map and in pie charts at nodes, which indicate relative probabilities of an ancestor residing in one or more areas as inferred with BioGeoBEARS. All areas or combinations of areas with < 20% probability are indicated with white. The BioGeoBEARS analysis was conducted with its most closely related outgroup, a single New World outgroup clade with Prestonia clarki, Kricogonia lyside and Nathalis iole, which were removed for presentation. The Old World Clade is indicated with a tick mark; all other taxa live in the New World. Selected species are shown to scale. The left half is a dorsal image, and the right half is a ventral image. The best side was selected for presentation before manipulation in Adobe Photoshop (adobe.com). Image credits: 1, 3, 5, 6 Y. Inayoshi; (10) Field Museum of Natural History, FMNHINS-0000-124-056. All other photos Yale Peabody Museum: (2) YPM-ENT-736151, (4) YPM-ENT-736034, (7) YPM-ENT-735775, (8) YPM-ENT-737671, (9) YPM-ENT-736140, (11) YPM-ENT-756643 and (12) YPM-ENT-735823.