To and fro in the archipelago: Repeated inter-island dispersal, eustasy and New Guinea’s orogeny affect diversification of Delias, the world’s largest butterfly genus

Author

Weijun Liang, CUNY City CollegeFollow

Date of Award

2023

Document Type

Thesis

Department

Biology

First Advisor

David J. Lohman

Keywords

biogeography, butterflies, diversification, eustasy, Indo-Australian Archipelago, Lepidoptera, orogeny, phylogenetics, systematics, taxonomy

Abstract

Delias, commonly known as Jezebels, is the largest butterfly genus, comprising ca. 248 species found throughout Asia and Australasia. Most species are endemic to islands in the Indo-Australian Archipelago or to New Guinea and nearby islands in Melanesia. All species in the genus have brightly colored wing patterns, presumably as warning coloration. However, probable factors explaining the species-richness of this genus remain unclear. Previous studies lacked sufficient data and sampled less than half the species. In where Delias is found, the diversification of many other animal taxa can be explained by episodic fluctuations of sea level during the past 3 Myr and the orogeny of the New Guinea central highlands about 5 Mya. I therefore reconstructed the evolutionary history of 212 Delias species and inferred the timing of their divergence to examine whether eustasy (sea level fluctuations), and/or New Guinea orogeny coincide with Delias diversification. The MRCA of a clade with ~ 80% of species dispersed out of New Guinea ca. 14 Mya, but at least six subsequently diverging lineages dispersed back to New Guinea. Diversification is associated with frequent dispersal of lineages among the Southeast Asian islands, and—with the exception of New Guinea—divergence of sister taxa on a single landmass is rare and occurred only on the largest islands. We surmise that frequent eustasy during the Neogene likely aided inter-island dispersal that preceded differentiation. Many extant New Guinea lineages started to diversify after 5 Mya, suggesting that orogeny facilitated their diversification. We have revised the species group classification system to avoid poly- and paraphyly. Factors including wing pattern evolution, mimicry, and sexual selection might also contribute to these butterflies’ rapid speciation and diversification.

Recommended Citation

Liang, Weijun, "To and fro in the archipelago: Repeated inter-island dispersal, eustasy and New Guinea’s orogeny affect diversification of Delias, the world’s largest butterfly genus" (2023). CUNY Academic Works.
https://academicworks.cuny.edu/cc_etds_theses/1086