Evolution of myrmecophytes and mechanisms of speciation in Southeast Asian ant plants of the genus Macaranga (Euphorbiaceae)
Myrmecophytes (= ant plants) are plants permanently colonized by ants and are found only in the tropics. The ants receive a home and food from the plant, in return they protect "their" plant from herbivores, pathogens and plant competitors. The paleotropical plant genus richest in ant plants is Macaranga (Euphorbiaceae). About 30 species of Macaranga are obligate myrmecophytes associated with nine ant species of the genus Crematogaster. They occur exclusively in Southeast Asia in "Sundaland," i.e., Borneo, Sumatra, and the Thai-Malay Peninsula. The goal of our work is to use molecular systematics to answer questions about the evolution and biogeography of Southeast Asian Macaranga species. Nuclear (ncSSR) and plastid (cpSSR) microsatellite analyses, comparative sequencing of individual loci, and next generation sequencing technologies (genotyping-by-sequencing, GBS) are used.
The initial molecular systematics studies on the genus Macaranga aimed to elucidate the relationships of the myrmecophytic species and their closest relatives. The phylogenetic trees obtained in this work revealed that myrmecophyly evolved independently several times in Macaranga. Furthermore, we are investigating the spatio-temporal evolution of the species, including when, where, and under what circumstances the morphological traits associated with myrmecophyly arose (or were lost) during evolution. This will further contribute to a better understanding of the biogeography of Sundaland, which in part underwent extreme paleogeographic changes. To this end, comparative population genetic and phylogeographic studies of selected Macaranga species is being conducted.
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