Figure: a, Maximo Vicente-Zakaro, a Matsigenka native, standing by a swollen and scarred trunk in a “spirit clearing” near Yomybato Native Community, Manu, Peru. b, Swollen trunk at Los Amigos Research Center, Peru. c, Swollen and scarred trunk, Los Amigos Research Center. d, Myrmelachista schumanni ants and brood in a chamber within a swollen trunk. e, Cross section of a trunk reveals that chambers can extend to the center. f, Lengthwise section of another swollen trunk, with passageways and chambers.

 

Hundreds of tropical plant species obligately host ant colonies within hollow branches, trunks, or leaves. The origins of these plants, called ant-plants or myrmecophytes, and the benefits of their associations with ants were debated by naturalists for nearly a century.

Douglas W. Yu in Kunming Institute of Zoology (KIZ) and the Scientists in UK conducted the relative study and found that domatia (hundreds of tropical plant species house ant colonies in specialized chambers) are not galls and that most ant-plant inter- actions are mutualisms and not parasitisms, they revisit Spruce’s suggestion that ants can gall in light of our observations of the plant-ant Myrmelachista schumanni, which creates clearings in the Amazonian rain forest called “supay-chakras,” or “devil’s gardens.” They observed swollen scars on the trunks of nonmyrmecophytic canopy trees surrounding supay-chakras, and within these swellings, they found networks of cavities inhabited by M. schumanni.

They summarize the evidence supporting the hypothesis that M. schumanni ants make these galls, and hypothesize that the adaptive benefit of galling is to increase the amount of nesting space available to M. schumanni colonies.

http://www.journals.uchicago.edu/doi/pdf/10.1086/606022