Natures wonders: trees induce ants to protect them (Introduction)

by David Turell , Monday, September 18, 2017, 22:54 (2621 days ago) @ David Turell

Tropical trees provide habitats for ants that protect the trees from other insects:

https://www.sciencedaily.com/releases/2017/09/170918123539.htm

"Examing the relationship between the Amazon rainforest plant Cordia nodosa in Peru and the Amazonian ant Allomerus octoarticulatus, they found the degree to which the ants express two genes significantly impacts the amount of protection they provide to their hosts.

The ant-plant relationship is an example of a phenomenon in nature known as mutualism, in which two seemingly disparate species interact in a manner that is mutually beneficial for both. Two common examples of mutualisms are pollination and seed dispersal, both of which involve plants attracting animals that perform an important service by offering them a food reward. The features of mutualisms, however, vary across animals and species.

"'Around 400 species of tropical plants have evolved specialized structures called domatia to house ant colonies that defend them, mainly against herbivorous insects," said Megan Frederickson, associate professor in the Department of Ecology & Evolutionary Biology at U of T and senior author of a new study published in Proceedings of the Royal Society B. "Because there are many, many arboreal ants in rainforests, tropical trees are often completely covered in ants."

"Frederickson suggests that these domatia that give ants a home probably evolved because they attract the ants that keep herbivores off plants.

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"The researchers zeroed in on two genes of Allomerus octoarticulatus that regulate foraging behaviour, knowing that how an animal forages for food often determines how much benefit its plant partner receives. Working in the field in the Peruvian Amazon, they fed some colonies a chemical that increases the activity of the genes' products, and observed how it changed ant behavior. They then collected the ants and brought them back to Toronto for molecular analysis.

"'We found that when we activated the products of these two ant genes, more workers were recruited to attack herbivores, resulting in less damage to the trees," Frederickson said. "Gene expression in ant workers was also correlated with whether an ant colony discovered a grasshopper and how much damage was inflicted on leaves."

"The results suggest a molecular basis for ant protection of plants in this mutualism. Previously, little was known about the genes or molecular mechanisms that make some ants better bodyguards than others."

Comment: The mutualism in this case must have caused epigenetic changes in the ants' DNA to develop the foraging genes.