Scott Poethig the Biology and also Aaron Leichty, GR’18, examine the components that govern the advancement of the acacia’s ant-sustaining traits.


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A establishing queen acacia-ant cut her very first entrance hole into the swollen mandrel in which she will begin her colony, the first thorn do by this young seedling ant-acacia in Veracruz, Mexico, 1962.

You are watching: Ants and acacia trees symbiotic relationship

Dan Janzen


During his doctoral studies in the 1960s, Dan Janzen, currently Thomas G. And also Louise E. DiMaura hatchet Chair in the department of Biology, re-described what has come to be a classic example of biological mutualism: the obligate relationship between acacia-ants and their organize acacia trees. The acacia trees produce specialized structures to shelter and feed the ant colony, and the ants, in turn, defend the tree against herbivores.

In a current study in Proceedings the the national Academy that Sciences, partner of Janzen’s in the biologic department i found it a genetic mechanism the programs the plant side of the ant-acacia relationship. Scott Poethig, the john H. And also Margaret B. Fassitt Professor of Biology, and also Aaron Leichty, GR’18, proved that these species of acacia develop the traits crucial to feed the ant colony—hollow swollen thorn to home them, and also nectaries and nutrient-rich leaflet tips dubbed Beltian body to feed them—as part of an age-dependent phenomenon in tree development.

“There is a cost linked with making this traits,” states Poethig, an elderly author on the report, “but the plant needs them, otherwise the a goner. So there’s a tradeoff happening. And what we discovered is that these characteristics seem to have advanced on the back of a preexisting pathway the governs a developmental change in plants.”

Leichty, now a postdoctoral researcher in ~ the college of California, Davis, says, “When we dug right into the literature, we found that a most plant defense strategies room age-dependent. It’s counterintuitive because you think the young plants would desire to start making this structures right away for this reason they wouldn’t gain eaten, yet our findings and profound logic indicate there are organic constraints on making them.”

To examine the traits in the context of plant development, Poethig and Leichty gathered acacia seed from virtual sellers in Belize and from Janzen himself. They it was observed what Janzen had actually seen in the wild a half-century before.

“Sure enough, the properties appear, but not right away,” Leichty says.

After obtaining the first genome sequence of a Vachellia species, the researcher looked specifically at certain microRNAs —short, non-coding sections of the genome—miR156 and miR157, i beg your pardon they had previously uncovered to be connected with controlling the developmental timing of characteristics in other plant species.

As the swollen thorn and other ant- attracting traits began to show up in the acacia, level of miR156 and miR157 declined, and also the level of different protein transcription factors repressed by this microRNAs increased.

To acquire a feeling of how the regulation of these traits may have arisen evolutionarily, the researcher explored various other acacia species that carry out not make Beltian bodies or puffy thorns however do do nectaries on your leaves. In these species, as in the ant-acacias, miR156’s decrease coincided with the figure of the nectaries. The similarity among the acacias in this regard says that the present pathway to be coopted to manage the various other traits the are required for a healthy and balanced bodyguard—swollen mandrel and great food—the researcher say.

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To Janzen, the finding is donate of his field discoveries, make a instance for the blending of field and lab investigations.

“I watched and asked why,” claims Janzen. Of Poethig and also Leichty, that notes, “They watched and asked how.”