Plants Fight over Ants for Seed Dispersal

A new study has found that some plants fight over friendly ants for seed dispersal.

Some woodland plants depend on ants to spread their seeds. These plants are called myrmecochores. An estimated 3,000 species of plants attract ants by offering them elaiosome, a lipid-rich seed appendage.

Previous research has shown that some plants cheat ant species by making seeds that appear as elaiosome from true myrmecochores.

Researchers led by Robert Warren from Buffalo State found that plants increase their seed size or release their seeds at a different time of the year to avoid losing their ant friends. The team showed that the ants ignored small seeds and preferred large ones.

"It is well known that plants compete for the light, water, and nutrients they need to thrive," said Warren. "However, we show that plants also compete for living resources such as ants to disperse seeds."

For the study, researchers observed 96 hours of video footage of ants at a seed-bait station and assessed 210 ants on their seed dispersing behaviour.

"Our results show that ants clearly prefer larger seeds to smaller seeds," said Warren, according to a news release. "A comprehensive analysis of ant- and non-ant dispersed plants suggests that small seeded plants must then release their seeds very early in spring when ant foraging is unreliable to avoid competing with the larger seeds, which are released later in spring, for ant attention."

The study, "Competition as a mechanism structuring mutualisms," is published in the Journal of Ecology.

Unlike animals, plants don't have the luxury to move around to seek better environments. Their 'rootedness,' thus, forces them to find novel ways to fight over nutrients, avoid predators and most importantly, reproduce.