Evolving a Bolder Voice—How One Amazonian Bee Species Defends Its Daily Sweets

For bees, a nectar-filled flower field abundant with pollen may as well be the Holy Grail. And as such, protecting this sweet source is a primary cause for concern. Most species display a poker face of sorts to hide the spoils from anyone other than its nestmates, but one study shows that in Brazil one species of bees is defending its pollen with a much stronger signal.

Utilizing "shouts" in their food-recruitment signals, bees of the genus Trigona known by their species name "spinipes" communicate to competitors their property rights to flower fields and their intent to defend, says a UC San Diego paper recently published in the journal Currently Biology.

Conveying their boldly aggressive message using chemical signals in the form of pheromones, spinipes are successful in warding off competitors by communicating their power in large numbers. 

"It's a signal with honest aspects and the possibility of lies" professor of biology at UC San Diego and research advisor to the project James Nieh says. "It tells nestmates where to find good food and hints at a larger occupying force."

Best explained with concepts of the philosophy behind biology, this pheremone signalling is a successfully derived altruistic characteristic inherent in the species. Altruism meaning that the energy and 

overall health of the individual may be compromised for the overall health of the hive, the species is able to flourish and survive, thanks to a group mentality and an effective poker face that few competitors or eavesdroppers would readily bet against.

But what if some species were to call it's bluff? Thought to have derived as a coevolutionary adaptation to the presence of thieving eavesdroppers, a species known as hyalinata, the signalling is effective in large abundances but less threatening in small doses. 

"Our study provides a new way of looking at how eavesdroppers affect the evolution of animal 

communication signals" lead researcher and PhD student in Nieh's lab, Elinor Lichtenberg says. "Our results show that eavesdroppers can help select for conspicuous signals that are easiest for intended recipients to detect and understand." 

Complicated evolutionary tactics that are not quite entirely understood, these signalling approaches not only allow for scientists to observe how species interact in our current day and age, but also how their ancestors once did. And in bees, these cues which shape pollination and competition, the role has been crucial in the organisms' survival.

 "Researchers have in general thought about eavesdropping as a force that makes signals less conspicuous, leading to the evolution of 'whispers' to counter spying" Nieh says. "However, we show that eavesdropping can also lead to 'shouts'. In this stingless bee system, with aggressive colonies jockeying for limited resources, more conspicuous food-recruitment signals indicate a higher likelihood that a resource will be harder to wrest away."

But even still, hyalinata foragers who seek out spinipes' abundant food sources can challenge for supremacy by aggregating enough nestmates to compete in a physical battle with spinipes. However, a single misstep or calling the wrong bluff may lead to a fatal error.