Aug. 12 (UPI) -- Scientists have discovered a frog species in Brazil's Atlantic rainforest that practices harem polygyny.
The discovery, described Wednesday in the journal Science Advances, marks the first time biologists have observed a male frog offering his companionship and loyalty to two females during a breeding season.
"Single-male polygyny with reproductive fidelity occurs in invertebrates, bony fishes, and some tetrapods, such as lizards, mammals, and birds," researchers wrote in the new paper.
According to the study's authors, the practice is not well-documented among amphibians.
To confirm the practice of polygyny among Thoropa taophora frogs, researchers observed the behavior of males during the course of the breeding season.
The research team, led by Fabio de Sá, a biologist at Sao Paulo State University, watched as male frogs regularly patrolled their territory and emitted loud calls to scare off intruders. For several weeks, males remained close to their eggs and tadpoles, guarding them from predators.
Female behavior observed by the research team suggests each harem features a hierarchical structure. Scientists noted that when a higher ranking female started cannibalizing eggs, the male would mate with her, ensuring that her genes would be carried by the new eggs.
"When a secondary or a peripheral female cannibalizes eggs, the monopolist male immediately approaches and briefly embraces the female, which stops cannibalism," researchers wrote.
When scientists analyzed the genes of tadpoles produced by different harems, they found the dominant female's genes accounted for between 56 percent and 97 percent of the offspring.
De Sá and colleagues estimate the unique behavior of Thoropa taophora frogs evolved due to the pressures of the competition among males for ideal breeding grounds and fit females.