Know what sets us mammals apart? Well it's not our good looks and inquisitive natures. In fact, it boils down to only two distinguishable traits: bearing children through live birth, and then feeding these children through breast milk. That's it. But as it is constantly made ever apparent, nature is not so easily defined.
While most amphibians, in fact nearly every species known to man, are parents that lay clutches of eggs, one new frog species revealed that they too are of the nurturing variety.
The new species described in this week's issue of the journal PLOS ONE, is a species of fanged frog indigenous to the Sulawesi Island of Indonesia. Known as Limnonectes larvaepartus, the newly described frog species revealed to researchers, who tracked them down for the better part of a decade, that not only are they capable of internal fertilization but they are also capable of giving live birth. While nearly a dozen other species of internal fertilizers within the world of frogs, who either deposit fertilized eggs or give birth to froglets, these fanged frogs are the first to ever give birth to developing tadpoles in the middle of both development stages.
"This new frog is one of only 10 or 12 species that has evolved internal fertilization, and of those, it is the only one that gives birth to tadpoles, as opposed to froglets or laying fertilized eggs" lead researcher of the study and ecologist at the University of California, Berkeley, Dr. Jim McGuire says. " [However] because we have not witnessed natural birth of tadpoles in free-living frogs, two possible alternative reproductive modes are possible for this species. Limnonectes larvaepartus reproduction may simply reflect what we have observed in the hand- direct birth of tadpoles. Alternatively, this species may be capable of retaining developing young in the oviducts through metamorphosis with subsequent birth of froglets. [But] the latter mode seems unlikely for several reasons."
But in spite of the discovery, much is left up to question. Discovered by accident, when what Dr. McGuire believed to be a male frog in his hands at the time gave birth to a clutch of tadpoles in his hands, researchers do not yet have enough information or data available to describe the precise mechanisms or features of this strange phenomenon. In fact, what the researchers hope to discover next, in a continued branch of their ongoing study, is exactly how this species is capable of internal fertilization. As most frogs have no conventional sexual organs to speak of, from which to transfer their sperm into the females of the species, there is still much mystery as to how these males are able to do it.
As most of Sulawesi's forest is currently gone, courtesy of some of the highest deforestation rates in the world, researchers are hopeful that they may be able to learn a lot about this species just in the nick of time. And since they may be unique unto this region of the world alone, conservationists are also hopeful that this discovery may lead to some changes in the deforestation practices displacing and decimating species in its path.
"These kind of findings are really valuable, especially in Salwesi where most of the forest is gone" lead herpetology researcher at the Zoological Society of London, not involved in the study, Ben Tapley says. "It's great that we're learning about these species before it's too late."
