To Mate, This Frog and Her Sex Partners Work Up a Lather
The female gray foam-nest tree frog increases her odds of reproducing by mating with multiple males and bubble-wrapping her eggs.
These frogs put the “group” in “group sex”—and that helps them thrive.
Of all vertebrates, gray foam-nest tree frogs exhibit the most extreme form of simultaneous polyandry, or a female mating with multiple males, says behavioral ecologist Phillip Byrne of the University of Wollongong in Australia.
After a heavy rain swells pools in the African landscape, male frogs gather in poolside vegetation and call for mates, while females in the pools absorb water through their skin. When she’s hydrated enough, a female heads for an overhanging branch. En route she is amplexed—gripped in a sexual embrace—by a male.
The joined pair climb to a nesting site. There the female discharges a watery fluid, whips it to a foam with her back legs, and puts in her eggs. At this point, says Byrne, up to 20 more males “line up in an orderly fashion by the female and vigorously and synchronously beat their back legs to help make a big wonderful nest,” where they deposit their sperm.
The group spends hours pumping out gametes and bubble-wrapping them in foam that will shield growing embryos. Five days later tadpoles will wiggle free of the nest and plop into the water below.
Nearly all C. xerampelina females mate with multiple males to produce one egg clutch, says Byrne—and that confers genetic advantages. His research shows that 20 percent more offspring survive from those females than from females that mate with just one male.
Unlike species whose males compete brutally to mate, these frogs’ orgies are calm affairs, Byrne says. “By the females’ letting lots of males sire offspring, it makes this a pretty relaxed business.”
Gray Foam-Nest Tree Frog
HABITAT/RANGE: Tree-, crop-, and grass-covered lands in parts of southeastern Africa
CONSERVATION STATUS: Least concern
OTHER FACTS: Polyandry makes offspring more genetically diverse. That could help insulate C. xerampelina from threats that have resulted in about a third of the globe’s amphibian species being classified as threatened or extinct.
Related Topics
You May Also Like
Go Further
Animals
- This ‘saber-toothed’ salmon wasn’t quite what we thoughtThis ‘saber-toothed’ salmon wasn’t quite what we thought
- Why this rhino-zebra friendship makes perfect senseWhy this rhino-zebra friendship makes perfect sense
- When did bioluminescence evolve? It’s older than we thought.When did bioluminescence evolve? It’s older than we thought.
- Soy, skim … spider. Are any of these technically milk?Soy, skim … spider. Are any of these technically milk?
- This pristine piece of the Amazon shows nature’s resilienceThis pristine piece of the Amazon shows nature’s resilience
Environment
- This pristine piece of the Amazon shows nature’s resilienceThis pristine piece of the Amazon shows nature’s resilience
- Listen to 30 years of climate change transformed into haunting musicListen to 30 years of climate change transformed into haunting music
- This ancient society tried to stop El Niño—with child sacrificeThis ancient society tried to stop El Niño—with child sacrifice
- U.S. plans to clean its drinking water. What does that mean?U.S. plans to clean its drinking water. What does that mean?
History & Culture
- Séances at the White House? Why these first ladies turned to the occultSéances at the White House? Why these first ladies turned to the occult
- Gambling is everywhere now. When is that a problem?Gambling is everywhere now. When is that a problem?
- Beauty is pain—at least it was in 17th-century SpainBeauty is pain—at least it was in 17th-century Spain
- The real spies who inspired ‘The Ministry of Ungentlemanly Warfare’The real spies who inspired ‘The Ministry of Ungentlemanly Warfare’
- Heard of Zoroastrianism? The religion still has fervent followersHeard of Zoroastrianism? The religion still has fervent followers
Science
- Here's how astronomers found one of the rarest phenomenons in spaceHere's how astronomers found one of the rarest phenomenons in space
- Not an extrovert or introvert? There’s a word for that.Not an extrovert or introvert? There’s a word for that.
- NASA has a plan to clean up space junk—but is going green enough?NASA has a plan to clean up space junk—but is going green enough?
- Soy, skim … spider. Are any of these technically milk?Soy, skim … spider. Are any of these technically milk?
- Can aspirin help protect against colorectal cancers?Can aspirin help protect against colorectal cancers?
Travel
- What it's like to hike the Camino del Mayab in MexicoWhat it's like to hike the Camino del Mayab in Mexico
- Is this small English town Yorkshire's culinary capital?Is this small English town Yorkshire's culinary capital?
- This chef is taking Indian cuisine in a bold new directionThis chef is taking Indian cuisine in a bold new direction
- Follow in the footsteps of Robin Hood in Sherwood ForestFollow in the footsteps of Robin Hood in Sherwood Forest