Pheromone fingers may help poison frogs mate

During mating, immoderate antheral poison frogs clasp their partner’s look successful a love-potion-laced hug. 

The amorous amphibians may create pheromones successful glands successful their fingers, researchers study July 21 successful Molecular Ecology, highlighting an evolving knowing of nan complexity of frog mating.

Field biologist Diana Abondano Almeida and her colleagues were studying chemic connection successful amphibians and noticed a operation of quirks successful antheral poison frogs. The males of immoderate type person 1 markedly swollen fingertip connected each manus that becomes moreover much bulbous during nan reproductive season. Mating successful frogs often includes “amplexus,” which often is wherever the antheral grips onto nan female from behind, sometimes for hours aliases days (SN: 6/14/16). In cephalic amplexus, an different version unsocial to astir poison frogs, nan males grasp nan females by nan face, pinch nan fingers resting adjacent their mate’s rima and nostrils. 

This placement — particularly pinch nan concurrence of swollen fingers successful immoderate type — seemed excessively circumstantial to beryllium “mere coincidence,” says Almeida, of Goethe University successful Frankfurt. Other amphibians, specified arsenic salamanders, are known to usage chemicals called sodefrin precursor-like factors, aliases SPFs, during courtship. Some salamanders nutrient these SPFs utilizing tegument glands and transportation them to their mate done adjacent contact. Almeida and her squad wondered if nan frogs’ fingers were producing akin pheromones utilized successful mating.

The swollen digit (arrow) of this antheral Anthony’s poison arrow frog (Epipedobates anthonyi) whitethorn nutrient pheromones akin to what salamanders usage successful their ain courtship rituals.D. Abondano Almeida et al/Molecular Ecology 2024

The researchers took insubstantial samples from nan fingers of nan males of 2 type of poison frogs: stripe-throated rocket frogs (Leucostethus brachistriatus) from Colombia and a lab-reared organization of Anthony’s poison arrow frog (Epipedobates anthonyi). Using familial analysis, they compared nan comparative numbers of RNA transcripts — copies of nan DNA series utilized to make proteins, including pheromones — successful swollen and normal fingers. In some frog species, dozens of SPF genes were churning retired hundreds to thousands of times much RNA successful nan swollen fingers.

Almeida and her colleagues deliberation nan males are channeling these digit pharmaceuticals into nan females’ nostrils aliases tegument done nan prolonged nonstop contact. Given that amplexus occurs good aft nan frogs person paired up, nan pheromones astir apt aren’t utilized for attraction, Almeida says. Rather, they whitethorn footwear disconnected physiological changes successful nan female. “[They] could induce nan female to deposit eggs, aliases astatine slightest accelerate this process.”

Historically, frog courtship has been studied mostly pinch a attraction connected sound, peculiarly their repertoire of croaks and creaks, says Sarah Woodley, an integrative physiologist astatine Duquesne University successful Pittsburgh. But successful caller years, researchers person started recognizing nan domiciled of nan visual, tactile and chemic components of frog mating (SN: 6/2/14; SN: 2/2/23). 

“They’re blase animals,” Woodley says. “They are not conscionable utilizing 1 sensory modality to communicate. It’s not each astir calling.”

Almeida says location are plentifulness of adjacent steps successful this research. While nan elephantine upswing successful SPF transcripts surely hints astatine nan fingertips being specialized pheromone factories, early studies could find and isolate these proteins and find if and really they power nan female frogs’ biology.