Frog dads establish territories around high-quality reproductive resources

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Some things in life are worth fighting for. When you’re a single golden rocket frog living atop the world’s largest single-drop waterfall, a high-quality nursery is one of the major things worth the fight. This is according to a new publication in Evolutionary Ecology coauthored by Dr. Johana Goyes Vallejos.  

Golden rocket frogs spend their entire lives in enormous plants called giant tank bromeliads. Eggs are laid in the lower leaves, where they hatch as tadpoles. They then wriggle onto the backs of their waiting fathers, who transport them to a suitable aquatic nursery higher in the plant. Since the tadpoles will stay put until metamorphosis, the quality of the nursery can have profound implications for their survival.

“Of course, if a frog’s only suitable breeding ground is on top of an isolated waterfall in the middle of the Guyanian Amazon, it isn’t surprising that frogs call dibs on the best spots,” says Goyes Vallejos, who is an Assistant Professor of Biological Sciences. “Thus, in addition to their intense parental care duties, male rocket frogs are extremely territorial and aggressively defend established areas in bromeliads from potential intruders.”

Goyes Vallejos teamed up with Dr. Chloé Fouilloux with the University of Jyväskylä, Finland, and Dr. James Tumulty with the College of William and Mary to ask if the intense territoriality of males had any relationship to their intensive caregiving duties. The team first measured variation in bromeliad pools to understand what made nurseries desirable. One feature that stood out is the amount of mucilage, or “goop” as the researchers affectionately call it, in a nursery.

“Mucilage can decrease the amount of oxygen in the water, which is not good. The more mucilage, the lower the quality of the nursery,” says Goyes Vallejos. The team then mapped out male territories to see if the locations of high-quality nurseries coincided with the territories. They found that clear pools -- that is, pools with low levels of mucilage -- occurred more frequently within defended territories, suggesting males choose which plants to defend based on their characteristics.

Dr. Johana Goyes Vallejos (center) with her colleagues, Dr. Chloé Fouilloux (left) and Dr. James Tumulty (right)

“In other words, males defend territories with high-quality nurseries, characterized by clear pools with low mucilage levels, crucial for the survival of their tadpoles, a behavior that may benefit their future reproductive output —especially if females are attracted to high-quality resources. But this remains to be tested," says Goyes Vallejos.

The study suggests a fascinating connection between the territorial behavior of male golden rocket frogs and their caregiving duties, as they strategically defend areas with high-quality nurseries. The findings highlight the remarkable ability of these frogs to discern the quality of nursery sites, effectively demonstrating a sort of “real-estate” knowledge that plays a crucial role in their future reproductive success.

Fouilloux, C.A., Goyes Vallejos, J., Tumulty, J.P. Home is where the high-quality resources are: nursery characteristics and territory distribution suggest reproductive resource defense in golden rocket frogs. Evol Ecol (2023).

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