STEM

Sex, food, and Montessori schools

science

Interested in reading the full article? Access our peer-reviewed manuscript in Evolutionary Ecology

“Some things in life are worth fighting for. . .” — for animals the defense of space, known as territoriality, usually functions to safeguard valuable resources like food and mates. However, for a remote species of tropical frog, we have recently discovered a surprising addition to things that adults find worth defending: suitable nurseries.

Human parents are well aware of the lengths some will go to to secure a first-rate nursery school for their children. Oddly enough, a parallel can be found on top of the world’s tallest single-drop waterfall (Kaieteur Falls, Guyana) where there exists the only known population of golden-coloured rocket frogs (Anomaloglossus beebei). These small poison frogs spend their entire development in giant tank bromeliads (i.e., 2-4 meters tall, Brocchina micrantha): within these plants, eggs are laid in the lower leaves and hatch as tadpoles. Fathers then transport their young to water-filled leaf axils higher in the plant through an elaborate piggyback ritual where tadpoles cling to a father’s back. Tadpoles must survive in selected leaf axils until metamorphosis, meaning the quality of a nursery can have profound implications for the success of the tadpoles contained within them.

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 there isn’t room for everyone. Thus, in addition to their intense parental care duties, male rocket-frogs are extremely territorial and aggressively defend established areas in bromeliads (which consist of multiple leaves) from potential intruders. Along with Johana Goyes Vallejos (University of Missouri) and James Tumulty (College of William and Mary) we wondered if the intense territoriality of males had any relationship to their intensive care-giving duties. In a bromeliad, what is the function of the space males are defending? Our study, recently published in Evolutionary Ecology, consisted of first characterizing leaf axils in bromeliads to understand the differences between pools that were used as nurseries versus those that were not. Once having established the “high-quality” parameters that characterized occupied pools, we took advantage of Tumulty’s long-term mark-recapture dataset to see if the location of high-quality nurseries coincided with the territories of established males. Indeed, these characteristic pools occurred significantly more frequently within defended territories.

In other words, males defend areas that may benefit their reproductive output in a non-immediate future– a cognitive feat of future planning that is not typically associated with amphibians.

In human terms, these parents are securing spots in Montessori schools before they were even pregnant.

The combination of the geographical isolation and specialized behaviors that characterize golden rocket frogs make them a key species to unlock our understanding of the evolution of parental care and cognition in amphibians and beyond. 

In the eye of the tadpole

science

Tadpole responses to environments with limited visibility: what we (don’t) know and perspectives for a sharper future

Access our peer-reviewed Perspective article here.

Throughout my encounters with different languages I have always been fascinated by words that cannot easily be translated. Some words hold a certain weight, cultural insinuation, or biological inference that isn’t fully described when translated on a word-to-word basis. For me, as a young French girl, my family would describe me as “gourmande” which is essentially a lover of delicacies in large quantities. Not so easy to translate into English without the misinterpretation of being a glutton. . .

Anyway. One of my favourite untranslatable words is umwelt, which from German is directly translated into “environment” in English, but is more profound at its core. In high school I learned this was the word used to describe the world perceived (or experienced) by a particular organism. For example, I might mistakenly design a task where I ask an animal to differentiate between two colors that they are biologically unable to distinguish (like red and purple for dogs) or I may not consider colors that are vital for the animal’s perception (like UV in birds and bees), and from there draw false conclusions. Being misled in this way stems from not considering an organism’s umwelt which has limited our understanding of aggression, cooperation, and intelligence throughout the animal kingdom.

The various nurseries where tadpoles are deposited to develop. Water samples in the top panel corresponds to the pool where they were sampled in the bottom panel.

But, we’re doing a bit better now. And that’s what this Perspective article is all about– briefly, (to get you up to speed on the system set up) various tadpoles from different species are deposited in a large range of aquatic nurseries. From size to water color and pool turbidity, it seems pretty intuitive that these vastly different rearing environments would have different implications for the larvae developing within them. What happens to tadpole eyeballs when they grow up in the dark? How does growing up in the dark affect behaviour (i.e., scavenging, predation, sociality)? Does that carry over across metamorphosis?

From a proximate perspective could the eye actually change? Is there even a precedence for this? (yes, there is. . . think along the lines of Vitamin A ratio shifts recorded in fishes 😉 ) From a behavioural perspective, what happens to predatory tadpoles (e.g. Dendrobates tinctorius) when their visual landscape breaks down; what about the tadpoles that depend on visual cues from their parents for feeding (e.g. oophagy by Oophaga pumilio)?

What happens, indeed! I have no clue. But look at this big ol’ gaping hole ready for questions!

Curious for more hypotheses and my first drawings published in a real, live journal? Check out our recently published paper in Frontiers in Ecology and Evolution.