“In animal life there are certain moments where what happens at that moment, could be more important than you would think…Hatching is one of those moments.”
- Dr. Karen Warkentin
Studying the adaptive plasticity in Red-Eyed Tree Frog Embryo’s is in part, studying the behaviors of organisms that have not yet been born. At first glance it is clear that frog eggs, clutches sometimes deposited on leaves hanging over water sources, will react to subtle changes in their environment by hatching early. Biologist and Professor Karen Warkentin made this observation when she bumped into a clutch of eggs while wading through the dense forest of Costa Rica, this was over a decade ago. Further into her research, Warkentin discovered that these pre-natal beings have the ability to make evaluative decisions in response to environmental conditions in order to stay alive. Warkentin explains that while the organisms are extremely vulnerable to predation, they can receive information about the world around them and, “for some (time) period,” make the decision to hatch.
Phenomena so subtle as these can go unnoticed, the ferocious and loud wilderness of this planet often drowning out the nearly noiseless drop of a egg into its aquarian home. Even more so, how perceptive of an eye would it take to capture the writhing’s of these minuscule creatures, hesitant in their egg sac waiting for the right moment to hatch or not. Warkentin’s research embarks on the journey of Red Eyed Tree frogs from inception, to hatching and into the adolescent and adult lives of the species. Understanding how the life patterns of these organisms are shaped is highly informed by the, “critical transition point,” of frog embryos making the decision to hatch. Taking a critical view of the many different elements of Warkentin’s research we can begin to ask further questions about the abilities of these organisms and how they might relate to our place within The Animal Kingdom. One such question might be whether these embryos are making a decision to hatch based on something inherent or something external.
The ‘will’ of an organism to survive has been described as an inherent ability, the survival mechanism a function able to be switched on and off in response to environmental pressures. Amidst this concept remains the fact of mortality, the physiological inevitability of death. Given this boundary organisms are armed with (r)evolutionarily designed tools to increase opportunities and chances for survival. Which tools to use and when to use them can be considered variable from one individual to the next, an individual's decision or in simpler terms an individual’s own will.
If there is to be an understanding of, whether the ability to make a critical decision to survive is inherent or acquired, at what point in the development of an organism does this will or ability to choose a survival mechanism arise? Further, is the choosing simply a physiological and behavioral response to environmental stimuli or rather a sentient device that actively makes personal decisions to modify the onset of death. Consider the concept of adaptive plasticity in Agalychnis Callidryas, the Red-Eyed Tree Frog.
Like the Red Eyed Tree Frog, Glass Frogs lay their eggs terrestrially, on land. While studying the behavioral similarities between these species of frog can give scientist key insight into their evolutionary histories, finding a frog that is nearly transparent in a densely covered rainforest can be quite the challenge. Join Field Biologist Javier Mendez as he leads us into the realm of the elusive Glass Frog.
A. Terrestrial vs. Aquatic Colonization
Lineages of frogs that evolved the ability to lay eggs on land as opposed to in water, also had to evolve mechanisms to deal with the differences in biotic and abiotic components found in these environments. How can comparing Glass Frogs and their behaviors give us further knowledge of plastic hatching?
B. Glass Frog Dads
In the world of Glass frogs, it is common for the male to provide most of the parental care to their eggs. How they do so while fending off the various threats posed by the environment is an example of a evolutionary behavior that went on to alter the fate of a species.
C. Parental and Offspring Success
“Waste disposal is an issue that life faces,” explains Dr. Warkentin, and in many animals waste disposal is aided by water in its ability to flush out toxic substances which makes waste disposal much easier for aquatic animals. So how do terrestrial animals who have far less access to water cope with the issue? One answer is to let parents take care of it, but how can frog embryo’s be sure that they will be given this life saving tender love and care?