Summer Internships at STRI

The development of adaptive embryo behavior

BACKGROUND ­– When to hatch is a decision embryos make, based on environmental cues. Hatching is also a physical feat that embryos perform. The ability to assess cues, exit from the egg, and survive outside the egg all change as embryos develop. Thus, under the same external conditions, both what embryos can do and what they should do to survive change developmentally. The overall project examines the development and regulation of environmentally cued hatching in red-eyed treefrogs, Agalychnis callidryas. These embryos hatch up to 40% prematurely to escape from threats to the egg, using cues in at least two sensory modalities, and multiple selective trade-offs shaping hatching timing are known. The project integrates work on hatching mechanisms and performance, sensory system development, and hatching decision rules for responses to simple hypoxia cues and complex mechanosensory cues, to examine why and how development changes behavior. It will improve our understanding of embryo lives, behavioral development, and how animals use different kinds of information to make decisions.

TRAINING, DUTIES, AND INDIVIDUAL PROJECTS – Work will include fieldwork at local ponds, and perhaps streams, and lab research based at the Gamboa schoolhouse. Schedules will include work during the day and at night, and will be dictated by when eggs are laid, and thus by weather conducive to frog breeding; days off will be unpredictable until eggs are laid. Interns will participate in multiple parts of the project, working directly with Prof. Warkentin and potentially also with PhD students Kristina Cohen, Julie Jung,  Jesse Delia, and/or Javier Méndez to gain a broad understanding of research in our laboratory. They will learn a substantial amount about the behavior, ecology, and natural history of red-eyed treefrogs and their natural enemies, and may also work with glassfrogs, hourglass treefrogs, and/or foam-nesting leptodactylids. They will gain experience with appropriate methods for collecting and handling frog embryos, larvae, and perhaps also their predators, as well as with analytical methods and scientific computer software. Daily interactions in the Warkentin lab will build a strong theoretical framework for the research, including fundamentals of experimental design and behavioral observation. Interns will be mentored to develop an individual project, or a collaborative project with another intern, focusing on a tractable question within the overall research project. Project specifics will depend on student interests, skills, and results of pilot observations or experiments. Possibilities include vibration playback experiments or hypoxia experiments to assess developmental changes in hatching decision rules, respirometry to quantify developmental changes in metabolism, studies of developmental changes in hatching performance, or tests of mechanosensory mechanisms underlying predator-induced early hatching.

QUALIFICATIONS – Interns will be selected based on merit, potential for the experience to benefit the intern, and potential for the intern to benefit the project. We will consider academic training and skills relevant to the research – background and/or interests in behavior, physiology, development, ecology, evolution, and/or herpetology are relevant, as are skills in photography or videography, familiarity with scientific software, and experience working with amphibians. We will also consider personal suitability for working under field conditions and living in shared accommodations in Gamboa. We work in both English and Spanish; ideally interns should have some facility with both languages. We strive to create a diverse, congenial, and productive team each field season.


Warkentin KM (2011) Environmentally cued hatching across taxa: Embryos respond to risk and opportunity. Integr Comp Biol 51:14-25

Warkentin KM (2011) Plasticity of hatching in amphibians: Evolution, trade-offs, cues and mechanisms. Integr Comp Biol 51:111-127

Warkentin KM, Caldwell MS (2009) Assessing risk: embryos, information, and escape hatching. In: Dukas R, Ratcliffe JM (eds) Cognitive ecology II. University of Chicago Press, Chicago, pp 177-200

Warkentin KM (2007) Oxygen, gills, and embryo behavior: mechanisms of adaptive plasticity in hatching. Comp Biochem Phys A 148:720-731  (Warkentin2007)


Living & Working in Gamboa (Information from Prof. Warkentin, 2015.)

Advice from a 2009 Intern (Note: internet is now better and prices are higher than in 2009.)


How to apply for an internship

ALL APPLICANTS (US and Latin American) – Apply directly to the Warkentin Lab using the form and instructions below.

Internship Application Form (fillable pdf) and Internship Application Instructions

For 2017, the application deadline is February 26.