Projects: Heather Green & Taylor Edwards


The Implications of Isolation: A Collaboration Between Heather Green and Taylor Edwards

Edwards, Taylor, Gavenus, Erika, Green, Heather | May 18, 2017

A chuckwalla in La Cholla, March 2017 courtesy of Heather Green & Taylor Edwards

Fine artist and educator Heather Green, has teamed up with herpetologist and geneticist, Taylor Edwards, for the 6&6 Collaboration. Forged by the Next Generation Sonoran Desert Researchers network (N-Gen,, 6&6 is a collaboration between artists and scientists to explore the patterns and processes of the Sonoran Desert and Gulf of California. Green and Edwards started the collaboration from scratch –with lots of ideas and concepts, but no tangible project in mind. Geographically, they narrowed in on Bahía La Cholla, an area they are both familiar with and in which Green has worked extensively. “We went about a year ago down to Cholla Bay along the Gulf of California and examined all of the different biomes that comprise the bay. We were sort of thinking that we might get into something marine.”

As is often the case, nature had other plans. During that same field visit as they hiked along the periphery of a small mountain Edwards and Green spotted some chuckwalla (a large lizard primarily found in the southwestern United States and northern Mexico). Despite years exploring and working in the region, Green had never seen a live chuckwalla in the area, only skeletal remains: “I’ve always had an interest in trying to find a chuckwalla, and never in all my years of going down had I ever seen one before.”

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March Trip

In March we traveled to La Cholla to explore its diverse biomes—the bay, estuary, rocky intertidal and bluff—to try to hone our project hypothesis. It was beautiful, with still so many plants in bloom, a new moon and a large tidal shift.

The first evening we explored the expanse of the bay by headlamps—walking ankle- deep among buried flounder, bullseye puffers that seemed to be just dreamily floating, sea hares, swimming two-spotted octopus, a giant blooming metridium anemone and undulating sting rays. It grew foggy, and through the beam of our headlamps we could make out numerous great blue herons wading in the distance, with a multitude of stars visible overhead.

The next morning we ventured out in the rocky intertidal between Pinto and Pelican Point, encountering dozens of heliasters, a swimming clam, buried mantis shrimp, a colorful wounded wrasse, and so many other creatures. The rich textures of all of the life on the underside of rocks were also of interest—bryazoans, tunicates, sponges, limpets and chitons—Taylor wondered how their individual gut flora might differ from the surrounding ocean water, and what eDNA might reveal about the possible symbiotic relationships that might otherwise go unnoticed. He collected internal liquid from anemones, sponges and sea cucumbers to test from.

Then we hiked the circumference of the rocky and isolated bluff, Roca del Toro—an island now surrounded by encroaching development, although perhaps it has always been a sequestered setting for the creatures that live there. Over two days we spotted two chuckwallas and collected scat from outside their dens. We were able to see them tucked deep inside with the reflective light of Taylor’s field mirror. We hope to gather enough DNA from the surface of the scat to identify the lizards and their relationship to the surrounding landscape. Have these chuckwallas diverged geneticaly due to of the secluded area they live, or are they the same common Sonoran Desert species, only recently becoming isolated due to the intruding development?

Back in the lab in Arizona, we successfully isolated DNA from both the sea water and the scat samples. We are trying to characterize the genetic lineage of the chuckwalla population at Roca del Toro and have successfully isolated a small ‘sentence’ of mitochondrial DNA that will act as a barcode to identify how this small, isolated population fits into the genealogy of Chuckwallas in the rest of their range.

Finding a Theme

Meeting at Taylor’s house to discuss ideas
Meeting at Taylor’s house to discuss ideas

We have now had a few meetings and are starting to narrow in on the theme of our project. We are both intrigued by the ephemeral stories found in the changing tides, such as the tracks left during low tide but soon washed away as the tide comes in. We are also interested in how these stories change over time, including deep time as sea levels changed during the Pleistocene and more recently as development transforms the shoreline in the Sea of Cortez. We have decided to focus our project on Bahia la Cholla in the Northern Sea of Cortez. Heather is currently working on a project titled 'Palimpsests of Bahia Adair' that captures the stories of this region through casting of mud flat textures and a time-lapse video of the tracks left by cerithium. Similarly, we may explore other ‘casts’ left as the fossils in geologic record to characterize changes and similarities over time. We may also explore the invisible ‘tracks’ present in the composition of microorganisms by performing comparative environmental DNA analyses on these ephemeral surfaces (eDNA).

We plan to visit the site together early in 2016 and hope that through finding patterns in our preliminary explorations, we can develop hypotheses which we will test during the realization of this project.

Example casts of tracks left in the mud flats at Cholla Bay
Example casts of tracks left in the mud flats at Cholla Bay