Adam Roddy is an F&ES postdoc who works on plant physiology with Craig Broderson. His research spans multiple projects, including one in Mexico of the genus Encelia that he is working on with colleagues Christopher DiVittorio (UC Berkeley) and Sonal Singhal (University of Michigan). Field Notes will soon be publishing interviews and stunning photos from this groundbreaking study of how natural selection and adaptation to extreme climates causes speciation – one species becoming two.
As researchers dealing with large questions about evolution, Adam and his colleagues spend a lot of time in the field. Sometimes, fieldwork means literally searching for the species they want to study. From one year to another, populations can shift, move, change and even quietly slip into extinction. The following story about the Encelia genus sheds light on just how important environmental research is to understanding why and when this happens, and to improving strategies for conservation.
“There is a species of the flowering plant we work on, Encelia densifolia, which seems to be the basalmost species [earliest common ancestor] in the genus. It was first described about 125 years ago. Donald Kyhos and Curtis Clark went to look for it in the late 1980s and found it in the Sierra de Santa Clara mountain range in Mexico, but only at one of the sites where it was first spotted, on rural ranchland.
Chris [DiVittorio] led an expedition a few years ago to see if it was still there. He found it in a wash where it was abundant but then, last year, we both went back and all the plants were gone. We thought then that the species was extinct, as that particular wash was the only place Chris had found it on his previous expedition. Then we realized it was still there! It had moved away from the wash onto the adjacent slope and, honestly, we were freaking out about the first individual we found. As far as we know, every individual of the species lives on that slope. All sixty-one of them.
But then we realized that the species is hybridizing with the much more common Encelia farinosa that exists all over the area from Arizona to Baja. Basically, the rare species is crossing with the common one, and this continued mixing may ultimately lead to the demise of the rare, endemic Encelia densifolia. If that turns out to be the case, it would be the first time that hybridization of two naturally occurring, related species has led to extinction.
This is an exceptional conservation case and we really need to study and understand this better, but we may be running out of time.”
As told to Agnes Bridge Walton by Adam Roddy