Senior’s paper on sea turtles published in biology journal

By David Lim and Catherine Wang

Alexander Jaffe ’11 led a study that was published in the peer-reviewed scientific journal “Biology Letters” Jan. 26. The paper reports the first quantitative evidence that supports an evolutionary correlation of habitat and body size in turtles and tortoises, a theory long assumed by evolutionary biologists but never statistically proven.

“Biology Letters” is published bimonthly by the United Kingdom’s The Royal Society, the world’s oldest scientific academy and ranked as the 14th most important biology journal in terms of its scientific impact.

The study demonstrated through statistical analysis that different ecological environments have different optimal body sizes for turtles and tortoises inhabiting those areas. The results showed that marine turtles have the largest optimal shell length, followed by island tortoises, while freshwater and mainland turtles are several times smaller. The results also showed a surprisingly strong correlation between habitat change and significant adjustments in body size.

“I’ve always had a passion for science, especially biology and marine biology,” Jaffe said. “It’s something I’ve focused on a lot extracurricularly over the last few years and I was intrigued by evolutionary and ecological biology because it was something I had less experience with at the time and wanted to learn more about.”

Jaffe conducted the research in Dr. Michael Alfaro’s evolutionary biology lab where he had worked for past the two summers. Alfaro, an assistant professor at UCLA, co-authored the study along with another post-doc student.

He spent almost 30 hours a week in the lab during summer after sophomore year helping undergraduates with their own research projects.

In Alfaro’s lab, he was trained by other researchers in lab techniques such as DNA processing and the statistical analysis that would be central to his data-based study. Prior to his internship, Jaffe had not been exposed to the programming skills necessary to analyze the large amounts of data needed to process.

Jaffe enjoyed his encounter with college-level academic research and returned the next year to the lab.

“I already worked there one summer and [Alfaro] said ‘You’re ready for your own project,’” Jaffe said.

Jaffe said he eventually decided to focus his research efforts on turtles, which he describes as a “relatively small group with an interesting evolutionary history” and a topic he could work on during his summer internship.

His research, which was federally funded by the National Science Foundation, involved collecting genetic data and fossil records from previously published scientific literature and analyzing this information in order to create statistical computer models.

After two months, Jaffe had analyzed enough data for his study to start writing his conclusions in his paper.

“I was the lead author on the paper but by no means did I do all the work,” Jaffe said. “It’s a really cooperative process, working with a post-doc and university professor.”

After weeks of collaboration with his fellow authors, who Jaffe said were definitely more experienced with the “vocabulary and style and writing,” the paper was formally submitted to the journal “Biology Letters” in November and underwent a rigorous review by other experts in evolutionary biology before it was accepted in January.

Jaffe hopes to study biological sciences and pursue further research in college, he said.

“I was able to pursue my passion for science with the experienced staff and incredible resources of UCLA, something I’m really grateful for,” he said.

The study is currently available in Biology Letters’ online journal and will appear in a print edition later this year.