The elephant seal in the room

Pinniped researcher’s funny and insightful presentation at Grad Slam 2019 answers the burning question: Why do male and female elephant seals look so different?

The Grad Slam is available to watch online.
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This year's Grad Slam finalists posed for a picture with Lori Kletzer, vice provost and dean of the Division of Graduate Studies (left.) Photos by Steve Kurtz.
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Lori Kletzer congratulates this year's Grad Slam champion Sarah Kienle as runner-up prize-winner Rachel Harbeitner and People’s Choice award winner Priscilla Sung cheer her on. 

Sixth-year ecology and evolutionary biology Ph.D. student Sarah Kienle wowed the judges and cracked up an audience of 200 people at UC Santa Cruz’s annual Grad Slam, a competition that requires grad students to distill years of research into fast-paced three-minute elevator pitches.

Grad Slam, also known as the Three-Minute Thesis Challenge, is a University of California systemwide competition.

UC Santa Cruz’s version is sponsored by the campus’s Division of Graduate Studies, with sponsorship of the prizes by the five academic divisions: Arts, Baskin School of Engineering, Humanities, Physical and Biological Sciences, and Social Sciences.

The dramatic sexual dimorphism (a scientific term for differences in size and appearance between males and females of the same species) and foraging behaviors of male and female elephant seals may sound like unlikely material for comedy.

But Kienle, the evening’s $3,000 grand prize winner, made clever use of her comic timing at the sold-out Kuumbwa Jazz Center in downtown Santa Cruz. She began the speech with a deadpan question: “What if I told you that males and females are … different?”

In nature, she explained, sexual dimorphism can take many forms, from the quintessential mane of the lion to the showy plumage of the male peacock.

“This begs the question,” Kienle continued. “Why are males and females of  the same species different?” This question led her to pursue a Ph.D. on what she described as “one of the most sexually dimorphic species on the planet—the northern elephant seal.”

As Kienle explained, male and female elephant seals are extremely different in size and shape. “Males weigh up to 5,000 pounds, making females look dainty in comparison, at only 1,000 to 2,000 pounds.”

They also have different appearances, including, most famously, the males’ large floppy noses that give the seal species its name. The females lack that distinctive feature.

Kienle wanted to know how those differences in size and shape translated to differences in other aspects of their  biology including feeding, “a rather important process if you like living,” she said, drawing appreciative snickers from the crowd.

As it turns out, those varying shapes correspond to the males’ and females’ different feeding strategies. The males are “continental shelf predators,” meaning they feast on life forms at the bottom of the sea floor, while females travel across wide swaths of the northern Pacific Ocean in search of prey at mid-sea layers.

But why are the males such burly bruisers, and the females so svelte and slight in comparison? As Kienle pointed out, the males eat a lot more food on their foraging trips, which is important because they must bulk up quickly to fight other males for dominance and fend off challengers who are vying for the same females.

Time is of the essence because so many of the males get killed during their foraging journeys. They must get huge, and mate as soon as possible to sustain the life cycle. It is a short and brutish existence; “if you are lucky you get to do that for one to two years,” Kienle said, inserting a dramatic pause. “And then you die!”

Females are much  smaller, with greater longevity, because they forage for less food, giving them a “lower risk, lower reward strategy.”

UCSC Grad Slam’s $1,500 runner-up prize winner is fifth-year ocean sciences Ph.D. student Rachel Harbeitner, who is studying deep-sea microbes that consume stored-up carbon in the world’s oceans, making them an essential part of ocean ecology, as well as global atmospheric conditions. She is part of a team that undertook experiments on the ocean floor, studying how long it takes for these bacteria to gobble up carbon in the bodies of dead plankton.

On the bottom of the ocean, “it’s really cold and completely dark, and they’re living under high pressure,” Harbeitner said. “I thought, ‘Maybe in the course of a year, they will eat these carbon bodies?” Instead, the bacteria ate the carbon in only a week, which is 50 times faster than the researchers predicted.

While the bacteria are microscopic, the implications of their dining habits are enormous.  

“We know that oceans regulate global climate,” she said. “But tiny organisms, down in the deep sea, are impacting how carbon circulates through the ocean and atmosphere. We can use this new information to better predict how oceans are going to respond to the human impacts of climate change.”

Customarily, the Grad Slam grand prize winner goes on to represent UC Santa Cruz at the UC Office of the President’s systemwide Grad Slam competition. However, Sarah Kienle will be in Antarctica studying leopard seals.

This is the direct result of the recent federal government shutdown, which forced the research mission to reschedule. That means Harbeitner instead of Kienle will represent UC Santa Cruz at the systemwide competition on May 10 in San Francisco.

The  People’s Choice award—which comes with a $750 prize—went to seventh-year psychology Ph.D. student Priscilla Sung, whose research explores “task-switching,” a term for the human brains general ability to change or toggle between tasks, such as when you are interrupted by text messages while writing a work email.

Sung described the ability to task-switch as a mental muscle that is developed over time, through experience and practice. The more task-switching that people do, the stronger and more flexible that muscle will be. And being bilingual could help people strengthen this task-switching muscle, she adds.

“Switching back and forth between languages—or code-switching—might use the same muscle you use when you switch between emailing and texting,” she said. “It’s this hidden workout behind bilingualism that fascinates me.”

Sung’s current project investigates this connection between task-switching and code-switching in an unusually young group of subjects: 3- and 4-year-olds at a bilingual preschool in the Bay Area.

The preschoolers complete a series of tasks that require them to switch between different sets of rules, such as sorting objects first by shape and then by color.

“To you, it might sound simple, but for little kids, it’s actually pretty tough—like, hilariously tough,” she said with a laugh.

Then, to get a sense of how much code-switching the kids are doing at home and at school, she consults their parents and preschool teachers.

“It’s amazing how differently every kid uses language,” she remarks. “There’s really no such thing as the ‘typical’ bilingual experience.”

For now, the project is still underway, but she hopes to have results in the next few months, by the time these kids graduate from preschool and head to kindergarten.

Sung, a developmental psychologist, says that kids’ ability to task-switch holds implications for how they will learn to handle the growing demands in their lives.

“What we do as kids lays a path for how we learn to navigate our complex roles as adults,” she said.

Though the evening was entertaining for the audience, it has a serious purpose. Lori Kletzer, vice provost and dean of the Division of Graduate Studies, pointed out that the UC Office of the President asks all 10 UCs to hold Grad Slams for the professional development it gives the graduate students who participate.

“Grad Slam has become perhaps the most fun way that our graduate students communicate (about) the research they’re working on,” Kletzer told the audience. “This is really a platform for graduate students to share their passion for their research.”

For more information on Grad Slam, and a full list of the 13 finalists and their research presentations, visit the event website and watch the video of the competition.

Grad Slam is inspired by The Three Minute Thesis program founded by The University of Queensland (Australia).