Ecologist Louie Yang (Photo by Kathy Keatley Garvey)

The ecologist, an associate professor, UC Davis Department of Entomology and Nematology, has been named the faculty recipient of the 2017 Eleanor and Harry Walker Academic Advising Award from the College of Agricultural and Environmental Sciences (CA&ES).

The award will be presented at the college's Celebration of Advising Reception, set from 4:30 to 6 p.m., Tuesday, May 2 in the Robert Mondavi Institute Sensory Theater, Old Davis Road. Also honored will be student advisor Emma Martinez of the Student Affairs Officer, Animal Science.

The committee was especially impressed with Yang's focus on student diversity, his efforts in helping students link their academic studies to research and other career goals, and his innovative programs working with high school students and connecting these students with undergraduate and graduate student mentors, said Sue Ebeler, the CA&ES associate dean of Undergraduate Academic Programs. 

“His tremendous contributions in advising students seeking to expand their research experience, and programmatic development to enhance such opportunities have helped change the face of undergraduate education in our department,” wrote nominator Steve Nadler, professor and chair of the UC Davis Department of Entomology and Nematology. Nadler described him as a gifted teacher, mentor and scientist who has been instrumental in influencing the lives of many undergraduates.

Yang, who holds a bachelor's degree (ecology and evolution) from Cornell University, 1999, received his doctorate from UC Davis in 2006, and joined the UC Davis faculty in 2009. He is one of the three co-founders of the campuswide Research Scholars in Insect Biology (RSPIB)  with professors Jay Rosenheim and Joanna Chiu. The program's goal: to provide academically strong and highly motivated undergraduates with a multi-year research experience that cultivates skills that will prepare them for a career in biological research.

In addition to his RSPIB mentoring, Yang mentors many undergraduates in his lab. He has welcomed and mentored students from UC Davis and from around the country with the National Science Foundation Research Experiences for Undergraduates Program and the UC Davis-Howard University Historically Black Colleges and Universities (HBCU) Ecology & Evolution Graduate Admissions Pathways (EEGAP) program (Kabian Ritter).

Over the past year, Yang mentored 15 undergrads in his lab. The studies involved:

• The nonconsumptive effects on monarch development to see if parasitoid avoidance behaviors in early development have a long-term cost for monarch development. 
• the factors that contribute to herbivory by generalist herbivores on milkweed.
• the effects of a recently observed plant foliar fungal pathogen on milkweed on monarch growth and development. 
• the costs of switching milkweed species for monarch larvae.
• The density dependence in larval and adult blue milkweed beetles
• the fractionation of H and O isotopes from water to milkweeds to monarchs, using three species of native California milkweeds reared with water from two distinct isotopic sources

Yang also launched the Monitoring Milkweed-Monarch Interactions for Learning and Conservation (MMMILC) Project  in 2013 for high school students in the environmental science program at Davis Senior High School or those associated with the Center for Land-Based Learning's GreenCorps program. They monitor milkweed-monarch interactions in a project funded by the National Science Foundation. Yang and UC Davis undergraduate and graduate students serve as mentors.

“The goal of the MMMILC Project is to better understand the ecology of milkweeds and monarch butterflies,” Yang explains on his website. “We are particularly focused on understanding the role of seasonal timing (phenology) on the interactions between milkweeds and monarchs…While this project is centered around milkweed-monarch interactions, we are really interested in all of the creatures that interact with milkweed. The ecological community of surrounding milkweeds includes lots of fascinating species interactions, and we are interested in understanding how those interactions are connected over time.”

MMMILC accomplishments include weekly measurements on 318 plants for eight months/year; approximately 89 participants spent 24,000 field minutes; about 30,000 plant and 1100 monarch measurements; and weekly data quality checks and internal cross-validation.

Yang strongly supports student diversity, under-represented groups, and graduate education. Two of his undergrads, including one Latina, were supported by a supplemental Research Experiences for Undergraduates (REU). He has mentored grad students from the Entomology Grad Group, the Grad Group in Ecology and the Pop Bio Grad Group. In addition, he serves on many guidance, exam and advising committees and has participated in mentoring workshops at the Center for Population Biology. 

Yang was nominated by the Associated Students of UC Davis in 2012 for an Excellence in Education Award. In 2013, he received a prestigious National Science Foundation Faculty Early Career Development Award of $600,000

Three monarch November caterpillars chowing down on milkweed. (Photo by Kathy Keatley Garvey)

No, the stuffed turkey didn't slip out of the oven and fall on the floor. Nor did the pumpkin pie turn another shade of orange.

Some unexpected guests arrived--four to be exact.

That's the number of monarch caterpillars we found on our tropical milkweed (Asclepia curassavida) in our pollinator garden in Vacaville, Calif.

Between Nov. 15 and Nov. 24, we've discovered 12 caterpillars on our tropical milkweed, a non-native perennial. (Three other species of milkweed, Asclepias tuberosa, Asclepias speciosa, and Asclepias fascicularis, also thrive in our pollinator garden.)

Just when we thought our small-scale conservation project of rearing and releasing monarchs is all over 'til next year, it's not. Our season total of 54 monarchs is likely to increase.

"This is really far inland for such late breeding," said butterfly expert Art Shapiro, distinguished professor of evolution and ecology who has been studying Central California butterflies for more than four decades and maintains a website on his work and monitoring observations. "Winter breeding has been occurring near the coast for some years now, but I recall no records this late east of the East Bay. October, yes. November? We really need to understand the physiology and genetics of non-repro-diapausing winter monarchs!"

"We've been seeing evidence of a significant fall window of opportunity for larval monarch development for a few years now, which seems different than the historical pattern," noted Louie Yang, associate professor of entomology, UC Davis Department of Entomology and Nematology. "I've wondered if these are returning migrants that are breaking reproductive diapause when they encounter warm conditions in the Valley. I've mostly seen them on late season native milkweeds, but of course the tropical milkweeds are even more persistent."

Meanwhile, the 12 monarchs are the center of attention--well, at least a corner of attention--on our kitchen counter.   Our setup: two mesh, zippered containers from the Bohart Museum of Entomology, UC Davis; and four narrow-necked, flat-bottomed bottles filled with water and milkweed stems. 

The monarch caterpillars are doing what monarch caterpillars do best--and what folks around the Thanksgiving dinner table do best. Eat.

Soapberry bugs, also known as red-shouldered bugs (Jadera haematoloma) are found throughout much of the world. This photo of mating soapberry bugs was taken in March 2015 just outside the Storer Garden, UC Davis Arboretum. (Photo by Kathy Keatley Garvey)

Forget the soaps; let's talk about soapberry bugs and an entomologist at the University of California, Davis, who studies them.

And why and how she decided to pursue entomology as a career. That we'll save until the end of this blog.

Doctoral candidate Meredith Cenzer of the Louie Yang lab, UC Davis just published her research on soapberry bugs, which are a classic evolutionary example of how rapidly insects can switch hosts, adapting from a native to an invasive plant. 

Her research shows that soapberry bugs have not only lost adaptations to their native host plant but are regionally specializing on an invasive host.

The work, "Adaptation to an Invasive Host Is Driving the Loss of a Native Ecotype," published in the current edition of the journal Evolution, “collapses a classic and well-documented example of local adaptation,” said doctoral candidate Meredith Cenzer of the Louie Yang lab, UC Davis Department of Entomology and Nematology. The plant-host switch can lead to disruption of native plant communities and a breakdown of the ecosystem.

The players involved are the soapberry bug (Jadera haematoloma), also known as “the red-shouldered bug”; its native host plant, the balloon vine (Cardiospermum corindum), and the invasive host,  the golden rain tree or Taiwanese rain tree (Koelreuteria elegans).

The study, which took place in Florida, expands on the 1989 groundbreaking research of UC Davis evolutionary ecologist and soapberry expert Scott Carroll, who documented local adaptation in beak length, survival, and development time and other traits between soapberry bugs, balloon vine and the golden rain tree in Florida.

Said Carroll: "Meredith Cenzer's findings carry an important message for those concerned with biodiversity conservation, because she shows that even highly distinct adaptive specializations can disappear rapidly due to human influence on the environment– even in cases where the key native habitat has not been lost."

The soapberry bug, which lives throughout the United States and much of the world, feeds on seeds within the soapberry plant family, Sapindaceae, which includes soapberries, boxelders and maples. Mostly black, it has red eyes, red lateral stripes on the sides of its head and red on its “shoulders” (pronotum).  It is often mistaken for the boxelder bug.

“As part of my doctoral dissertation, I documented that this pattern of local adaptation has been lost in the last 27 years,” Cenzer said, “and that all populations of soapberry bugs in Florida-- even those still found on the native --are now adapted only to the invasive host.“

“Locally adapted populations are often used as model systems for the early stages of  rccological speciation, but most of these young divergent populations will never become complete species,” Cenzer noted in her abstract. “The maintenance of locally adapted populations relies on the strength of natural selection overwhelming the homogenizing effects of gene flow; however, this balance may be readily upset in changing environments.”

 “All populations that were adapted to the native host--including those still found on that host today--are now better adapted to the invasive host in multiple phenotypes,” she wrote in her abstract.” Weak differentiation remains in two traits, suggesting that homogenization across the region is incomplete. This study highlights the potential for adaptation to invasive species to disrupt native communities by swamping adaptation to native conditions through maladaptive gene flow.”

Cenzer characterized local adaptation as “high performance in one habitat coming at the cost of performance in other habitat types, such that populations specialized on each habitat will have higher fitness in that environment than immigrants from other habitats.”

“This results directly in two types of ecological reproductive isolation between locally adapted populations: 1) selection against migrants, who will be outcompeted by residents, and 2) selection against hybridization (if hybrids show intermediate phenotypes), as hybrid offspring will be outcompeted in each habitat by one parental type,” she wrote in her research paper. “However, such reproductive isolation relies on ongoing differential selection balanced with low rates of gene flow between habitats. In most well studied systems demonstrating local adaptation, we do not know how perturbation – either to selection pressures or gene flow – will influence the long-term stability of differentiation.”

Carroll, who maintains a website, “Soapberries of the World,”  says the soapberry bugs are “very approachable native guides to how evolution is taking place on earth day.” His website shows “how evolution happens every day and why it matters.”

How did Meredith Cenzer, a native of Gainesville, Fla., become interested in entomology? We love her answer.

"I first became interested in entomology as a kid," she recalled. "The defining moment in my memory is when my gifted science teacher, Ms. Linda Osborne, told me in third grade that there are people who study insects for a living and that they're called entomologists. She was going to put me in timeout for being too loud (a lifelong problem), but told me she'd let it slide this time if I promised to become an entomologist."

"Two years later, she let me come in and teach her first graders about insects. For my first science fair project, in sixth grade, I tracked the progress of tent caterpillar aggregations; we weren't allowed to manipulate animals, so I photographed them every day and made notes on their behavior - my parents still have the poster from that one."

So, she promised her teacher she'd become an entomologist. And she kept her promise. She received her bachelor of science degree in entomology at the University of Florida in 2009.

Future plans, after receiving her doctorate in entomology from UC Davis?

“I am broadly interested in evolutionary ecology, particularly in plant-insect interactions, and the balancing roles of selection, gene flow, and plasticity on determining the phenotypes we see in nature,” she said. After receiving her doctorate in entomology from UC Davis in the fall, she will start a postdoctoral position at Florida State University with biology professor Leithen M'Gonigle, developing theory on the evolution of dispersal in patchy landscapes.

A tip of the insect net to Meredith Cenzer!

(Editor's Note: Meredith Cenzer participated in the Entomological Society of America's Linnaean Games competition in 2011. See Bug Squad blog of Nov. 22, 2011.)

Louie Yang

The more we know about monarch butterflies, the better we can understand them and help conserve them.

Newly published research on California's overwintering monarch butterflies (Danaus plexippus) confirmed many previous migratory studies, but found some unexpected and surprising patterns of movement, said lead researcher Louie Yang, a community ecologist with the UC Davis Department of Entomology and Nematology. 

The study, “Intra-Population Variation in the Natal Origins and Wing Morphology of Overwintering Western Monarch Butterflies (Danaus plexippus)," published in the early online version of the journal Ecography, examined the natal origins, or “birthplaces,” of butterflies at four California overwintering sites.

It will be incorporated into an online issue, perhaps within six months, but it has not yet been assigned to an issue, said journal managing editor Maria Persson.

Natal origins of butterflies collected from the two northern sites--Lighthouse Field State Beach and Moran Lake, both in Santa Cruz County--varied significantly from those collected at the two southern overwintering sites--Pismo State Beach, San Luis Obispo County; and the Coronado Butterfly Preserve, Santa Barbara County, they said. 

“We hope that this paper improves our understanding of where monarch butterflies grow up in western North America,” said Yang, an associate professor. “This study uses a naturally occurring continental-scale pattern of hydrogen isotopes in precipitation in order to estimate the natal origins of overwintering butterflies. Building a clearer understanding of where they come from could help us better understand many aspects of their ecology.” 

The research is the work of Yang; Dmitry Ostrovsky of the University of Colorado, Denver; and Matthew Rogers and Jeffery Welker of the University of Alaska. 

The research team set out to answer two key questions: “How do broad geographic areas of potential natal habitat contribute to the overwintering population of western monarch butterflies in California?” and “How does the individual variation in the wing morphology of overwintering western monarch butterflies correlate with estimated migratory distance from their natal origins?” 

They first compared the wings of 114 monarch butterflies collected from the four overwintering sites with a continental-scale monarch butterfly wing isoscape derived from the U.S. Network for Isotypes in Precipitation (USNIP) database. They used spatial analyses of stable isotype ratios and correlations with wing morphology. Then they examined the correlations of monarch butterfly forewing size and shape. 

Of the 114 butterflies sampled, they found that 30 percent developed in the southern coastal range; 12 percent in the northern coast and inland range; 16 percent in the central range, and 40 percent developed in the northern inland range.

“Interestingly, the two most northern overwintering sites in the study showed the largest contributions from the southern coastal range (Lighthouse Field, 45 percent; Moran Lake, 37 percent; Pismo Beach, 22 percent; and Coronado Preserve, 24 percent) while the two most southern overwintering sites showed the largest contributions from the northern inland range (Lighthouse Field, 30 percent; Moran Lake, 35 percent; Pismo Beach, 53 percent; and Coronado Reserve, 39 percent),” they wrote.

The researchers randomly collected the monarchs Dec. 4-6, 2009 from aggregations in trees. The collecting resulted in: 19 males and 9 females from Coronado; 22 males and 8 females from Pismo State Beach; 20 males and 10 females from Moran Lake; and 18 males and 8 females from the Lighthouse Field State Beach.

In addition, the male monarch butterflies showed mean total masses that were 5.8 percent larger than those of the females.

The monarch butterfly of North America overwinters along the California coast and in the central mountains of Mexico. Previous studies have indicated that the western monarchs or those from natal habitats west of the Rocky Mountains, overwinter along the California coast. Those that develop east of the Rockies overwinter in central Mexico.

The project was funded in part by a National Science Foundation (NSF) Early Career Development Program grant awarded to Louie Yang, and a NSF Major Research Instrumentation Program grant awarded to Jeffrey Welker.

(Note: For more information on monarchs, read the Xerces Society's website. Xerces also encourages us all to plant milkweed. See Project Milkweed.)