The UC Davis Department of Entomology and Nematology and the Bohart Museum of Entomology will be participating in the virtual 107th annual UC Davis Picnic Day on Saturday, April 17, a traditional event being held untraditionally this year due to the COVID-19 pandemic.
The entomological events will include cockroach racing and a series of talks. Among them: Bohart Museum associate and natural historian Greg Kareofelas will present a pre-recorded video on Gulf Fritillary butterflies and entomologist Jeff Smith, the Bohart's volunteer curator of the Lepidoptera collection, will deliver a live Zoom talk on butterfly and moth mimicry from 1 to 2 p.m.
Said Smith: "For my presentation on mimicry within Lepidoptera, it will briefly mention camouflage and spend most of the time on mimicry for defense-- mimics of toxic or distasteful species, mimicry using odors or sounds, mimics of snakes or spiders, and mimics of non-food materials such as bird feces."
More events--and the schedule--are pending.
The Bohart Museum, temporarily closed, is located in Room 1124 of the Academic Surge Building on Crocker Lane. Directed by Professor Lynn Kimsey, the Bohart Museum includes nearly eight million insect specimens, a live "petting zoo" (Madagascar hissing cockroaches, stick insects and tarantulas) and an online gift shop stocked with insect-themed t-shirts, jewelry, hoodies, books, posters and more.
Discovering Silver Linings
This year's theme is “Discovering Silver Linings.” Despite all that has happened this year, the UC Davis community has continued to find silver linings everywhere, the Picnic Day officials reported on their website. "Our campus always strives to inspire hope and works towards a better and brighter tomorrow."
Last year's in-person events also were canceled and some virtual events took place.
"This long-standing campus tradition began in 1909 when the University Farm invited the surrounding community to view their new dairy barn. Two thousand visitors attended, bringing picnics to complement the coffee, cream, and sugar provided by the University. Following the success of the 1909 picnic, the faculty of the University Farm continued to plan and sponsor the event until a student committee took over the task in 1912. Through the years of Picnic Day history, the event has only been canceled five times. In 1924, an outbreak of hoof-and-mouth disease among the cowherds caused the first cancellation. In 1938, delayed construction of the gymnasium, which was needed to accommodate the ever-increasing number of participants, led to a second cancellation. During World War II, the Army Signal Corps controlled the campus, and Picnic Day disappeared from 1943 to 1945. Since 1946, Picnic Day has been growing strong and now boasts an annual attendance of more than 70,000 people. This year, there will be more than 200 events on campus and an estimated 75,000 visitors attending this special event. Since 1959, the parade was extended to include downtown Davis to celebrate the fact that Davis became a separate UC campus and not just the Farm School for UC Berkeley."
Newly published UC Davis research analyzing modern-day and museum collections of monarch butterflies over a 200-year period indicates that the loss of migration and range expansion leads to smaller and shorter wings.
The research, “Two Centuries of Monarch Butterfly Collections Reveal Contrasting Effects of Range Expansion and Migration Loss on Wing Traits,” appears this week in the Proceedings of the National Academy of Sciences.
“We measured the wings of 6,000 museum specimens of monarch butterflies collected from 1856 to the present, as well as contemporary wild-caught monarchs from around the world,” said lead author Micah Freedman, a former UC Davis doctoral candidate in population biology and now a postdoctoral fellow at the University of Chicago.
“The major implications of the research,” Freedman said, “are that it shows (1) loss of migration can affect the evolution of monarch butterflies over contemporary time scales--dozens to hundreds of years; and (2) monarchs with large forewings are better-suited for long distance movement, and this likely contributed to their global expansion over the past 200 years.”
Co-Authors of PNAS Paper
Freedman works closely with noted migratory animal authority and co-author Hugh Dingle, emeritus professor, UC Davis Department of Entomology and Nematology, who received a 2014 UC Davis Edward A. Dickson Professorship Award to research “Monarchs in the Pacific: Is Contemporary Evolution Occurring on Isolated Islands?” They co-authored the research with Sharon Strauss, professor and Santiago Ramirez, associate professor, Center for Population Biology and the Department of Evolution and Ecology.
Their research documents how migration-associated traits may be favored during range expansion but disfavored when species cease seasonal migration. “Furthermore, it highlights the value of museum collections by combining historical specimens with experimental rearing to demonstrate contemporary evolution of migration-associated traits in natural monarch populations,” Freedman said.
Said Dingle: “At a time when museum collections are under pressure from a scarcity of funding, the results also show just how valuable such collections can be to evolutionary research and to the understanding of ongoing biological processes in the face of anthropogenic change.”
In their abstract, they pointed out that “migratory animals exhibit traits that allow them to exploit seasonally variable habitats. In environments where migration is no longer beneficial, such as oceanic islands, migration-association traits may be selected against or be under relaxed selection.”
“Monarch butterflies are best known for their continent-scale migration in North America but have repeatedly become established as non-migrants in the tropical Americas and on Atlantic and Pacific Islands,” they wrote. “These replicated non-migratory populations provide natural laboratories for understanding the rate of evolution of migration-associated traits.”
What They Determined
They determined (1) how wing morphology varies across the monarch's global range, (2) whether initial long-distance founders were particularly suited for migration and (3) whether recently-established non-migrants show evidence for contemporary phenotypic evolution.
Under controlled conditions in a UC Davis lab, they also reared more than 1000 monarchs from six populations around the world and measured migration-associated traits.
“Historical specimens show that initial founders are (1) well-suited for long-distance movement and (2) loss of seasonal migration is associated with reductions in forewing size and elongation,” they related. “Monarch butterflies raised in a common garden from four derived non-migratory populations exhibit genetically based reductions in forewing size, consistent with a previous study.”
Dingle said the findings “provide a compelling example of how migration-associated traits may be favored during the early stages of range expansion, and also the rate of reductions in those same traits upon loss of migration.”
Statistics show that the population of monarch butterflies in the United States has declined by 90 percent over the past 20 years.
Undergoing Contemporary Evolution
The monarch butterflies established just 200 years ago in remote Pacific Islands are undergoing contemporary evolution through differences in their wing span and other changes, Dingle said. He and Freedman studied monarchs in the Pacific Islands for a week in 2016 in a project funded by Dingle's UC Davis emeritus faculty grant, the Edward A. Dickson Professorship Award. The research involved measuring the wingspans of Guam monarchs to determine whether there has been an evolutionary decrease in size or shape due to their migration-free lifestyle on the island. They also measured the wings of monarchs in the University of Guam's museum collection.
An analysis of a monarch population in Hawaii shows that resident monarchs have shorter, broader wings than the long-distance migrants, Dingle noted. The Hawaii butterfly wings were shorter than the eastern U.S. long-distance migrants, but “not so short-winged as the residents in the Caribbean or Costa Rica, which have been present in those locations for eons, rather than the 200 years for Hawaii.”
Dingle, author of two editions of Migration: The Biology of Life on the Move (Oxford University Press), a fellow of the American Association for the Advancement of Science and a past president of the Animal Behavior Society, said previous studies by various authors revealed that migrant and long-resident monarchs exhibit different wing shapes. "Thus, it was desirable to examine populations with only short residency to see if the same phenomenon was evident.”
Dingle, who served as a UC Davis entomology professor from 1982 to 2002, achieving emeritus status in 2003, has engaged in research throughout the world, including the UK, Kenya, Thailand, Panama, Germany and Australia. National Geographic featured Dingle in its cover story on “Great Migrations” in November 2010. LiveScience interviewed him for its November 2010 piece on“Why Do Animals Migrate?”
The Bohart Museum of Entomology at UC Davis was among the 22 global museum collections studied. The research also included private collections and online databases. Freedman and assistant Christopher Jason reared some of the butterflies included in the PNAS paper in a UC Davis greenhouse.
The project drew funding from the National Science Foundation (NSF) Graduate Research Fellowship Program, the NSF East Asia and Pacific Summer Institute Program, the UC Davis Center for Population Biology, and the National Geographic Society to Freedman, as well as the Dickson Emeritus Professor Award to Dingle, a California Agricultural Experiment Station grant to Strauss, and a David and Lucille Packard Fellowship to Ramirez.
“Migratory animals exhibit traits that allow them to exploit seasonally variable habitats. In environments where migration is no longer beneficial, such as oceanic islands, migration-association traits may be selected against or be under relaxed selection. Monarch butterflies are best known for their continent-scale migration in North America but have repeatedly become established as non-migrants in the tropical Americas and on Atlantic and Pacific Islands. These replicated non-migratory populations provide natural laboratories for understanding the rate of evolution of migration-associated traits. We measured more than 6,000 museum specimens of monarch butterflies collected from 1856 to the present, as well as contemporary wild-caught monarchs from around the world. We determined (1) how wing morphology varies across the monarch's global range, (2) whether initial long-distance founders were particularly suited for migration and (3) whether recently-established non-migrants show evidence for contemporary phenotypic evolution. We further reared more than 1,000 monarchs from six populations around the world under controlled conditions and measured migration-associated traits. Historical specimens show that (1) initial founders are well-suited for long-distance movement and (2) loss of seasonal migration is associated with reductions in forewing size and elongation. Monarch butterflies raised in a common garden from four derived non-migratory populations exhibit genetically-based reductions in forewing size, consistent with a previous study. Our findings provide a compelling example of how migration-associated traits may be favored during the early stages of range expansion, and also the rate of reductions in those same traits upon loss of migration.”
As a postdoctoral fellow at the University of Chicago, Freedman said he is "currently using breeding experiments and DNA sequencing trying to figure out which genes affect migratory traits and behaviors in monarchs. This includes wing traits (shapes and size) discussed in the PNAS paper.”
Community ecologist Louie Yang of the UC Davis Department of Entomology and Nematology, is the newly announced recipient of an international award for his outstanding academic advising activities.
Yang, who joined the UC Davis faculty in 2009, will receive the Outstanding Faculty Academic Advising Award from NACADA, also known as the Global Community for Academic Advising, at its Sept. 30-Oct. 3 conference in Phoenix, Ariz.
He earlier received the 2017 Faculty Advisor Award of Excellence in NACADA's Pacific Region 9, comprised of California, Nevada and Hawaii.
“Professor Yang is dedicated to helping students link their academic studies to research and other careers,” said associate dean Susan Ebeler of Undergraduate Academic Programs, College of Agricultural and Environmental Sciences. “ He has developed innovative mentoring programs that help students develop as scholars and scientists and he is committed to enhancing diversity and retention in STEM (Science, Technology, Engineering, and Math) fields. He has made exemplary contributions to student success in our college and campus-wide and it is great to see his contributions recognized.”
Yang, an associate professor, teaches Insect Ecology and Field Ecology. He holds a bachelor's degree (ecology and evolution) from Cornell University, 1999 and received his doctorate from UC Davis in 2006.
He is known for fostering creative and critical thinking, and challenging his students to succeed by linking their academic studies to research and other goals.
“Professor Yang epitomizes what makes a great professor: his command of the subject matter, his ability to stimulate discussions and involvement, and his kindly concern for their education, welfare and success,” said nematologist Steve Nadler, professor and chair of the UC Davis Department of Entomology and Nematology. “He engages and challenges students in his lectures, in the lab, and in the field and encourages them not only to expect success but to pursue their goals.”
“His mentees not only include undergraduate and graduate students, but high school students and postdoctoral scholars and beyond,” Nadler said. “He attends to the unique needs and interests of each student, respecting their perspectives and ideas. Mentorship, he finds, is really about helping students identify the questions that they want to ask. His success is their success."
An important part of his advising is his work in the Research Scholars Program in Insect Biology (RSPIB), a campuswide program co-founded by Jay Rosenheim, Joanna Chiu and Yang. Aware that some of the most important skills for research biologists cannot be taught in big lecture halls or even in lab courses, they set out to help students learn cutting-edge research through close mentoring relationships with faculty. The program crosses numerous biological fields, including population biology; behavior and ecology; biodiversity and evolutionary ecology; agroecology; genetics and molecular biology; biochemistry and physiology; entomology; and cell biology. The 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 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 and Evolution Graduate Admissions Pathways (EEGAP) program
In the past year, Yang mentored 15 undergrads in his lab in studies that included: 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; and the density dependence in larval and adult blue milkweed beetles.
Former student Allyson Earl, now a researcher in Guam, credits Yang with shaping her academic career: "I had the pleasure of working under Louie Yang for the last year of my undergraduate degree at UC Davis as one of his research assistants. I watched as he worked tirelessly with several other student assistants in the lab on personal projects focused on our study subjects, Monarch butterflies. His mentorship style in these projects was one that guided students to draw their own conclusions rather than handing them answers, leading them to ask more complex questions and develop themselves as better students and scientists. I can say with confidence, he not only nurtured my desire to study the intricacies of ecology, but also to pursue a career in this field, without his guidance and support I would not be where I am today."
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.
Established in 1983, the NACADA Annual Awards Program for Academic Advising honors individuals and institutions making significant contributions to the improvement of academic advising within higher education. Its membership totals more than 11,000.
The research, published in the early online version of the journal Ecography, examined the natal origins of butterflies at four overwintering sites. Each of the four sites showed substantial variations in wing morphological values, indicating local and long-distance, the researchers said.
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 (Danaus plexippus) 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.
Their research paper, “Intra-Population Variation in the Natal Origins and Wing Morphology of Overwintering Western Monarch Butterflies (Danaus plexippus), is can be read in early view at http://onlinelibrary.wiley.com/doi/10.1111/ecog.01994/abstract. 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.
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.
Information on map: Isoscape of estimated δDm values for the wings of monarchs originating throughout western North America, based on a weighted average of precipitation δDp values throughout the growing season (see Methods). Isoclines are shown at δDm = –130, –115 and –100‰ to show four broad regions; estimated δDm values become increasingly negative moving inland and northward. Pie charts show the proportion of individual monarchs from (a) Lighthouse Field, (b) Moran Lake, (c) Pismo Beach and (d) Coronado Preserve with δDm values that correspond with the four isoscape regions. Filled points represent precipitation collection sites in the USNIP database; unfilled points represent overwintering sites. (Courtesy of Louie Yang)
“Equally apparent are the migrations of insects like armyworm moths and locusts that have severe negative impacts on agricultural systems,” says Hugh Dingle, an emeritus professor of entomology at the University of California, Davis, and a worldwide authority on animal migration.
“What is not so appreciated, however, are the numerous tiny insects, mites, and spiderlings that also migrate.”
“Even to the most casual observer of nature it is apparent that migration is a conspicuous behavior for many organisms,” said Dingle, author of the newly published second edition of Migration: The Biology of Life on the Move (Oxford University Press), a sequel to the first edition published in 1996. “The great whales move up and down our coasts and are often viewable from promontories like Pt. Reyes; millions of birds appear in high latitudes to breed in the spring and depart in the fall; and millions of bright orange monarch butterflies inspire awe with their migrations from North America to overwintering sites in Mexico or on the coast of California.”
Winged aphids and ballooning spiders often escape the human eye. ““On summer evenings at temperate latitudes the air to considerable altitudes is often filled with winged aphids and ballooning spiders that with the aid of selected winds can migrate for hundreds or even thousands of kilometers,” he said. “Birds, grasshoppers, and moths are also adept at selecting winds of the right speed and direction, the more impressive because many of these migrations are at high altitude or at night when the ground cannot provide information on direction. Recent studies have shown that information may be derived from the kinetic energy of wind turbulence.”
The book covers a wide taxonomic diversity of organisms from aphids to whales. Included is a discussion of recently developed techniques, such as radar and geolocators, used for tracking migrants. “These methods,” Dingle said, “reveal just how astonishing some migratory journeys can be; godwits and plovers, for example, make nonstop flights over the central Pacific Ocean from Alaska to Australia and New Zealand.”
However, not all migration is a round trip; sometimes it's one-way. “Important defining behavioral characteristics are specific departure and arrival tactics and the refusal to stop even in favorable habitats until the migration program is complete,” Dingle says. “In the words of National Geographic reporter David Quammen migrants ‘are flat-out just gonna get there.'
“The program or syndrome includes specific modifications of metabolic physiology like enhanced fat storage to fuel migration and of sensory systems to detect inputs from the sun, stars, and magnetic field lines to determine compass direction. Intimately involved in the latter are daily and yearly biological clocks. The pathway followed is an outcome of the syndrome of migratory behavior and is part of the ecology that provides the natural selection acting to determine the evolution of migration.”
“Natural selection acts differently on long versus short lives. With long lives there are usually many opportunities to produce offspring; with short lives there may be only one,” Dingle said. “Thus reproductive opportunities may determine when and where to migrate. Migrating aphids postpone reproduction until they colonize new host plants; birds reproduce following migration in the spring, but not in the fall. Some birds and insects use migration to exploit ‘rich patches' and breed in different places in different years or even in the same year.
There are also insects that alternate between winged generations for migration and colonization and wingless generations devoted exclusively to high reproductive effort once colonization is accomplished. Genes influence not only migratory effort but also the relation between behavior, reproduction, and morphological traits such as wing length (longer narrower wings in migrants).
“'They are flat-out just gonna get there,' as David Quammen said.”
Dingle, a fellow of the American Association for the Advancement of Science and the Animal Behavior Society, has done research throughout the world, including the UK, Kenya, Thailand, Panama, Germany and Australia.
He served as a professor at UC Davis Department of Entomology from 1982 to 2002, achieving emeritus status in 2003. He chaired the Animal Behavior Graduate Group from 1985 to 1988; and was acting director of the Animal Behavior Center, 2000-2002.
Dingle is a former secretary of the International Society for Behavioral Ecology and past president of the Animal Behavior Society.