The UC Davis winners, all doctoral students, are Erin Taylor Kelly of the Geoffrey Attardo lab, Hyoseok Lee of the Christian Nansen lab, Jill Oberski of the Phil Ward lab, Lacie Newton of the Jason Bond lab, and Clara Stuligross of the Neal Williams lab.
- Kelly won first place for her poster, “Metabolic Snapshot: Using Metabolomics to Compare Near-Wild and Colonized Aedes aegypti,” in the Physiology, Biochemistry and Ecology Section.
- Lee won first place for his entry, “Predicting Spring Migration of Beet Leafhoppers, Circulifer tenellus (Hemiptera: Cicadellidae) from Natural Overwintering Sites into Tomato fields in California" in the Graduate 10-Minute Papers category of the Plant-Insect Ecosystems, Behavioral Ecology Section
- Oberski won first place for her entry, “Why Do Museum Collections Matter?” in the Graduate Infographics category, Systematics, Evolution and Biodiversity Section.
- Newton won second place for her entry, “Integrative Species Delimitation Reveals Cryptic Diversity in the Southern Appalachian Antrodiaetus unicolor (Araneae: Antrodiaetidae) Species Complex,” in the Graduate 10-Minute Papers category in the Systematics, Evolution and Biodiversity Section, Genomics.
- Stuligross won second place for her entry, "Larval Pesticide Exposure Reduces Adult Wild Bee Reproduction,” in the Graduate 10-Minute Papers category in the Plant-Insect Ecosystems, Pollinators 2 Section.
The first-place winners received a $75 cash prize, a one-year membership in ESA and a certificate, while the second-place winners won a year's membership and a certificate.
Erin Taylor Kelly of the Geoffrey Attardo lab expects to receive her doctorate in June 2023. She holds a bachelor of science degree in biology (2016) from Santa Clara University, where she minored in chemistry, with an emphasis in molecular an cell biology.
On her Aedes aegypti poster:
Research in our lab has identified significant variability in the resistance phenotype of mosquitoes with target-site mutations, prompting us to wonder about the metabolic mechanisms involved in resistance in California populations of Aedes aegypti. The resistance phenotype is thought to have multiple fitness costs, including reduced fecundity, adult body size and longevity (6–9). We hypothesize that looking at the insect's metabolome may allow us to better understand the physiology behind these potential fitness costs by providing a snap shot of the insect's metabolite composition and insight into pathway demands and energetic deficiencies. Metabolomics has the benefit of providing insight into mosquito biology at the level of phenotype.
Hyoseok Lee, who joined the Christian Nansen lab in 2017, holds a master's degree in entomology (2014) from Seoul National University.
Most of tomato production in California occurs in the Central Valley, which has “the foothills” as its western boundary. Beet leafhoppers overwinter in green natural vegetation in the foothills and migrate into crop fields, including tomato, during spring as natural vegetation dries out and green crop vegetation becomes available. In this study, we built a simulation model predicting spring migration of beet leafhoppers based on vegetation greenness in the foothills. Vegetation greenness (EVI, Enhanced vegetation index) in the foothills was calculated based on analyses of satellite imagery. Spring migration of s was monitored at three different locations in the foothills for two years using yellow sticky cards. Spring migration of beet leafhoppers was well described by the Weibull function. At all monitoring locations, the spring migration was started when the EVI values dropped to 0.2, and the proportion of migrating beet leafhoppers rapidly increased as the EVI values decreased. Our study indicates that the decrease in vegetation greenness triggers spring migration of beet leafhoppers and shows great potential for developing an early warning system.
Why Do Museum Collections Matter?
"Cabinets of curiosity” and natural history museums are the original basis of our knowledge of global biodiversity. Such collections, however, are more than just well-organized dead organisms. Museums are enormous libraries of identified species, localities, and dates, constantly updated and reorganized based on the best new information. These data inform countless fields of research, and can even answer future questions no one has yet thought to ask. Most importantly, they preserve irreplaceable type specimens, which are a crucial part of species description. Now that many of these insect collections are being digitized and accessed from around the globe, why is it necessary to maintain them as physical materials? While many datasets do lend themselves well to digitization, insect specimens experience significant data loss. Most commonly, photographs are taken of the specimens, but photos are usually inadequate for discerning taxonomic features. Even high-resolution 3D scans are no substitute for direct observations. Finally, museums are centers of education and public outreach. Through collections, biology students and communities can physically experience global insect biodiversity they might not otherwise see, regardless of location or mobility. The “wow” factor of magnificent specimens is most powerful in person. As our lives become increasingly computer-oriented, we must recognize that to enjoy and study nature, no digital replacement will suffice.
Lacie Newton of the Jason Bond lab, expects to obtain her doctorate in entomology in June 2022. She holds a bachelor of science degree in biological sciences (2016) from Millsaps College, Jackson, Miss.
Although species delimitation can be highly contentious, the development of reliable methods to accurately ascertain species boundaries is an imperative step in cataloguing and describing Earth's quickly disappearing biodiversity. Spider species delimitation remains largely based on morphological characters; however, many mygalomorph spider populations are morphologically indistinguishable from each other yet have considerable molecular divergence. The focus of our study, the Antrodiaetus unicolor species complex containing two sympatric species, exhibits this pattern of relative morphological stasis with considerable genetic divergence across its distribution. A past study using two molecular markers, COI and 28S, revealed that A. unicolor is paraphyletic with respect to A. microunicolor. To better investigate species boundaries in the complex, we implement the cohesion species concept and use multiple lines of evidence for testing genetic exchangeability and ecological interchangeability. Our integrative approach includes extensively sampling homologous loci across the genome using a RADseq approach (3RAD), assessing population structure across their geographic range using multiple genetic clustering analyses that include structure, principal components analysis and a recently developed unsupervised machine learning approach (Variational Autoencoder). We evaluate ecological similarity by using large‐scale ecological data for niche‐based distribution modelling. Based on our analyses, we conclude that this complex has at least one additional species as well as confirm species delimitations based on previous less comprehensive approaches. Our study demonstrates the efficacy of genomic‐scale data for recognizing cryptic species, suggesting that species delimitation with one data type may underestimate true species diversity in morphologically homogenous taxa with low vagility.
Clara Stuligross, who joined the Neal Williams lab in 2016, received her bachelor of science degree in environmental studies, with minors in biology and outdoor education, in 2014 from Earlham College, Richmond, Ind.
Bees encounter pesticides across landscapes as they forage for pollen and nectar. Exposure to pesticides has negative effects on wild bees, but little is known about the effects of chronic larval exposure on adult performance. We investigated the effects of larval and adult pesticide exposure on the foraging and reproduction of the solitary bee, Osmia lignaria. We established nesting O. lignaria females in 16 field cages containing wildflowers treated with or without imidacloprid, the most widely used neonicotinoid insecticide. As larvae, these parent bees were reared on provisions containing imidacloprid or controls. Larval and adult pesticide exposure directly affected bee nesting activity. Bees exposed to pesticides as adults were less likely to start nesting and produced fewer offspring. Additionally, bees exposed to pesticides as larvae provisioned fewer offspring than unexposed controls. Our research provides experimental evidence of the effects of pesticide exposure on solitary bees across multiple life stages, a critical step in understanding mechanisms underlying pollinator health.
The Entomological Society of America, headquartered in Annapolis, Md., and founded in 1889, is the largest organization in the world serving the professional and scientific needs of entomologists and people in related disciplines. They include educators, extension personnel, consultants, students, researchers, and scientists from agricultural departments, health agencies, private industries, colleges and universities, and state and federal governments. It is a scientific and educational resource for all insect-related topics. For more information, visit www.entsoc.org.
A newly installed UC Davis mural created by students enrolled in a remote-instructed class on symbolism and design is more than enough—it's considered “gorgeous, awesome and amazing.”
“The assignment was to design a symbol that was meaningful to them and that addressed a problem in the world,” said artist-entomologist Diane Ullman, professor and former chair of the UC Davis Department of Entomology and Nematology who taught the class, “The Power of Visual Language through Symbolism and Expression in Clay” with designer-lecturer Gale Okumura of the UC Davis Department of Design.
The nine-tile mural, featuring flora and fauna designs, graces the wall just outside Room 126 of the Environmental Horticulture Building, 200 Arboretum Drive. Measuring 36 x 34-inches, it's the collaborative work of students Leslie Briceno-Marquez, Jason Hu, Analiese Ignacio, Heewon Shin, Emma Storm, Anushka Vispute and Mia Xiong, and their instructors.
The mural includes a honey bee, created by Storm, an anise swallowtail butterfly by Briceno-Marquez, and an octopus by Anushka Vispute.
Students learned the history of the use of symbols and signs in visual language from ancient to contemporary times, and gained an introduction to basic design principles, including the golden ratio, rule of thirds, and the use of lines, shapes, composition and perspective, as well as color theory and Gestalt Principles. They then applied them to their designs.
The instructors billed the course as “how to use symbolic representation in design and visual narrative to enhance expression and understanding of ideas and concepts.” Each student designed a symbol and then integrated it with their classmates' symbols in an online collaborative process. The work was then printed on tiles using a screen-printing method.
“The ability of the students to absorb such diverse information and transform their learning into meaningful designs was impressive,” Ullman said. “Each of the designs is very personal, but also expressive of a world view based on hope. Transforming their work into the cohesive mural we had all imagined together was exciting and transformative for the students and for us as teachers.”
Remote instruction proved to be challenging at times. “This class was meant to be highly participatory and hands on, so leading discussions in a remote environment and not being able to have students in our classroom, also called the Labudio (Lab plus Studio) was really difficult,” Ullman said. “We overcame this obstacle by sending them the materials they needed to draw their designs and then we used their digitized designs to print the design on ceramic tiles that were sent to them for completion, along with the glazes and brushes they needed. They then sent them back to us and we fired them.”
“This meant that all the steps of screen printing they would have learned and done themselves in the Labudio—printing film positives of their designs, coating silk screens with special emulsion, burning the screens with their designs, printing their designs with underglaze on ceramic tiles, had to be done by us. In addition, we had to prepare and address the packages. Even though the class was relatively small, this was labor intensive.”
Several artists from the UC Davis and local community rushed to their aid: Sarah Rizzo, Teresa Slack, Val Jones and Heather Mechling Eckels. Some are associated with the UC Davis Art-Science Fusion Program, co-founded by Ullman and artist Donna Billick of Davis, now a retired co-director of the program.
“It was a challenge because we maintained all social distancing mandates and could not be there all at the same time,” Ullman pointed out. “Everyone wore masks when they came to help, and we disinfected the space with bleach every time we worked there. They all came at different times to help—entirely out of the goodness of their hearts. We are so grateful for their helping hands.”
The instructors credited Bay Area artist Jos Sances with “sharing his printing techniques and loaning us emulsion when we couldn't buy it due to the pandemic. Donna Billick helped install the mural and taught us how to do it for the next mural installation. We are grateful for the life-long learning opportunity this work has been for us and our opportunity to meet and learn from these great artists.”
The mural has drawn dozens of accolades on Ullman's Facebook page:
- “It's just gorgeous!”
- "That octopus is amazing. Well, in fact each square has such awesome treasures.”
- “Love this!”
- “So beautiful!
- “Wow! This is beautiful—and even more impressive given the challenges with online learning”
- “This is so cool”
The instructors are teaching the same class this quarter and look forward to more creativity.
The Environmental Horticulture Building mural is one of 36 projects either installed or exhibited by students of Ullman—who teaches Entomology 001 and first-year seminars--and her collaborators, including Billick and Okumura.
If you answered “Michigan,” as the UC Davis Entomology Team did, you're right.
Doctoral students Jill Oberski, Zachary Griebenow and Hannah Kahl of the UC Davis Department of Entomology and Nematology teamed to compete in the Entomological Society of America's Virtual Entomology Games, a college-bowl type of competition formerly known as the Linnaean Games.
Oberski and Griebenow are both fourth-year doctoral students in the Phil Ward lab, while Kahl, a member of the Jay Rosenheim lab, is currently a third-year doctoral student who will begin her fourth year in January.
The UC Davis team won its preliminary round and then entered the highly competitive finals, placing 11th. Alabama's Auburn University edged the Boiler Bugs of Purdue to win the championship.
The champions, from Auburn University's Department of Entomology and Plant Pathology, answered 27 of the 40 questions correctly, tying with the Boiler Bugs of Purdue, “but Auburn had the closest answer for the tiebreaker question,” Rominiecki said.
In the Entomology Games, teams of two to four students test their entomological knowledge by answering questions drawn from all disciplines of insect science: behavior and ecology, biological control, entomology in culture, integrated pest management (IPM) and insect/plant interactions, medical and veterinary entomology, biochemistry and toxicology economic entomology, history of entomology, morphology and physiology, and systematics and evolution.
In this year's event, the games were divided into four rounds of 10 questions each. All teams competed to answer the same sets of questions. Each question was worth one point, with 40 being the best possible score.
“All in all, we were pleased with how the Entomology Games went this year, in an entirely new format," he said. "Our organizers worked hard in just a few short months to create a virtual version of the Games, and it was great to have teams from all over the country participating as usual, despite the new circumstances. We look forward to returning to an in-person event in the future, of course, but the 2020 virtual edition will be a memorable one. Congratulations to Auburn on their victory, and kudos to all the teams who participated!”
Some of the questions the UC Davis team answered correctly (answers below):
- Keye Luke, Jay Chou, and Bruce Lee have all portrayed Kato, the crimefighting partner of what fictional vigilante?
- What is the full scientific name (genus and species) of the bacterium classified by IRAC as a microbial disruptor of insect midgut membranes?
- "Yoke-winged" is the literal translation of the name of what insect suborder, which can be distinguished from other members of its order by the presence of caudal gills on the aquatic immatures?
- A worker honey bee has how many pairs of wax glands on its abdomen?
- Although this year's festivities were postponed due to COVID-19, the small town of Point Pleasant, West Virginia, normally hosts an annual festival that commemorates the 1966 sightings of what paranormal figure?
- A widely-publicized 2017 study reported a 75 percent decline in insect biomass over the past 27 years. This study was conducted across 63 protected natural areas in what European country?
- What striking form of structural coloration involves color changes based on the angle of the observer, and was recently shown to help jewel beetles camouflage in order to avoid bird predation?
- These specialty loaves of bread are labeled "kuwagata," which is a Japanese word that refers to insects in what family?
- "Stimulo-deterrent diversion" was one of the earlier names for what IPM strategy that uses volatile cues from both repellent and attractant plants to reduce damage from insect pests?
- The megalopteran family Corydalidae is divided into two clades: Corydalinae (aka dobsonflies) and what other subfamily, whose members are commonly known as fishflies?
- Bombykol and bombykal are components of a sex pheromone emitted by certain females in what insect order?
- What term refers to a parasitoid that halts the development of its host shortly after the initial parasitization?
- Paederus dermatitis, also known as whiplash dermatitis, is a type of skin irritation caused by contact with the hemolymph of certain species in what insect family?
- What type of semiochemical benefits the receiver and harms the emitter?
- What sixteen-letter adjective is most commonly used to describe fungi and nematodes that can potentially act as biological control agents of insect pests?
- Of the three types of lobes typically found in an insect brain, which lobe innervates the labrum and foregut?
- A 2020 Ig Nobel Prize was awarded to Richard Vetter for collecting evidence that many entomologists exhibit what psychological condition? This condition is also the title of a movie that won the 1990 Saturn Award for Best Horror Film.
- What twelve-letter term was coined by entomologist Willi Hennig to refer to a derived character that is shared between multiple species and their most recent common ancestor?
- Green Hornet
- Bacillus thuringiensis
- Push pull
The tiebreaker question? It dealt with the number of Far Side comics referencing insects. The question: "Gary Larson is known for using insects as a source of humor in his acclaimed comic strip 'The Far Side.' A survey of 4,300 'Far Side' comics revealed that exactly how many contained some sort of entomological reference?" Answer: 359.
Over the last few years, UC Davis teams have won the national championship three times in the fun and lively competitions. (See Bug Squad blog)
"Hopefully, we can be back onstage in person next year," said Oberski.
Lead author Clara Stuligross, a doctoral student in the lab of pollination ecologist Neal Williams, a professor in the Department of Entomology and Nematology, teamed with Williams to study the results of food scarcity and pesticide exposure.
They exposed the bees to the neonicotinoid insecticide imidacloprid, widely used in agriculture, and found that the combined threats—imidacloprid exposure and the loss of flowering plants—reduced the bee's reproduction by 57 percent, resulting in fewer female offspring.
Of the two stressors—food scarcity and pesticide exposure—pesticide exposure showed the great impact on nesting activity and the number of offspring produced, they said.
The study, Pesticide and Resource Stressors Additively Impair Wild Bee Reproduction, accomplished in the spring of 2018 on the grounds of the UC Davis Harry H. Laidlaw Jr. Facility, is published in the journal Proceedings of the Royal Society B.
Other scientists have conducted similar research on honey bees, but this is the first comparable research on wild bees in field or semi-field conditions.
The blue orchard bee, nicknamed BOB, is a dark metallic mason bee, smaller than a honey bee. It is prized for pollinating almond, apple, plum, pear, and peach trees. California almond growers often set up bee boxes or bee condos for them in their orchards to aid in the honey bee pollination. In the wild, the bees nest in reeds or natural holes.
To study the survival, nesting and reproduction of the blue orchard bee, they set up nesting females in large flight cages, some with high densities of wildflowers and others with low densities that were treated “with or without the common insecticide, imidacloprid.” Bees are commonly exposed to insecticides when they forage on treated flowers.
"Understanding how multiple stressors interplay is really important, especially for bee populations in agricultural systems, where wild bees are commonly exposed to pesticides and food can be scarce,” said Stuligross, who holds a bachelor of arts degree in environmental studies (2014) from Earlham College, Richmond, Ind. She joined the UC Davis ecology doctoral program in 2016.
Onset of Nesting Delayed
Key factors in affecting bee reproduction are the probability that females will nest and the total number of offspring they have. The UC Davis research found that pesticide-exposed and resource-deprived female bees delayed the onset of nesting by 3.6 days and spent five fewer days nesting than unexposed bees.
Professor Williams pointed out that this is a substantial delay because bees nest only for a few weeks, and it's crucial to reproduce female offspring to carry on the future generations. “Fewer females will reduce the reproductive potential of subsequent generations," said Williams, a UC Davis Chancellor's Fellow and a newly elected fellow of the California Academy of Sciences.
They found that only 62 percent of pesticide-exposed bees produced at least one daughter compared to 92 percent of bees not exposed to pesticides.
The study drew support from a UC Davis Jastro Research Award, a UC Davis Ecology Graduate Research Fellowship, a National Science Foundation Graduate Research Fellowship, and the UC Davis bee biology facility
The blue orchard bee bee is one of the few native pollinators that is managed in agriculture. North America has 140 species of Osmia, according to a Pollinator Partnership (PP) article in a U. S. Forest Service publication, authored by entomologist and PP member Beatriz Moisset and PP director Vicki Wojcik. “Mason bees use clay to make partitions and to seal the entrance,” they wrote. “This unique mud-building behavior leads to their common designation as mason bees. Honey bees are very important to commercial agriculture, but native bees like the blue orchard bees are better and more efficient pollinators of native crops.”
Imidacloprid, a systemic insecticide that acts as an insect neurotoxin, is used to control sucking insects, termites, some soil insects and fleas on pets, according to National Pesticide Information Center. It mimics nicotine, toxic to insects, which is naturally found in many plants, including tobacco. More than 400 products for sale in the United States contain imidacloprid.
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.”