When Professor Elizabeth Crone of Tufts University, Medford, Ma., zeroes in on that topic to the UC Davis Department of Entomology and Nematology, she will discuss the challenges that both monarchs and ecologists face.
Her seminar is from 4:10 to 5 p.m., Wednesday, Jan. 29 in 122 Briggs Hall. Her longtime collaborator, pollination ecologist and professor Neal Williams, will introduce her.
"Ecologists now face the dual challenge of documenting changes in the environment, and figuring out appropriate strategies for conserving and recovering natural resources in changing environments," says Crone, who is completing a research sabbatical at UC Davis.
In her talk, she will focus on “using the tools of population ecology to address both sides of this challenge: quantifying changes in the abundance of western monarch butterflies (and factors associated with these changes), and using theory and data to design strategies and targets for restoration and recovery.”
“Analyses of past dynamics (1980-2017) showed that western monarch butterflies have declined more quickly than their eastern counterparts, and that these declines were most strongly associated with loss of overwintering habitat, and more weakly (but significantly) associated with increased pesticide use and warmer breeding season temperatures,” Crone writes in her abstract. “Analyses of current conditions (2018-2019) suggest that a recent dramatic drop in abundance occurred in spring, between when monarch butterflies leave coastal overwintering sites and arrive in the Central Valley and Sierra Foothills.”
“Surprisingly, we don't really know where western monarch butterflies are during this time period, roughly mid-February through mid-May," Crone says. "Future research will focus on filling this knowledge gap, as well as building quantitative knowledge of the western monarch demography throughout their complex annual life cycle, which is needed to understand the relative contributions of habitat at different points in the life cycle to population declines and recovery.”
The Xerces Society for Invertebrate Conservation reported this week that its Western Monarch Thanksgiving Count shows a decline for the second consecutive year. “Sadly, fewer than 30,000 monarchs were counted—29,418 to be exact—for the second year in a row, so the western monarch population remains at a critical level,” according to Matthew Shepherd, director of communications and outreach. (See press release and a blog article about the population count for this winter.)
A native of Alexandria, Va., Crone received her bachelor's degree in biology, summa cum laude, from the College of William and Mary, Williamsburg, Va., in 1991, and her doctorate in botany from Duke University in 1995. She served as a postdoctoral researcher at the University of Washington, Seattle, from 1996-1997. Her career encompasses academic appointments at Harvard University, University of Montana, and the University of Calgary.
"I am grateful to Neal and the Entomology Department for hosting me during this extended stay!" she added.
Crone is a co-principal investigator (PI) with PI Cheryl Schultz, associate professor of biological sciences at Washington State University and co-PI Sarina Jepson, endangered species program director, Xerces Society, on a federal grant, "Western Monarch Breeding Phenology" (awarded May 2017-June 2020, with the potential for annual renewal). The grant was funded through the Department of Defense's (DoD) Natural Resources Program, DoD Legacy Program.
Of her research, Crone says "My research focuses on population ecology, especially of plants and insects, and plant-animal interactions. Specifically, I am interested in how environmental changes translate to changes in population dynamics: For example, is there a simple, linear matching of changes in resources to abundance of consumers, or do interactions among individuals and species moderate these responses? Much of my research also involves developing novel quantitative approaches to predict long-term dynamics from small scale observations and experiments. Current projects include studies of butterflies, bees, perennial wildflowers, sugar maples, and acorn-granivore interactions. Past projects include some of the best documented examples of cyclical dynamics in plant populations and spatial metapopulation dynamics in animal populations. I was also one of the first ecologists to adapt generalized linear mixed models to estimate variance terms for stochastic population models."
Of her teaching: "I am interested in introducing people to general principles of ecological theory, as a guide to interpreting data and understanding the potential implications of environmental change. Making this link requires training students to understand basic biology and natural history, while knowing how to approach problems like a mathematician. I have a strong track record of training graduate students who have gone on to work in quantitative ecology, and in teaching lecture courses that introduce biology students to modeling and statistics. In biology classes, students expect to understand material as it is presented in class, and use time outside class to explore these ideas further, or memorize facts. In math classes, students do not expect to understand the material as it is presented; many of the best math majors come to understand the ideas later by working through problem sets. This difference means that biology students find math classes intimidating and tend to underestimate their own math skills. My approach is to start with tractable problems, and introduce students to the approach of learning by doing problem sets, in the context of ecologically-motivated problems."
Her honors and awards are many:
- Project of the Year Award, SERDP (Strategic Environmental Research and Development Program) 2018
- Foreign Member, Finnish Academy of Science and Letters (elected 2017)
- Vice Chair / Chair, Theoretical Ecology Section, Ecological Society of America, 2010-2012
- Ecological Research Award, Ecological Society of Japan, 2014
- Fulbright Fellowship, 2007-2008
- National Science Foundation (NSF) Postdoctoral Fellowship in Biosciences Related to the Environment (1996-1997)
- U.S.Department of Energy Graduate Fellowship for Global Change (1991-1995)
- Baldwin Speece Award (College of William and Mary, for scholarship/service in ecology, 1991)
How did you get interested in science? Was there an "ah ha" moment?
I was in an REU (Research Experiences for Undergraduates) program studying plant-insect interactions in 1990. The thing that made me want to go to grad school was the fun puzzle of designing an experiment AND figuring out how to interpret the data - I had collected data on beetle feeding rates, and when I didn't know how to analyze them my advisor said "read a statistics book" ... so I did--since then I have always especially loved the puzzle of matching models to data.
From an earlier age, I have always enjoyed being outdoors, which is probably why I chose to study biology. But that was the moment when I knew I would enjoy a life of research.
Some of your major accomplishments?
From an applied ecology perspective, the biggest is helping the Fender's blue butterfly move from being listed as endangered to nearly ready for down-listing. From a basic ecology perspective, I figured out the ecological interpretation of variance terms in mixed models as estimates of spatial heterogeneity and environmental stochasticity, and worked out one of the best examples of how mast-seeding species are synchronized by their pollinators.
What fascinates you about monarchs?
The possibility that we can recover the western monarch population from its recent steep decline to being abundant again. This should be a problem we can fix.
What do you like best about science?
The puzzle of matching models to data and the possibility of saving species from extinction.
Any scientists in the family?
My sister is an astronomer. My dad was a math professor. Before him, though, no one in the extended family had even gone to college.
What do you do in your leisure time?
I once gut-renovated a house (with help from carpenters, but doing some of the work myself), I am very proud of my urban pollinator garden in Somerville (near Boston, Mass., and I am a good enough trombonist to (just barely) keep up with my trombonist friends.
I am waiting to find out whether our monarch funding will be extended or whether I will go back to a regular teaching schedule at Tufts. Even if I go back to "full-time" teaching, I am sure I will be doing western monarch and bumble bee research for the indefinite future, and will continue to be at least partly bicoastal.
(Editor's Note: the Xerces Society's site-by-site monarch count data is available at https://www.westernmonarchcount.org/data/. This covers all years since the first count in 1997.)
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)
Dingle, a UC Davis emeritus professor of entomology and author of two editions of “Migration: The Biology of Life on the Move,” said his previous studies reveal that migrant and resident monarchs exhibit different wing shapes.
Dingle is the recipient of the UC Davis Edward A. Dickson Professorship Award to research “Monarchs in the Pacific: Is Contemporary Evolution Occurring on Isolated Islands?”
Dingle will be working with community ecologist Louie Yang and molecular geneticist Joanna Chiu, assistant professors in the UC Davis Department of Entomology and Nematology, to examine the ecology and physiology of monarch butterflies (Danaus plexippus) in three islands where contemporary evolution might be expected. The islands are Oahu (Hawaii), Guam (Marianas) and Weno (Chuuk or Truk).
“This is the necessary first step in a long-term analysis of the evolutionary ecology and physiology of monarch butterflies on remote Pacific islands,” said Dingle, a fellow of the American Association for the Advancement of Science and the Animal Behavior Society.
Dingle said the monarch, widely distributed “for eons” in the New World, is fairly new to the Pacific islands and to Australia. “In addition to North America, the monarch occurs as a resident throughout the Caribbean and Central and northern South America—and probably as a migrant farther south. One of the more intriguing aspects of its distribution is that beginning in the early part of the 19th century, it spread throughout the Pacific all the way to Australia, where there are now well-established migratory and non-migratory populations.”
Dingle speculates that the monarchs arrived in the Pacific islands with their host plant, milkweed, which was valued at the time for its medicinal properties. Some of the islands are extremely isolated, he said.
An analysis of a monarch population in Hawaii shows that resident monarchs have shorter, broader wings than the long-distance migrants. 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.”
“If there are indeed wing shape changes associated with evolution in isolation, are there other changes that may have occurred under selection and local adaptation for residency?” Dingle wonders. “Are there other changes that may have occurred under selection and local adaptation for residency? Examples of such traits might be changes in flight muscle physiology, changes in photoperiodic diapause response, changes in the characteristics of orientation ability and its relation to antennal circadian rhythms, or changes in the reproductive capacity or tactics (re-colonization of ‘empty' habitats is no longer part of the life cycle).
“Diapause and fat storage, necessary to support migration, are triggered by short photoperiods,” Dingle said, “and the butterflies orient using a sun compass synchronized to a circadian rhythm in the antennae. Overwintering sites in North America include the Transvolcanics Mountains of central Mexico, and the California Coast, particularly Santa Cruz, Pismo Beach, and Pacific Grove.
The UC Davis team will study the monarchs on the three islands and compare them with California mainland monarchs. Using an image analyzer and camera equipment available in Yang lab, the team will photograph “chilled” butterflies in a fixed position with wings spread and then release them back into the wild. The image analyzer will measure different variables, including length, width and angles from the photographs and compute multivariate-shape parameters.
The Chiu lab will assess genetic differences using a transcriptomic approach with monarch caterpillars. “This assessment will be greatly facilitated by the fact that the monarch genome has now been sequenced,” Dingle noted. “A major focus of Dr. Chiu's research is circadian rhythm genes, and these will be especially relevant here because of the association of these genes with monarch capabilities. Because the monarch cell line is cycling and has a functional circadian clock, effects of mutations in specific clock genes can be examined with regard to clock function.”
Dingle expects the one-year research program not only to form the basis for “long-term research on the evolutionary genetics of behavior, ecology and physiology on Pacific island monarch butterflies” but on “the general aspects of island biogeography, a subject of great practical theoretical interest in evolutionary biology.”
Both Yang and Chui currently have grants involving research on monarch butterflies. Yang also studies island ecology.
Dingle, who received his bachelor's degree in zoology from Cornell University and his doctorate in zoology from the University of Michigan, served on the faculty of the UC Davis Department of Entomology (now the UC Davis Department of Entomology and Nematology) from 1982 to 2002 and achieved emeritus status in 2003. He is a past president of the Animal Behavior Society and former secretary of the International Society for Behavioral Ecology.
Dingle published the second edition of “Migration: The Biology of Life on the Move” (Oxford University Press) in November 2014. It is the sequel to the widely acclaimed first edition, published in 1996. 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?”
Dingle was interviewed recently by Italian journalist Giovanna Faggionato for a piece on migration in the Pirelli magazine.