- Author: Kathy Keatley Garvey
Dingle, who served as a professor in the UC Davis Department of Entomology from 1982 to 2002, achieving emeritus status in 2003, recently published the second edition of Migration: The Biology of Life on the Move (Oxford University Press), a sequel to the first edition published in 1996.
A worldwide authority on animal migration, Dingle says the full understanding of migration, or “life on the move,” involves genetics, physiology, and morphology, as well as behavior and ecology. Among the animals that migrate: whales, monarch butterflies, armyworm moths, pelicans, locusts, winged aphids and ballooning spiders.
Dingle has researched in seven countries: UK, Kenya, Thailand, Panama, Germany and Australia, as well as the United States. National Geographic featured him in its cover story on “Great Migrations” in November 2010. LiveScience interviewed him for its November 2010 piece on“Why Do Animals Migrate."
Now Dingle will be heading to the Pacific islands to study monarchs. He just received the UC Davis Edward A. Dickson Professorship Award to research “Monarchs in the Pacific: Is Contemporary Evolution Occurring on Isolated Islands?”
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 believes. He 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.
The monarch, widely distributed “for eons” in the New World, is fairly new to the Pacific islands and to Australia. He speculates that the monarchs arrived in the Pacific islands with their host plant, milkweed, which was valued at the time for its medicinal properties.
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.”
That's exciting research. We look forward to the results!
- Author: Kathy Keatley Garvey
For years we've marveled at the migrating whales passing Point Reyes as we stood glued to our binoculars.
And we've expressed awe that a bird--a plover--makes nonstop flights over the central Pacific Ocean from Alaska to Australia and New Zealand.
Amazing. Nothing short of incredible, especially when you consider that many homo sapiens can't find their way out of a parking lot.
They're all on the move. But how many of us have seen the lesser known migrants, such as winged aphids, ballooning spiders, mites, locusts, pelicans, grasshoppers, and armyworm moths, on the move?
Enter Hugh Dingle, an emeritus professor of entomology at the University of California, Davis, and a worldwide authority on animal migration.
Dingle, who was featured in National Geographic's cover story on "Great Migrations in November 2010 and interviewed by LiveScience for its November 2010 piece on “Why Do Animals Migrate?", has just published the second edition of his book, Migration: The Biology of Life on the Move (Oxford University Press), a sequel to the first edition published in 1996.
The full understanding of migration, or “life on the move,” involves genetics, physiology, and morphology, as well as behavior and ecology, Dingle says.
"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.”
Not all migration is a round trip; sometimes it's one-way, Dingle says. “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.'"
Why is it important to understand the biological basis of migration and its evolution? “Because migration is so widespread and because migrants have such impact on both natural and man-altered ecosystems,” says Dingle, who achieved emeritus status in 2003 after serving on the faculty of the UC Davis Department of Entomology (now the UC Davis Department of Entomology and Nematology) from 1982 to 2002.
In his book, Dingle covers the interaction between behavior and outcome. Another important focus: he covers the relation between migration and life histories, including the evolutionary genetics of the relationship. Long-distance round-trips, for example, require long lifespans, hence most insects, although not all, migrate only one-way.
“Natural selection acts differently on long versus short lives," Dingle says. "With long lives there are usually many opportunities to produce offspring; with short lives there may be only one. 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."
Dingle, former secretary of the International Society for Behavioral Ecology and past president of the Animal Behavior Society, says he wrote the book for "students of migration and for those biologists who are generally interested in the functioning and adaptations of whole organisms."
Dingle is a fellow of the American Association for the Advancement of Science and the Animal Behavior Society. His research has taken him throughout the world, including the UK, Kenya, Thailand, Panama, Germany and Australia.
In some respects, he, too, migrated.
- Author: Kathy Keatley Garvey
If you think people don't care about monarch butterflies, think again.
A recent survey published in Conservation Letters showed that Americans are willing to spend at least $4.78 billion to help conserve monarchs (Danaus plexippus), one of the most recognizable of all insects. Indeed, what is more spectacular than the multigenerational migration of monarchs heading from their breeding grounds in northern United States and southern Canada to their wintering grounds in central Mexico and coastal California?
The study of 2,289 U.S. households, led by Jay Diffendorfer of the U.S. Geological Survey, Geosciences and Environmental Change Science Center, Denver, found that we Americans love monarchs so much that we're more than willing to plant milkweed, their larval host plant, to save them.
Yes!
The article, published Oct. 28 and titled National Valuation of Monarch Butterflies Indicates an Untapped Potential for Incentive-Based Conservation, calls attention to the destruction of the monarch's habitat and the importance of conservation.
"Since 1999, the size of the overwintering colonies in Mexico and California have declined, and the 2012 survey in Mexico showed the lowest colony size yet recorded, which prompted wide-scale media reports," the authors wrote. "Habitat loss in the overwintering sites in Mexico and California is well-documented, although no direct empirical link between declining overwintering habitat and monarch numbers exists. In addition, the growing use of glyphosate-tolerant genetically modified crops has reduced larval host plant (milkweed, Asclepias spp) abundances in farm fields across United States and Canada. Increasing acreage of glyphosate-tolerant corn and soybeans are negatively correlated to monarch numbers, with the area of milkweed in farm fields in the United States declining from an estimated 213,000 to 40,300 ha."
Biologist Hugh Dingle, emeritus professor of entomology at UC Davis, is among those studying their migration. (Read his quotes in the National Geographic cover story, "Mysteries of Great Migrations," published in November 2010. Dingle is now working on a much-anticipated book on migration from his headquarters in the Sharon Lawler lab, UC Davis Department of Entomology and Nematology.
Butterfly expert Art Shapiro, distinguished professor of evolution and ecology at UC Davis, monitors butterflies in Central California. Here's what he has to say about monarchs on his website, Art's Butterfly World.
Meanwhile, a day before Conservation Letters published the survey, a lone monarch butterfly fluttered into our backyard to sip nectar from lantana. It lingered for 10 minutes.
What a treat to see!
- Author: Kathy Keatley Garvey
But how many people know about its migration?
Steve Reppert, chair and professor of the Department of Neurobiology at the University of Massachusetts Medical School, will speak on "Monarch Butterfly Migration: Behavior to Genes" at the Department of Entomology seminar on Wednesday, Feb. 13 from 12:10 to 1 p.m. in Room 1022 of the Life Sciences Addition, corner of Hutchison and Kleiber Hall drives.
"Studies of the iconic migration of the eastern North American monarch butterfly have revealed mechanisms behind its navigation using a time-compensated sun compass," Reppert says. "Skylight cues, such as the sun itself and polarized light, are processed through both eyes and integrated in the brain’s central complex, the presumed site of the sun compass. Circadian clocks that have a distinct molecular mechanism and that reside in the antennae provide time compensation. The draft sequence of the monarch genome has been presented, and gene-targeting approaches have been developed to manipulate putative migration genes. The monarch butterfly is an outstanding system to study the neural and molecular basis of long-distance migration." (See lab research.)
Hosts are Joanna Chiu, assistant professor of entomology, and Hugh Dingle, emeritus professor of entomology, will host the talk. Dingle, an authority on animal migration, was featured in a National Geographic cover story, "Mysteries of Great Migrations" in November 2010.
Reppert received his bachelor's degree from the University of Nebraska, Omaha, in pre-medicine, and his medical degree from the University of Nebraska College of Medicine. He completed a post-doctoral fellowship in neurobiology at the National Institutes of Child Health (NICHD), NIH, in 1979. He is a professor of pediatrics (neuroscience) at Harvard Medical School (2001 to the present) and since 2000, a pediatrician at the Massachusetts General Hospital.
Reppert became the chair of the Department of Neurobiology, UMass Medical School in 2001, the same year he became the Higgins Family Professor of Neuroscience at UCMass Medical School. He is a fellow of the American Association for the Advancement of Science.
Among his publications on monarchs:
Reppert SM, Gegear RJ, Merlin C (2010). Navigational mechanisms of migrating monarch butterflies. Trends in Neurosciences (TINS) 33:399-406.
Heinze S, Reppert SM (2011). Sun compass integration of skylight cues in migratory monarch butterflies. Neuron 69:345-358.
Zhan S, Merlin C, Boore JL, Reppert SM. The monarch genome yields insights into long-distance migration. Cell 2011; 147:1171-1185.
Reppert's talk will be video-recorded and posted on UCTV at a later date.
- Author: Kathy Keatley Garvey
We're accustomed to seeing a solitary monarch butterfly (Danaus plexippus) flitting around a garden.
But millions of them?
It was interesting to read the National Public Radio piece (Oct. 4) on Flight: A Few Million Little Creatures That Could.
The feature news story traces how a "young boy in Canada wondered where butterflies go in the winter--and spend 40 years trying to answer that question."
"In 1973, Dr. Fred Urquhart--all grown up by then--placed an ad in a newspaper in Mexico looking for volunteers to tag and observe butterflies and find their destination."
A woman and her husband answered the ad, and in the course of two years, found "hundreds of millions of butterflies."
Monarch sanctuaries!
If you access the NPR website, you'll see clips of a documentary made by Mike Slee. It's called the "Flight of the Butterflies," which NPR describes as a "3-D IMAX film about the migration of the monarchs to sanctuaries."
"What you see, you can't imagine nature ever being like this," Slee tells NPR. "Trees that are draped — that are made, almost, of butterflies. It's got a surreal, supernatural feeling to it. It sends a sort of tingle up your spine when you see it in 3-D. And then they wake up and they all begin to fly."
NPR goes on to say that "the migration of the monarch butterfly is a staggering natural phenomenon. It takes two or three generations for the creatures to make their way north to Canada — but then one 'supergeneration' makes the 2,000-mile trip back to Mexico for the winter."
At UC Davis, emeritis professor Hugh Dingle is a noted authority on the migration of animals. He's been featured in National Geographic and other magazines. The good news is that he's writing the second edition of his popular textbook, Migration: The Biology of Life on the Move (Oxford University Press).
Dingle, who is headquartered in the Sharon Lawler lab in the UC Davis Department of Entomology, was featured in the National Geographic magazine's cover story, "Mysteries of Great Migrations."
He was quoted in a LiveScience news story on “Why Do Animals Migrate?”
Excellent information!
Frankly, we don't see as many monarchs as we'd like to. Seeing even one monarch "sends a tingle up the spine."
Plant and insect enthusiast Gary Zamzow of Davis--and an excellent photographer--recently planted some milkweed (the monarch's host plant) in the Häagen-Dazs Honey Bee Haven, a pollinator friendly garden located next to the Harry H. Laidlaw Jr. Honey Bee Research Facility on Bee Biology Road, UC Davis.
Hopefully, the milkweeds will attract many of those mighty monarchs next year and send lots of "tingles up the spine."
