Nov. 12, 2012
Mallet will discuss "Mimicry and Speciation in Amazonian Butterflies: From Jungle to Genome" from 12:10 to 1 p.m. in Room 1022 of the Life Sciences Addition (LSA). The talk, open to all interested persons, is part of the UC Davis Department of Entomology’s fall seminar series. (His talk was initially titled "Hybridization, Mimicry and the Origin of Species in Heliconius Butterflies."
The adults’ brightly colored wing patterns signal their distastefulness to potential predators.
“It is a seductive idea that species are independent evolutionary units,” says Mallet, whose research focuses on the evolution and genetics of Amazonian butterflies. “Natural hybridization is rare in nature on a per-individual basis, but it may affect many species. Brightly colored Heliconius butterflies engage in Müllerian mimicry of other species. Although most of this mimicry is due to adaptive reconstruction of similar patterns, we've long suspected that color patterns are exchanged among some closely related species that hybridize occasionally in nature.”
Müllerian mimicry, named after German naturalist Fritz Müller, occurs when two or more poisonous species, “that may or may not be closely related and share one or more common predators, have come to mimic each other’s warning signals” (Wikipedia).
“We have recently shown that genomic regions that determine mimicry have been exchanged repeatedly among species to form new, adaptive combinations,” Mallet says. “Through their joint effects on mating behavior and signaling to predators, these novel color patterns are also involved in triggering evolution of new species.”
Before moving to Harvard, Mallet was a professor of biodiversity at University College London (UCL). He describes himself as an avid natural historian and a Darwin enthusiast. He has led courses in tropical ecology in southern Europe, Africa and across South America.
Mallet, appointed a distinguished lecturer earlier this year with Harvard's Department of Organismic and Evolutionary Biology, served as a UCL professor from 1992 to 2012. He was a Helen Putnam Fellow at Harvard's Radcliffe Institute for Advanced Study from 2009 to 2010.
Among his many appointments, Mallet is an honorary research fellow at the Natural History Museum, London, and a research associate at the Smithsonian Tropical Research Institute, Balboa, Panama.
Mallet received his bachelor’s degree in zoology in 1976 from Oxford University; his master’s degree in applied entomology from the University of Newcastle-upon-Tyne in 1978; and his doctorate in zoology at the University of Texas, Austin in 1984. He was a NERC Fellow (Natural Environment Research Council Fellowship) in genetics and biometry from 1985 to 1988 at UCL before joining Mississippi State University's Department of Entomology as an assistant professor.
Mallet will be introduced by medical entomologist/professor Greg Lanzaro of the UC Davis School of Veterinary Medicine.
--Kathy Keatley Garvey
Communications specialist
UC Davis Department of Entomology
(530) 754-6894
Robert E. Page, emeritus professor and former chair of the UC Davis Department of Entomology, and now the vice provost and dean of the College of Liberal Arts and Sciences, Arizona State University, Tempe, has been selected one of 10 new fellows of the 6000-member Entomological Society of America (ESA). He will be recognized Nov. 11, 2012 at the ESA’s annual meeting in Knoxville, Tenn.
Page is among the 10 new fellows announced today by the ESA Governing Board. Three others are linked to the University of California: Joseph Morse, professor of entomology at UC Riverside; Henry H. Hagedorn, who received his doctorate in entomology from UC Davis in 1970; and R. Michael Roe, who trained at the UC Davis Department of Entomology from 1981 to 1984 as a National Institutes of Health fellow in cellular and molecular biology.
Page, who studies the evolution of complex social behavior in honey bees, from genes to societies, retired from UC Davis in 2004 to be the founding director of the new School of Life Sciences. Arizona State University, where he built a Social Insect Research Group that is now recognized worldwide. He has held his current position of vice provost and dean of the College of Liberal Arts and Sciences since July 2011. Page, a member of the UC Davis faculty from 1989-2004, chaired the Department of Entomology from 1999 to 2004.
Hagedorn, a professor emeritus at the University of Arizona, Tucson, is internationally recognized for his research on the physiology of reproduction in mosquitoes, and as founder and editor-in-chief of the Journal of Insect Science.
Roe is a William Neal Reynolds Distinguished Professor in the Department of Entomology and the Department of Environmental and Molecular Toxicology at North Carolina State University in Raleigh, N.C. He is internationally recognized for his research in insect and acarine physiology, biochemistry, genomics and toxicology, and the use of fundamental research in chemistry, nuclear science, and biology to solve practical problems and develop new commercial technologies.
Biosketches:
Robert E. Page Jr.
Page, who received his bachelor’s degree in entomology from San Jose State University and his doctorate in entomology from UC Davis, completed postdoctoral training at the USDA Honey Bee Research Laboratory in Madison, Wisc. He was then appointed assistant professor of entomology at The Ohio State University in 1986. He joined the UC Davis faculty in 1989, serving as chair from 1999-2004. He moved to Arizona State University in 2004 to be the founding director of the new School of Life Sciences, where he built a Social Insect Research Group that is now recognized worldwide. He has held his current position of vice provost and dean of the College of Liberal Arts and Sciences since July 2011. Page was trained as an entomologist, evolutionary population geneticist, classical animal breeder, and mechanistic behaviorist. This training has defined his research approach of looking at the genetics and evolution of complex social behavior. He has taken a vertical approach to understanding the mechanisms of honey bee social foraging and how it evolves. His work is contained in more than 225 research articles. Page has also co-edited three books and authored or co-authored two. Page is a highly cited ISI (Institute for Scientific Information) author in plant and animal science. He is a fellow of the American Association for the Advancement of Science (AAAS) and an elected member of the American Academy of Arts and Sciences, the German National Academy of Science, and the Brazilian Academy of Science. In 1995 he was awarded the Alexander von Humboldt Research Prize by the government of Germany.
Hagedorn received his bachelor’s and master’s degrees from the University of Wisconsin-Madison and his doctorate in 1970 from UC Davis. He joined the entomology faculty at the University of Massachusetts, Amherst, and then at Cornell University before moving to the University of Arizona, Tucson, in 1988. Now a professor emeritus at the University of Arizona, he is internationally recognized for his research on the physiology of reproduction in mosquitoes, and as founder and editor-in-chief of the Journal of Insect Science. His honors include a Von Humboldt Senior Science Fellowship in Tübingin, Germany, and fellow of the AAAS. Research in Hagedorn’s laboratory focused on egg development in the mosquito Aedes aegypti and made significant discoveries. At the University of Arizona, Hagedorn directed the Center of Insect Science for five years. He led a group of students and teachers that produced materials for primary school teachers (Using Live Insects in Elementary Classrooms for Early Lessons in Life). Working with Emory and Marlene Sekaquaptewa, Hagedorn also produced a video, Hopi Corn: The Mother of Life. In 2001 Hagedorn launched the Journal of Insect Science, an open-access, online journal to provide an alternative to commercial journals. Hagedorn retired in 2005 and moved back to Wisconsin, where he is a member of the Department of Entomology at UW-Madison.
Roe obtained three degrees from Louisiana State University, including his master’s degree in physiology with a minor in biochemistry, and his doctorate in entomology and a minor in nuclear science. He moved to the UC Davis Department of Entomology from 1981 to 1984, serving as a National Institutes of Health fellow in cellular and molecular biology. He joined the North Carolina State University (NCSU) entomology faculty in 1984. Roe’s laboratory focuses on understanding how insect and acarine systems function at the molecular level, the use of synthetic organic chemistry to understand structure-activity, and applications in bioassay, chemistry, molecular biology, and physics to solve practical pest problems in the context of integrated pest management. His lab is especially active in technology transfer and product development. Some of his greatest successes include a U.S. EPA-registered, insect-tick repellent more effective than DEET and a fast-acting, natural, broad-spectrum herbicide. He is the author of more than 250 published papers, 7 books, 36 patents and 10 licensed technologies. He is the president of InTox Biotech in Middlesex, N.C., and serves on a number of advisory boards for several U.S. companies and non-profit organizations. Roe is also a founding member of the interdepartmental biotechnology program at NCSU and has developed new courses in physiology, insect morphology, molecular entomology, toxicology, and professional development. Although the recipient of numerous awards, he considers his greatest professional successes and greatest joy in the graduate students and postdoctoral researchers he has trained.
Morse received his bachelor’s degree in electrical engineering from Cornell University and then enrolled at Michigan State University where he received his master’s degree in entomology and systems science and his doctorate in entomology. He joined the UC Riverside faculty in 1981 and now teaches biology, entomology, evolution and ecology, and the natural history of insects.
Over the past 20 years, Morse’s laboratory has focused on applied and fundamental research dealing with the management of arthropod pests of citrus and avocados in California. Morse has specialized in the areas of integrated pest management, invasive species research, applied biological control, parasitoid behavior and ecology, insectary rearing of natural enemies, the acute and sub-lethal impact of pesticides on both target pests and non-target organisms, modeling and computer simulation, and pesticide resistance.
Morse has published 322 papers or book chapters, including more than 145 peer-reviewed articles. Serving in several UC administrative positions, he was the associate director of the UC IPM Program, charged with oversight of the statewide competitive grants program. In 1994, during the height of the Mediterranean fruit fly outbreak, he worked with local and systemwide administration to help found the UC Riverside Center for Invasive Species Research (CISR) and served as associate director and director of the center. CISR, along with UC IPM, oversaw the Exotic Pest and Disease Research Program, which awarded more than $10.3 million in grants.
When the UC Division of Agricultural and Natural Resources reorganized in 1999, Morse was asked to serve for six years (1999-2005) as one of four new statewide program leaders charged with overseeing systemwide activities in pest management and agricultural policy. Highly recognized for his work, he has received the ESA Recognition Award in Entomology, the Citrus Research Board Award of Excellence, the Art Schroeder Memorial Award for Outstanding Contributions to Avocado Research, Fellow of the American Association for the Advancement of Science, the Award of Honor from the California Avocado Society, and the Entomological Foundation Award for Excellence in Integrated Pest Management (IPM).
Morse also has an interest in international agriculture and has been involved in citrus and avocado pest management and/or cooperative projects with researchers and industry personnel in Arizona, Florida, Hawaii, Texas, Argentina, Australia, Brazil, Chile, Cyprus, Egypt, Israel, Japan, Mexico, New Zealand, South Africa, and Spain, and in a 1996 FAO-sponsored analysis of citrus integrated pest management in 13 countries of the Near East.
With the addition of Page, the UC Davis Department of Entomology now has 16 fellows who are current or former faculty members. The first was Richard M. Bohart (1913-2007), for whom the Bohart Museum of Entomology is named. He received the honor in 1947. Fiteen others followed: Donald McLean, elected in 1990; Harry H. Laidlaw Jr. (1907-2003), 1991; John Edman, 1994; Robert Washino, 1996; Bruce Eldridge, 2001; William Reisen, 2003; Harry Kaya, 2007; Michael Parrella and Frank Zalom, 2008; Walter Leal, 2009; Bruce Hammock and Thomas Scott, 2010; James R. Carey and Diane Ullman, 2011, and now Robert E. Page Jr., 2012.
(Editor's Note: Communications officers Iqbal Pittalwala of UC Riverside and Richard Levine of ESA contributed to this report.)
DAVIS--“Insect Societies,” featuring honey bees, ants and termites, will set the theme for the Bohart Museum of Entomology’s open house on Sunday, Nov. 18.
The event, free and open to the public, takes place from 1 to 4 p.m. Room 1124 of the Academic Surge building on Crocker Lane, formerly California Drive, on the UC Davis campus.
Senior museum scientist Steve Heydon said the bee displays will include a bee observation hive from the Harry H. Laidlaw Jr. Honey Bee Research Facility; a cartoon of a waggle/round/break dance created by former UC Davis student and cartoonist Beth Urabe; and a framed photo of a bee sting by Kathy Keatley Garvey, UC Davis Department of Entomology, that went viral.
Billy Synk, staff research associate at the Laidlaw facility, will provide the bee observation hive, which he also brought to the debut event of the Honey and Pollination Center on Oct. 27 at the Robert Mondavi Institute for Wine and Food Science.
Urabe’s cartoon depicts a waggle and round dance, behaviors performed by honey bees, and then on a humorous note, she added break dancing. She is a former cartoonist for the California Aggie newspaper,
The photo of the bee sting depicts a bee stinging Extension apiculturist Eric Mussen in the apiary at the Harry H. Laidlaw Jr. Honey Bee Research Facility. It won first place in a photo feature contest sponsored by an international agricultural-related organization and then was named “one of the most amazing photos of 2012” by Huffington Post.
Also planned are displays on ants and termites. Visitors can also “get up close and personal” with the live specimens in the year-around “petting zoo.” They include Madagascar hissing cockroaches, walking sticks and tarantulas, including a rose-haired tarantula.
“We have about two dozen in the petting zoo,” Heydon said.
Featured in the gift shop will be California dogface butterfly t-shirts at a discounted prices; and caddisfly cases that can be used to string together necklaces.
The Bohart Museum, directed by Lynn Kimsey, professor of entomology at UC Davis, houses a global collection of nearly eight million insect specimens and is the seventh largest insect collection in North America. It is also the home of the California Insect Survey, a storehouse of the insect biodiversity. Noted entomologist Richard M. Bohart (1913-2007) founded the museum in 1946.
Bohart officials schedule weekend open houses throughout the academic year so that families and others who cannot attend on the weekdays can do so on the weekends. The Bohart’s regular hours are from 9 a.m. to noon and from 1 to 5 p.m., Monday through Thursday. The insect museum is closed to the public on Fridays and on major holidays. Admission is free.
The remainder of the open houses for the 2012-2012 academic year are:
Saturday, Dec. 15, 1 to 4 p.m.
Theme: "Insects in Art"
Sunday, Jan. 13, 1 to 4 p.m.
Theme: "Extreme Insects"
Saturday, Feb. 2, 1 to 4 p.m.
Theme: "Biodiversity Museum Day"
Sunday, March 24, 1 to 4 p.m.
Theme: "Aquatic Insects"
Saturday, April 20: 10 a.m. to 3 p.m.
Theme: UC Davis Picnic Day
Saturday, May 11, 1 to 4 p.m.
Theme: "Moth-er's Day"
Sunday, June 9, 1 to 4 p.m.
Theme: "How to Find Insects"
More information is available on the Bohart website at http://bohart.ucdavis.edu/ or by contacting Steve Heydon at slheydon@ucdavis.edu or (530) 752-0493. The nearest intersection to Crocker Lane is LaRue Road.
--Kathy Keatley Garvey
Communications specialist
UC Davis Department of Entomology
(530) 754-6894
Speakers for the winter quarter seminar series, UC Davis Department of Entomology, have been announced by assistant professors Joanna Chiu and Brian Johnson, coordinators.
All will take place from 12:10 to 1 p.m. in Room 1022 of the Life Sciences Addition. Plans are to record the seminars for later posting on UCTV under the coordination of professor James R. Carey.
Winter Quarter 2013
Wednesday, Jan. 9
Erin Wilson
Postdoctoral Associate, University of Maryland
Title: Effects of Omnivorous Invaders on Arthropod Communities in a Fragmented Landscape
Host: Louie Yang
Wednesday, Jan. 16
Michael Branstetter
Buck Postdoctoral Fellow, Smithsonian National Museum of Natural History
Title: "Uncovering the Origins of a Middle American Ant Radiation: insights from Natural History, Biogeography and Molecular Data."
Host: Phil Ward
Wednesday, Jan. 23
Nick Haddad
William Neal Reynolds Professor of Biology, North Carolina State University
Title: Landscape Conservation for Rare Insects
Host: Neal Williams
Wednesday, Jan. 30
Paul de Barro
Senior Principal Research Scientist, CSIRO ecosystem sciences
Title: Unravelling the Complex Bemisia tabaci (Silverleaf Whitefly): From Biotype to Species
Host: Michael Parrella
Wednesday, Feb. 6
Jim Cane
Entomologist, USDA-ARS Bee Biology Lab
Title: The Spectrum of Managed Nesting for Pollination by Non-Social Bees
Host: Leslie Saul-Gershanz
Wednesday, Feb. 13
Steven Reppert
Higgins Family Professor of Neuroscience, University of Massachusetts Medical School
Title: Monarch Butterfly Migration: Behavior to Genes
Hosts: Joanna Chiu and Hugh Dingle
Wednesday, Feb. 20
Nick Mills
Professor, UC Berkeley
Title: Light Brown Apple Moth – Not a Typical Invader
Host: Mary Louise Flint
Wednesday, Feb. 27
Anupama Dahankar
Assistant Professor, UC Riverside
Title: Taste Receptors and Feeding Preferences in Insects
Host: Joanna Chiu
Wednesday, March 6
Sergio Rasmann
Assistant Professor
UC Irvine Department of Ecology and Evolutionary Biology
Title: Ecological, Evolutionary and Genetic Drivers of Plant Defenses against Herbivores
Host: Rick Karban
Wednesday, March 13
Anna Whitfield
Associate Professor, Kansas State University
Title: Dissecting the Molecular Interplay Between Plant Viruses and their Arthropod Vectors
Host: Diane Ullman
--Kathy Keatley Garvey
Communications specialist
UC Davis Department of Entomology
(530) 754-6894
Nov. 2, 2012
A trio of entomologists affiliated with the Bohart Museum of Entomology at the University of California, Davis, recently published a humorous take on the evolutionary development and history of the 646 fictional species depicted in the Pokémon media over the last 16 years.
“We made a very real phylogeny of the very fake Pokémon creatures,” commented lead author Matan Shelomi, the UC Davis entomology graduate student who conceived the idea.
The article, “A Phylogeny and Evolutionary History of the Pokémon,” appeared in the Annals of Improbable Research (AIR), a tongue-in-cheek journal meant “to make people laugh and then think,” according to the editors. In keeping with the “laugh-and-then-think” concept, the journal also awards the infamous IG Nobel Prizes.
Shelomi, a graduate of Harvard where the IG Nobel Prizes are awarded, said he based his idea “in part on other AIR papers like the phylogeny of Chia Pets and the taxonomic description of Barney the Dinosaur.”
Devoted Pokémon fans know that Pokémon, which means “Pocket Monsters,” is the 1996 brainchild of video game developer Satoshi Tajiri of Japan, who collected insects in his childhood and initially toyed with the idea of becoming an entomologist. Today the Nintendo-owned Pokémon is the world’s second most successful video game-based media franchise, eclipsed only by Nintendo’s Mario.
Until now, however, no one has traced the evolutionary history of the 646 fictional species, let alone develop a 16-generation phylogenetic or evolutionary tree.
“I had a lull in my dissertation research and decided to spend the weekends and downtime making this phylogeny,” said Shelomi, who is studying for his doctorate in entomology with Lynn Kimsey, director of the Bohart Museum and professor of entomology at UC Davis. “It took at least a month to actually collect all the data, which I did manually by scrolling through Pokémon websites.”
His interest in Pokémon? “I’ve played the Pokémon Stadium games and watched some of the TV shows when I was in junior high,” he said, describing the influence as strong. “I was in the right target audience range right when Pokémania was hitting the United States, and everyone I knew could recognize a Pikachu on sight.”
“What I love in Pokémon is similar to what I love in entomology--and I suspect Tajiri would agree with me,” Shelomi said. “It provides me with a wide array of unique and colorful creatures to study, all of which are connected in certain fascinating ways. It's a fun way to tie biology with imagination; I just decided to take it a step further and make a paper out of it.”
After collecting the data, Shelomi sent it to Andrew Richards, a junior specialist at the Bohart Museum of Entomology, for the actual phylogram making. When the AIR editors asked for illustrations, Shelomi sought out artist Ivana Li, a fifth-year entomology student and president of the UC Davis Entomology Club. Li, who works part-time at the Bohart Museum, honed her talents as a student cartoonist for the Schurr High School, Montebello, newspaper.
The trio added a fourth co-author, Yukinari Okido, whom Pokémon fans may recognize as the Japanese name of one of the fictional Pokémon professors from the game/TV show, Professor Oak.
“This was a very clever exercise and drew on the talents of some very gifted students,” Kimsey said. Their phylogenetic tree can be seen in the Bohart Museum, located at 1124 Academic Surge on Crocker Lane, UC Davis campus.
Richards described working on the project as “fun, educational and nostalgic.”
“Matan sent me the information to process, I plugged it into a phylogeny program, and let it run, simulating generations for about a day,” Richard said. “I took the results and generated a tree. That took some time to add pictures and some color-coding. I wanted the tree to look nice and be pretty easy to interpret.”
The project also embraces educational elements. “I think it can be a good way to explain phylogeny to people with no background in it, since the characteristics and traits used here are easier to grasp than those used in molecular phylogeny or even those done using physical characters,” Richards said.
Richards, who finds playing Pokémon games “both fun and creative,” said the project included a nostalgic aspect, too. “I remember when they first came out and loving them then. When Matan told me about his idea for doing this I thought it would be fun. I wanted to see how well the data would come out, considering everything is just made up by the game makers without any thought to phylogeny or actual evolutionary relationships.”
“It turned out surprisingly well given the data we put into it,” Richard said. “Things fell into good places and it looks very nice.”
Li, who has played Pokémon “for at least a decade,” considers the game and the monsters “pretty creative, especially ones with an actual biological basis. Of course, breathing fire and shooting lightning is pretty cool, too.”
“I like the overall project,” Li said, “because it takes a rather extreme amount of nerdiness to appreciate. However, you have to admit that it is pretty interesting to be able to apply a phylogeny to a bunch of game characters. I really enjoy the simplicity of Pokémon because a lot of people can understand it and relate to it.”
Her sister, a teacher and an even more avid Pokémon fan, “is actually able relate to a lot of her students due to her knowledge of Pokémon,” Li pointed out. “There are aspects to cartoons and video games that might have other applications later on in your life that you would never expect.”
The UC Davis entomologists prefaced the journal article by relating why they did it. “With the phylogenetic and evolutionary relationships of the kingdoms Animalia, Plantae, and Fungi mostly out of the way, attention is now turning toward the Monstrasinu, commonly known as ‘Pocket Monsters’ or ‘Pokémon’ for short. Starting from the 151 original ‘species’ described by Japanese scientist Satoshi Tajiri in a 1996 monograph, Pokémon science today continues to be a rewarding field for taxonomists. Every three to four years, several new species are discovered and described almost simultaneously. A total of 646 Pokémon have been described, most of them in Japan.”
“This paper,” they wrote, “represents the first attempt to create a quantitative phylogeny of the Pokémon, using the underlying assumption that Pokémon evolved via natural selection independently from the animals and plants more familiar to Western zoologists. The goal was to apply modern evolutionary theory and techniques to a field previously limited to pre- Darwinian methods of inquiry.”
The trio acknowledged that some of the specimens are “threatened by the Pokémon fighting rings that are growing rapidly in popularity, particularly among urban youth.”
They also agreed that disagreements over species concepts exist, and that “several sexually dimorphic taxa have had males and females identified as separate species,” offering the examples of Nidoqueen and Nikoking.
“Further complicating the issue is the fact that Pokémon are quite willing to interbreed successfully,” they wrote, adding that “the lack of post-zygotic reproductive isolation is one thing, but how a 400-kilogram Wailord is able to mate with an 11-kilogram Skitty at all remains a mystery.”
As to methods used, they revealed that undergraduate, high school and primary-school aged interns/ trainers from Japan and New York state captured wild Pokémon. “Trainers may or may not have used their Pokémon for combat during the course of their research,” they quipped.
The result: a phylogenetic or evolutionary tree detailing 16 million generations of simulated Pokémon evolution. They concluded that “Pokémon life began in the water, with Pokémon similar to lampreys and bony fishes being among the earliest to reach their present state.” Terrestrial life, they said, rose independently three times.
“This paper,” they summarized, “thus sheds considerable doubt on whether Pokémon use DNA to transmit genetic information, and further suggests the Monstrasinu are a unique domain of life.”
What about reader reaction? “The paper is slowly making the rounds,” Shelomi said. “We've had quite a few people disagree with the tree, as some of the conclusions violate Pokémon canon, and we do have the usual phylogenetic problems of long-branch attraction, etc. The disconnect between the tree and Pokémon mating groups is a problem, but I argue that the Biological Species Concept should not be assumed for Pokémon and I stand by my tree.”
“So far, one scientist--a linguist in Japan--has asked for a copy of the dataset to use in a class on phylogram building, and he apparently came up with a different tree.”
“It would be nice to see a wide set of articles responding to this one,” Shelomi said. “I think it would be quite easy to fill a journal of Pokémon science, although much harder to justify creating one.”
Editor's Note: The Bohart Museum of Entomology, directed by entomology professor Lynn Kimsey, is located at 1124 Academic Surge on Crocker Lane, formerly California Drive), UC Davis campus. It is open to the public from 9 a.m. to noon and from 1 to 5 p.m. Mondays through Thursdays. It is closed to the public on Friday and weekends, but has special weekend hours.)
--Kathy Keatley Garvey
Communications specialist
UC Davis Department of Entomology
(530) 754-6894