The research paper, “Introduced Herbivores Restore Late Pleistocene Ecological Functions” is the work of an 11-member international team led by Australian ecologist Erick Lundgren of the University of Technology, Sydney.
The authors pored over scientific literature; created a list of living and extinct herbivores over the last 126,000 years; and categorized them by their body size, anatomy, habitat, diet, and how their bodies digested the vegetation. Then they compared their lifestyles in overlapping regions.
Carroll, affiliated with the UC Davis Department of Entomology and Nematology, said one of the studies dealt with the abandoned hippos of Colombian drug lord Pablo Escobar (1949-1993), who purchased a male and three females in the 1980s from a California zoo and kept them in fields along the Magdalena River, northwestern Colombia. Without humans and other predators decimating them, the population today is 80 and is expected to reach 800 to 5000 by 2050.
The out-of-place hippos may be filling the exotic roles of extinct massive animals, such as giant llamas and rhinoceros-sized relatives, the ecologists said.
Said Carroll: “That paleontological analysis found that, amazingly, introduced herbivores– including Pablo Escobar's escaped Colombian hippos– often match the functional traits of extinct natives better than do those missing species' closest living native relatives. In this way, the ‘out-of-place' make the world more similar to the pre-extinction past. The ‘shoot-first- and-ask-questions later' approach as a maxim is as reckless as it sounds, and it's not going to sustain our life-saving drugs, nor the species we revere or ecosystems we rely on, into the future.”
“Many introduced herbivores restore trait combinations that have the capacity to influence ecosystem processes, such as wildfire and shrub expansion in drylands,” the team wrote.
As for feral hogs in North America, Carroll said their rooting increases tree growth and attracts bird flocks, like the ecological work of their extinct ancestors. Likewise, the feral horses and burros, known for their well-digging behavior, are replacing the original American horses, which went extinct 12,000 years ago.
In their abstract, the authors pointed out that humans “have caused extinctions of large-bodied mammalian herbivores over the past 100,000 years, leading to cascading changes in ecosystems. Conversely, introductions of herbivores have, in part, numerically compensated for extinction losses. However, the net outcome of the twin anthropogenic forces of extinction and introduction on herbivore assemblages has remained unknown. We found that a primary outcome of introductions has been the reintroduction of key ecological functions, making herbivore assemblages with nonnative species more similar to preextinction ones than native-only assemblages are. Our findings support calls for renewed research on introduced herbivore ecologies in light of paleoecological change and suggest that shifting focus from eradication to landscape and predator protection may have broader biodiversity benefits.”
Carroll, who also co-led an author group of the newly published “Coevolutionary Governance of Antibiotic and Pesticide Resistance” in the journal Trends in Ecology, said that the publications together “address both sides of the human-environment co-existence issue.”
“Reading the titles, you might not expect these two studies are two sides of the same coin,” Carroll said, “but for me they address both sides of the human-environment issue that most compels me: How can we create more workable, productive and respectful long-term relationships with other species? To help think about this as an evolutionary biologist, I divide the key challenges of human interactions with Nature into those that arise from competitor and parasite species that adapt too quickly for us to control, and those that arise in in our efforts to protect more valued species– like endangered large mammals– that adapt too slowly to survive human impacts.”
“Pesticide and drug resistance are nature's predictable resilience to our reliance on an escalating war of toxic eradication,” Carroll commented. “A broader understanding shows how we can develop our own behavior to instead cultivate susceptibility to control in species we fight, using both new and known practices for improved sanitation, locally diversified agriculture, and eating lower on the food chain to inflect their evolution in a positive direction. Similarly, after millennia of driving much of the Earth's giant mammal community to extinction, we need to step back from our reflex to extinguish the errant survivors to preserve a modern sense of what's natural, without stopping to consider how these new neighbors (commonly fading from their native lands) may restore ancient ecological functions our own ancestors extinguished not so long ago.”
Carroll emphasized that “neither of these studies dismisses the serious problems irruptive populations can cause for meeting our food, health and environmental needs, nor seeks to oversimplify complex challenges. But it's actually important to work against being limited by prejudicial generalizations that lead us to sort other species into ‘good' versus ‘bad' bins. This is a sensibility that ecologists in particular should strive to cultivate. To continue to feed and shelter ourselves and remain healthy while sharing the Earth with other species, we need to develop methods that respect the tremendous information and know-how inherent in each species. I want us to do a much better job of working with that intrinsic functional diversity and adaptive potential as our best resource for advancing resilient and biodiverse ecological systems into the future.”
Carroll and his wife, UC Davis ecologist Jenella Loye, own Carroll-Loye Biological Research, Davis. They engage in public health and environmental entomology and natural product development.
(Editor's Note: The lead author of Coevolutionary Governance of Antibiotic and Pesticide Resistance is Peter Søgaard Jørgensen, who during his University of Copenhagen graduate work, spent a year at Davis studying soapberry bug host adaptation in California with Scott Carroll. The duo led the multi-year international "Living with Resistance" pursuit at the National Science Foundation's National Socio-Environmental Synthesis Center. Carroll served as the senior author.)
It's somewhat like that when plant-parasitic nematodes (microscopic round worms) play “chemical hide and seek” with their plant host, says plant pathologist Shahid Masood Siddique, an assistant professor in the UC Davis Department of Entomology and Nematology.
“The success of plant-parasitic nematodes depends on their ability to locate a suitable host in the soil,” says Siddique, corresponding author of the newly published Spotlight article, “Chemical Hide and Seek: Nematode's Journey to Its Plant Host,” in the journal Molecular Plant.
Nematodes can be deadly to plants, not only because of the direct damage they cause (they extract water and nutrients from their hosts such as wheat, soybeans, sugar beets, citrus, coconut, corn, peanuts, potato, rice, cotton and bananas) but the role of some species as virus vectors.
“Plant-parasitic nematodes are among the most destructive agricultural pests, causing more than $100 billion in losses per year in the United States,” Siddique said, noting that nematodes are especially damaging to potato, soybean and wheat crops.
Although the success of nematodes depends on their ability to locate a suitable host in the soil, what attracts them to their host “has largely remained unknown,” wrote the four-member UC Davis team of Siddique, Natalie Hamada, Henok Zemene Yimer and Valerie Williams. “Recent studies have revealed that host-seeking by nematodes is a complex process that involves multiple stages in the interaction.”
“Most damage is caused by a small group of root-infecting sedentary endoparasitic nematodes including cyst nematodes and root-knot nematodes (RKNs),” the team of UC Davis researchers wrote in their abstract. “Second stage juveniles (J2s) of plant-parasitic nematodes hatch from eggs into the soil and localize to the roots of host plants. The success of these non-feeding J2s depends on their ability to locate and infect a suitable host.”
For eight decades, scientists have researched the attraction of plant-parasitic nematodes to the host root, ever since the pioneering Maurice Blood Linford (1901-1960) of the University of Illinois, Urbana, Ill., observed in 1939 that the larvae of root-knot nematodes congregate in the cell elongation region behind the root cap.
“Both volatile and soluble components in the rhizosphere have been shown to influence nematode movement,” the UC Davis researchers wrote. “Methyl salicylate, a volatile chemical root signal, has been demonstrated to be a strong root attractant for RKN towards several Solanaceous plants (nightshade family). The non-volatile tomato root exudate quercetin was shown to elicit concentration dependent attraction or repulsion effect against Meloidogyne incognita to host root. Three recent studies have revealed that the recognition of and response to hosts by infective juveniles is a complex process that involves multiple stages in the interaction.”
Siddique focuses his research on basic as well as applied aspects of interaction between parasitic nematodes and their host plants. “The long-term object of our research is not only to enhance our understanding of molecular aspects of plant–nematode interaction but also to use this knowledge to provide new resources for reducing the impact of nematodes on crop plants in California.”
Entomologist Marlin Rice, a past president of the Entomological Society of America (ESA), penned the piece, titled "Bruce D. Hammock: Science Should Be Fun!"
Wrote Rice: "Bruce D. Hammock is widely known for his groundbreaking research in insect physiology, toxicology, pharmacology, and experimental therapeutics. Early contributions were in fundamental regulatory biology, development of both small molecules and recombinant viruses as environmentally friendly pesticides, and the application of accelerator mass spectrometry to biological science. His laboratory pioneered the use of immunoassay for the analysis of human and environmental exposure to pesticides and other contaminants.His laboratory provides graduate training that is diverse in disciplines and research areas. He recently formed a company, EicOsis, to develop an orally active non-addictive drug for inflammatory and neuropathic pain for humans and companion animals."
Hammock, who joined the UC Davis faculty in 1980 from UC Riverside, has directed the UC Davis Superfund Research Program (funded by the National Institutes of Health's National Institute of Environmental Health Sciences) for nearly four decades. He is a member of the National Academy of Sciences, and a fellow of the National Academy of Inventors and ESA.
A native of Little Rock, Ark., Bruce received his bachelor's degree in entomology (with minors in zoology and chemistry) magna cum laude from Louisiana State University, Baton Rouge, in 1969. He received his doctorate in entomology-toxicology from UC Berkeley in 1973 with John Casida at UC Berkeley. Hammock served as a public health medical officer with the U.S. Army Academy of Health Science, San Antonio, and as a postdoctoral fellow at the Rockefeller Foundation, Department of Biology, Northwestern University, Evanston, Ill.
Read the feature story here.
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(Editor's Note: Thanks to Lisa Junker, ESA's director of publications, communications and marketing, who reached out to "our publishers at Oxford" to grant free community access to this feature story in American Entomologist)
Before accepting her UC Davis appointment, Meineke served as a National Science Foundation postdoctoral fellow at the Harvard University Herbaria, where she studied how urbanization and climate change have affected plant-insect relationships worldwide over the past 100-plus years.
A native of Greenville, N.C., Emily received her bachelor of science degree in environmental science, with a minor in biology, in 2008 from the University of North Carolina, Chapel Hill, and then went on to obtain her doctorate in entomology in 2016 from North Carolina State University. Advised by Steven Frank and co-advisor Robert Dunn, she completed her dissertation on "Understanding the Consequences of Urban Warming for Street Trees and Their Insect Pests."
1. Please expand on the kind of research you do.
"Insects have eaten plants for around 400 million years. These interactions have given rise to most of terrestrial biodiversity. Over the past 12,000 years, humans have disrupted plant-herbivore relationships by building cities, domesticating crops, and changing the global climate."
"I investigate these disruptions, focusing on species that are of cultural importance, such as street trees, crops, crop wild relatives, and plants that support rare insect species. My work combines experiments, observations, citizen science, and biological collections to address key hypotheses in ecology."
2. What do you like best about your work?
"I love discovery, the moment when you as a scientist know something that no one else knows. I love passing that experience on to students. I also love that my work reflects my personal values. Biodiversity is critically important, and the fact that I get to study it for a living is a real privilege."
3. How did you get interested in entomology? Can you recall an occasion that sparked your interest?
"I have no idea, honestly. I never had an insect collection as a kid, and I was equally interested in all living things, from my family's pets to the toads that lived in my backyard. At some point after my undergraduate education, I realized that insects are both invisible to us most of the time and are incredibly present in our lives and imaginations. Ecologically, because they are small in size, they can seem unimportant because we are biased to think creatures our size or larger are important, but insects are really the little things that run the world."
4. How would you describe yourself?
"I'm a pretty serious person who is always working to be more light-hearted. I am both easily discouraged and tenacious. I would describe myself as creative and am drawn to diversity in all forms."
5. What drew you to UC Davis?
"When I visited, I got the feeling that UC Davis encourages creativity while valuing research that produces real solutions. When I interviewed here, I felt I would be able to be myself as a researcher and that my fellow faculty would support that. On top of that, UC Davis is such an established institution with great resources in a beautiful part of the world. I can't think of a better place to be."
6. What do you like to do in your leisure time?
"All I really ever want to do is eat and spend time with people I love. 'People' includes my two dogs, who rule the house."
9. What would people be surprised to know about you?
"I have a hidden talent. I can make very realistic cat meows. I can fool anyone's cat and most humans."
In addition to her NSF Postdoctoral Research Fellowship, she received a number of other honors, including Student Appreciation for the Biology of Insect Pests Award; Garden Club of America Urban Forestry Fellowship; and the EPA Science to Achieve Results (STAR) Fellowship.
A member of the Entomological Society of America (ESA), Ecological Society of America and the Botanical Society of America, she has presented talks across the continent, as well as in Finland, Spain, Canada, France and Denmark. She delivered a presentation at the 2016 International Congress of Entomology in Orland, Fla., and at ESA's national and regional meetings.
Meineke has published her work in Ecological Monographs, Ecology and Evolution, Journal of Applied Ecology, and the Journal of Urban Ecology, among others.
The Boston Globe featured her research in a news story published Oct 11, 2018: "Rising Temperatures May Cause Insects to Eat More Plants, Harvard Study Says"
Nature journal featured her in a research highlights piece, "Warmer Forests Store Less Carbon," published Oct. 12, 2016
Los Angeles Times spotlighted her in its Oct. 6, 2016 piece, "As Cities Get Warmer, These Trees Lose Some of their Ability to Take Carbon Out of the Atmosphere."
DAVIS--Newly published research in the Proceedings of the National Academy of Sciences (PNAS) indicates that a drug discovered and developed in the laboratory of Bruce Hammock,UC Davis Department of Entomology and Nematology, may have a major role in preventing and treating llnesses associated with obesity.
More than 43 percent of adults in the United States are obese, according to the Center for Disease Control and Prevention (CDC). Obesity increases the risk of coronary artery disease, stroke, type 2 diabetes, and certain kinds of cancer.
The drug, a soluble epoxide hydrolase (sEH) inhibitor, appears to regulate “obesity-induced intestinal barrier dysfunction and bacterial translocation,” the 12-member team of researchers from UC Davis, University of Massachusetts and University of Michigan discovered. The same non-opioid drug is being investigated in human clinical safety trials in Texas to see if it blocks chronic pain associated with diseases such as spinal cord injury, diabetes and inflammatory bowel disease.
The research, funded by multiple federal grants, is titled “Soluble Epoxide Hydrolase Is an Endogenous Regulator of Obesity-Induced Intestinal Barrier Dysfunction and Bacterial Translocation.”
“Obesity usually causes the loss of tight junctions and leaky gut,” said first author Yuxin Wang, a postdoctoral researcher who joined the Hammock lab in 2019 from the Department of Food Sciences, University of Massachusetts, Amherst. “In normal conditions, the gut mucosal barrier is like a defender to protect us from the ‘dirty things' in the lumen, such as bacteria and endotoxin. For obese individuals, the defender loses some function and leads to more ‘bad things' going into the circulation system, causing systemic or other organ disorders.”
Although intestinal dysfunction and other problems enhancing bacterial translocation underlies many human diseases, “the mechanisms remain largely unknown,” said Wang, who holds a doctorate in biochemistry and molecular biology from the Chinese Academy of Sciences. “What we found is sEH inhibition can repair the defender function (barrier function), decrease the ‘bad things' going into the blood (bacteria translocation), and reduce inflammation of fat.”
“Our research shows that sEH is a novel endogenous regulator of obesity-induced intestinal barrier dysfunction and bacterial translocation,” said corresponding author Guodong Zhang, a former researcher in the Hammock lab and now with the Food Science Department and Molecular and Cellular Biology Graduate Program at the University of Massachusetts. “To date, the underlying mechanisms for obesity-induced intestinal barrier dysfunction remain poorly understood. Therefore, our finding provides a novel conceptual approach to target barrier dysfunction and its resulting disorders with clinical/transitional importance.”
Corresponding author Hammock, a distinguished UC Davis professor who holds a joint appointment with the Department of Entomology and Nematology and the Comprehensive Cancer Center, praised Zhang's “amazing record while he was a postgraduate at UC Davis, and now in Food Science Department at the University of Massachusetts, where he recently received tenure.”
Zhang mentored two co-authors of the paper: Yuxin and Weicang Wang, both formerly of the Department of Food Science, University of Massachusetts and now with the Hammock lab.
“I feel so lucky that Yuxin and Weicang have joined my laboratory,” Hammock said. “The drugs studied in this PNAS paper are now in human clinical trials and on a path to replace opioid analgesics for pain treatment. I hope the continuing work of Guodong, Weicang and Yuxin will evaluate them as treatments for a variety of inflammatory bowel diseases.”
Andreas Baumler, professor and vice chair of research in the UC Davis Department of Medical Microbiology and Immunology, who was not affiliated with the study, said: “Obesity-induced gut leakage and bacterial translocation can be ameliorated by targeting microbes with antibiotics, suggesting that the microbiota contributes to disease. However, the work by Zhang and co-workers suggest that rather than targeting the microbes themselves, obesity-induced gut leakage and bacterial translocation can be normalized by silencing a host enzyme, which identifies host metabolism as an alternative therapeutic target.”
In addition to Hammock, Zhang, Yuxin and her husband Weicang, the other eight co-authors on the team are:
- Jun Yang, Sung Hee Hwang, and Debin Wan of the Hammock lab, UC Davis Department of Entomology and Nematology, and UC Davis Comprehensive Cancer Center
- Kin Sing Stephen Lee, formerly of the Hammock lab, and Maris Cinelli, both of the Department of Pharmacology and Toxicology, Michigan State University, Lansing
- Katherine Sanidad and Hang Xiao, Department of Food Science and the Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst
- Daeyoung Kim, Department of Mathematics and Statistics, University of Massachusetts, Amherst
The abstract: “Intestinal barrier dysfunction, which leads to translocation of bacteria or toxic bacterial products from the gut into bloodstream and results in systemic inflammation, is a key pathogenic factor in many human diseases. However, the molecular mechanisms leading to intestinal barrier defects are not well understood, and there are currently no available therapeutic approaches to target intestinal barrier function. Here we show that soluble epoxide hydrolase (sEH) is an endogenous regulator of obesity-induced intestinal barrier dysfunction. We find that sEH is overexpressed in the colons of obese mice. In addition, pharmacologic inhibition or genetic ablation of sEH abolishes obesity-induced gut leakage, translocation of endotoxin lipopolysaccharide or bacteria, and bacterial invasion-induced adipose inflammation. Furthermore, systematic treatment with sEH-produced lipid metabolites, dihydroxyeicosatrienoic acids, induces bacterial translocation and colonic inflammation in mice. The actions of sEH are mediated by gut bacteria-dependent mechanisms, since inhibition or genetic ablation of sEH fails to attenuate obesity-induced gut leakage and adipose inflammation in mice lacking gut bacteria. Overall, these results support that sEH is a potential therapeutic target for obesity-induced intestinal barrier dysfunction, and that sEH inhibitors, which have been evaluated in human clinical trials targeting other human disorders, could be promising agents for prevention and/or treatment.”
The research was funded by grants from the National Institute of Food and Agriculture, U.S. Department of Food and Agriculture (USDA); National Cancer Institute; USDA Hatch Grant; National Institute of Environmental Health Sciences (NIEHS) Superfund Research Program; and a National Science Foundation.
According to the CDC, many of obesity-related conditions that lead to diseases are preventable. In 2008, the estimated annual medical cost of obesity in the United States tallied $147 billion. The medical cost for obese individuals averaged $1,429 higher than those of normal weight.
Contact: Bruce Hammock, firstname.lastname@example.org