In Their Own Words: Daniel Simberloff
In Their Own Words: Daniel Simberloff https://academic.oup.com/bioscience/article/72/10/945/6612801#no-access-message
Dung beetle mothers protect their offspring from a warming world by digging deeper
Kimberly S. Sheldon, University of Tennessee
If the TV series “Dirty Jobs” covered animals as well as humans, it would probably start with dung beetles. These hardworking critters are among the insect world’s most important recyclers. They eat and bury manure from many other species, recycling nutrients and improving soil as they go.
Dung beetles are found on every continent except Antarctica, in forests, grasslands, prairies and deserts. And now, like many other species, they are coping with the effects of climate change.
I am an ecologist who has spent nearly 20 years studying dung beetles. My research spans tropical and temperate ecosystems, and focuses on how these beneficial animals respond to temperature changes.
Insects don’t use internally generated heat to maintain their body temperature. Adults can take actions such as moving to warmer or colder areas. However, earlier life stages such as larvae are often less mobile, so they can be strongly affected by changing temperatures.
But dung beetles appear to have a defense: I have found that adult dung beetles modify their nesting behaviors in response to temperature changes by burying their brood balls deeper in the soil, which protects their developing offspring.
Champion recyclers
It’s easy to joke about these busy insects, but by collecting and burying manure, dung beetles provide many ecological benefits. They recycle nutrients, aerate soil, lessen greenhouse gas emissions from cattle farming and reduce pest and parasite populations that harm livestock.
Dung beetles are also important secondary seed dispersers. Dung from other animals, such as bears and monkeys, contains seeds that the beetles bury underground. This protects the seeds from being eaten, makes them more likely to germinate and improves plant growth.
There are roughly 6,000 species of dung beetles around the world. Most feed exclusively on dung, though some will feed on dead animals, decaying fruit and fungi.
Some species use stars and even the Milky Way to navigate along straight paths. One species, the bull-headed dung beetle (Onthophagus taurus), is the world’s strongest insect, able to pull over 1,000 times its own body weight.
That strength comes in handy for dung beetles’ best-known behavior: gathering manure.
Rolling and tunneling
Most popular images of dung beetles show them collecting manure and rolling it into balls to spirit away. In fact, some species are rollers and others are tunnelers that dig into the ground under a dung pat, bring dung down into the tunnel and pack it into a clump or sphere, called a brood ball. The female then lays an egg in each brood ball and backfills the tunnel with soil. Rollers do the same once they get their dung ball safely away from the competition.
When the egg hatches, the larva feeds on dung from the brood ball, pupates and emerges as an adult. It thus goes through complete metamorphosis – from egg to larva to pupa to adult – inside the brood ball.
Warmer temperatures produce smaller beetles
Dung beetle parents don’t provide care for their offspring, but their nesting behaviors affect the next generation. If a female places a brood ball deeper underground, the larva in the brood ball experiences cooler, less variable temperatures than it would nearer the surface.
This matters because temperatures during development can affect offspring survival and other traits, such as adult body size. If temperatures are too hot, offspring perish. Below that point, warmer, more variable temperatures lead to smaller-bodied beetles, which can affect the next generation’s reproductive success.
Smaller males can’t compete as well as larger males, and smaller females have lower reproductive output than larger females. In addition, smaller-bodied beetles remove less dung, so they provide fewer benefits to humans and ecosystems, such as nutrient cycling.
Beetles in the greenhouse
Climate change is making temperatures more variable in many parts of the world. This means that insects and other species have to handle not just warmer temperatures, but greater changes in temperature day to day.
To examine how adult dung beetles responded to the types of temperature shifts associated with climate change, I designed cone-shaped mini-greenhouses that would fit over 7-gallon buckets buried in the ground to their brims. Will Kirkpatrick, an undergraduate student in my lab, led the field trials.
We randomly placed a fertilized female rainbow scarab, Phanaeus vindex, in each greenhouse bucket and in the same number of uncovered buckets to serve as controls. Using temperature data loggers placed at four depths in the buckets, we verified that soil temperatures in “greenhouse” buckets were warmer and more variable than soil temperatures in uncovered buckets.
We gave the beetles fresh cow dung every other day for 10 days and allowed them to make brood balls. Then we carefully dug through the buckets and recorded the number, depth and size of brood balls in each bucket.
Digging deeper
We found that beetle mothers in greenhouse environments created more brood balls overall, that these brood balls were smaller, and that these females buried their brood balls deeper in the soil than beetle mothers in control buckets. Brood balls in the greenhouses still ended up in areas that were slightly warmer than those in the control buckets – but not nearly as warm as if the beetle mothers had not altered their nesting behaviors.
However, by digging deeper, the adults fully compensated for temperature variation. There was no difference in the temperature variation experienced by brood balls in greenhouse buckets and control buckets. This reflects the fact that soil temperatures become increasingly stable with depth as the soil becomes more and more insulated from the changing air temperatures above it.
Our findings also hint at a possible trade-off between burial depth and brood ball size. Beetle mothers that dug deeper protected their offspring from temperature changes but provided less dung in their brood balls. This meant less nutrition for developing offspring.
Climate change could still affect adult dung beetles in ways we did not test, with consequences for the next generation. In future work, we plan to place brood balls of Phanaeus vindex and other species of dung beetles back into the greenhouse and control buckets at the depths at which they were buried so that we can see how the beetle offspring develop and survive.
So far, though, my colleagues and are encouraged to find that these industrious beetles can alter their behavior in ways that may help them survive in a changing world.
Kimberly S. Sheldon, Associate Professor of Ecology and Evolutionary Biology, University of Tennessee
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Sheldon Publishes Research on Dung Beetles and Climate Change
Assistant Professor Kimberly Sheldon published results from a recent study in Biology Letters that suggest adult dung beetles may be changing their behavior to partially buffer developing offspring from temperature changes related to climate change.
“I developed mini-greenhouses that raised the temperature average and variance in experimental buckets,” Sheldon said. “We put beetles in the buckets and recorded their behaviors, and we found that females buried their offspring farther in the soil to avoid warmer temperatures.”
Will Kirkpatrick, an undergraduate student researcher in the Sheldon Lab, ran the field component.
Russo Co-Authors Planting for Pollinators
Assistant Professor Laura Russo is part of a research team that published findings from an experiment to provide evidenced-based recommendations for pollinator-friendly native perennials in eastern Tennessee.
Download the UT Institute of Agriculture Extension Publication: Planting for Pollinators in East Tennessee, authored by Virginia Sykes, Department of Plant Sciences, Karl McKim and Laura Russo, Department of Ecology and Evolutionary Biology, and Amani Khalil, Oak Ridge Institute for Science and Education.
For the Love of Plants
As you walk on the UT campus, you may see the large glass greenhouses overlooking Neyland Stadium. The University of Tennessee Department of Ecology and Evolutionary Biology greenhouses were first built in 1934 and have gone through multiple renovations. There are still plants from the original collection that are almost 100 years old now.
Recently, the UT Greenhouses received an extremely generous donation from Suzanne Herron and her late husband, Drew Herron. The collection included mostly succulents and cacti plants. Some of the plants are very rare and possess unique traits and modifications. UT Greenhouses were fortunate to receive Herron’s beloved collection.
“Drew Herron knew what UT Greenhouses mission is and he wanted to enhance our outreach and education by donating his collection,” said Jeff Martin, manager of UT Ecology and Evolutionary Biology Greenhouses. “These plants will also be a great addition to our teaching and research.” One example, according to Martin, is demonstrating convergent evolution, which occurs when organisms independently find their way to the same evolutionary solution for the same environmental problem
Martin also just made a donation of one of their own rare flowers to Zoo Knoxville. In July of 2021, the rare Amorphophallus titanum, or more commonly known as the corpse flower, bloomed on UT’s campus. The bloom of the corpse flower only occurs once every 7-10 years and lasts for about a day before wilting. As it blooms, the flower releases a putrid stench that becomes even more potent as the flower’s temperature rises to about 90 degrees Fahrenheit.
After seeing how the corpse flower bloom sparked excitement in the community, Martin chose to donate the flower to the zoo to be placed in the new Arc exhibit with the turtles. Martin hopes that by having the plant at the zoo, it will be able to reach a larger audience outside of East Tennessee. He wants this to be an opportunity to educate more people about the importance of plants and hope to share the positive impact the flower had on UT’s community.
“We donated one to the zoo because I wanted to continue to share something as interesting and unique as the corpse flower,” Martin said. “We want to take advantage of opportunities we have to educate others about the importance of plants and the natural world. Anything that piques people’s interest in plants is excellent.”
–Story by Sarah Berry
Darwin Day Highlights Evolution Education
This year, graduate students hosted Darwin Day UT, a series of events on campus to promote awareness of the importance of evolution to the study of biology and scientific research at UT and other institutions. Charles Darwin was born February 12, 1809. He is a critical figure in the history of evolutionary biology and during the week of his birthday, graduate students in the UT Department of Ecology and Evolutionary Biology celebrate his contributions to science.
Events throughout the week included Evolution Trivia, a graduate student research panel discussion, Darwin’s birthday party full of family fun in conjunction with the McClung Museum, and more. Students and faculty on campus may have also seen the large Darwin puppet mascot on the pedestrian walkway handing out flyers and prizes. These events were led by graduate students in the ecology and evolutionary biology department including Hope Ferguson, Wieteke Holthuijzen, Tara Empson, Nicole Lussier, Lauren Lyon, and Krista De Cooke. More than 300 people attended events throughout the week.
“Understanding evolution is key to understanding our world. For over two decades, Darwin Day at UT has been a fun, inclusive way to educate people about the topic,” said Dr. Brian O’Meara, faculty advisor for Darwin Day.
The tradition of Darwin Day celebrations at UT go back to 1997. UT prides itself on being among the most active institutions in celebrating and promoting evolution education, which is possible with support from several units at UT.
“Darwin Day has historically been an interdepartmental event with generous donations, volunteers, and coordinators from other UT departments. It’s been great working with colleagues across the campus to think of innovative activities, especially during the pandemic,” said Krista De Cooke, Darwin Day President 2020-2022.
–Story by Sarah Berry
Gross Investigates Relationship Between Climate Change Beliefs and Risk
Louis Gross, Chancellor’s Professor in the UT Department of Ecology and Evolutionary Biology, recently co-authored an article, “Determinants of Emissions Pathways in the Coupled Climate-Social System” published in the journal Nature, which investigates whether or not there is a link between humans’ belief in climate change risk and the Earth’s changing climate.
“This research indicates that there are significant feedbacks between the physical climate system and human behavioral, societal and economic responses that affect our ability to project future climate,” said Gross. “Our research demonstrates that these feedbacks can somewhat reduce the negative impacts of climate change that are projected to occur when the feedback to human behavior and societal responses are not taken into account.”
This research focuses on how social, political, and technological factors are all critical for predicting the degree our climate will change overtime. Gross explains how this research can be a driving force for society to take more progressive steps to help reduce the negative impact of climate change. People’s beliefs in climate change and its relevance can affect the policies in place. This along with other factors will ultimately have an impact on the earth’s climate.
This research was supported by the National Institute for Mathematical and Biological Synthesis (NIMBioS), which is headquartered at UT. It was funded by the National Science Foundation with additional support from UT.
“This research is part of a set of collaborative efforts which began several years ago through the support of the NIMBioS. It fostered a highly interdisciplinary group of researchers, with backgrounds in economics, public policy, psychology, mathematics, ecology and climate science, which allowed this effort to be successful,” said Gross.
The collaborations established through Gross and his colleague’s research is continuing using new models, alternate theories, and approaches to enhance climate projections that account for societal responses.
–Story by Sarah Berry
Doctoral Student Lauren Lyon Publishes Chapters on Red Panda Conservation in East Tennessee
Millions of years ago, Red Pandas used to roam the hills of East Tennessee. Now, Zoo Knoxville leads one of the most successful captive breeding programs of Red Pandas in the world. Lauren Lyon, a PhD candidate from the University of Tennessee, Knoxville, in collaboration with ETSU researchers, Steven Wallace and Andrew Joyner, recently published two chapters in the book, Red Panda. Her chapters focus on the conservation of Red Pandas and the reconstruction of Red Panda fossils that were discovered in Tennessee. In her research, Lyon has been able to work closely with Zoo Knoxville and the Gray Fossil Site in Gray, Tennessee. Observing the Zoo Knoxville’s captive breeding program helped aid Lyon and Wallace in the reconstruction of the Red Panda fossils at the site.
“Red pandas are part of our Tennessee heritage,” Lyon said. “They roamed here long ago living much like raccoons do today, and perhaps this long and storied history is part of why Zoo Knoxville is so successful breeding red pandas today. Locals should take pride in knowing what a beautiful animal once lived in their backyard and that we have even more discoveries to make.”
In other countries, researchers have only been able to identify a few teeth and jaws from Red Panda fossils. At the Gray Fossil Site, researchers recovered the two most complete fossils in the world, a male that is 75% complete and a female that is 98% complete. Lyon’s publications focusing on Red Panda conservation are used by biologists, zoo staff, and conservationists all over the world.
“Close proximity both to the zoo and the national park have been critical. UT’s ecology and evolutionary biology department has funded my doctoral research and allowed me to be in close proximity to the zoo. Because UT has done such a great job with departmental funding, this is research that will be continuing and that you will be hearing about in the near future!” said Lyon.
Lyon’s research with the Appalachian Red Panda is important for understanding Red Panda evolution. It helps researchers piece together how we ended up with this endangered bamboo eating Red Panda in Asia that is well known today. Moving forward, Lyon is working on her dissertation, which focuses on climate change and its effect on endangered species in the Smokies and Appalachian Mountains. She is working with several conservation agencies and hopes to spread awareness on this pressing issue.
“I want people to know that they can make a difference even with minimal effort,” Lyon said. “It’s up to us to preserve these animals for our future. It is very easily an achievable goal that we can all benefit from, but to start we need to simply raise awareness.”
-Story by Sarah Berry
Local University Joins Global 4-day Effort to Digitize Centuries of Data About Life on Earth
For centuries, scientists have explored and documented the natural world, collecting the billions of specimens housed in museums, universities, and field stations worldwide. And now, the University of Tennessee and other institutions across the globe want to help make that information available to the general public.
But they need your help.
The University of Tennessee Herbarium invites members of the public to one of the many virtual transcription parties that will be held next week during the Worldwide Engagement for Digitizing Biocollections (WeDigBio) Event. The WeDigBio Event will transform the often handwritten or typewritten data sequestered on the labels of plant, insect, fish, and fossil specimens into an open, globally accessible, digital resource with the help of the public.
“Natural history collections are a physical record of our planet’s biodiversity across space and time,” said Budke, who is also an assistant professor in the UT Department of Ecology and Evolutionary Biology. “These specimens not only serve as records of the past, but they are a critical resource for our future. They help us to answer important questions surrounding invasive species, conservation biology, and help us to describe species that are new to science.”
The University of Tennessee Herbarium (TENN) is a member of The GLOBAL Bryophyte & Lichen Thematic Collections Network (TCN). This collaboration of 25 universities, museums, and botanical gardens located across the United States is funded by the National Science Foundation (NSF) with the goal of digitizing almost 1.2 million bryophyte (moss) and lichen specimens. It is the first large scale project to image physical specimens in addition to labels and focuses on specimens collected outside of North America. These specimens document the distribution and natural variation of species that form the basis for important ecological communities across the globe. Digitized data will be shared freely online, making these specimens available to researchers, teachers, students, and communities around the world.
The WeDigBio Event emerged within the museum community to accelerate the rate of digital data creation about the historical what, when, and where of the perhaps 9 million species on Earth. It has a core leadership team that includes researchers from the Smithsonian Institution, the Australian Museum, Florida State University, University of Florida, and the major online transcription platforms, including the U.S.-based Smithsonian Transcription Center, Notes from Nature, and Symbiota, the Australia-based DigiVol, the UK-based Herbaria@Home, and the France-based Les Herbonautes.
This one-of-a-kind event will be held from October 14-17 at locations across the globe. Members of the public can contribute at any time from anywhere during the event at one of the participating online transcription platforms.
More information about the GLOBAL Bryophyte & Lichen TCN WeDigBio Event can be found on the project website, https://globaltcn.utk.edu/crowdsourcing/.
The Knoxville-based virtual transcription party will take place from 12 p.m. to 3 p.m. Eastern Time on Friday, Oct. 15, and Saturday, Oct. 16. Activities will include virtual presentations and collections tours from the TENN herbarium and five of their GLOBAL partner institutions. Volunteers can register to participate here: https://tinyurl.com/WeDigBioGlobal.
Contact:
Jessica M. Budke, Assistant Professor & Herbarium Director
Ecology and Evolutionary Biology
University of Tennessee
(865) 974-6204
jbudke@utk.edu
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