Graduate Highlight

Tree “Fitbits” Track Urban Growth, Flowering, More

Anonymous — Tue, 17 May 2022 18:03:51 +0000

Tree “Fitbits” Track Urban Growth, Flowering, More Anonymous (not verified) Tue, 05/17/2022 - 12:03

CU �鶹ӰԺ study: trees outfitted with accelerometers could be the future of arborism, agriculture

Low-cost “tree fitbits” can pinpoint the precise timing of tree activities, like spring bloom or autumn leaf change, according to a new CU �鶹ӰԺ study. Researchers outfitted two East �鶹ӰԺ ash trees with high-resolution accelerometers, efficiently tracking how the trees responded to changing seasons. And in the coming years, arborists could efficiently monitor trees by the thousands with this technology—ultimately giving researchers insight into how tree phenology is changing with a warming climate.

“Accelerometers are in cars, smartphones and fitbits—they track movement in real time. When we put them on trees, accelerometers detect vibrations on the trunk as the tree sways in the wind,” said Deidre Jaeger, recently minted CIRES PhD researcher and lead author of the study out this week in Agricultural and Forest Meteorology. “That sway corresponds to the tree's mass, which tells us what the tree is doing.”

A tree’s mass all depends on its water uptake throughout the seasons, creating the structural differences that determine how it dances in the wind. In the winter, trees are dry and brittle. “Think of the quick, shaky rattling sound of leafless trees in the dead of winter,” Jaeger said. “Now think of spring: the trees are lush with leaves, full of water, and sway with flexibility.”

A previous accelerometer study was able to detect when trees’ leaf buds opened or when leaves dried and fell off—but Jaeger’s team proved how much more detailed data such tree fitbits can collect. The team picked up the precise moment when white ash trees flowered, catching the subtle change in movement that corresponded to the trees blossoming and pollen release.

AN ACCELEROMETER STRAPPED TO A TREE ON CU BOULDER’S EAST CAMPUS. PHOTO: DEIDRE JAEGER/CIRES

Jaeger and her team outfitted two white ash trees on CU �鶹ӰԺ’s East Campus in 2018, working with CU �鶹ӰԺ arborist Vince Aquino to strap equipment to the trunk of each tree. “Previous work suggested trees would need to be out in the open to have enough wind to sway, but we found it not only works on trees inside a city—it’s actually an ideal way to track urban tree growth,” said Jaeger.

Satellite-based, remote sensing tracking methods are useful for monitoring greenness changes in forests dominated by a single species, but it’s hard to learn about a tree species within the city because of the high diversity of species contained within each city block, the team says. Time-lapse cameras also aren't ideal: they are expensive and raise privacy concerns in populated areas. And while drone imagery can provide high-resolution imagery, getting permission to do daily or weekly fly-overs would be unsustainable. “Accelerometers are discrete, continuous and unaffected by the action or physical barriers a city environment presents. We get high-res, reliable data.”

“Now that we know accelerometers can determine flowering dates, that could be useful in agriculture, predicting when tree fruit may ripen or knowing when to apply interventions to protect tree buds from extreme weather,” Jaeger said. The technology could also forecast when leaves change color in the fall, measure how much snow sits in forest canopies, or even detect tree damage from bugs.

“Trees are also bioindicators of climate change,” Jaeger said, “So having high-resolution, long-term accelerometer data would help scientists better anticipate how a changing climate will impact tree bloom, tree health and beyond.”

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Expedition to highest active volcano unearths clues about life on other worlds

Anonymous — Fri, 11 Mar 2022 20:11:53 +0000

Expedition to highest active volcano unearths clues about life on other worlds Anonymous (not verified) Fri, 03/11/2022 - 13:11

A harsh sun shines down through a cloudless sky, across a vast and unforgiving landscape. It’s covered in gray rock, giant ice sculptures and expansive fields of spiky, yellow and orange bushes. In the distance, intimidating mountain peaks dominate the desolate scene, many miles from the nearest town. Yet alpacas roam freely and flamingos seek out scarce water, both unexpected sights in this wild world.

The extreme environment resembles something from a sci-fi film or another planet, but it’s right here on Earth, on the flanks of the world’s highest active volcano, 22,615-foot Ojos del Salado. Here, on the border of Argentina and Chile, a team of CU �鶹ӰԺ scientists seek to discover how tiny organisms persist at one of the driest and highest points on the planet.

Left to right: Brian Hynek, professor of geological sciences and LASP research associate; Adam Solon, graduate student in ecology and evolutionary biology; and Amanda Steckel, graduate student in geological sciences and LASP.

Supported in part by a grant from the National Geographic Society, the first-of-its-kind project may ultimately help inform the search for existing and extinct life on other planets.

“There's been almost no scientific studies on this volcano. So it's a new frontier in terms of geology, microbiology and the environment itself,” said project lead Brian Hynek, professor of geological sciences and research associate at the Laboratory for Atmospheric and Space Physics (LASP).

For three weeks in December, Hynek was joined by Adam Solon, graduate student in ecology and evolutionary biology, and Amanda Steckel, graduate student in geological sciences and LASP, as the first researchers to ever explore and survey this high up on the Argentinian side of the mountain. Project co-leader Steve Schmidt, professor of ecology and evolutionary biology, and Nick Dragone, graduate student in ecology and evolutionary biology, are now hard at work analyzing the samples they brought back. And a second trip is in the works.

The team’s previous research on neighboring volcanoes suggests this trip will provide valuable insights about the microbiology and flow of chemical elements through this habitat, which mimics those of the past on neighboring planet Mars and possibly the present of Jupiter’s fourth largest moon, Europa.

Image credit: Amanda Steckel

Training for great heights

While they didn’t plan to spend much time at the summit, the team had to prepare for a base camp at 19,000 feet and to conduct research at 21,000 feet—the highest any of them have ever climbed.

That high up, oxygen is scarce. So in the months leading up to the trip, they often hiked and camped near Leadville, Colorado—the highest incorporated city in North America, at over 10,000 feet—to acclimate and break in their mountaineering boots.

Next, getting to Ojos del Salado was its own challenge, taking them two days and multiple flights to get to Northern Argentina, two days drive from the jungle to the high desert, and a day-and-a-half journey on a rough four-wheel-drive road to the base of the volcano at 19,000 feet. From there, the team climbed through the frigid night to over 21,000 feet, where they conducted their research.

From life on Ojos to life on Mars

Once settled in high above the Atacama Desert, the team set out to conduct research in an environment which closely mimics that of ancient Mars. Extremely dry conditions, high levels of ultraviolet radiation, large day-to-night temperature swings and limited water are all elements that make Ojos del Salado an ideal analog to the red planet.

Going to places on Earth that mimic either the chemistry or the physics or volcanic conditions of early Mars can help us understand it better. In the past, Mars probably was a lot like Ojos, and not as extreme as it is now. So by studying this, we can get a good glimpse at habitability on past Mars.”
–Brian Hynek, professor of geological sciences and LASP research associate

“Going to places on Earth that mimic either the chemistry or the physics or volcanic conditions of early Mars can help us understand it better,” said Hynek, a National Geographic explorer. “In the past, Mars probably was a lot like Ojos, and not as extreme as it is now. So by studying this, we can get a good glimpse at habitability on past Mars.”

Hynek, a planetary geologist, was eager to examine the hydrothermal systems, steam vents, fumaroles and hot springs on the volcano. These are places where water and fluids interact with rocks, create minerals and can support microbial life from the energy involved in these chemical reactions.

Today, Mars is riddled with remnant minerals from these interactions. By documenting under what temperatures, pressures and chemistries these minerals are created here in Earth’s extremes, Hynek can apply that information to what remains on Mars today. So when a rover or an orbiter discovers particular minerals on Mars, he and fellow scientists can deduce what historical conditions in those places must have been like to produce them—and if they could have also supported life.

“The ultimate question is whether this is a good place where life could have come about,” said Hynek. “Because life on Earth probably started in hydrothermal systems, it's probably where it would have started on Mars. These are key targets for looking for life on our neighbor.”

Solon and Steckel venture into a giant, frozen maze of icy, stalagmite-like spikes called penitentes. Credit: Amanda Steckel

Otherworldly ice fields

Solon and Steckel ventured into a giant, frozen maze of icy, stalagmite-like spikes called penitentes to conduct their research. Ranging from a few inches tall to 6 feet high, these snowy marvels exist not only in spite of, but as a result of the extreme conditions, providing a rare opportunity to underestand how life can thrive there. They have only been sampled on two other volcanoes in the region, on expeditions lead by Schmidt.

Solon collected ice samples with tiny microbes living in them and the soil around them, and collaborators on the project are currently sequencing their DNA back in a lab in Argentina.

Image credit: Christian Vitry

“Even as extreme an environment as it is, it might be surprising how many different types of microbes are actually here. There can be a whole food web that is developed, even with these very limited resources,” said Solon.

These persistent creatures may hold clues for the types of life which could exist on Jupiter's moon, Europa, as the conditions in these fields closely resemble those of the icy moon. The sixth-largest moon in the solar system, Europa’s icy crust covering a global ocean make it a promising place to look for life.

Alongside Solon in the ice fields, Steckel used sensors to capture the light bouncing around and inside the cone shapes—part of what hollows them out into their unique designs. She nailed sensors into the ice at different heights to measure the intensity of the light at varying heights. Where Solon’s samples assess the microbial diversity, Steckel’s measurements will track radiation levels throughout the ice fields, illuminating what microbes have done to adapt to the intense UV conditions.

“I wanted to capture the uniqueness of this environment,” said Steckel.

Steckel’s measurements are also the first data collected at this altitude, providing valuable insights into real-life conditions under extreme UV.

Her preliminary numbers will also inform a more detailed study, when she or others from her team are able to return to the volcano. Hynek is already plotting the trip—potentially yet again this year—as they didn’t make it to the summit and over to Chile, due to 70 mph winds.

“There will definitely be several studies that come out of the data, and also further understanding of this region, which has had a limited amount of study,” said Solon. “This would be a pretty good expedition to build off of.”

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Introduced Avian Malaria Strain Found in Colorado Chickadees

Anonymous — Mon, 25 Oct 2021 19:37:58 +0000

Introduced Avian Malaria Strain Found in Colorado Chickadees Anonymous (not verified) Mon, 10/25/2021 - 13:37

When Angela Theodosopoulos began studying Colorado's Mountain and Black-capped Chickadees four years ago, her original goal was to research hybridization among the species and the various parasites they each co-evolved with. But when the PhD candidate at the �鶹ӰԺ began analyzing the birds' blood, she made a worrisome discovery: Some of the chickadees were infected with a strain of introduced avian malaria.

According to a report published this month in Biology Letters, Theodosopoulos' finding is the first record of this particular strain in a non-migratory bird species in North America. The parasite was found in two Mountain Chickadees and a single Black-capped Chickadee, but the low number of infections makes Theodosopoulos, lead author of the paper, believe that another avian species might be the main host. While the strain has the potential to be damaging to bird populations, Theodosopoulos stresses that more research is needed.

“I definitely would not panic at this point,” she says. “But it is important to think about it and to understand it, because it is a very invasive parasite, it can cause disease, and it has been associated with population declines in other places. We just don't know if that's going to be what happens here.”

Avian malaria is caused by a parasite that reproduces in birds’ red blood cells and is spread via mosquitoes. Though some cases of avian malaria are mild or asymptomatic, infected birds can experience a loss of red blood cells, lethargy, a shortened life span, or in extreme cases, convulsions or death.

The strain found in �鶹ӰԺ is called SGS1, named for the species it was first identified in: a Sudan Golden Sparrow in 2002. Generally speaking, genetic variation in parasites leads to different strains of the disease, which tend to infect species in different geographic areas. But when a strain reaches birds that haven't encountered it before and are not adapted to fight it, “it can cause much harm to the population,” says Staffan Bensch, professor of animal ecology at Lund University in Sweden and co-author on the paper. Researchers can’t say yet how North American birds will respond to SGS1, but in London, SGS1 has been linked to declines of House Sparrows.

The fact that the parasite has infected non-migratory chickadees is concerning because it's “a sign that it is already spreading,” Theodosopoulos says. A migratory bird can be infected anywhere along its journey, but the chickadees had to have contracted the disease locally. Until now, the only recorded North American birds with SGS1 were captive birds in New York and one wild, migratory tree swallow in Canada. Theodosopoulos speculates mosquitoes may have spread the disease from infected birds in zoos, which could have contracted it before they were imported.

“Many of them recover in captivity,” Bensch says. “But in the wild, such a bird is very easy prey for a raptor.”

Next, the researchers want to find out if SGS1 really is more prevalent in another local species—and which one. They think it could be House Sparrows, given the high infection rate of that species in Europe and their large populations in urban areas. Theodosopoulos hopes to discover if and when SGS1 infected House Sparrows in Colorado and, afterward, learn what other species it may have reached.

To do so, she partnered with Dr. Garth Spellman, curator of ornithology at the Denver Museum of Nature & Science. Spellman has a collection of tissue samples from House Sparrows from the Denver metropolitan area dating back 10 years. Incidentally, a paper published approximately a decade ago found no instances of SGS1 in House Sparrows in the Colorado Front Range, a mountain region including Denver and �鶹ӰԺ. So, Spellman and Theodosopoulos believe that if SGS1 has infected House Sparrows, it likely did so in the past 10 years.

“We can look at 20, 30 birds every year for the last decade to see if we can find SGS1,” Spellman says. “If so, we might be able to chronicle the year that it arrived in the Front Range.” Based on the prevalence of SGS1 in those samples, they could also estimate how common it is in House Sparrows today.

This future research will be crucial to understanding the extent of risk to North American birds. If SGS1 is found at a high rate in Colorado’s House Sparrows, Spellman believes that would be a sign that House Sparrows in metro areas nationwide are infected. Moreover, a high presence of SGS1 in urban birds might increase the chances of avian malaria spreading to birds outside cities.

“In Denver, it could be particularly important, because we have a number of grassland species, for example, that could be exposed right at that urban-wildland interface,” Spellman says. Already, 74 percent of grassland bird species are in decline. “If just one of those species is exposed to a novel pathogen, that could have dire consequences.”

For now, it’s a waiting game as scientists gather more information. If, theoretically, researchers find SGS1 in other places in the country, if dead birds test positive for SGS1, and if the birds that carry SGS1 start having negative health impacts while uninfected individuals don’t, then this strain would be something to really worry about, Theodosopoulos says.

Even if SGS1 winds up not causing any major issues for North American birds, as the paper notes, the appearance of this strain is yet another reminder of the human impact on the environment and the need for diligence in a more globalized world. “We're changing the habitat; we’re moving species around,” Theodosopoulos says. “This certainly plays a role in the way that parasites and their diseases are able to spread.”

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Sheela Turbek: Genetic and Phenotypic Divergence in the Barn Swallow Species Complex and Southern Capuchino Seedeaters

Anonymous — Fri, 21 Apr 2017 21:02:19 +0000

Sheela Turbek: Genetic and Phenotypic Divergence in the Barn Swallow Species Complex and Southern Capuchino Seedeaters Anonymous (not verified) Fri, 04/21/2017 - 15:02

I am a PhD student in Dr. Rebecca Safran’s lab in the EBIO department. My research focuses on behavioral mechanisms of reproductive isolation that contribute to the generation of biodiversity. To investigate how animal behavior influences genetic and phenotypic divergence in the initial stages of speciation, I am working in two avian systems: the barn swallow species complex, which consists of numerous closely related subspecies that breed throughout the temperate zone, and the southern capuchino seedeaters, a recent radiation that contains seven co-occurring forms in northern Argentina.

Migratory behavior and speciation in the barn swallow species complex

While animal migration is a widespread phenomenon, we lack a solid understanding of how divergent migratory strategies influence population differentiation and the formation of new species. Previous work on barn swallows has demonstrated that subspecies boundaries in Asia may be maintained in part by differences in migratory behavior. In particular, individuals are thought to follow divergent migratory routes around the Tibetan Plateau, a high-altitude desert in central Asia that poses a significant barrier to migration. To further examine how migratory behavior may be promoting and/or maintaining reproductive isolation, I traveled to northwest China and deployed animal-borne tracking devices known as geolocators across a contact zone between two hybridizing subspecies. I will return to the zone next month to retrieve the devices, reconstruct individual migratory routes, and examine how migratory behavior influences gene flow between recently diverged groups.

Patterns of mate choice in the southern capuchino seedeaters

Variation in phenotypic traits, such as body size and plumage coloration, has been hypothesized to play an important role in initiating speciation, as organisms often use phenotypic cues to identify suitable mates. However, recent genomic advances have revealed that very small genomic regions can underlie striking phenotypic differences, thereby complicating our understanding of the role of phenotypic variation in divergence. I am investigating the processes that maintain patterns of phenotypic differentiation on a background of genomic similarity in the southern capuchino seedeaters, a recent radiation characterized by extremely low levels of ecological and genomic divergence despite conspicuous differences in male plumage coloration and song. By tracking patterns of genetic exchange between overlapping capuchino species, I am studying how non-random mating and selection against hybrids may facilitate the accumulation of phenotypic diversity extremely early in speciation.

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Attractive males advertise clean territories

Anonymous — Mon, 01 Feb 2016 18:12:24 +0000

Attractive males advertise clean territories Anonymous (not verified) Mon, 02/01/2016 - 11:12

Amanda Hund.

I am a PhD student in EBIO working with Dr. Rebecca Safran. My research focuses on understanding how parasites may play an important role in how new species form. Specifically, I am interested in how parasites influence the evolution of sexual traits across closely related populations.

To explore these questions, I work with three subspecies of barn swallows that are found in Colorado, the Czech Republic, and Israel. Each of these subspecies use different sexual traits to select their mates: plumage color in Colorado, tail streamers in the Czech Republic, and both color and tail in Israel. These three populations are also infected by different communities of parasites. My research has shown that different sexual traits in at least two of the populations are signaling information to females about the costly parasites in a male's territory. These parasites reduce the health and survival of nestlings as well as influence their ability to develop their own attractive sexual traits in the future. In barn swallows, I have found evidence that sexual traits have evolved to advertise valuable information to females about local parasites.

This video was filmed at one of my field sites in �鶹ӰԺ Colorado and highlights some of my work with barn swallows.

Several of Amanda's field sites are located just outside the city of �鶹ӰԺ

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Deep, Steep, and Narrow

Anonymous — Tue, 13 Oct 2015 19:33:13 +0000

Deep, Steep, and Narrow Anonymous (not verified) Tue, 10/13/2015 - 13:33

Between 2-4 October 2015, students enrolled in Plant Systematics (EBIO 4520/5520) traveled to Black Canyon of the Gunnison National Park for a botany camping trip. Participatory were: Reese Beeler, Ryan Byrne, Keric Lamb, Mandy Malone, Kelsey McCoy, Matt Schreiber, and Sydney Sharek along with Erin Tripp (course instructor) and Matt Sharples (teaching assistant). A botany fieldtrip anywhere in October in Colorado is risky, given we hit the end of the growing season a month ago. We needed a site that was sheltered from early frosts and cold weather, and speculated that the depths of a deep canyon might provide such refuge for a few lingering plants in flower or fruit.

We were right! On Friday afternoon, we punched it down to Black Canyon of the Gunnison, arriving late but not too late for homemade tostadas. We stayed at the North Rim Campground, which is a very small, funky, climbers favorite. The Black Canyon is without doubt one of the most dramatic landscapes in Colorado and indeed much of the west. It derives its name from the darkness created by the sheer walls, narrow width, and tremendous depth, which limit sunlight illumination of some portions of the canyon bottom to less than 30 minutes on any given day. Over the last 2 million years of Earth's history, the canyon was carved out by the massive and in some parts very remote Gunnison River. Other canyons of the West are longer, and some are deeper, but none combine the length, depth, and sheerness of Black Canyon.

We awoke Saturday morning to start our long descent down quite the extreme slope - only 1.75 miles in length but 2,000 ft. vertical descent - a Class 3 scramble affectionately known as the “S.O.B route”. This is one of the only routes in the entire area that can be used to reach the bottom of the canyon without advanced, technical climbing. Conveniently, it leaves directly from the campground. We took our time descending, learning the dominant plant community along the way: Artemesia tridentata (Sagebrush), Juniperus osteosperma (Utah Juniper), Quercus gambelii (Gambel Oak), Amelanchier alnifolia (serviceberry), Cercocarpus ledifolius (Mountain Mahogany), and Pinus edulis (Pinyon Pine - one of many sources of pine nuts, which are actually not nuts but rather seeds). The bottom of the canyon was lush and thrilling - we learned several additional species as a group before setting out on our own in various directions. Many of us took a welcomed dip into the Gunnison - a perfect 58˚F.

We reached camp around 5 pm. The weather was balmy - mid 60s and so delightful. We spent the next 2 hours sitting at the picnic table keying various plants we saw at the bottom of the gorge. Among them was Petrophytum caespitosum (Rock Spiraea), which grows “on precipitous and often inaccessible canyon walls” (in Dr. Bill Weber’s words) and Polanisia dodecandra (Clammyweed) - a curious member of the caper family (Capparaceae) and one that represents a new plant record for Montrose County! Dinner was a botanical medley (squash and zucchini [Cucurbitaceae], shallots & garlic [Alliaceae], carrots [Apiaceae], potatoes [Solanaceae]), lightly tossed with olive oil [Oleaceae], salt, black pepper [Piperaceae], and chipotle powder [Solanaceae again…sigh], wrapped in foil then cooked on hot embers in the fire for a perfect 25 minutes. We all had a solid night’s rest before heading home the next morning.

The journey home: complete with blazing aspens and a flat tire with no easy means for a fix. But we managed with a tire plug and the compressor of a kind stranger. That's life as a biologist: never a dull moment.

Story by Erin Tripp.

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Can gut microbes help insects overcome plant defenses?

Anonymous — Wed, 09 Sep 2015 19:37:32 +0000

Can gut microbes help insects overcome plant defenses? Anonymous (not verified) Wed, 09/09/2015 - 13:37

EBIO graduate student Tobin Hammer and Professor Deane Bowers were recently featured on the cover of Oecologia. How are herbivorous insects able to subsist on a diet that is often rich in toxic chemical compounds? In this issue Hammer and Bowers outline the ‘Gut microbial facilitation hypothesis,’ arguing that symbioses with gut microorganisms may help insects overcome plant chemical defenses. Many bacteria and fungi in soil, leaf litter, and the mammalian gut withstand and degrade plant toxins but the importance of microbes to the ecology and evolutionary diversification of insect herbivores is just beginning to be unveiled. Shown is the caterpillar Citheronia lobesis consuming Spondias mombin leaves, which contain a variety of plant chemicals to potentially ward off insects.

Check out the full text hosted by Springer Link.

Photo: Tobin Hammer.

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Collin Schwantes: Bee Behavior Experiment

Anonymous — Wed, 15 Jul 2015 16:07:42 +0000

Collin Schwantes: Bee Behavior Experiment Anonymous (not verified) Wed, 07/15/2015 - 10:07

This short documentary goes into the world of Native Bees and how they interact with other insects in the plant community around them. This experiment was designed by Collin Schwantes to test how bees interact with competitors and predators in a sunflower patch located behind the 30th street greenhouse in �鶹ӰԺ, Colorado.

[video:https://vimeo.com/130907410]

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Miranda Redmond: Ecosystems and Management Practices

Anonymous — Tue, 14 Jul 2015 21:40:05 +0000

Miranda Redmond: Ecosystems and Management Practices Anonymous (not verified) Tue, 07/14/2015 - 15:40

I am a Ph.D student in the EBIO department and my research focuses on understanding ecosystems so that better management practices can be developed.

My research examines patterns of pinyon pine (Pinus edulis) and juniper (Juniperus osteosperma) recruitment following recent drought and insect-induced pinyon mortality. Pinyon-Juniper woodlands are the third most extensive vegetation type in the continental U.S and have recently experienced widespread mortality pinyon pine mortality due to combination of a multi-year drought and beetle infestations. However, pinyon and juniper regeneration patterns following this recent mortality event is not well understood.

Globally, woody species are experiencing extensive mortality due to a combination of drought, insect-outbreaks, and warmer temperatures, with implications for significant changes in forest and woodland structure. However, long-term changes in species distributions will be dependent upon the ability of species to regenerate following these regional mortality events under a warmer, drier climate.

Effects of management on vegetation in pinyon-juniper woodlands

Across the western U.S., there is an increasing need to effectively manage ecosystems to both mitigate hazardous wildfire and maintain, and in some cases restore, ecosystem integrity. Of particular importance to the management of public lands in the western U.S. are ecosystems dominated by species of pinyon and juniper, which represent the 3rd most extensive vegetation type in the continental U.S. and are one of the predominant vegetation types administered by federal land management agencies. Consequently, various tree-removal methods have been applied to pinyon-juniper woodlands since the 1950s. However, the efficacy of these different treatment methods are poorly understood.

My research aims to better understand both the short-term (1-2 yr) and long-term (18-40 yr) effects of the various tree-removal treatments commonly used in pinyon-juniper woodlands on vegetation structure. By quantifying the ecological consequences of past tree-removal treatments, my goal is to help develop better future management strategies.

Relationship between climate, seed production & pinyon jay declines

Increasing temperatures and altered precipitation regimes are predicted to cause large shifts in species distributions due to both direct physiological effects and indirect effects on resources. In this project, we examine 1.) The effects of climate on annual variations in pinyon pine cone production 2.) How increasing temperatures over the past several decades have altered cone production and 3.) How both changes in pinyon pine cone production and recent pinyon pine mortality has affected pinyon jay populations.

Pinyon jay: Live from South Main

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Daniel Preston: Ecology of Parasites and Invasive Species in Freshwater Ponds

Anonymous — Tue, 14 Jul 2015 21:06:58 +0000

Daniel Preston: Ecology of Parasites and Invasive Species in Freshwater Ponds Anonymous (not verified) Tue, 07/14/2015 - 15:06

My research focuses on understanding the ecological roles of parasites and invasive species in freshwater ecosystems. Current projects are investigating the roles of parasites in food webs, energy flow and nutrient cycling within wetlands; the influence of nutrients on host-parasite relationships; the effects of parasites on host behavior; and the effects of nonnative fish and bullfrogs on native aquatic communities. Much of my work involves the integration of field observations with experiments at various scales. I also make it a priority to extend the impact of my work to society through outreach activities with local students and the public.

These interests form my main areas of research investigations, which are:

Parasites in Aquatic Ecosystems
Ecological Stoichiometry and Disease
Behavioral Ecology and Host-Parasite Interactions
Invasions in Wetlands
Tropical Amphibian Declines

Parasites in Aquatic Ecosystems

Although arguably the most common life history strategy on earth, parasitism has historically been omitted from much of food web ecology; One current research focus aims to assess how parasites influence the structure and dynamics of wetland food webs over time. Although arguably the most common life history strategy on earth, parasitism has historically been omitted from much of food web ecology. One current research focus aims to assess how parasites influence the structure and dynamics of wetland food webs over time.

Ecological Stoichiometry and Disease

Ecological stochiometry can link processes within individuals (feeding, assimilation, growth) to processes on the ecosystem scale (nutrient cycling, productivity, food web dynamics). Current research in this area aims to determine how host resource stoichiometry, and mismatches in the elemental composition of hosts and parasites, influences disease. Artificial pond ecosystems (‘mesocosms’) are shown at right in a field at the Hopland Research and Extension Center. Mesocosms are useful for ecological stoichiometry experiments because we can carefully manipulate ratios of nutrients in a controlled manner.

Behavioral Ecology and Host-Parasite Interactions

While parasite-induced mortality and pathology of hosts are often obvious, more subtle effects of parasitism might also have important consequences for ecological communities. We are examining how parasites influence host behavior, both before and after infection. Prior to infection, the “threat” of disease might induce anti-parasite behaviors, similar to the manner in which predators induce certain behavioral changes in prey. This work is being done using trematodes (larval stage shown below) and amphibian larvae.

Invasions in Wetlands

Invasive species have become major drivers of ecosystem change, a problem that is particularly prominent in freshwaters. We have combined regional field surveys with outdoor mesocosm experiments to disentangle the individual and combined effects of two common wetland invaders, the western mosquitofish and the American bullfrog. Ongoing work aims to evaluate how enviornmental variables such as productivity, influence the magnitude of invader impacts on native communities.

Tropical Amphibian Declines

I have recently received funding to begin a project on the eastern slope of the Andes Mountains in Ecuador. The aim of this project will be to disentangle some of the enviornmental drivers of amphibian declines in the area.

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