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CU researchers find hyper evolution in walking stick insects
Oct 21st
off a cascade of ecological impacts,
new CU-Boulder study finds
A California walking stick insect that has evolved to produce individuals with two distinct appearances—an all-green form that camouflages well with broader leaves and a form with a white stripe running down its back that blends better with needle-like leaves—can markedly affect its broader ecological community when the appearance of the bug is mismatched with the plant it’s living on.
The new findings, based on research carried out at the University of Colorado Boulder, illustrate the ability of rapid evolution to cause a cascade of ecological impacts.
The scientists found that a walking stick insect that is not well camouflaged is more likely to be eaten by birds, and in turn, those birds are then also more likely to feast on the spiders, caterpillars, plant hoppers, ants and other arthropods living on the same plant. The resulting overall reduction in bugs living on the plant also means that the plant itself was less likely to be attacked by sap-feeding insects.
“Our study shows that the evolution of poor camouflage in one species can affect all the other species living there and affect the plant as well,” said Tim Farkas, lead author of the study published in the journal Current Biology. “It’s intuitive, but also really surprising.”
Farkas led the study as an ecology and evolutionary biology doctoral student in Assistant Professor Patrik Nosil’s lab at CU-Boulder. Nosil and CU-Boulder doctoral student Aaron Comeault are also study co-authors. All three have since moved to the University of Sheffield in England.
Evolution is often thought of as a process that unfolds slowly over centuries if not millennia, as individuals with genetic advantages have a greater chance of surviving to pass down their genes to the next generation.
But scientists are increasingly identifying instances when evolution works on a much shorter time scale. An oft-cited example of rapid evolution is the peppered moth. The light-colored moths were historically able to camouflage themselves against lichen-covered tree bark in England. A darker variant of the moth existed but was more rare, since birds were able to easily spot the dark moth against the light trees. But during the industrial revolution, when soot blackened the trees, natural selection favored a darker variation of the moth, which began to flourish while the light-colored variant became less common.
Evolution on such a rapid scale opens up the possibility that the process could have ecological effects in the short term, impacting population sizes or changing the community makeup, for example.
Researchers have begun to compile examples of these “eco-evolutionary dynamics.” The new study offers some of the most comprehensive evidence yet that evolution can drive ecological change.
“We have combined both experimental and observational data with mathematical modeling to show that evolution causes ecological effects and that it does so under natural conditions,” Farkas said. “We also focused simultaneously on multiple evolutionary processes—including natural selection and gene flow—rather than just one, which affords us some unique insights.”
Farkas and his colleagues—including Ilkka Hanski and Tommi Mononen, both of the University of Helsinki in Finland—focused their attention on the walking stick Timema cristinae, which lives in Southern California. The flightless insect lives primarily on two shrubs: chamise, which has narrow, needle-like leaves; and greenbark ceanothus, which has broad, oval-shaped leaves. The variant of the walking sticks that have a white stripe down their backs are better camouflaged on the chamise, while the solid-green walking sticks are better camouflaged on the greenbark ceanothus.
The research team began by cataloguing the walking sticks living on the two types of shrubs in 186 research patches, and determined that the striped walking sticks were indeed more common on chamise and vice versa.
In a second experiment, the researchers artificially stocked the needle-like chamise with the different variants of walking sticks. A month later, they sampled the shrubs and found that more striped walking sticks survived than un-striped walking sticks. They also found that chamise stocked with striped walking sticks were home to a greater number of arthropods as well as a greater variety of arthropods than shrubs stocked with un-striped walking sticks. Finally, there were more leaves damaged by hungry insects on chamise stocked with striped walking sticks.
The scientists surmised that the differences were caused by scrub jays and other birds that feed on walking sticks. A group of easy-to-spot walking sticks could attract birds, which might then feed on other arthropods as well. To test their idea, the researchers repeated the experiment, but in this case, they caged some of the shrubs to keep the birds from feeding. As they expected, the caged chamise stocked with un-striped walking sticks did not have the same drop in numbers as they did when the bushes were not caged.
“Studies of how rapid evolution can affect the ecology of populations, communities and ecosystems are difficult to accomplish and therefore rare,” Farkas said. “We’re hoping our research helps biologists to appreciate the extent of dynamic interplay between ecology and evolution, and that it can be used by applied scientists to combat emerging threats to biodiversity, ecosystem services, and food security.”
Funding for the study was provided by CU-Boulder, the European Research Council and the Academy of Finland.
-CU-
80% of OSMP trails to be open by Jan.1
Oct 17th
The department anticipates having more than 50 percent of its trail system open on Saturday when dozens of volunteers will help the department complete rebuilding projects on the Doudy Draw trail complex south of Boulder. The volunteer assistance – which will build on the work of OSMP trail crews – will enable the department to open more miles of trails.
“We’ve made significant strides in reopening Boulder’s prized trails, but we know we have much more work ahead of us,” said Mike Patton, director of the city’s Open Space and Mountain Parks Department. “Our approach has been to reopen trails that serve the broadest segment of the community and to leverage the immense generosity of volunteers to help us rebuild our community’s trail system.”
When the recent flooding subsided, OSMP conducted a preliminary assessment that found it caused significant or severe damage to 77 miles of trails. Floodwater also caused some damage to dozens of miles of other trails. The department then diverted its staff – including trail crews, seasonal employees and full-time employees – to provide immediate trail access to neighborhoods and areas across Boulder.
Since the September flood, OSMP has opened 70 miles of trails, along with 20 trailheads. It has also opened climbing areas on the First and Third Flatirons, and it is working with volunteers from the Flatirons Climbing Council and Rocky Mountain Rescue Group to assess local climbing access areas and explore additional openings.
As first responders and local climbers help OSMP survey climbing areas, hundreds of other volunteers continue to help the department rebuild and restore important drainages and ecosystems. In recent weeks, OSMP has held 15 volunteer projects, which have helped the department make progress in opening more trails. Volunteers have also assisted OSMP by providing guided hikes, which give area residents insights about how the flood has impacted the city’s open space system. More than 600 people have participated in the guided hikes.
“We’re fortunate to have so many volunteers helping us to rebuild,” Patton said. “We’ve been inspired by their hard work and willingness to help the community.”
In the coming weeks, OSMP anticipates opening the following trails and areas:
- Spring Brook-Doudy Draw trail complex; Foothills Trail; Hogback Loop; Old Kiln Trail; Wonderland paragliding/hang gliding access area; Greenbriar/Thomas Lane with the South Boulder Creek West Trailhead; Flagstaff Trail and nearby climbing areas, including Flagstaff Summit, Crown Rock and Contact Corner.
By the end of 2013, OSMP expects to open:
- Sanitas Valley Trail; Amphitheatre/Gregory Loop and its nearby climbing opportunities; Skunk Canyon Trail; and the Upper and Lower Big Bluestem trails.
While OSMP is making progress opening many trails and trailheads, some trails will remain closed to the public after Jan. 1. These trails have become eroded and buried in debris, and will require significant repairs. In addition, their closure will help reduce the creation of new social trails, which causes adverse environmental impacts. Areas that will likely remain closed past the beginning of the year include:
- Four Mile Creek Trailhead: Flood water expanded the creek from 3 feet to 30 more than feet, necessitating a new bridge. Flooding also spread extensive debris in the area.
- Chapman Drive/Tenderfoot: Flooding severely damaged the road and OSMP needs to provide a walkable trail in the area.
- Access road to Green Mountain Lodge: The recent flood created a flowing creek in the roadway, which prevents access to Ranger Trail and Gregory Canyon. Re-opening this trail now would damage environmental resources.
- Multiple Mesa Trail junctions: The Bear, Skunk and Bluebell drainage crossings of the Mesa Trail have been damaged.
- East Boulder Trail at Boulder Creek (White Rocks): Large gullies and extensive debris have severely damaged the trail.
“We understand the desire to get back on the trails,” Patton said. “We’re doing everything we can to provide our community with exceptional recreational opportunities as we continue our commitment to ensure long-term resource protection.”
Role of natural gas in municipal power generation to be examined
Oct 10th
Boulder to convene community working group on the future role of natural gas in local energy supply
The City of Boulder announced today that it will create a community working group of industry specialists and local stakeholders to explore concerns and opportunities related to the use of natural gas to generate electricity for the City of Boulder, should it decide to form a local electric utility. Natural gas will likely play a significant role in Boulder’s energy portfolio, whether the community continues to be served by Xcel Energy or by a municipal utility. The focus of the group’s work will be to examine issues and concerns related to fracking and methane releases and to explore current and possible industry best practices.
On Nov. 5, Boulder voters will be asked to weigh in on a ballot measure that would institute a five-year moratorium on fracking in Boulder and on Boulder-owned open space property. However, given the tremendous growth in natural gas production in Colorado, the current and future use of natural gas as an energy source for Boulder customers has raised concerns over fracking — a process that uses a pressurized water mixture to release oil or natural gas from deep underground.
In addition to discussing concerns over fracking, the community group will also discuss the issue of methane leakage. While it is widely accepted that burning natural gas emits significantly less carbon dioxide than burning coal, recent studies have found that using natural gas may actually release more greenhouse gases over its lifecycle. That’s because quantities of raw methane, a major component of natural gas, can escape into the atmosphere during natural gas extraction, production and distribution.
“If Boulder chooses to municipalize, before we commit to a particular energy portfolio, we want to address concerns around the use of natural gas supplied from fracking and how we can minimize the negative impacts through best practices or other means,” said Heather Bailey, executive director of energy strategy and electric utility development. “Natural gas is likely to be a necessary transition energy source as Boulder makes what we hope will be a dramatic shift away from coal and other fossil fuels toward renewable sources. Recognizing this, we have been working on what we can do as a municipal utility to influence the development of responsibly sourced gas that limits or eliminates the harmful impacts of fracking and methane release.”
Executive Director Bailey also commented that the city has a “unique opportunity” to benefit from a discussion with local experts on the feasibility of a future municipal utility to push aggressively towards responsible development of natural gas. Expertise from the University of Colorado, federal labs, as well as the numerous local companies and entrepreneurs developing leading-edge energy technologies could help Boulder in its work to curb climate change and support a robust clean energy market.
The city’s Energy Future team anticipates holding the first meeting of the natural gas community working group shortly after the Nov. 5 election. Members of the community, stakeholders and industry personnel who are interested in participating are encouraged to contact Heather Bailey at 303-441-1923 or baileyh@bouldercolorado.gov.
More information about the Energy Future project and associated municipalization exploration study is available at www.BoulderEnergyFuture.com.
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