Prairie Research Institute
Prairie Research Institute
News Article | April 17, 2017
Waste diversion is an essential goal for labs and cleanrooms, as well as virtually every other kind of facility. It can be achieved through a variety of ways, such as source reduction, reuse, composting and recycling. In 2014, more than 89 million tons of municipal solid waste were recycled and composted, providing an annual reduction of over 181 million metric tons of carbon dioxide equivalent emissions, comparable to the annual emissions from over 38 million passenger cars, according to the Environmental Protection Agency (EPA). The benefits of recycling are well known: • Reduces the amount of waste sent to landfills and incinerators • Conserves natural resources such as timber, water and minerals • Prevents pollution by reducing the need to collect new raw materials • Saves energy • Reduces greenhouse gas emissions that contribute to global climate change • Helps sustain the environment for future generations As recycling becomes the norm, rather than the exception, in labs and cleanrooms, facilities are getting pretty good at recycling primary commodities such as cardboard, paper, plastic and aluminum. But to get to a higher level of diversion and potentially reach the holy grail of zero waste, other non-traditional or secondary commodities must also be diverted from landfill, and recycled and repurposed into usable products and durable goods. Glove and apparel recycling is a relatively new form of recycling that is beginning to gain traction in lab and cleanroom settings. In 2011, Kimberly-Clark Professional launched The RightCycle Program, the first large-scale recycling effort for non-hazardous lab and cleanroom waste. Since then, the program has diverted more than 350 tons of waste from landfill. RightCycle removes gloves, masks, garments, shoe covers and other apparel accessories from the waste stream. The products are collected and shipped to domestic recycling centers, where they are turned into nitrile pellets that are then used to create eco-responsible consumer products and durable goods. As long as gloves, garments and accessories (such as masks, hoods, shoe covers and hairnets) do not contain bio-hazardous materials, they can be safely recycled and turned into items such as: lawn furniture, flowerpots and planters, shelving, totes and storage bins. It all adds up Gloves are ubiquitous in labs and cleanrooms, and workers can go through several pairs in the course of a day. While this is necessary to protect both the worker and the process, the amount of waste can add up. Consider these statistics: • One university estimated that nearly 30 percent of its waste stream came from laboratory and research buildings. • A University of Washington lab waste audit found that 22 percent of its research waste consisted of nitrile gloves. • A University of California Santa Cruz (UCSC) laboratory waste assessment found that nitrile gloves made up a majority of laboratory waste destined for landfill. Because of this, many labs are participating in The RightCycle Program. The environmental benefits of glove and apparel recycling programs are evident. They take commonly used and essential lab and cleanroom products out of the solid waste stream, significantly reducing waste generation. Putting glove recycling into practice The University of Washington and UCSC now participate in The RightCycle Program, as does the Illinois Sustainable Technology Center (ISTC) at the University of Illinois and Purdue University. ISTC is a division of the Prairie Research Institute at the University of Illinois Urbana-Champaign. Its mission is to drive statewide economic growth through sustainability. To fulfill that mission, ISTC conducts scientific research and, in the process, uses a lot of gloves. “We conducted a waste audit to see how we could go to zero waste in our own building and realized that gloves were about 10 percent of our total waste by weight,” said Shantanu Pai, ISTC assistant sustainability researcher. “We were already effectively recycling other items—glass, aluminum, paper and cardboard.” With RightCycle, ISTC was able to reach 89 percent compliance for gloves in its labs—even higher than the rate for paper and cardboard recycling. It then decided to take the program a step further, piloting it in the university’s main dining hall and achieving an estimated diversion rate of 90 percent. It is in the process of expanding the effort to all dining facilities and campus labs. In fact, the university has purchased a storage container to house the gloves so shipments can be made just once a year. Since implementing The RightCycle program in 2013, the center and the university have diverted 4,945 pounds from landfills. “RightCycle has had a huge impact on our activities and our sustainability metrics,” said Kevin O’Brien, Director of the Illinois Sustainable Technology Center. “If you ever used gloves as part of your laboratory work, you quickly appreciate the value this program brings from a sustainability perspective.” Purdue University Across its campus in the course of a year, Purdue University uses approximately 360,000 disposable gloves. That’s a lot of trash—3.5 tons to be exact, all of which would normally wind up in a landfill. The university, based in West Lafayette, Ind., has won numerous awards for sustainability. Its efforts extend to many different areas—recycling, planning management, landscaping and green construction. With a diversion rate goal of 85 percent, the university is always seeking new and different ways to reduce its solid waste stream. In 2014, Purdue University added glove recycling to its list of sustainability accomplishments when it adopted The RightCycle program. Since November 2014, the chemistry department at Purdue University has diverted 8,163 pounds of lab gloves from landfills. Michael Gulich, director of campus master planning and sustainability, is looking to expand the program to other campus labs as well as food preparation areas. “Once you address cans, bottles, paper and cardboard recycling, you get into smaller niche streams,” he said. “We have some addressed very well, such as electronics waste and landscape debris. Previously, gloves didn’t have a solution. Anything that increases our diversion rate is good.” Other participants University laboratories aren’t the only facilities that have adopted this innovative recycling solution. Cell Signaling Technology (CST), a life sciences company, uses about 200,000 pairs of gloves each year. Reducing its environmental footprint has long been a core company value, so finding a way to reduce the volume of glove waste was important. CST began researching The RightCycle Program in 2013, and made its first recycling shipment in 2015. The program has helped CST reduce the costs of trash removal and move closer to its goal of zero waste to landfill. “We’re glad to have made an impact on our waste profile and to have our lab gloves repurposed for safe practical purposes,” said Sustainability Coordinator Elias Witman. “And it was fun for our employees to see our recycled gloves come back to CST in the form of a flying disc, which was tossed around after a company meeting.” Since joining The RightCycle Program, Cell Signaling Technology has recycled approximately 150,000 pairs of gloves. “The RightCycle Program is highly visible and practical,” Witman added. “People see it and want to participate. Programs like this can help shape a culture of sustainability in the lab and yield positive impacts for the planet.”
News Article | May 1, 2017
They found it in the Illinois River near the city of Marseilles, Illinois, about 80 miles west of Lake Michigan - a strange entry point for an invasive Asian clam. The scientists who found it have no idea how it got there. But the discovery - along with genetic tests that confirm its uniqueness - means that a new species or "form" of invasive clam has made its official debut in North America. The researchers report the find in the journal BioInvasions Records. This is only the latest invasive aquatic species to settle in North America, said Illinois Natural History Survey aquatic ecologist Jeremy Tiemann, who discovered the new clam with INHS mussel field biologist Sarah Douglass in late 2015. The INHS is a division of the Prairie Research Institute at the University of Illinois. "In the Midwest, you have invasive bivalves, including zebra mussels, and several species of invasive fish: Asian carp, black carp and even goldfish," Tiemann said. There are exotic plants, like Eurasian milfoil. There is an invasive water flea from Africa, Asia and Australia. There also are several kinds of invasive snails, the researchers said. All of these create problems for the natives. The new invader is a member of the genus Corbicula, which was first observed in Vancouver, British Columbia, in 1924. It likely was brought to North America by immigrants from Asia who used the clams as food, the researchers said. Within a few decades, it had colonized many of the major waterways of North America. (See animated map). Douglass and Tiemann found the new clams while hunting through a mudflat for a federally endangered native clam, the scaleshell, that had been spotted in the same location two years before. They noticed that this tiny creature, roughly the size of a fingernail, had unusual physical characteristics compared with the other invasive species of Corbicula found in this region. The Illinois team shared the find with researchers at the University of Michigan, who conducted genetic tests that confirmed the new clams were distinct from earlier Corbiculainvaders. Despite the genetic and physical differences, the researchers can't say whether the clam is a new species. Corbicula have reproductive strategies that make them difficult to classify, the researchers said. To begin with, they are androgenic clones. "When the sperm fertilizes the egg, it kicks out the maternal nuclear DNA, retaining only the male's, and thus producing clones of the father," Tiemann said. "These offspring, however, retain the mother's mitochondrial DNA, which resides in tiny organelles outside the nucleus." Corbicula also can hybridize with other Corbicula taxa, further complicating the task of classifying them, Tiemann said. "To compound matters even more, Corbicula can also be hermaphrodites, so they can fertilize themselves," he said. "This means that it takes only a single clam to spawn a new population." To help distinguish among species, researchers can examine the nuclear or mitochondrial DNA, Tiemann said. "With Corbicula, the nuclear DNA tells one story, but the mitochondrial DNA can suggest something different," he said. "As a result, we use the word 'form' to distinguish different taxa within a group, as is the case with Corbicula." No matter how it is classified, the new invader is likely not good news for native clams or the river ecosystem as a whole, the researchers said. "Corbicula consume the same resources as the natives," Tiemann said. "It's thought that they also can consume the larvae of the natives, although that hasn't been proved," Douglass said. Invaders often have no natural enemies in a new locale, and tend to overpopulate, driving out the natives and sometimes overextending themselves, she said. So far, the ultimate consequences of the latest exotic to take up residence in U.S. waters remains to be seen, the researchers said. "But if past invasions are any indication, it may signal further erosion of ecosystem services traditionally provided by watersheds already impacted by Corbicula," Tiemann said.
Stodola K.W.,Prairie Research Institute |
Ward M.P.,Urbana University
American Naturalist | Year: 2017
Multiple biotic, abiotic, and evolutionary constraints interact to determine a species’ range. However, most species are not present in all suitable and accessible locations. Dispersal ability may explain why many species do not occupy all suitable habitat, but highly mobile species also exhibit a mismatch. Habitat selection behavior where individuals are site faithful and settle near conspecifics could create a social pressure that make a species’ geographic range resistant to change. We investigated this possibility by using an individual-based model of habitat selection where habitat quality moved each year. Our model demonstrated the benefits of conspecific attraction in relatively stable environments and its detrimental influence when habitat quality shifted rapidly. These results were most apparent when adult survival was high, because site fidelity led to more individuals occupying poor-quality habitat areas as habitat quality changed. These individuals attracted other dispersing individuals, thereby decreasing the ability to track shifts in habitat quality, which we refer to as “social inertia.” Consequently, social inertia may arise for species that exhibit site fidelity and conspecific attraction, which may have conservation implications in light of climate change and widespread alteration of natural habitats. © 2017 by The University of Chicago. 0003-0147/2017/18906-56693$15.00. All rights reserved.
News Article | February 27, 2017
CHAMPAIGN, Ill. -- An iconic bird whose booming mating calls once reverberated across "the Prairie State" can survive in Illinois with the help of periodic human interventions, researchers report. The greater prairie chicken once dominated the American Midwest, but today the bird is in trouble in many parts of its historic range. It is no longer found in Arkansas, Indiana, Kentucky, Michigan, Ohio, Tennessee, Texas or Wyoming, states where it once flourished. And in Illinois, an estimated 186 birds remain in two adjoining counties in the southern part of the state. "They used to be all over the state," said Illinois Natural History Survey conservation biologist Mark Davis, who participated in a genetic analysis of the Illinois birds. "This was the tallgrass prairie state. You couldn't throw a rock into a field without hitting a prairie chicken." The reason for the decline is simple, Davis said. "We changed our land-use practices from having a lot of prairie, then to wheat, hay and alfalfa, and now to vast expanses of corn and soybeans," he said. "Prairie chickens used to have 20 million acres of prairie in Illinois. Now, they have around 2,000. At the same time, population size went from 10 to 14 million in the 1860s to the 100 to 200 or so we have today. There just isn't enough habitat." Environmental officials have made two efforts to rescue Illinois' dwindling prairie chicken populations, which are suffering from a lack of habitat and declining genetic diversity. Between 1992 and 1998, teams imported more than 200 prairie chickens from other states. "In Illinois, the first translocation brought in birds from all over the upper Midwest - from North Dakota, Minnesota, Kansas and Nebraska," Davis said. "And for a short period of time, it seemed to work." More chicks survived to reproductive age and genetic diversity spiked, he said. To understand how well the birds were doing long after that first translocation, Davis and his colleagues analyzed the DNA from feathers collected in the birds' courtship grounds from 2010-13. The researchers report their findings in the journal Royal Society Open Science. "What our paper reveals is that about 20 years after the translocation of new prairie chickens into Illinois, we see another decrease in genetic diversity and a decline in the number of birds," Davis said. The study confirmed that the only two remaining populations of prairie chickens in Illinois -- one in Marion County and the other in Jasper County -- are genetically isolated from one another, Davis said. The birds have access to a few hundred acres of territory overall, but the land is subdivided by roads and power lines, which represent additional barriers. "They're also surrounded by an agricultural desert of corn and soybeans," Davis said. The study identified 88 unique males using the courtship grounds, where the birds strut and boom to attract females. The team estimates that roughly the same number of females live in Illinois. The researchers' conclusion: A lack of habitat endangers prairie chickens' long-term survival in Illinois. Without periodic human intervention - in the form of translocations of birds from other states - the population could die out. "This is the issue that sage grouse are facing out West," Davis said. "This is the issue that lesser prairie chickens are facing in Texas and Oklahoma. These are big birds that need a big landscape that we don't have anymore." There are still strongholds for prairie chickens in Kansas, Minnesota, Nebraska and South Dakota, Davis said. In western Minnesota, for example, a tradition of protection for game animals and a hefty excise tax on hunting and fishing licenses has allowed the state to purchase lands and protect a patchwork of interconnected grassland habitat, he said. "Now you have this swath of restored prairie and the birds are doing really well -- so much so that a few years ago, on a very limited basis, Minnesota was able to have the first prairie chickens taken by hunting in many years," he said. But Illinois has strong agricultural traditions, and Davis doesn't foresee a similar effort in the state. "Providing food for the world does come at a cost, and that cost is habitat for wildlife," he said. "To sustain prairie chickens in Illinois, we have two options," Davis said. "We can purchase and restore as much prairie habitat as possible. In lieu of that, we need to support the periodic translocations of new birds to Illinois to preserve this prairie icon." The INHS is a division of the Prairie Research Institute at the U. of I. To reach Mark Davis, call 217-333-6294; email firstname.lastname@example.org. The paper "Genetic rescue, the greater prairie chicken, and the problem of conservation-reliance in the Anthropocene" is available online and from the U. of I. News Bureau.DOI: 10.1098/rsos.160736
News Article | March 4, 2016
That's the conclusion of a new study conducted by University of Arkansas biologists Michael Douglas and Marlis Douglas and their colleagues at the University of Illinois at Urbana-Champaign and Western Kentucky University. The researchers published their findings in the journal PLOS One. The research team, using head shapes and genetic analyses, recommend that six groups of subspecies of the western rattlesnake be elevated to full species status, with the following names: The scientific and standard English names will be submitted to the International Committee on Zoological Nomenclature for ratification. The study has important implications for ecological conservation efforts across the United States, said Michael Douglas, professor of biological sciences and Twenty-First Century Chair in Global Change Biology. "These snakes have been long been recognized by herpetologists as being demonstrably different, and in fact were designated as western rattlesnake subspecies in the first half of the 20th century," Douglas said. "None are currently considered rare, but species designation allows them to gain certain legal protection, particularly within individual states." Marlis Douglas, associate professor of biological sciences and Bruker Chair of Life Sciences, said the genetic data were also evaluated to identify these snakes as individual species. The Douglases collaborated with Mark Davis, research scientist at the Illinois Natural History Survey, part of the Prairie Research Institute at the University of Illinois, and Michael Collyer, associate professor of biology at Western Kentucky University. As part of his doctoral research, Davis collected data from nearly 3,000 western rattlesnakes available in natural history museums across the western United States. In addition to genetic traits, the team examined head shape, which can vary drastically between different species of snakes and potentially reflect what kind of prey the snake prefers. Explore further: Mysterious fungus killing snakes in at least nine states More information: Mark A. Davis et al. Correction: Deconstructing a Species-Complex: Geometric Morphometric and Molecular Analyses Define Species in the Western Rattlesnake (Crotalus viridis), PLOS ONE (2016). DOI: 10.1371/journal.pone.0149712
Zahniser J.N.,Prairie Research Institute
International Journal of Tropical Insect Science | Year: 2012
Stenogiffardia Evans, 1977 is considered the senior synonym of Pratura Theron, 1982 syn. nov. and Doraturella Emeljanov, 2002 syn. nov., resulting in four new combinations. Duraturopsis Melichar, 1908 syn. nov. is considered a junior synonym of Chiasmus Mulsant and Rey, 1855, resulting in one new combination. Figures of the ovipositor of Stenogiffardia parvula (Kirkaldy) are provided for the first time, and habitus images of S. parvula and Chiasmus katonae (Melichar) comb. nov. are provided. © Copyright ICIPE 2012.
Taylor C.A.,Prairie Research Institute |
Robison H.W.,9717 Wild Mountain Drive
Zootaxa | Year: 2016
A new primary burrowing crayfish, Fallicambarus schusteri, is described from the Red River drainage of extreme south-eastern Oklahoma and southwestern Arkansas and is placed in the subgenus Fallicambarus. The species occurs in road-side ditches that seasonally flood and have silt and silt-loam dominated soils. Falllicambarus schusteri differs from all other members of the genus Fallicambarus in possessing a thin gradually tapering central projection and a wide triangular cephalic process on the first pleopod of form I males, a sufflamen on the cheliped, and an antennal scale that is widest at its midpoint. © 2016 Magnolia Press.
News Article | February 15, 2017
CHAMPAIGN, Ill. -- A new study contradicts decades of thought, research and teaching on the history of corn cultivation in the American Bottom, a floodplain of the Mississippi River in Illinois. The study refutes the notion that Indian corn, or maize, was cultivated in this region hundreds of years before its widespread adoption at about 1000 A.D. The findings, reported in the journal American Antiquity, are important in understanding how and why Cahokia, the first major metropolitan center in North America, arose, said Thomas Emerson, the director of the Illinois State Archaeological Survey at the University of Illinois, where the new study was conducted. Cahokia was a vast, highly organized settlement with tens of thousands of inhabitants in its heyday, Emerson said. Its dramatic rise near present-day St. Louis and East St. Louis, Illinois, at about A.D. 950 and its sudden demise by 1350 have long been a source of fascination. There is broad agreement that corn was cultivated in this region at about 1000 and widely consumed by the people of this time period, Emerson said. Corn fragments, including cobs and kernels, show up in sites dating to 1000 or later. Skeletal analyses from bodies buried at Cahokia also reveal the devastating impact of corn on people's teeth. These signs, as well as chemical signatures of corn consumption in the teeth and bone, also date to 1000 and after, he said. The new findings challenge earlier reports that maize was cultivated and consumed in the American Bottom as early as 60 years B.C. The early conclusions - in studies conducted before 2000 - were based on flawed approaches to analyzing ancient materials, said Mary Simon, an archaeobotanist with ISAS who conducted the new study. Rather than dating charred plant fragments directly, researchers analyzed charcoal or other "associated materials" to determine the age of the plants, she said. "We have since learned that a piece of charcoal or other material found adjacent to a corn kernel in an archaeological site could date to a later or earlier time period than the corn," Simon said. Also, visual identifications can be wrong, she said. Scientists now date plant fragments directly using accelerated mass spectrometry, a technology that was just "coming into vogue in the 1990s" and used at that time to determine the age of materials, Simon said. Today, stable isotope mass spectrometry can be used in conjunction with AMS to detect differences between plant types, information that aids in plant identification, she said. Corn and other grasses absorb atmospheric carbon differently than other plants. This is reflected in the ratio of carbon isotopes - carbon atoms with differing masses - in plant tissues, Simon said. "The beauty of this procedure is not only do you get an absolute date, you also get that carbon isotope ratio, so you know, first, how old it is, and, second, whether or not it's corn," she said. In the new study, Simon revisited botanical samples from Holding, an archaeological site in western Illinois that was occupied from about 150 B.C. to A.D. 300. Simon was among those who mistakenly identified plant fragments from this site as very early corn, and later AMS data confirmed its age. Those findings were published by a group of archaeologists in 1994, and were widely recognized as being the oldest directly dated corn in the eastern United States. The new analysis, of remaining botanical samples from the Holding site, used both AMS and SIMS and found that the samples that looked like corn either were not corn or dated to A.D. 900 or later, Simon said. Researchers at Arizona State University found samples from the original study and also tested those for carbon isotope ratios. Their results confirmed that although it was old, the material dated in 1994 was not, in fact, corn. "Basically, what we found is that myths of early corn in the central Mississippi River Valley are simply inaccurate. They've been disproved. We no longer believe that corn was at all important, that people were growing corn, that anybody was using corn to any extent at A.D. zero," Simon said. The two new studies suggest that corn was not in widespread use until 900 or later, she said. "You can never say it wasn't present here before then," she said. "For example, there was Wyoming obsidian here at A.D. 60, so it's totally possible that a cob of corn made it here from the southwestern U.S. at an earlier date. But, until it was cultivated here, it doesn't really count." The ISAS is a division of the Prairie Research Institute at the U. of I. The paper "Reevaluating the evidence for middle woodlands maize from the Holding site" is available online and from the U. of I. News Bureau.
News Article | January 28, 2016
Using head shape and genetic analyses, new research challenges the formerly designated subspecies within the western rattlesnake species. These findings have important implications for ecological conservation efforts across the United States and could provide the basis for new species designations. The results are published in the journal PLOS ONE. The western rattlesnake (Crotalus viridis) is found across a significant portion of the United States, from Mexico to Canada and from the Missouri River to the West Coast. Most work classifying rattlesnake species and subspecies was conducted in the mid-20th century. Since then, scientific methods have advanced to allow for a more comprehensive understanding of the path of rattlesnake evolution. Mark Davis, a research scientist at the Illinois Natural History Survey, part of the Prairie Research Institute at the University of Illinois, collected data from nearly 3,000 western rattlesnakes for this study. He gathered data from preserved samples of this group available at natural history museums across the western United States. “We are able to see that these different subspecies, which have different habits, live in different areas and have other different characteristics, have heads that have been shaped differently over evolutionary time,” Davis said. For western rattlesnakes, the head is the primary organ for conducting daily life. It is especially important for feeding and reproductive rituals. Head shape has evolved to better accommodate these critical behaviors, Davis said. The shape can vary drastically between different species of snakes. Given the importance of this feature, Davis and his colleagues used geometric morphometrics, a relatively novel method that allows researchers to quantify head shape without any influence of head size. To complement the shape analyses, Davis and his team analyzed genetic data from the snakes. Combining head shape and genetic information created a comprehensive perspective, Davis said. Together, these data confirm that several groups of snakes previously labeled as subspecies have substantial enough differences to qualify for a separate species designation. One of the greatest challenges to ecological conservation is identifying what species actually exist. For legal protections – including the Endangered Species Act – to be effective, scientists must specifically identify the units of biodiversity that may be in need of protection. ”It’s important to me to try to work with conservation practitioners to develop strategies for preserving biodiversity,” Davis said. With this study, Davis and his colleagues recommend officially elevating to the level of full species several groups of snakes previously believed to be subspecies. Davis expects that the national and international organizations responsible for naming various species will adopt the recommendations proposed in the study.
News Article | January 27, 2016
The results are published in the journal PLOS ONE. The western rattlesnake (Crotalus viridis) is found across a significant portion of the United States, from Mexico to Canada and from the Missouri River to the West Coast. Most work classifying rattlesnake species and subspecies was conducted in the mid-20th century. Since then, scientific methods have advanced to allow for a more comprehensive understanding of the path of rattlesnake evolution. Mark Davis, a research scientist at the Illinois Natural History Survey, part of the Prairie Research Institute at the University of Illinois, collected data from nearly 3,000 western rattlesnakes for this study. He gathered data from preserved samples of this group available at natural history museums across the western United States. "We are able to see that these different subspecies, which have different habits, live in different areas and have other different characteristics, have heads that have been shaped differently over evolutionary time," Davis said. For western rattlesnakes, the head is the primary organ for conducting daily life. It is especially important for feeding and reproductive rituals. Head shape has evolved to better accommodate these critical behaviors, Davis said. The shape can vary drastically between different species of snakes. Given the importance of this feature, Davis and his colleagues used geometric morphometrics, a relatively novel method that allows researchers to quantify head shape without any influence of head size. To complement the shape analyses, Davis and his team analyzed genetic data from the snakes. Combining head shape and genetic information created a comprehensive perspective, Davis said. Together, these data confirm that several groups of snakes previously labeled as subspecies have substantial enough differences to qualify for a separate species designation. One of the greatest challenges to ecological conservation is identifying what species actually exist. For legal protections - including the Endangered Species Act - to be effective, scientists must specifically identify the units of biodiversity that may be in need of protection. "It's important to me to try to work with conservation practitioners to develop strategies for preserving biodiversity," Davis said. With this study, Davis and his colleagues recommend officially elevating to the level of full species several groups of snakes previously believed to be subspecies. Davis expects that the national and international organizations responsible for naming various species will adopt the recommendations proposed in the study. More information: Deconstructing a Species-Complex: Geometric Morphometric and Molecular Analyses Define Species in the Western Rattlesnake (Crotalus viridis), dx.doi.org/10.1371/journal.pone.0146166