Dr. Hsiao-Hsuan (Rose) Wang has a new project through The National Socio-Environmental Synthesis Center (SESYNC), through the National Science Foundation. Her project will cover “Simultaneously managing scale and uncertainty using innovate software design concepts in a tiered, system-of-systems modeling framework.” Read more…
New research estimates species’ niche by treating above, below taxonomic levels
Contacts: Dr. Hsiao-Hsuan “Rose” Wang, 979-845-5702, firstname.lastname@example.org
Dr. Adam Smith, 314-577-9473 ext. 6314, email@example.com
COLLEGE STATION – Endangered and invasive species may be better managed in the future with new techniques outlined by a Texas A&M University scientist and others.
Texas A&M department of wildlife and fisheries research scientist Dr. Hsiao-Hsuan “Rose” Wang and four international researchers teamed up during the National Institute for Mathematical and Biological Synthesis to publish an article in Trends in Ecology & Evolution highlighting “Niche Estimation Above and Below the Species Level.”
The “ecological niche” describes how an organism or population responds to its habitat and its distribution of resources and competitors, and in turn, how it alters those same factors.
Reaching beyond the species level would assist in introducing endangered species to habitats beyond their normal realms, Wang said. This could provide an opportunity to conduct field surveys and/or implement endangered species restoration and reallocation plans. And with invasive species introductions, vulnerable habitats could be identified for control and prevention strategies.
Wang focuses on the application of techniques in endangered species management, management of invasive species and vectors of emerging diseases.
“For example, my colleagues and I have estimated the niches of an endangered species, Navasota Ladies’ Tresses; a native and economic species, Loblolly pine; and an invasive species, Chinese tallow tree,” Wang said. “Ideally, we should estimate a species’ niche/range by considering information above or below its taxonomic level.”
“Many ecologists have been trying to estimate where a species can sustain itself under climate change,” Wang said.
“Ecological niche models (ENMs) and species distribution models (SDMs) are two of the most popular tools in ecology and evolution used to address diverse research questions such as niche evolution and conservatism, invasion and extinction risk, and impacts of climate change on species distributions,” said Dr. Adam Smith, ecologist, Center for Conservation and Sustainable Development at the Missouri Botanical Garden in St. Louis, Missouri.
“For example, if we could preserve some habitats for Navasota Ladies’ Tresses where the results of ENMs/SDMs suggest good locations, we potentially could reallocate some Navasota Ladies’ Tresses there,” Wang said. “Also, we could use some future climate or urban sprawl scenarios in ENMs/SDMs to see the potential decrease of Navasota Ladies’ Tresses habitat.”
In the study, http://bit.ly/NicheEstimationAboveBelowSpeciesLevel, three strategies were reviewed for incorporating evolutionary information into niche models.
“We hope the approaches we reviewed become adopted by the conservation community because it will help them design better conservation plans,” said Smith.
With ENMs and SDMs popularity, one of the assumptions is that the species have the same responses to the environment in different locations, noted Wang.
“Unfortunately, it is not always true, especially for invasive species,” she said. “Therefore, my coauthors and I hope this collaborative work will provide guidance on which modeling strategy is appropriate under a range of ecological and evolutionary scenarios.”
This research was conducted by three different researchers along with Smith and Wang from around the world including:
- Dr. William Godsoe, senior lecturer in community ecology, BioProtection Research Centre, Lincoln University, New Zealand.
- Dr. Francisco Rodríguez-Sánchez, postdoctoral researcher at Estación Biológica de Doñana, Spain.
- Dr. Dan Warren, senior scientist, Senckenberg Biodiversity and Climate Research Center, Germany; and visiting scientist at Biodiversity and Biocomplexity Unit, Okinawa Institute of Science and Technology, Japan.
The post Scientists strategize for better conservation plans appeared first on AgriLife Today.
COLLEGE STATION – The battle against fever ticks rages on, and a group of Texas A&M University and French National Institute for Agricultural Research scientists are doing their best to determine where the fray will head by synthesizing historical models for use in curbing the pest globally.
Texas A&M’s departments of wildlife and fisheries sciences and entomology and the French institute have collaborated for a number of years to model systems approaches meant to address ecological and regulatory questions about fever ticks, said Dr. Pete Teel, who works within the entomology department’s Tick Research Laboratory.
Teel, a Texas A&M AgriLife Research entomologist, said the two species of cattle ticks affecting Texas, Rhipicephalus (Boophilus) annulatus and R. (B.) microplus, were at the center of the study. These two closely related species are able to transmit pathogens causing bovine babesiosis, or Texas cattle fever. Both ticks and pathogens were brought to the U.S. on livestock with early settlers from other parts of the world.
Economic losses in cattle include direct losses in meat and milk production through tick blood-feeding. The R. (B.) microplus species now plagues cattle throughout the tropical and subtropical regions of the world. It is also now recognized as one of the world’s most pesticide-resistant parasites.
Teel said global prevention of disease and of the direct economic effects of tick parasitism is highly dependent on tick suppression or elimination. Mortality rates in naïve cattle to bovine babesiosis range from 70 to 90 percent.
Dr. Hsiao-Hsuan “Rose” Wang, an AgriLife Research scientist at the wildlife and fisheries sciences department’s ecological systems laboratory, is lead author on the recently published “Quantitative models of Rhipicephalus ticks: historical review and synthesis,” which appeared in the Sept. 14 Ecosphere Journal. Go tohttp://onlinelibrary.wiley.com/doi/10.1002/ecs2.1942/abstract to see the abstract, then click on the article.
Wang was joined by co-authors Drs. Michael Corson, researcher with the French National Institute for Agricultural Research, Ouest, Rennes, France; Bill Grant, AgriLife Research ecologist, department of wildlife and fisheries sciences, College Station; and Teel to conduct the work.
Wang said the work is meant to put a global perspective on a number of aspects researchers encountered and how these modelers approached various problems differently.
The U.S. has long had a permanent quarantine zone hugging the Mexican border to prevent the re-establishment of ticks from Mexico. As a result of recent outbreaks of cattle ticks in Texas, there are 2,720 premises under quarantine covering almost 9 million acres.
“Rhipicephalus ticks are among the most studied group of ticks in the world due to their wide global range and the devastation they cause,” Teel said.
Researchers have developed quantitative computer models of Rhipicephalus ticks since the early 1970s to study the complex biological and ecological relationships that influence the management or eradication of ticks and tick-borne diseases, he said.
“For our study, we reviewed the 45-year history of Rhipicephalus models developed first in Australia, a decade later in North and South America and then still later in Africa,” he said.
According to the paper, these started as analytical models studying parts of the ticks’ life cycles, progressed to simulations of their complete life cycles on to the current emphasis, which is on GIS-based bioclimatic envelope models derived from remotely sensed data and tick presence records, and then back to simulations with spatially explicit, agent-based models.
“Those earlier models predicted management techniques, such as pasture rotation, resistant cattle and anti-tick vaccines,” he said. “But with global climate change, new wildlife hosts and the ticks’ potential for widening its global reach, our study emphasis concentrated on the complexities of tick-host-landscape interactions and the potential for range expansion.”
Teel said their study and future efforts would focus on the development of clearer comparisons for Rhipicephalus ticks to provide ways to hypothesize specific cause-effect relationships, test tick abundance patterns and pathogen prevalence in the field, and simulate how these patterns might be interrupted to achieve tick suppression or eradication.
Researchers focus on eradicating sand flies that transmit the disease since medical treatment is impractical.
You might expect a disease that can kill 95 percent of its victims would be on everyone’s radar. But in the case of visceral leishmaniasis, that’s not the case.
Known as Black Fever, the affliction remains on the World Health Organization’s list of neglected tropical diseases. Why? Well, because it affects “the poorest of the poor,” said David Poché, director of field research at Genesis Laboratories. Transmitted by adult sand flies that bite cattle and whose larvae feed on their feces, it affects 400,000 people every year and kills as many as 30,000. (Malaria, by comparison, was contracted by 214 million people last year, killing 438,000.)
More than 90 percent of new VL cases occur in India, Brazil, Bangladesh, Ethiopia, South Sudan, and Sudan, but Poché said the disease is spreading. VL and other forms of leishmaniasis are “subtle diseases” that kill untreated individuals slowly—sometimes over the course of multiple years—meaning there’s still “not a perception of urgency” among infected individuals and the medical community, said Mark Wiser, a professor in Tulane University’s department of tropical medicine.
Estimating the growth of VL and other forms of leishmaniasis is challenging because of its slow-burn progression as a disease, as well as its rapid appearance in specific locations, Wiser said. Although mortality has decreased in some areas, recent conflicts in the Middle East and an increase in Syrian refugees caused spikes elsewhere.
Poché worked with colleagues from Texas A&M’s department of wildlife and fisheries sciences to study how the insecticide fipronil can be used to kill the sand flies that spread VL. Their findings, published on Thursday in the journal PLOS Neglected Tropical Diseases, showed that when used on cattle, single annual fipronil treatments could reduce sand fly populations by more than 90 percent. Using a model, the researchers showed that monthly treatments could eradicate the flies within two years. Their work was funded by the Bill and Melinda Gates Foundation.
Because of the lack of information about the proportion of sand flies that feed on cattle, and the proportion of eggs laid in cattle feces, they had to use a probabilistic model to study the potential impact of the insecticide. In their simulations, they found that the timing of insecticide application as it related to the sand fly life cycle was also important. Sufficient planning would be needed to apply the insecticide at the right time to avoid the compliance issues that prevent drugs from being effective. The researchers hope to start a field trial to gather more data about how fipronil could limit sand fly populations.
Unfortunately for those affected by the disease, which causes fever, weight loss, and anemia, frequent insecticide treatment of cattle that live in close proximity might be too costly.
A drug to treat VL, miltefosine, was approved by the U.S. Food and Drug Administration in 2014 and is available at little or no cost in India—specifically Bihar, which has a vast majority of that country’s VL cases, Wiser said. (The insecticide study’s model was based on Bihar.) But Poché noted that in Bihar, one of the poorest areas in India, testing is costly. Transportation is an additional barrier, as is the fact that drugs like miltefosine have to be taken for 45 to 60 days, said Rajesh Garlapati, senior vector ecologist at Genesis Labs.
Once fever goes down, “people neglect to take the whole course of treatment. They act as reservoirs and spread disease,” Garlapati said. Other leishmaniasis drugs come with toxic side effects, and the prospect of developing a more practical treatment is unlikely, Wiser said. He contends there is little incentive for pharmaceutical companies to invest in the necessary research.
“Rich people get cancer, so developing an anti-cancer drug, you know people can afford to buy it. If it’s a disease that only poor people get, it’s a little bit different story,” he said. “Drug companies aren’t particularly interested because the people with the disease don’t have a lot of money, so they can’t make a profit on these things.”