Texas Has No Need for Second Veterinary College, Coordinating Board Study Concludes

COLLEGE STATION, Texas – A new report issued by the Texas Higher Education Coordinating Board concludes that a second veterinary college would be expensive to create and operate and is unnecessary in the state of Texas, particularly with the opening of a $120 million veterinary teaching complex at Texas A&M; University.

“The high cost of establishing a new veterinary school would outweigh the potential benefits to the state, given the small to moderate workforce demand and the issue that building a new school would not guarantee that any of the graduates would practice on livestock, which is the state’s principal area of need, but there are more cost-effective ways of addressing the need for medical care for food animals in Texas,” the study concluded. The staff report was presented at Thursday’s meeting of the Coordinating Board.

“I concur with the overall conclusion because it confirms the Coordinating Board’s past recommendations to the Texas Legislature,” said Dr. Eleanor M. Green, the Carl B. King Dean of the College of Veterinary Medicine & Biomedical Sciences at Texas A&M; University. “It is clear they were diligent and thoughtful in their study, which has resulted in a substantive, data-driven report about veterinary medical education in Texas. I believe this report bolsters our announcement in January for a judicious expansion of veterinary education, research and undergraduate outreach into several regions of the state through four Texas A&M; System universities.”

In January, Texas A&M; University announced partnerships with West Texas A&M; University, Prairie View A&M; University, Texas A&M; University-Kingsville and Tarleton State University that would add veterinary faculty and researchers at those universities to support the state’s important agricultural industries while focusing on increasing the number of successful applicants to veterinary college from those regions.

The partnerships address two ongoing concerns repeated in the new study: Increasing the number of underrepresented minority students in veterinary college and ensuring a supply of large animal veterinarians practicing in the state’s rural areas.

All four of the A&M; System universities have significant underrepresented minority student populations as well as unique animal science programs and ties to the livestock or wildlife industries in their regions.

“The thought is that students from those regions are more likely to return home to practice veterinary medicine,” said Green. “Our proposal is the only one that tries to address all the key concerns, including achieving greater diversity in the veterinary profession, increasing the number of large animal and rural veterinarians and meeting the unique needs of multiple regions of the state. And we do it at a fraction of the cost of creating a new veterinary medical education program from scratch.”

The creation of the regional partnerships became possible with this fall’s opening of a state-of-the-art veterinary teaching complex at College Station that allows the veterinary college to accept more applicants, particularly from the four regional universities. The $120 million facility, which is located at the heart of the university’s main campus and works closely with the Texas A&M; Health Science Center, was funded from the Permanent University Fund.

Texas A&M;’s decision to invest in the new complex was prompted by a 2009 report issued by the Coordinating Board, which similarly concluded that no new veterinary school was needed and encouraged Texas A&M; to expand its enrollment. At the time, the American Veterinary Medical Association Council on Education warned that the college’s existing facilities could not handle such an expansion. With the opening of the new complex, there are no longer any constraints on the college’s ability to meet the state’s future veterinary educational needs.

“The new building will accommodate a first-year, class-size increase of 20 to 30 students easily, with more room to grow, should there be a future need,” the Coordinating Board study noted.

Texas A&M; University already has hired veterinary faculty assigned to West Texas A&M; and is asking the Legislature for an appropriation to further support all of the partnerships.

The veterinary faculty at those universities will teach students, further support animal agriculture and mentor students to successfully enter the rigorous veterinary curriculum. They will also offer relevant veterinary courses on site.

“For the sake of taxpayers and our students and alumni, it is vital that we approach the expansion of veterinary education strategically and judiciously,” Green said.

Michael Dicks, the director of the American Veterinary Medical Association’s Veterinary Economics Division,
issued a report
in December 2015 concluding that the creation of new veterinary schools could have an adverse impact on the starting salaries of veterinarians.

“This decline in income would exacerbate the existing disparity between growth rates in income and debt, causing the debt-to-income ratio to rise. The rising debt-to-income ratio will likely accelerate the reduction in applicants, perpetuating the potentially negative effects on the market for veterinary education,” he wrote.

The Coordinating Board study noted that tuition and fees at Texas A&M;’s veterinary college are not only below the national average but in the bottom third of all U.S. veterinary schools. Texas A&M; veterinary students already have the lowest debt-to-income ratio in the nation.

The report also said that the workforce demand for veterinarians is “moderate and closely aligned with supply.”

About The Texas A&M; University System

The Texas A&M; University System is one of the largest systems of higher education in the nation, with a budget of $4.2 billion. Through a statewide network of 11 universities, seven state agencies and a comprehensive health science center, the Texas A&M; System educates more than 140,000 students and makes more than 22 million additional educational contacts through service and outreach programs each year. System-wide, research and development expenditures exceeded $946 million in FY 2015 and helped drive the state’s economy.

Contact: Laylan Copelin
Vice Chancellor of Marketing and Communications
(979) 458-6425
(512) 289-2782 cell
lcopelin@tamus.edu

Texas A&M’s College of Veterinary Medicine & Biomedical Sciences Researcher’s Study Reveals the Underlying Genetic Diversity of One of the World’s Most Abundant Fish

COLLEGE STATION, Texas – The Atlantic herring-one of the world’s most abundant fish and historically a staple of the Northern European diet-has recently helped scientists understand how species adapt and evolve. Previous studies only examined a few genes and suggested that different groups of the Atlantic herring were genetically indistinguishable despite marked differences in behavior, such as when they reproduce and the salinity of their habitat. However, a study published in eLife and led by Dr. Leif Andersson, professor at Texas A&M; University and Uppsala University in Sweden, revealed that there is in fact much underlying genetic diversity between various groups of herrings.

Herring ball
Herring ball: Atlantic herring forming a ball in the presence of predator (Photo by Per Eide from the film The Silver of the Sea by blaastfilm.no).

In the study, researchers sequenced the whole genomes of several groups of Atlantic herring, including both herring that live in the high-salinity Atlantic Ocean and the low-salinity Baltic Sea. The study also compared herrings that spawned in the fall versus in the spring. A total of 500 loci-or locations on chromosomes-were identified as being different between the various herring groups. This genetic diversity indicates how herring are able to adapt to varying conditions.

“The new study reveals that the Atlantic herring is a near ideal model to study genes underlying ecological adaptation,” said Andersson. “Firstly, it is highly adaptable and it shows a considerable diversity in spawning time. Secondly, the population size is enormous which makes random fluctuations in the frequency of gene variants of minor importance. Thus, the signal-to-noise ratio for detecting natural selection is exceptionally good in this species.”

“By comparing the genome sequences between fall-spawning and spring-spawning population samples, Dr. Leif Andersson and colleagues identified a number of potential genetic factors that affect spawning time,” said Dr. James Cai, assistant professor in the Department of Veterinary Integrative Biosciences (VIBS) at the CVM, who was not an author of this study. “These genetic determinants for the timing of reproduction can be used as markers for stock assessment, which has important implications for sustainable fishery management.”

Prior to this study, scientists wondered how it was possible that these groups of herrings could have such distinct behaviors despite being so genetically similar. They came up with two possible explanations. One explanation suggested that herrings were flexible and could adapt to a range of environments, meaning their genetics did not need to change. The other explanation was that the differences were in the genes that had not yet been identified.

“I was involved in one of these early studies as an undergraduate student at Stockholm University in the late 1970s, and during the last 35 years I have wondered which of these explanations is the correct one,” Andersson said. “I was convinced that by applying the new sequencing technologies that have revolutionized biology, we would eventually get the final answer.”

A number of the identified genetic differences do not have a known function, but finding these differences lay the foundation for future research. Additionally, this discovery is expected to have implications to understanding speciation and sustainable population management.

“This study exemplifies how the population-level genome sequencing can help us understand the genetic basis of adaptation of animals to their habitats,” Cai said. “Herring, unlike zebrafish and stickleback, is not a model fish species commonly used in genetic studies. The availability of the genome information has made herring an emerging model, which is ideal for studying salinity adaptation.”

“I am convinced that further research on this rich collection of genes associated with ecological adaptation will lead to new basic knowledge about gene functions that will be relevant also for human medicine since the majority of genes in herring are also found in humans and are expected to have similar functions,” Andersson said.

“I congratulate Dr. Andersson and his team on another stunning piece of work. This study is remarkable not only for its boldness and breadth, but even more for its implications for species adaptation and survival in a changing climate,” said Dr. Evelyn Tiffany-Castiglioni, head of VIBS.

Texas A&M Researcher’s Team Discovers Evolution in Action in Darwin’s Finches

COLLEGE STATION, Texas – Long and pointy, short and blunt, large and prominent: these are just a few of the beak variations of Darwin’s finches. Beaks are not only highly variable among species, but also they are shaped by evolution. In a study published in Science, a research team led by Leif Andersson, professor at the Texas A&M; College of Veterinary Medicine & Biomedical Sciences and Uppsala University in Sweden, has discovered a gene-HMGA2-affecting the variation in beak size in Darwin’s finches.

A large ground finch (Photo credit: K.T. Grant)

 

Finch
A large ground finch (Photo credit: K.T. Grant)

Previously, the team discovered that the ALX1 gene affects beak shape, specifically whether the beak is pointed or blunt. Both studies help unveil the genetic basis of the beak variation in Darwin’s finches and further explain this iconic example of evolutionary adaptation.

“Our data shows that beak morphology is affected by many genes, as is the case for most biological traits,” Andersson said. “However, we are convinced that we now have identified the two loci with the largest individual effects that have shaped the evolution of beak morphology among Darwin’s finches.”

Aptly named, Darwin’s finches greatly influenced Charles Darwin’s theory of evolution through natural selection. The finches descended from a common ancestor, which arrived in the Galápagos Islands about two million years ago. Since then, the finches have evolved into 18 species, differing in body size, beak shape, song, and feeding behavior. Variations in beak size and shape allow the different species to consume different foods, such as insects, seeds, and nectar.

Specifically, the researchers compared the medium ground finch and the large ground finch on Daphne Major Island in the Galápagos. The average beak size in the medium ground finch was reduced following a drought because birds with a large beak could not compete well with the large ground finch.  Having two different beak sizes allowed the two species to use different food sources, reducing competition for a single food source. The team now demonstrates that the HGMA2 gene played a prominent role in this rapid evolution.

The HMGA2 gene is known to play a role in body size in dogs and horses as well as height in humans.

“The HMGA2 gene regulates the expression of other genes, but the exact mechanism how it controls beak size in Darwin’s finches or human stature is unknown,” Andersson said. “It is very fascinating that this gene pops up in many different species as a gene affecting growth. In humans is also a gene affecting dysregulated cell growth in cancer, and it is clear that more research to better understand the function of the gene is well justified.”

“Dr. Andersson’s research is not limited to discovering genes, but extends deeply into the biology of inheritance and adaptation,” says Evelyn Tiffany-Castiglioni, head of the Department of Veterinary Integrative Biosciences at Texas A&M; University. “This new paper is an elegant example of how the function of a gene can play a role in survival of a bird lineage when the environment changes. It will undoubtedly shed light in future on how this gene and others influence growth and body size of important domestic animal species.”

Andersson has been a Texas A&M; University Institute for Advanced Study (TIAS) Faculty Fellow-one of the nationally and internationally renowned scholars invited by the Institute to come to the campus for extended stays to teach, conduct research, and interact with Texas A&M; students and faculty.

Texas A&M Researchers “Paint” the Congo African Grey Parrot’s Chromosomes

COLLEGE STATION, Texas – Congo African grey parrots are well known for their intelligence and beloved by many as pets, but little is known about their genetic make up. Researchers at the Texas A&M; College of Veterinary Medicine & Biomedical Sciences (CVM) are changing that by studying the parrot’s chromosomes.

African GreyIn a paper published in Cytogenetic and Genomic Research, scientists looked at the Congo African grey parrot’s chromosomes and compared them to other parrot species from South America and Australia. “This is the first study of its kind in true African parrots,” said Dr. Terje Raudsepp, associate professor and lead author of the study. “So far, analogous work in parrots has been done in three South American macaws, Australian budgerigars and cockatiels, and peach-faced lovebirds from Asia and Africa.”

The study found that Congo African grey parrots were strikingly similar to Neotropical macaws found in South America. Unexpectedly, Congo African grey parrots were genetically more similar to Neotropical macaws, such as the scarlet macaw and the red-and-green macaw, than parrots from Australia, such as cockatiels and budgerigars.

“We found that the rearrangements are essentially, but not completely, indistinguishable from the scarlet macaw,” said Dr. Ian Tizard, distinguished professor of immunology at the CVM, director of the Schubot Exotic Bird Health Center, and an author of the study. “That was a bit of a surprise because you’re talking about an African parrot and a South American parrot. It implies a much closer relationship between the South American parrots and the African parrots than we would have predicted.”

Further, Tizard suggested that this genetic similarity could have originated before Africa and South America were separated over 70 million years ago. The African and South American parrot species ended up on opposite sides of the world due to continental drift, yet much of their genome remained similar.

To get a better look at the African grey parrot’s chromosomes, the researchers “painted” them, using a technique known as Zoo-FISH (Fluorescence In-situ Hybridization). This color codes a known genome-in this case the chicken’s genome-and compares it to a less understood genome, such as the Congo African grey parrot. By painting the chromosomes with Zoo-FISH, researchers can identify identical or similar sets of genes between species that get rearranged during the process of evolution. For example, genes that are all together on one chromosome of one species may appear on two different chromosomes in another species.

“Zoo-FISH, or comparative chromosome painting, allows comparison of chromosomes of different species at a molecular level and exchange genome sequence or gene mapping data between the species,” Raudsepp said. “Zoo-FISH shows chromosomal correspondence between species but also allows indirect transfer of genetic information from well-studied species, such as the chicken, to species with no genome sequence information, such as African grey parrots.”

Although the genes’ locations on the chromosome don’t greatly affect the animal, the comparative location of these genes can give researchers clues about evolutionary relationships. Species with genes in similar chromosomal locations are generally more closely related than those with dissimilar genetic arrangements. “From the body’s point of view, it doesn’t matter whether a gene is on chromosome one or chromosome seven, as long as it’s there,” Tizard said.

Increased understanding of the Congo African grey parrot also has conservation implications, Tizard said. Although parrots may look the same, they might be genetically distinct and, in some cases, separate species. “We’re trying to dissect out these relationships and they’re proving to be a little bit more complex than expected,” he said.

This is the third collaboration between Raudsepp’s research group and researchers at the Schubot Center, including sequencing the genome of the scarlet macaw. More collaborations between the groups are expected in the future, according to Raudsepp. Tizard agreed and suggested that similar studies could be done on other exotic birds.

Texas A&M Faculty and Researchers Develop Chagas Case Study Learning Module

COLLEGE STATION, Texas – Faculty and researchers at the Texas A&M; College of Veterinary Medicine & Biomedical Sciences (CVM) have turned the recent increase in Chagas disease cases in Texas into a learning opportunity by developing an online case study learning module. The case study was one of only 15 selected for web
publication
by the American Association of Veterinary Medical Colleges’ (AAVMC) and the Association for Prevention Teaching and Research’s (APTR) joint One Health Interprofessional Education Initiative.

Chagas disease, an infectious disease caused by the parasite
Trypanosoma cruzi and transmitted by the kissing bug, has many Texans concerned. Recent spread of Chagas disease, which affects humans and animals in the southern United States and Latin America, has made media headlines. This increase in cases and growing concern over the disease led researchers to develop the Chagas case study as an educational tool for health professionals.

The module was created through a collaboration between faculty and researchers at the CVM, Baylor College of Medicine, and Texas A&M; Health Science Center–McAllen. The module was supported through funding from the Texas A&M; One Health Initiative.

The module’s content was developed by faculty and students at the CVM: Associate Professor Dr. Ashley Saunders, expert in clinical cardiology in dogs, as well as Assistant Professor Dr. Sarah Hamer, Ph.D. student Rachel Curtis-Robles, and veterinary student Trevor Tenney, experts in the ecology and epidemiology of the kissing bug and T. cruzi. Additional content addressing public health was contributed by Dr. Ann Millard, associate professor at the Texas A&M; Health Science Center–McAllen, and Dr. Melissa Garcia, research associate at Baylor College of Medicine.

The case was developed in collaboration with The Center for Educational Technologies (CET) at the CVM, including Dr. Jodi Korich and Dr. Jordan Tayce. The web-based case study allows students to make a series of clinical decisions as they follow a real case from diagnosis through treatment and is supplemented with instructional video lectures, diagnostic charts, and other reference materials in an interactive and media-rich format.

“The case study turned out really cool, and it’s interactive. That is the beauty of working with the CET,” said Saunders, who was designated as an AAVMC One Health Scholar as the principal investigator. “The whole point is that faculty at another university in other health professions could teach their students with a case study that was developed by experts from Texas A&M.;”

“It’s all digitally interactive,” said Tayce, an instructional assistant professor at the CET. “A user can be in any location at any time and still go through this case. That’s what makes our case study unique.”

The case study features a dog diagnosed with Chagas disease in Texas, but it is not limited to veterinary applications. According to the researchers, the Chagas case highlights the One Health Initiative by focusing on important connections between humans, animals, and the environment. Therefore, it can be used by students in a variety of disciplines, including human and veterinary medicine.

“It’s not just veterinary,” Tayce said. “It’s geared toward medical students, public health students, environmental science students, and others.”

According to Saunders, the collaborations that built the case study are what make it so versatile. “The AAVMC and APTR wanted the case study to not just be veterinary focused, but they also wanted to include people from all disciplines,” she said. “I knew we had enough people, and it was going to be a successful collaborative effort. I knew we could do it, so I started pulling people in from all different places to help us.”

The Chagas case study uses technology to enhance students’ knowledge and understanding of the disease, including the clinical presentation and cardiac manifestations in dogs, when to test for infectious diseases, kissing bug ecology and epidemiology, and client education on animal and human health aspects and kissing bug management.

“At the CET, we work to make sure we’re using proven educational practices in all of the material we build,” Tayce said. “We work with the faculty to make sure that from the beginning and all the way through to the end we’re using these established educational practices when we create content.”

Saunders said this module is not only suited for veterinary students, but also for students in other health-related disciplines. She noted that, as a veterinarian, she could imagine the benefits of increased education. “One of the difficult things about Chagas disease is the questions I receive from owners about how to save their dog,” she said. “We can definitely help the dogs, but even more important is what goes on at home, like where did they get exposed and who else can get infected. So, we brought in all these experts to build a case that was comprehensive and a really great collaborative effort.”

Texas A&M Professor Leads Team Awarded $1 Million Food Safety Grant from USDA

COLLEGE STATION, Texas – The USDA recently announced 35 Food Safety Grants, one of which was awarded to a team led by Dr. H. Morgan Scott, professor in the Department of Veterinary Pathobiology at Texas A&M; College of Veterinary Medicine & Biomedical Sciences (CVM), based on their research on antimicrobial resistance. The grant funding awarded to the team totaled $1 million.

The Food Safety Grants are administered by the USDA’s National Institute of Food and Agriculture (NIFA) and are designed to enable research that promotes safe and nutritious food as well as agricultural competitiveness.

Antimicrobials, including antibiotics, have been used for decades to successfully treat both humans and animals. However, strains of bacteria have evolved resistance to antibiotics, leading to growing concern about aspects of food safety related to animal agriculture. Through this research, Scott and his team hope to address these concerns.

Scott will lead a team of researchers and extension faculty: Mayukh Dass and Guy H. Loneragan of Texas Tech University, Yrjö T. Gröhn of Cornell University, Ellen R. Jordan and Jason Sawyer of Texas A&M; AgriLife Extension, Alex W. McIntosh of Texas A&M; University, and Gerald R. Midgley of the University of Hull in the United Kingdom. The team will focus on designing and implementing science-based and stakeholder-informed stewardship programs for beef and dairy cattle systems.

The overall goal of the project is to identify, evaluate, and implement practical and effective strategies for mitigating and preventing antimicrobial resistance. To do this, Scott and his team seek to recruit and engage stakeholders in designing and implementing voluntary antimicrobial stewardship programs. Additionally, the researchers will conduct field studies and develop models to better understand various aspects of this complex issue, including economics, microbiology, and the social sciences.

The research team aims to enhance environmental quality and food safety by reducing the burden of antibiotic resistance among enteric bacteria. Scott’s research will lay the foundation by which decisions can be made by stakeholders to prevent and combat antimicrobial resistance. This includes qualitative and quantitative modeling to test tools that support stakeholder’s decisions, both in the short and long term.

This project differs from previous attempts to mitigate antimicrobial resistance in animal agriculture because it focuses on voluntary stewardship programs rather than relying strictly on legislation or regulation.

“Dr. Scott’s research on antimicrobial resistance is truly exceptional,” said Dr. Eleanor M. Green the Carl B. King dean of veterinary medicine. “Receiving this grant is a testament to Dr. Scott’s commitment to excellence in research, and we are proud of him and the team he is leading.”

Texas A&M Researchers Discover How Hexavalent Chromium Impacts Early Ovarian Development

Hexavalent chromium (CrVI), a toxic form of the heavy metal chromium, is widely used in more than 50 industries such as welding and painting. Due to increased usage and improper disposal, CrVI contaminates the environment, including drinking water. New research from the Texas A&M; College of Veterinary Medicine & Biomedical Sciences (CVM) indicates that, despite its widespread use, CrVI can cause detrimental health effects, particularly when it comes to fetal ovarian development.

cover of Toxicology and Applied PharmacologyThe study, which appears on the cover of Toxicology and Applied Pharmacology, examined developing rat whole fetal ovaries in cell cultures to explain how early exposure to CrVI causes cell death, known as apoptosis, in the female offspring’s developing ovaries. Ultimately, increased apoptosis during ovarian development can lead to premature ovarian failure and early menopause in the adult life.

“My main goal is to see what happens to the children if pregnant women are exposed to hexavalent chromium, since it readily crosses the placenta and directly targets the fetal organs, mainly the ovary,” said Dr. Sakhila Banu, assistant professor in the Department of Veterinary Integrative Biosciences and the lead author of the study.

Banu and other Texas A&M; researchers studied the effect of CrVI on rat ovaries grown in a cell culture in the earliest stages of development-as soon as cells began to develop into ovaries. They looked at several genes and proteins that regulate the ovary’s development and the onset of apoptosis in ovarian cells.

Although it is normal for cell death to occur in some cells during the development of the ovary, accelerating apoptosis during early ovarian development can have consequences later in a woman’s life.

“Many chemicals can cause cell death,” Banu said. “If liver cells or intestinal cells are targeted they rejuvenate to a certain extent. But, every woman is born with a specific number of immature eggs, called oocytes, in the ovary. If during early development the oocytes are exposed to chromium, which particularly targets those cells, and if chromium accelerates those molecular pathways that program cell death, then you could end up with premature ovarian failure.”

Additionally, the researchers noted that this study creates a model in which the whole fetal ovaries can be grown in a organ culture for direct examination to determine harmful effects of chemicals on ovarian development. Thus, future research can be done to better understand the effects of other chemicals, such as drugs or environmental contaminants, on ovarian development.

Currently, the U.S. Environmental Protection Agency recommends 0.1 parts per million (ppm) as the safe limit for chromium in drinking water. However, Banu and her team determined that this level was still high enough to cause ovarian damage, suggesting that the regulatory limit of chromium be revisited.

“Dr. Banu is a highly productive young scientist and a leader in the area of chromium toxicity mechanisms and remediation strategies through funding support from the National Institute of Environmental Health Sciences,” said Dr. Robert Burghardt, associate dean for research and graduate studies at the CVM. “This is another outstanding example of One Health research being conducted at the College of Veterinary Medicine & Biomedical Sciences that benefits animals, humans, and the environment.”

Texas A&M-led Research Shows How Hybridization Shaped Feline Evolution

COLLEGE STATION, Texas – Research scientists at Texas A&M; University and Pontifícia Universidade Católica do Rio Grande do Sul in Brazil have moved a step closer to understanding the rich evolutionary history of the cat family. In a paper, featured on the cover of Genome Research, the researchers constructed extensive family trees of the 38 cat species, which illustrated maternal, paternal, and biparental lineages within the cat family. However, they found that lineages are not completely linear. Instead, this study revealed that feline ancestry has been shaped throughout its evolutionary history by hybridization.

Cover of Genome Research

 

Genome Research
Cover of Genome Research

For this study, researchers used genome-wide Single Nucleotide Polymorphism (SNP) data-which identifies differences in individual base pairs-with genes from both the X and Y chromosomes and autosomal, or non-sex chromosomes, in addition to sequencing complete mitochondrial genomes, which indicate maternal lineage. This data was complemented by new whole genome sequencing data from the closest species to the domestic cat, as well analysis of the tiger, snow leopard, and lion genomes.

“Our results finally resolve much of the discrepancies in the literature over the past two decades as to how cats are related and the cause for many of the conflicts between different scientific publications, ” said Dr. William Murphy, professor in the Department of Veterinary Integrative Biosciences (VIBS) at the Texas A&M; College of Veterinary Medicine & Biomedical Sciences and an author of the study.

“The results also highlight an emerging trend in the literature that hybridization between different species is common and may actually be adaptive. One novelty of our study is the illustration as to how common this process is across a broader phylogenetic scale-within an entire family of mammals-than previously has been shown in isolated pairs of species.”

“Dr. Murphy is an extremely meticulous investigator whose prior work helped create the field of phylogenomics, which uses genome analysis to establish evolutionary relationships of species,” said Dr. Evelyn Tiffany-Castiglioni, department head of VIBS. “This new work will contribute greatly to our understanding of hybridization as a force that has shaped and is shaping speciation in cats.”

The researchers found that there were nine differences between the maternal and biparental trees. For example, the maternal tree indicated that the puma lineage was more closely related to the lynx/bay cat group, whereas the biparental tree showed the puma lineage as more closely related to the Asian leopard cat/domestic cat group. Researchers concluded that the most likely cause of this, and other discrepancies between family trees based on different modes of inheritance, is due to ancient hybridizations. Hybrids may have then mated with non-hybrids, introducing variations back into the species.

Additional factors influencing feline evolution include the fact than male hybrids are more often sterile than female hybrids and the males are often more geographically dispersed than females.

“We identified traces of hybridization within the genomes of more than half of the eight cat lineages, where stretches of DNA sequences are far more closely related between pairs of non-sister species than would be expected by random processes,” Murphy said. “In several of these cases, the evidence for hybridization in the nuclear genome, which is inherited from both parents, is matched by similar patterns in the mitochondrial DNA, which is only inherited from the mother.”

Ancient hybridization may have led to the discrepancies between the biparental and maternal lineages of the snow leopard. Specifically, genes on the X chromosomes of lions and snow leopards were shown to have diverged at a more recent date than did genes on autosomal chromosomes. Additionally, snow leopards retained a mitochondrial genome that is more similar to the lions’ mitochondrial DNA, when compared to other parts of its genome. The study suggested that these results are likely due to early hybridization between the ancestors of the two species.

“We know that ancient hybridization in the wild is consistent with extensive evidence for hybridization that has occurred between many distantly related cat species in captivity, such as the liger-a male lion crossed with a female tiger,” Murphy said. “One of the world’s most popular cat breeds, the Bengal, is a hybrid between the domestic cat and the Asian leopard cat, and several other increasingly common cat breeds are of hybrid origin.”

The researchers also note that, while hybridization is a natural part of evolution, factors such as poaching, loss of habitat, and climate change have the capacity to affect future feline evolution, particularly in endangered species. They also emphasize the importance of understanding natural versus human-caused hybridization.

Texas A&M Scientist Leads Study to Unlock Genetic Secrets of the Dun Coat in Horses

COLLEGE STATION, Texas – Today, horses come in a variety of coat colors, but most lack the camouflaging coat of their ancestors. However, a trace of that legacy remains in horses with the dun pattern, which characterized by pale hair covering most of the body, a dark stripe along the back, and zebra-like stripes on the legs. A recent study, published in Nature Genetics, reveals a new mechanism that explains the genetic roots of the dun pattern and uncovers why the pattern does not appear in most domesticated horses.

 

 

Three Dun Stallions
Three Dun stallions. From left: Bay dun, blue dun, and red dun. (Photo credit: Freyja Imsland)

The study is the work of an international team of scientists, led by Texas A&M; University Institute for Advanced Study (TIAS) scholar Dr. Leif Andersson and is the result of a collaboration between groups at Texas A&M; University, Uppsala University in Uppsala, Sweden, and the HudsonAlpha Institute of Biotechnology in Huntsville, Alabama.

The dun pattern camouflaged ancient wild horses, protecting them from predators. However, domestic horses, like other domestic animals, have been selected over many generations to appear different from their wild counterparts. As a result of selective breeding, most domestic horses today are not dun and have coat colors that are more intensely pigmentation and uniformly distributed across the body.

“Dun is clearly one of the most interesting coat color variants in domestic animals because it does not just change the color but the color pattern,” Andersson stated. “We were really curious to understand the underlying molecular mechanism of why the dun pigment dilution does not affect all parts of the body.”

“Unlike the hair of most well-studied mammals, the dilute-colored hairs from dun horses are not evenly pigmented,” explained Freyja Imsland, a Ph.D. student in Andersson’s group. “They have a section of intense pigmentation along the length of the hair, on the side that faces out from the body of the horse, whilst the rest of the hair has more or less no pigment. The hairs from the dark areas of dun horses are in contrast intensely pigmented all around each individual hair. In spite of scientists having studied hair pigmentation in detail for a very long time, this kind of pigmentation is novel to science and quite unlike that seen in rodents, primates, and carnivores.”

Genetic analysis and DNA sequencing revealed that the dun color is determined by a single gene, which codes for the T-box 3 (TBX3) transcription factor. “Previous studies in humans and laboratory mice show that TBX3 controls several critical processes in development that affect bones, breast tissue, and cardiac conduction,” explained Dr. Greg Barsh, whose group at HudsonAlpha led the tissue analysis. “We were surprised to find that TBX3 also plays a critical role in skin and hair development.”

Researchers measured TBX3 distribution in individual hairs relative to other molecules known to regulate pigmentation. The researchers suggest that the signals governing where TBX3 is expressed could help to explain zebra stripes. In horses that have lost their dun color, TBX3 mutations do not inactivate TBX3 protein function and instead only affect where, both on the individual hair and on the horse’s body, the gene is expressed.

“In growing hairs, TBX3 mirrors the distribution of melanocytes, the cells that produce pigment,” explained Kelly McGowan, a senior scientist in Barsh’s lab. “Our results suggest that TBX3 affects differentiation of specific cells in the hair, creating a microenvironment that inhibits melanocytes from living in the ‘inner’ half of the hair.”

The team also discovered that there are two forms of dark, non-dun color: non-dun1 and non-dun2, which are caused by different mutations. Non-dun1 horses differ from dun horses in that they have a darker coat and less contrast between the stripes and the rest of the body. On the other hand, non-dun2 horses show no stripes at all.

“Non-dun horses have much more vibrant color than dun horses. Non-dun1 horses tend to show primitive markings similar to dun horses, whereas non-dun2 horses generally don’t show primitive markings,” Imsland stated. “These primitive markings in non-dun1 horses can sometimes lead horse owners to think that their intensely pigmented non-dun1 horses are dun.”

The study indicates that the non-dun2 variant occurred recently-most likely after domestication. In contrast, the dun and non-dun1 variants predate domestication. Evidence of this conclusion can be found in the DNA of a horse that lived about 43,000 years ago, long before horses were domesticated, which carried both dun and non-dun1 variants.

“This demonstrates that horse domestication involved two different color morphs-dun and non-dun1-and future studies of ancient DNA will be able to reveal the geographic distribution and the abundance of the two morphs,” Andersson said.

Texas A&M Researchers and International Collaboration Identify a ‘Supergene’ Underlying Genetic Differences in Testosterone Levels and Sexual Behavior in Male Ruff

COLLEGE STATION, Texas – The ruff is a Eurasian shorebird that has a spectacular “lekking” behavior where highly ornamented males gather in a single location and compete for females. Now two groups, one led by researchers at the Texas A&M; University College of Veterinary Medicine & Biomedical Sciences (CVM) and Uppsala University, report that males with alternative reproductive strategies carry a chromosomal rearrangement that has been maintained as a balanced genetic polymorphism, leading to three types of ruff males, for about 4 million years. The two studies are published today in Nature Genetics.

Independent male ruff at lek with colorful ruff and head tuft. Photo credit: Ola Jennersten.

 

Male Ruff
Independent male ruff at lek with colorful ruff and head tuft. Photo credit: Ola Jennersten.

Three different types of ruff males occur at the leks of this species. Independent males show colorful ruffs and head tufts and fight vigorously for territories. Satellite males are slightly smaller than Independents, do not defend territories and have white ruffs and head tufts. Faeder is the third body type, or morph; these are disguised males that mimic females by their small size and lack of ornamental feathers. The Independent and Satellite males show a remarkable interaction, where the Satellite males allow Independent males to dominate them on the leks.

“Both Independents and Satellites benefit from the interaction because it increases their mating success by attracting females that are ready to mate,” explained Dr. Fredrik Widemo, who did his Ph.D. on ruff lekking behavior. Widemo also noted that fighting over territories and females is both energetically costly and risky. This created an opportunity for the evolution of alternative male mating strategies in which males spend less energy on fighting.

Previous studies have indicated that these remarkable differences between male morphs are under strict genetic control and are determined by a single genetic region. These most recent studies represent an explanation for how such complex differences in behavior, size, and plumage have a simple genetic basis. To arrive at the answer, the research teams sequenced the entire ruff genome.

“This is a fascinating study that exemplifies the power of modern genomics to unravel a seemingly complex behavioral and morphological phenotype. Surprisingly the alternative male morphs found in the ruff are the product of a single, yet strongly differentiated locus that was dramatically altered in just a few million years. The authors provide an additional illustration of the increasing role that structural mutations play in evolution and disease,” said Dr. William Murphy, professor in the department of Veterinary Integrative Biosciences at the CVM.

“We discovered that both Satellite and Faeder males carry a ‘supergene,’ which is not a gene with superpower but a cluster of about 90 genes kept together by a chromosomal inversion indicating that there is no genetic exchange between the three different morphs,” said Sangeet Lamichhaney, one of the PhD students involved in the study, “The simple answer is that the ‘supergene’ contains both genes like HSD17B2 affecting the metabolism of sex hormones and the MC1R gene controlling pigmentation.”

The group reports that the sequence difference between the chromosome variants is as large as 1.4 percent-higher than the average sequence difference between human and chimpanzee chromosomes. The scientists estimate that the chromosome inversion happened about 4 million years ago.

“The Satellite and Faeder male morphs are the result of an evolutionary process over million of years and involve many genetic changes among the 90 genes in this ‘supergene,'” explained Dr. Leif Andersson, who led the study at Uppsala University and also served as a Texas A&M; Institute for Advanced Study fellow. “The ‘supergene’ contains five genes that have a role in the metabolism of steroid hormones. It is particularly interesting that we see an enrichment of genetic changes in the vicinity of a gene, HSD17B2, which determines an enzyme that converts active testosterone to a more inactive form. Independents have a significantly higher level of testosterone than Satellite and Faeder males, and we think this is the reason that in turn leads to an altered behavior.”

There are many examples of associations between behavior and pigmentation in animals, but the underlying causal relationships have rarely been revealed. The present study now provides insights into why there is such a strong association between altered behavior and white color in Satellite males.

“We think that this evolutionary process started with the occurrence of the inversion about 4 million years ago and that the inversion in itself altered the regulation of one or more genes affecting the metabolism of sex hormones,” added Andersson. “This created a primitive alternative male morph, which has been further improved step by step by the accumulation of many genetic changes.”

“Nature has certainly ‘experimented’ a lot on sex determination, sexual development, and reproduction,” said Terje Raudsepp, associate professor in the Department of Veterinary Integrative Biosciences (VIBS) at the CVM, “but only excellent research and researchers can reveal its full beauty and complexity. I applaud the researchers for this fascinating discovery-and also ruff Faeder males for their effortless reproductive success.”

“Dr. Andersson has a distinguished history of elegant discoveries in the field of genetics and evolution,” said Dr. Evelyn Tiffany-Castiglioni, professor and VIBS department head. “This is an example of his creative, non-invasive way of unraveling how a species has evolved successfully by maintaining males with diverse behaviors and appearances.”