Sheep Horn Research Articles

Genome-Wide Association Analyses and Population Verification Highlight the Potential Genetic Basis of Horned Morphology during Polled Selection in Tibetan Sheep.

The types and morphology of sheep horns have been extensively researched, yet the genetic foundation underlying the emergence of diverse horn characteristics during the breeding of polled Tibetan sheep has remained elusive. Genome-wide association analysis (GWAS) was performed on 103 subtypes (normal large horn, scurs, and polled) differentiated from G2 (offspring (G2) of parent (G1) of polled) of the polled core herd. Six single nucleotide polymorphisms (SNPs) located on chromosome 10 of the relaxin family peptide receptor 2 (RXFP2) gene exhibited positive correlations with horn length, horn base circumference, and horn base interval. Furthermore, in genotyping 382 G2 individuals, significant variations were observed for each specific horn type. Three additional mutations were identified near the target SNP upstream of the amplification product. Finally, the RXFP2-specific haplotype associated with the horned trait effectively maintained horn length, horn base circumference, and horn base interval in Tibetan sheep, as confirmed by population validation of nine loci in a sample size of 1125 individuals. The present study offers novel insights into the genetic differentiation of the horned type during improvement breeding and evolution, thereby establishing a robust theoretical foundation for polled Tibetan sheep breeding and providing valuable guidance for practical production.

Expression, Polymorphism, and Potential Functional Sites of the BMPR1A Gene in the Sheep Horn.

Sheep horns are composed of bone and sheaths, and the BMPR1A gene is required for cartilage and osteogenic differentiation. Therefore, the BMPR1A gene may have a function related to the sheep horn, but its relationship with the sheep horn remains unclear. In this study, we first utilized RNA sequencing (RNA-seq) data to investigate the expression of the BMPR1A gene in different tissues and breeds of sheep. Second, whole-genome sequencing (WGS) data were used to explore the functional sites of the BMPR1A gene. Lastly, the allele-specific expression of the BMPR1A gene was explored. Our results indicate that BMPR1A gene expression is significantly higher in the normal horn groups than in the scurred groups. Importantly, this trend is consistent across several sheep breeds. Therefore, this finding suggests that the BMPR1A gene may be related to horn type. A total of 43 Single-Nucleotide Polymorphisms (SNPs) (F-statistics > 0.15) and 10 allele-specific expressions (ASEs) exhibited difference between the large and small horn populations. It is probable that these sites significantly impact the size of sheep horns. Compared to other polled species, we discovered ten amino acid sites that could influence horn presence. By combining RNA-seq and WGS functional loci results, we identified a functional site at position 40574836 on chromosome 25 that is both an SNP and exhibits allele-specific expression. In conclusion, we demonstrated that the BMPR1A gene is associated with horn type and identified some important functional sites which can be used as molecular markers in the breeding of sheep horns.

Legal assessment of ingrown horns and other horn-related anomalies in cattle and sheep.

Cattle and sheep horns have the potential to grow in such a way that the horn bends toward the animal's head and, if left untreated, may penetrate the skin, causing pressure, pain, and suffering. According to the Swedish Animal Welfare Act, animals must be looked after in a way that prevents ingrown horns; otherwise, the person responsible for the animal may be prosecuted. Here, we present a review of 32 legal cases that occurred in Sweden between 2008 and 2022 for which the charge involved horn-related anomalies in cattle or sheep. The aim being to investigate the nature of these horn-related anomalies and the circumstances under which they occur. Of the legal cases, 53% were discovered during official animal welfare control on farms and 44% at an abattoir during pre-slaughter inspection. These include extreme injuries, e.g. both horns penetrating the periosteum into the skull bone, or a horn penetrating into the eye or oral cavity. The reasons offered by the accused for failing to detect animals with horn-related anomalies included that the animal appeared normal, that it was long-haired, shy, or hard to reach, or that the horns had not undergone gradual growth but had accidentally or suddenly penetrated the skin. Overall, 81% of the cases led to convictions; however, none of these resulted in imprisonment. Reasons for acquittals included insufficient crime description or evidence as to how the horn-related anomaly occurred or of the animal being exposed to suffering. A number of recommendations are provided that could help limit the occurrence of ingrown horns.

Sebaran rumpun, pola warna bulu, dan jenis tanduk domba lokal betina di Kabupaten Bandung

The variety of environmental and cultural conditions in each region in Indonesia causes differences in sheep rearing patterns, resulting in a variety of breeds, coat color patterns and types of horns of sheep being cultivated. The Bandung Regency area has a climate and environment that is suitable for raising livestock, so raising sheep has become a part of the culture in the area. Choosing flocks, coat color patterns and types of sheep horns that suit consumer needs can increase the selling value of sheep. The aim of this research was to determine the distribution of clump types, coat color patterns and horn types of local ewes in several animal markets in Bandung Regency. The research was conducted in June 2023 in three animal markets, namely Majalaya, Pacet, and Banjaran Animal Markets. The research method used is descriptive analytic and data collection uses the census method. Based on the research results, it can be concluded that the distribution of local ewes includes Garut sheep 86.78% and Priangan sheep 13.22%, while the distribution of local ewes's coat color patterns is dominated by white 63.64%, a combination of 25.62%, and black 10.74%, as well as muser horn types 54.55%, hornless 33.88%, and horned 11.57%. The total number of research objects was 121 animals, dominated by Garut sheep, the dominant white coat color pattern, and muser horn type

Dall's sheep horn growth and harvest management in the Mackenzie Mountains, Northwest Territories, Canada

AbstractAcross most of their native North American range, the horns of mountain sheep (Ovis spp.) males are getting smaller, a pattern attributed to selective hunting pressure. We measured the horns of 755 Dall's sheep males (Ovis dalli dalli) in the southern Mackenzie Mountains, Northwest Territories, between 2002 and 2017. For each male, we measured the circumference and length of each annulus for the right horn and calculated horn volume for each year. We examined changes in horn size in 4 different outfitter areas, using age at harvest as a covariate. Hunting pressure across years in the study area was consistently low, and this population did not experience the decline in horn size observed in several other mountain sheep populations in Canada. Over the 16‐year period, the average horn volume of harvested males was stable and even increased in 1 outfitter area. Local management of Dall's sheep delivered independently by the guide outfitters in the Mackenzie Mountains appears to contribute to maintaining a population of males that has not been adversely affected by strong selective hunting pressure. The resilience of this management strategy may be challenged by environmental changes associated with rapid warming in northern mountain environments.

The morphology of the interfacial tissue between bighorn sheep horn and bony horncore increases contact surface to enhance strength and facilitate load transfer from the horn to the horncore

The horns of bighorn sheep rams are permanent cranial appendages used for high energy head-to-head impacts during interspecific combat. The horns attach to the underlying bony horncore by a layer of interfacial tissue that facilitates load transfer between the impacted horn and underlying horncore, which has been shown to absorb substantial energy during head impact. However, the morphology and mechanical properties of the interfacial tissue were previously unknown. Histomorphometry was used to quantify the interfacial tissue composition and morphology and lap-shear testing was used to quantify its mechanical properties. Histological analyses revealed the interfacial tissue is a complex network of collagen and keratin fibers, with collagen being the most abundant protein. Sharpey's fibers provide strong attachment between the interfacial tissue and horncore bone. The inner horn surface displayed microscopic porosity and branching digitations which increased the contact surface with the interfacial tissue by approximately 3-fold. Horn-horncore samples tested by lap-shear loading failed primarily at the horn surface, and the interfacial tissue displayed non-linear strain hardening behavior similar to other soft tissues. The elastic properties of the interfacial tissue (i.e., low- and high-strain shear moduli) were comparable to previously measured values for the equine laminar junction. The interfacial tissue contact surface was positively correlated with the interfacial tissue shear strength (1.23 ± 0.21 MPa), high-strain shear modulus (4.5 ± 0.7 MPa), and strain energy density (0.38 ± 0.07 MJ/m3). Statement of significanceThe bony horncore in bighorn sheep rams absorbs energy to reduce brain cavity accelerations and mitigate brain injury during head butting. The interfacial zone between the horn and horncore transfers energy from the impacted horn to the energy absorbing horncore but has been largely neglected in previous models of bighorn sheep ramming since interfacial tissue properties were previously unknown. This study quantified the morphology and mechanical properties of the horn-horncore interfacial tissue to better understand structure-property relationships that contribute to energy transfer during ramming. Results from this study will improve models of bighorn sheep ramming used to study mechanisms of brain injury mitigation and may inspire novel materials and structures for brain injury prevention in humans.

Sheep with Partial RXFP2 Knockout Exhibit Normal Horn Phenotype but Unilateral Cryptorchidism1

Comprehending the genetic basis of economically important traits is of significant importance to enhance livestock breeding. In domestic ruminants, hornlessness is becoming a more desirable trait since horns could lead to accidental injuries to animals and producers. Recent studies have identified the relaxin family peptide receptor 2 (RXFP2) as a primary candidate gene associated with the presence and absence of horns in sheep. However, no sufficient molecular biology-based analyses were performed to validate the association and function of RXFP2 in sheep. Noticeably, previous studies in both humans and mice have provided evidence supporting the involvement of RXFP2 in testicular descent. To validate the potential function of the RXFP2 gene in sheep, we used the CRISPR/Cas9 technology to obtain RXFP2-disrupted sheep individuals. Initially, highly efficient sgRNAs, targeting RXFP2, were screening through in vitro cleavage assays and cellular assessments. Then, two RXFP2-disrupted lambs were generated by intracytoplasmic microinjection of CRISPR/Cas9-sg1 ribonucleoprotein, with an efficiency of 81.84 and 37.17%, respectively. No potential off-target events were detected. Western blot analysis showed that RXFP2 expression was significantly reduced in the pedicle skin of edited lambs (P=0.034). Intriguingly, although the partial disruption of RXFP2 did not affect the horn phenotype in sheep, it led to an obvious unilateral cryptorchidism. These results provide evidence for a hitherto ambiguous link between both horn and testicular development. In conclusion, this study represents the first successful generation of cryptorchid sheep models via the disruption of RXFP2 using CRISPR/Cas9. These findings provide new insights into the roles of RXFP2, whose partial disruption is associated with testicular descent rather than horn formation.

Designing impact-resistant bio-inspired low-porosity structures using neural networks

Biological structural designs in nature, like hoof walls, horns, and antlers, can be used as inspiration for generating structures with excellent mechanical properties. A common theme in these designs is the small percent porosity in the structure, ranging from 1 to 5%. In this work, the sheep horn was used as an inspiration due to its higher toughness when loaded in the radial direction compared to the longitudinal direction. Under dynamic transverse compression, we investigated the structure-property relations in low porosity structures characterized by their two-dimensional (2D) cross-sections. A diverse design space was created by combining polygonal tubules with different numbers of sides placed on a grid with varying numbers of rows and columns. The volume fraction and the orientation angle of the tubules were also varied. The finite element (FE) method was used with a rate-dependent elastoplastic material model to generate the stress-strain curves under plane-strain conditions. A gated recurrent unit (GRU) model was trained to predict the structures’ stress-strain response and energy absorption under different strain rates and applied strains. The parameter-based model uses eight discrete parameters to characterize the design space and as inputs to the model. The trained GRU model can efficiently predict the response of a new design in as little as 0.16 ms and allows rapid performance evaluation of 128,000 designs in the design space. The GRU predictions identified high-performance structures, and four design trends that affect the specific energy absorption were extracted and discussed.

Genetic diversity, tissue-specific expression, and functional analysis of the ATP7A gene in sheep.

In humans, variation of the ATP7A gene may cause cranial exostosis, which is similar to "human horn," but the function of the ATP7A gene in sheep is still unknown. Tissue expression patterns and potential functional loci analysis of the ATP7A gene could help understand its function in sheep horn. In this study, we first identified tissue, sex, breed, and species-specific expression of the ATP7A gene in sheep based on the RNA-sequencing (RNA-seq) data. Second, the potential functional sites of the ATP7A gene were analyzed by using the whole genome sequencing (WGS) data of 99 sheep from 10 breeds. Last, the allele-specific expression of the ATP7A gene was explored. Our result showed the ATP7A gene has significantly higher expression in the big horn than in the small horn, and the ATP7A gene has high expression in the horn and skin, suggesting that this gene may be related to the horn. The PCA results show that the region around the ATP7A can distinguish horned and hornless groups to some extent, further indicating that the ATP7A may be related to horns. When compared with other species, we find seven ruminate specific amino acid sites of the ATP7A protein, which can be important to the ruminate horn. By analyzing WGS, we found 6 SNP sites with significant differences in frequency in horned and hornless populations, and most of these variants are present in the intron. But we still find some potential functional sites, including three missenses, three synonymous mutations, and four Indels. Finally, by combining the RNA-seq and WGS functional loci results, we find three mutations that showed allele-specific expression between big and small horns. This study shows that the ATP7A gene in sheep may be related to horn size, and several potential functional sites we identified here can be useful molecular markers for sheep horn breeding.

Identification of Critical Genes for Ovine Horn Development Based on Transcriptome during the Embryonic Period.

Horns, also known as headgear, are a unique structure of ruminants. As ruminants are globally distributed, the study of horn formation is critical not only for increasing our understanding of natural and sexual selection but also for the breeding of polled sheep breeds to facilitate modern sheep farming. Despite this, a significant number of the underlying genetic pathways in sheep horn remain unclear. In this study, to clarify the gene expression profile of horn buds and investigate the key genes in horn bud formation, RNA-sequencing (RNA-seq) technology was utilized to investigate differential gene expression in the horn buds and adjacent forehead skin of Altay sheep fetuses. There were only 68 differentially expressed genes (DEGs) identified, consisting of 58 up-regulated genes and 10 down-regulated genes. RXFP2 was differentially up-regulated in the horn buds and had the highest significance (p-value = 7.42 × 10-14). In addition, 32 DEGs were horn-related genes identified in previous studies, such as RXFP2, FOXL2, SFRP4, SFRP2, KRT1, KRT10, WNT7B, and WNT3. Further, Gene Ontology (GO) analysis showed that the DEGs were mainly enriched with regard to growth, development, and cell differentiation. Pathway analysis revealed that the Wnt signaling pathway may be responsible for horn development. Further, through combining the protein-protein interaction networks of the DEGs, it was found that the top five hub genes, namely, ACAN, SFRP2, SFRP4, WNT3, and WNT7B, were also associated with horn development. Our results suggest that only a few key genes, including RXFP2, are involved in bud formation. This study not only validates the expression of candidate genes identified at the transcriptome level in previous studies but also provides new possible marker genes for horn development, which may promote our understanding of the genetic mechanisms of horn formation.

How the geometry and mechanics of bighorn sheep horns mitigate the effects of impact and reduce the head injury criterion

Male bighorn sheep (Ovis canadensis) participate in seasonal ramming bouts that can last for hours, yet they do not appear to suffer significant brain injury. Previous work has shown that the keratin-rich horn and boney horncore may play an important role in mitigating brain injury by reducing brain cavity accelerations through energy dissipating elastic mechanisms. However, the extent to which specific horn shapes (such as the tapered spiral of bighorn sheep) may reduce accelerations post-impact remains unclear. Thus, the goals of this work were to (a) quantify bighorn sheep horn shape, particularly the cross-sectional areal properties related to bending that largely dictate post-impact deformations, and (b) investigate the effects of different tapered horn shapes on reducing post-impact accelerations in an impact model with finite element analysis. Cross-sectional areal properties indicate bighorn sheep horns have a medial–lateral bending preference at the horn tip (p = 0.006), which is likely to dissipate energy through medial–lateral horn tip oscillations after impact. Finite element modeling showed bighorn sheep native horn geometry reduced the head injury criterion (HIC15) by 48% compared to horns with cross-sections rotated by 90° to have a cranial–caudal bending preference, and by 125% compared to a circular tapered spiral model. These results suggest that the tapered spiral horn shape of bighorn sheep is advantageous for dissipating energy through elastic mechanisms following an impact. These findings can be used to broadly inform the design of improved safety equipment and impact systems.

Modeling isotherm and mechanism adsorption of heavy metals from water using brut keratin powder prepared from Algerian sheep horns

Modeling isotherm and mechanism adsorption of heavy metals from water using brut keratin powder prepared from Algerian sheep horns

Experimental Study and an RSM Modelling on Drilling Characteristics of the Sheep Horn Particle Reinforced Epoxy Composites for Structural Applications

Recent environmental concern has been raised about the development of biocomposites because of their low cost, eco-friendliness, and biodegradability. Machining of polymeric composite is inevitable during assembly of structural components. In view of creating holes in structural composites, drilling is necessary and it is essential to carry out research to find the optimal machining parameters. The experimental assessment and prediction of the thrust force and torque involved in drilling composites reinforced with sheep horn are presented in this work. The matrix and sheep horn particles were combined in the right proportions before being moulded and poured into a mould, then allowed to cure at room temperature. Investigated properties included ultimate tensile strength, flexural strength, and hardness. To evaluate the quality of the hole, micrographs of the drilled hole were employed. When the mixture was optimised based on the properties, it was found that a 70:30 ratio produced the best results. Thrust force and torque of 58 N and 4.8 N-mm, respectively, were observed for sheep horn filler laminates which were drilled using the combination of 6 mm diameter, 0.1 mm/rev feed rate, and 400 rpm speed. This is by far the best among the combinations used in the experiment. Additionally, the experimental outcomes indicate that the feed rate and spindle speed are the most significant factors affecting the thrust force. Since there were minimal errors in the comparison, the central composite design modelling is consummate. Overall, the extensive experimental effort offers several options to utilise this composite material in future applications across a wide range of fields.

Effects of hunting pressure and timing of harvest on bighorn sheep (Ovis canadensis) horn size

Trophy hunting can affect weapon size of wild animals through both demographic and evolutionary changes. In bighorn sheep ( Ovis canadensis Shaw, 1804), intense harvest of young males with fast-growing horns may have partly driven long-term decreases in horn size. These selective effects could be dampened if migrants from protected areas, not subject to artificial selection, survived and reproduced within hunted populations. Bighorn rams undertake long-distance breeding migrations in the weeks preceding the late-November rut. We analysed records of >7800 trophy bighorn rams shot from 1974 to 2019 in Alberta, Canada, to test the hypothesis that high harvest pressure during breeding migrations was correlated with a greater decrease in horn size. We compared areas with and without a pronounced harvest peak in late October, when male breeding migrations begin. Areas without a pronounced harvest peak in late October, which likely experienced a lower harvest rate, showed a similar temporal decline in horn size, but no increase in age at harvest suggesting a possibly weaker decline in horn growth. Our study suggests that unselected immigrants from protected areas could partly buffer the effects of intense trophy hunting only if harvest pressure was reduced when breeding migrations commence.

The Complex and Diverse Genetic Architecture of the Absence of Horns (Polledness) in Domestic Ruminants, including Goats and Sheep.

Horns are the most obvious common feature of Bovidae. The naturally occurring absence of horns in these species, also known as polledness, is of surprisingly heterogeneous nature, although they are Mendelian traits. This review compares in detail the molecular differences among the causes of inherited polledness in the domestic ruminant species of cattle, yak, sheep, and goat based on the causal gene variants that have been discovered in recent years. The genetic causes for the lack of horns in small ruminants seem not only to be more complex, e.g., in sheep, breed-specific characteristics are still unexplained, but in goats, there is also the associated disorder of intersexuality—polled intersex syndrome (PIS). In connection with animal welfare and the associated discussion about a legal ban on the dehorning of all farm animals, naturally hornless animals and the causal genetic variants are of increasing research interest in the age of genome editing. However, the low acceptance of genetic engineering in livestock, especially in European societies, limits its use in food-producing animals. Therefore, genotype-based targeted selection of naturally occurring variants is still a widely used method for spreading this desired trait within and across populations, at least in cattle and sheep.

Thermal studies of big sheep horn as thermal barrier coating (TBC) material for gas turbine compressor blade

This research focuses on the decomposition temperature of a large sheep horn from Haveri District, Karnataka, India, which is 302.9?C. It also demonstrates the possible use of large sheep horn in the aerospace industry. It can be utilised as a Thermal Barrier Coating (TBC) in high-pressure compressor blades of jet engines. Because of its poor thermal conductivity and specific heat capacity, it is a superb insulator, and temperatures throughout the TBC take around 10 minutes to match.

Investigation of Mechanical and Physical Properties of Big Sheep Horn as an Alternative Biomaterial for Structural Applications.

This paper investigates the physical and mechanical properties of bighorns of Deccani breed sheep native from Karnataka, India. The exhaustive work comprises two cases. First, rehydrated (wet) and ambient (dry) conditions, and second, the horn coupons were selected for longitudinal and lateral (transverse) directions. More than seventy-two samples were subjected to a test for physical and mechanical property extraction. Further, twenty-four samples were subjected to physical property testing, which included density and moisture absorption tests. At the same time, mechanical testing included analysis of the stress state dependence with the horn keratin tested under tension, compression, and flexural loading. The mechanical properties include the elastic modulus, yield strength, ultimate strength, failure strain, compressive strength, flexural strength, flexural modulus, and hardness. The results showed anisotropy and depended highly on the presence of water content more than coupon orientation. Wet conditioned specimens had a significant loss in mechanical properties compared with dry specimens. The observed outcomes were shown at par with results for yield strength of 53.5 ± 6.5 MPa (which is better than its peers) and a maximum compressive stress of 557.7 ± 5 MPa (highest among peers). Young’s modulus 6.5 ± 0.5 GPa and a density equivalent to a biopolymer of 1.2 g/cc are expected to be the lightest among its peers; flexural strength 168.75 MPa, with lowest failure strain percentage of 6.5 ± 0.5 and Rockwell hardness value of 60 HRB, seem best in the class of this category. Simulation study identified a suitable application area based on impact and fatigue analysis. Overall, the exhaustive experimental work provided many opportunities to use this new material in various diversified applications in the future.

Horn growth appears to decline under intense trophy hunting, but biases in hunt data challenge the interpretation of the evolutionary basis of trends.

A recent article in Evolutionary Applications by LaSharr et al. reports on trends in the size of horns of bighorn sheep (Ovis canadensis) throughout much of the species’ range. The article concludes that there are “... stable or increasing trends in horn growth over nearly 3 decades in the majority of hunt areas throughout the western U.S. and Canada.” However, the article equates nonsignificance of predominantly negative trends in the areas with the most selective harvest as evidence for the null hypothesis of no trends and also fails to consider well‐known and serious biases in the use of data collected in size‐regulated hunts. By applying meta‐analysis to the estimates reported by LaSharr et al., we show that there has been a pervasive overall trend of declining horn sizes in Alberta, where the combination of horn size‐based legality, combined with unrestricted hunter numbers are understood to generate the greatest selective pressures. Given the nature of the biases in the underlying data, the magnitudes of the trends resulting from our re‐analysis of LaSharr et al.'s (Evolutionary Applications, 2019, 12, 1823) trend estimates are probably underestimated.

Does Headbutting Cause Traumatic Brain Injury? The Case of Combative Bovids

Forceful headbutting clashes occur every year during the rut for most bovids. Bighorn sheep (Ovis aries) and muskoxen (Ovibos moschatus) show extreme examples of this behavior, exerting head-to-head forces of over 3000 N. Their large horns are commonly thought to protect them from these impacts, to the extent of inspiring football equipment. However, whether their horns or thick skull successfully prevent brain trauma has not been investigated experimentally until now. The aim of our research is to study anatomical adaptations of animals with extreme behaviors in order to provide solutions to human problems. A better understanding of brain injury, or the prevention thereof in these animals, will provide insight for the reduction of traumatic brain injury (TBI) in humans at a time where clinical translation of experimental therapies is limited. In a preliminary study, we found early signs of chronic brain injury in a male muskox using immunohistochemistry staining for abnormally phosphorylated tau and high-resolution MRI. Applying the same techniques to bighorn sheep is complicated, as their tau expression is not well understood. Despite the possibility of brain trauma, the capacity to survive such forceful impacts and continue to thrive is not negligible. Thus, alongside the brain, we simultaneously investigated anatomical properties of the skull of both species, using an ontogenetic series of skulls and skull CT scans, respectively. The skulls of six muskoxen and six bighorn sheep were bisected to describe the braincase in detail for the first time. The differences between juveniles, adults, males, and females were especially important because of the sexually dimorphic nature of headbutting behavior. In muskoxen for example, the male skull is approximately 300% larger than that of the female. Although the large pneumatized sinuses of species such as the bighorn sheep have been suspected to contribute to force mitigation, they may simply be a scaffolding supporting the rapid growth of large horns. Furthermore, bighorn sheep horn cores are proven to have similar biomechanical properties to that of regular cortical bone. These findings indicate that the horns and sinuses may not be the main means of protection and we instead hypothesize that the brain's position within the braincase, its connection to meninges, and the rough inner-surface of the cranium are what allow these animals to survive such extreme forces. Anatomical descriptions will serve to increase our knowledge of bovid inner-cranial anatomy all while aiming to determine which anatomical features are most likely to protect bovid brains, which in turn could be translated to humans as a preventive strategy for TBI.

How Do Scientists Know? Answering High School Students’ Questions with an Ecological Sampling Unit

What do animals eat? What animals are present in a habitat? How many animals are present? How was the habitat different years ago? How old is this animal? These are all questions that scientists want to answer. We know the answers to questions like these from data collected by scientists in a variety of ways. Science is evidence based, and conclusions are arrived at after multiple replicable experiments. Presented here are six ecological scenarios that demonstrate how scientists arrive at answers to population ecology questions. These lessons can be implemented as single activities that supplement a high school ecology or environmental science curricular unit or as a multiday rotation of stations in which students practice field sampling techniques used in population and community ecology, designed to answer ecological questions. Student scientists learn how to use indirect sampling methods to estimate abundance, density, age, and population size using mark–recapture, transects, and quadrats to model authentic field methods. They calculate species richness and biodiversity with a simplified Simpson’s diversity index and describe species age structure and distribution using tree rings, sheep horns, and camera trap images. Students also learn to display population data appropriately, graphing survivorship and richness vs. area and studying trophic pyramids.