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Full-Text Articles in Life Sciences

Material Properties Of Coyote Dentine Under Bending: Gradients In Flexibility And Strength By Position, Patricia W. Freeman, Cliff A. Lemen Jun 2008

Material Properties Of Coyote Dentine Under Bending: Gradients In Flexibility And Strength By Position, Patricia W. Freeman, Cliff A. Lemen

University of Nebraska State Museum: Mammalogy Papers

We investigate the nonlinear properties of dentine from the upper canines of coyotes Canis latranswith bending tests. With the results we predict the behavior of whole canines under load. Coyote dentine is not homogeneous but is stronger and more ductile farther away from the pulp cavity. The modulus of rupture (MOR) first increases and then declines with distance from the pulp cavity. Our analysis of the composite nature of dentine produced by these gradients indicates that there may be an adaptive explanation with the composite having nearly the strength of the strongest dentine and a work of fracture greater …


Measuring Bite Force In Small Mammals With A Piezo-Resistive Sensor, Patricia W. Freeman, Cliff A. Lemen Apr 2008

Measuring Bite Force In Small Mammals With A Piezo-Resistive Sensor, Patricia W. Freeman, Cliff A. Lemen

University of Nebraska State Museum: Mammalogy Papers

We tested the use of piezo-resistive force sensors to measure bite force in small mammals. These force sensors are thin (less than 1 mm) and can be used to measure forces up to 4,500 N. A battery-operated unit, ideal for field research, can be built easily and inexpensively. We tested this sensor in the laboratory and in the field on a variety of small mammals. Although our results indicate that the sensor is somewhat less accurate (coefficient of variation = 4%) than a conventional load cell, the small size and ease of use of the piezo-resistive detector is highly desirable. …


Hybrid Zones, Genetic Isolation, And Systematics Of Pocket Gophers (Genus Geomys) In Nebraska., Hugh H. Genoways, Meredith J. Hamilton, Darin M. Bell, Ryan R. Chambers, Robert T. Bradley Jan 2008

Hybrid Zones, Genetic Isolation, And Systematics Of Pocket Gophers (Genus Geomys) In Nebraska., Hugh H. Genoways, Meredith J. Hamilton, Darin M. Bell, Ryan R. Chambers, Robert T. Bradley

University of Nebraska State Museum: Mammalogy Papers

Pocket gophers of the genus Geomys are common inhabitants of many habitats throughout most of the state of Nebraska. Because the taxonomic history of Geomys has undergone numerous changes through the years, these pocket gophers have been the subjects of ongoing taxonomic and distributional studies and in more recent years genetic studies to understand relationships among populations. In order to gain deeper insight into the relationships among these taxa of Geomys, we intensively collected specimens from areas where chromosomal races were thought to form contact zones. Results from examination of genetic (chromosomes, mitochondrial cytochrome-b gene sequences, and nuclear interphotoreceptor …


Obituary: Terry Lamon Yates, 1950-2007., Robert J. Baker, David J. Schmidly, Joseph A. Cook, Jorge Salazar-Bravo, Hugh H. Genoways Jan 2008

Obituary: Terry Lamon Yates, 1950-2007., Robert J. Baker, David J. Schmidly, Joseph A. Cook, Jorge Salazar-Bravo, Hugh H. Genoways

University of Nebraska State Museum: Mammalogy Papers

On December 11, 2007, the science of mammalogy lost one of its most valued and influential leaders. Terry Lamon Yates succumbed to complications of treatments for an aggressive form of brain cancer after a brief but courageous fight. He was born on March 17, 1950, in Mayfield, Kentucky, the older son of Ellen Wanda Byrd and William Hanley Yates. Terry’s only sibling was a brother, Johnny. He is survived by his wife Nancy Fennell Yates, his two sons, Brian Christopher and Michael Ryan, and daughter-in-law Laura Manchéno Macia.


A Simple Morphological Predictor Of Bite Force In Rodents, Patricia W. Freeman, Cliff A. Lemen Jan 2008

A Simple Morphological Predictor Of Bite Force In Rodents, Patricia W. Freeman, Cliff A. Lemen

University of Nebraska State Museum: Mammalogy Papers

Bite force was quantified for 13 species of North American rodents using a piezo-resistive sensor. Most of the species measured (11) formed a tight relationship between body mass and bite force (log 10(bite force) = 0.43(log 10(body mass)) + 0.416; R2 > 0.98). This high correlation exists despite the ecological (omnivores, grazers and more carnivorous) and taxonomic (Cricetidae, Heteromyidae, Sciuridae and Zapodidae) diversity of species. Two additional species, Geomys bursarius (Geomyidae) and a Sciurus niger (Sciuridae), bit much harder for their size. We found a simple index of strength based on two measurements of the incisor at the level of …


Speciation Within Bonneted Bats (Genus Eumops): The Complexity Of Morphological, Mitochondrial, And Nuclear Data Sets In Systematics, Molly M. Mcdonough, Loren K. Ammerman, Robert M. Timm, Hugh H. Genoways, Peter A. Larsen, Robert J. Baker Jan 2008

Speciation Within Bonneted Bats (Genus Eumops): The Complexity Of Morphological, Mitochondrial, And Nuclear Data Sets In Systematics, Molly M. Mcdonough, Loren K. Ammerman, Robert M. Timm, Hugh H. Genoways, Peter A. Larsen, Robert J. Baker

University of Nebraska State Museum: Mammalogy Papers

We phylogenetically analyze 705 base pairs of the cytochrome-b gene and 351 amplified fragment length polymorphism (AFLP) bands from populations of the karyotypically variable Wagner’s bonneted bat, Eumops glaucinus, and the Florida bonneted bat, Eumops floridanus (Chiroptera: Molossidae). Three karyotypes have been documented across the range of E. glaucinus, and we report that the karyotype from Cuba is morphologically similar to that from Jamaica. A 4th karyotype is present in specimens from western Ecuador. Three distinct lineages are present in both the cytochrome-b and AFLP trees. One lineage is restricted to western Ecuador and exhibits cytochrome-b …


Characterization Of A Contact Zone Between Two Subspecies Of The Big Brown Bat (Eptesicus Fuscus) In Nebraska, Justin D. Hoffman, Hugh H. Genoways Jan 2008

Characterization Of A Contact Zone Between Two Subspecies Of The Big Brown Bat (Eptesicus Fuscus) In Nebraska, Justin D. Hoffman, Hugh H. Genoways

University of Nebraska State Museum: Mammalogy Papers

Two subspecies of the big brown bat (Eptesicus fuscus) are reported to occur in Nebraska. The eastern race, E. f. fuscus, is reportedly bigger and darker than its western counterpart E. f. pallidus. Where these 2 subspecies come in contact is the subject of debate. We used external, cranial, and colorimetric data to investigate geographic variation among populations of E. fuscus in Nebraska to determine the location of the zone of contact between E. f. fuscus and E. f. pallidus. We discovered significant variation in external, cranial, and colorimetric data, suggesting that E. fuscus is …