Technical Session 19: Morphology 08:00 - 10:00 Tuesday, 2nd July, 2019 Location Congressional A Session Type Morphology Event Type Technical Session Moderator Noe 08:00 - 08:15 334 Morphological consequences of captivity: a meta-analysis Leila Siciliano-Martina, Jessica E. Light, A. Michelle Lawing Texas A&M University, College Station, Texas, USA Abstract Body Captive morphological change has been a recurrent theme in scientific literature for at least a century. While the topic has been examined in isolated studies, the commonality across these studies has yet to be examined using a thorough, quantitative approach. By conducting a meta-analysis, this study examined the documented morphological impacts of captivity to address whether captive animals show predictably distinct morphology and whether the magnitude and direction of those changes was impacted by lifestyle covariates shared across species. Cranial measures, including those associated with zygomatic breadth, palate width, basal length, and overall skull length differed significantly between captive and wild individuals of several mammalian orders, although the magnitude of change was greater among carnivorous species. The direction of these trends varied, however, certain traits, such as palate width and skull length, tended to increase among captive carnivorans but frequently decreased among herbivorous species. These results may support the notion that carnivorans experience more extreme changes in captivity due to differences in dietary abrasion, where captive carnivoran diets are often softer than wild diets, whereas captive herbivore diets may overlap more closely with wild preferences. This may also suggest that captive morphology frequently changes on a predictable trajectory and that captive specimens should be avoided in morphological studies unless hypotheses are directly related to captivity. Did an ASM award and/or grant assist in your research that culminated in this submission? No 08:15 - 08:30 335 Vertebral trabecular bone architecture in the hero shrew Scutisorex: evolution of an extraordinary morphology Stephanie M Smith1, Kenneth D Angielczyk1, Lawrence R Heaney1, Julian C Kerbis-Peterhans1, Zhe-Xi Luo2 1Field Museum of Natural History, Chicago, Illinois, USA. 2University of Chicago, Chicago, Illinois, USA Abstract Body Extraordinary bony reinforcements have evolved in the lumbar spine of the hero shrew, genus Scutisorex (Soricidae), but the purpose of these reinforcements is unclear. There are currently two species in the genus, which have different degrees of external vertebral modification. Because their vertebrae are so unique, they are difficult to compare with other shrews in conventional homology-based morphological analyses. To circumvent this problem, we used X-ray micro-computed tomography to analyze the internal structure of the vertebrae in a phylogenetically and ecologically broad sample of shrews. Internal trabecular bone architecture (TBA) correlates to in-vivo bone loading, and is therefore informative about locomotion, and by inference, behavior and ecology. We used phylogenetic comparative methods and a variety of measurements collected on soricid TBA to investigate the following hypotheses: i) vertebral loading schemes vary across Soricidae according to locomotor type rather than size; and ii) a greater degree of external modification corresponds to a vertebral column that is superior in bearing high in-vivo loads. Results show Scutisorex vertebral centra have higher bone volume fraction and trabecular thickness, but similar anisotropy values, compared to those of other shrews, even species of similar body size. This suggests Scutisorex may experience vertebral loads that are higher in magnitude but similar in direction to those experienced by other shrews of various locomotor ecologies. 08:30 - 08:45 336 Convergent evolution of olfactory and thermoregulatory capacities in small amphibious mammals Quentin Martinez, Pierre-Henri Fabre Institut des Sciences de l’Evolution (ISEM) - University of Montpellier, Montpellier, Languedoc Roussillon, France Abstract Body Olfaction is a key function for mammals that helps for feeding behaviours, sexual matting and predator avoidance. Despite studies related to olfaction in marine mammals, small amphibious mammals are poorly understood for that sense. We investigated olfactory capacities in amphibious mammals using a large-scale sampling representing most transition events toward amphibious lifestyle in Rodentia, Eulipotyphla, and Afrosoricida. We used a comprehensive 3D CT-scan dataset (N=189) to infer that amphibious mammals converged toward reduce olfactory turbinal bones and might rely on poor olfactory capacities as compared to their terrestrial counterparts. Using comparative phylogenetic methods, we tested and identified a convergent loss pattern of olfactory capacities related to amphibious lifestyle. Our results are consistent with genetic and histological evidences. We further demonstrate that amphibious species convergently display large respiratory turbinal bones that reflect efficient heat conservation capacities. Indeed, mammals also use the nasal cavity as a heat-exchanger with the environment. Because body heat is lost quicker in water than in air, the nasal cavity of amphibious mammals independently evolved to limit thermal loss. 08:45 - 09:00 337 Age matters: the hidden role of demography in mammal body size trends Miranda K Theriot1,2, Link E Olson1,2 1University of Alaska Museum, Fairbanks, Alaska, USA. 2University of Alaska Fairbanks, Fairbanks, Alaska, USA Abstract Body One of the many challenges in studying the biological effects of rapid climate change is measuring complex organismal responses over contemporary timescales. One predicted response—changes in body size—has been well documented in mammals, but increases and decreases have both been reported across taxa and, in some cases, within the same species. There are two primary hypotheses for these opposing trends. The first predicts size decreases consistent with Bergmann’s rule, which posits that individuals in warmer climates tend to be smaller than those in colder regions. The second attributes size increases to greater year-round resource availability. However, a third alternative has been overlooked in most studies. We hypothesize that age may be an important underlying factor. Specifically, increased survivorship due to milder winters and/or longer growing seasons may lead to a larger proportion of older, bigger individuals in a population. To test this, we reanalyzed published studies on American marten and Canadian lynx in Alaska that reported significant body size changes in the latter half of the 20th century. Our findings suggest that age is a confounding variable in these studies, which relied on cranial dimensions known to change over an animal’s lifetime as a result of muscle action. This work has the potential to improve our understanding of body size trends and climate change response in mammals over short timescales. 09:00 - 09:15 338 Functional anatomy and 3-D morphometric analysis of the occiput in the giraffe-necked gazelle (Litocranius walleri) Ariana N Klappert1, Eva V Bärmann2 1Zoological Research Museum Alexander Koenig, University of Bonn, Bonn, North-Rhine-Westphalia, Germany. 2Zoological Research Museum Alexander Koenig, University of Bonn, Bonn, North Rhine-Westphalia, Germany Abstract Body The gerenuk (Litocranius walleri, (Brooke 1879) is a medium-sized antelope closely related to springbok and gazelles. Distinguishing traits of the gerenuk are its very long neck and legs and its unique feeding behavior of standing in an upright position. The strict browser is able to support the vertical posture merely by standing on its hind legs. This ability and the gerenuks elongated neck allow it to reach foliage of up to two meters. The upright posture is not an ability the gerenuk is born with. Leuthold and Leuthold (1973) observed a captive young gerenuk, two weeks of age, attempting to perform this feeding posture. At one month, the youngling was able to successfully stand on its hind legs and at three months the position was mastered and frequently used when feeding. This behavior most likely leads to a change in muscle forces acting on the occiput, which could be responsible for the stark postnatal changes of the skull. The neonate skull resembles that of related gazelles, whilst the adult skull is comparatively flat and possesses an extremely elongated braincase. The relative length of the skull bones does not change during growth; however, the curvature of the skull and thus its overall shape does change. We quantify these developmental changes by analyzing 14 skulls of three different age classes with 3D-Landmark analysis. 09:15 - 09:30 339 Using geometric morphometrics to test resource partitioning in sympatric species in forest remnants. Damian C Gonzalez1,2, Gabriel Hernandez3, Aide Balcazar4, Noe U de la Sancha3,5 1Chicago State University, Chicago, IL, USA. 2The Field Museum of Natural History, Chicago , IL , USA. 3Chicago State University, Chicago , IL, USA. 4Chicago State University , Chicago , IL, USA. 5The Field Museum of Natural History, Chicago , IL, USA Abstract Body Resource partitioning results to reduce the stress of competition between sympatric species. General morphological patterns in skull are well documented in rodents based on diet. Akodon montensis, Akodon paranaensis, and Oligoryzomys nigripes can all be found in high abundances in the eastern Atlantic Forest