Groza, Ruth

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ESSAIVolume 11 Article 18Spring 2013Testing for Relationships between Size Variables ofSelect OrganismsRuth GrozaCollege of DuPageFollow this and additional works at: http://dc.cod.edu/essaiThis Selection is brought to you for free and open access by the College Publications at DigitalCommons@COD. It has been accepted for inclusion inESSAI by an authorized administrator of DigitalCommons@COD. For more information, please contact koteles@cod.edu.Recommended CitationGroza, Ruth (2013) "Testing for Relationships between Size Variables of Select Organisms," ESSAI: Vol. 11, Article 18.Available at: http://dc.cod.edu/essai/vol11/iss1/1848 Testing for Relationships between Size Variables of Select Organisms by Ruth Groza (Honors Biology 1151) ABSTRACT his study used mathematical scaling to determine if universal allometric relationships existamong organisms. Size variables in various species of hardwood trees, an individual Bur Oaktree (Quercus macrocarpa), North American pine trees, diurnal North American raptors, and the domestic dog (Canis familiaris) were investigated for allometric significance. Statistically significant findings indicated the presence of universal scaling principles. Biomechanical constraints may serve to regulate those universal principles. INTRODUCTION Knowledge of the relationships between size variables in organisms is significant to biologists for it can provide a greater understanding of underlying laws governing the diversification of life (Agrawal 2004). An organism‘s size is a primary factor in determining how its biological structures and processes covary with each other (Price et al. 2007). Scaling relationships are of particular relevance within an evolutionary framework, as they may aid in the prediction of evolutionary trends and in determining how selection influences specific traits (Agrawal 2004, Price et al. 2007). Unless they scale isometrically, an allometric relationship will occur between an organism‘s morphological and physiological traits (Marroig 2007). Thus, revealing mechanisms that influence allometric variation is integral to the study of biological scaling (Shingleton 2010). In order to identify underlying mechanisms of allometric scaling, relationships between size variables in relevant organisms must first be established. Mathematical scaling may be utilized in determining if an allometric relationship exists between a given trait and an organism‘s mass or height (Price et al. 2007). In this study the relationship between size variables of varying species of hardwood tree, an individual Bur Oak, North American pine trees, diurnal North American raptors, and the domestic dog are examined for allometric significance. The objective is to investigate the universal nature of allometric relationships among life forms. METHODS Stem basal diameter and weight were measured for comparison in selected species of hardwood trees and in an individual Bur Oak. All trees were located on the College of DuPage campus in Illinois. Stems from fourteen species of hardwood trees were oven dried at 70° C and measured for basal diameter and weight. Fourteen stems of varying sizes from a single Bur Oak tree were measured similarly. Morphological data comparing the maximum heights and basal diameters of North American trees in the genus Pinus were obtained from Little (1980).  Morphological data comparing the wingspans and weights of diurnal North American raptors were obtained from Sibley (2000). Shoulder height and weight were measured from a random sample of fourteen domestic dogs. Only adult dogs were selected for comparison. Linear regression was used to test for significant relationships between the pairs of morphological characteristics selected for analysis. T 1Groza: Testing for Relationships between Size VariablesPublished by DigitalCommons@COD, 201349 RESULTS AND DISCUSSION In the combined comparisons of selected morphological characteristics all regression coefficients were significant (p<0.05) (Table 1). Thus, there is evidence that biological scaling is occurring in diverse species of animals and plants. Although further study is needed, this finding is important because it indicates that universal underlying allometric scaling principals are governing life forms. Several constraining factors play a fundamental role in regulating these allometric relationships. Maintenance of biomechanical integrity is one such factor. If an organism is to survive, increases in body mass must correspond to viable changes in underlying skeletal structure (Sorkin 2008). The allometric scaling of trees is limited by the hydrodynamic demands of their vascular systems and by factors associated with maintenance of vertical growth (Enquist 2003). In the case of raptors, skeletal structure, wingspan and body mass must scale in a way that does not inhibit flight (Sato et al. 2009). Canine weight and limb length must scale in a way that does not inhibit locomotion or produce undue stress upon limb bones (Doube et al. 2009). Thus, animal and plant morphology is functionally dependent upon allometric scaling principles. Further study could determine how scaling principles influence the evolution of morphological characteristics.      LITERATURE CITED  Agrawal, A.A. 2004. The metabolic theory of ecology. Ecology 85: 1790-1791. Coomes, D.A. and R. B. Allen. 2009. Testing the metabolic scaling theory of tree growth. Journal of Ecology 97:1369-1373. Doube, M., C.A.Wiktorowicz, P. Christiansen, J.R. Hutchinson, and S. Shefelbine. 2009. Three-dimensional geometric analysis of felid limb bone allometry. PLoS ONE 4:4742-4752. Enquist, B.J. 2003. Cope‘s Rule and the evolution of long-distance transport in vascular plants: allometric scaling, biomass partitioning, and optimization. Plant, Cell and Environment 26: 151-161. Little, E. L. 1980. The Audubon Society Field Guide to North American Trees. Alfred A. Knopf Inc, New York, NY, USA. Marroig, G. 2007. When size makes a difference: allometry, life-history and morphological evolution of caphuchins (Cebus) and squirrels (Saimiri) monkeys (Cebinae, Platyrrhini). Evolutionary Biology 7:20-46. Price, C. A., B.J. Enquist, and V.M. Savage. 2007. A general model in botanical form for allometric covariation and function. Proceedings of the National Academy of Sciences of the United States of America 104: 13204-13209. Sato, K., K.Q. Sakamoto, Y. Watanuki, A. Takahashi, N. Katsumata, C. Bost, and H. Weimerskirch. 2009. Scaling of soaring seabirds and implications for flight abilities of giant pterosaurs. PLoS ONE 4:5400-5406. Shingleton, A. 2010. Allometry: The study of biological scaling. Nature Education Knowledge 3:2. Sibley, D. A. 2000. The Sibley Guide to Birds. Chantileer Press, Inc, New York, NY, USA. Sorkin, B. 2008. A biomechanical constraint on body mass in terrestrial mammalian predators. Lethaia 41:333-347. Stegen, J.C., B.J. Enquist, and Regis Ferriere. 2009. Advancing the metabolic theory of biodiversity. Ecology Letters 12:1001-1015.  2ESSAI, Vol. 11 [2013], Art. 18http://dc.cod.edu/essai/vol11/iss1/1850  Table 1.  Regression equations, coefficients of regression statistics, and significance between selected morphological parameters among plants and animals.  ______________________________________________________________________________________________________ Description of organism(s) Regression equation Regression Significance  coefficient ______________________________________________________________________________________________________  Bur oak  Stem weight (g) = -0.8676 + 0.8188(Basal diameter(mm)) 0.52 P < 0.05  Varying species of hardwood trees  Stem weight (g) = -0.9144 + 0.8376(Basal diameter(mm)) 0.55 P < 0.05  Pine trees  Height (m) = 11.725 + 16.626(Basal diameter(m) 0.41 P < 0.05  Domestic dog  Shoulder height (cm) = 19.956 + 1.212(Weight (kg)) 0.86 P < 0.05  Diurnal North American raptors  Wingspan (cm) = 92.731 + 0.0208(Weight(g)) 0.79 P < 0.05  _____________________________________________________________________________________________________    3Groza: Testing for Relationships between Size VariablesPublished by DigitalCommons@COD, 2013

Testing for Relationships between Size Variables of Select Organisms

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Testing for Relationships between Size Variables of Select Organisms

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