title: Using ecology to inform physiology studies: implications of high population density in the laboratory.
abstract: Conspecific density is widely recognized as an important ecological factor across the animal kingdom; however, the physiological impacts are less thoroughly described. In fact, population density is rarely mentioned as a factor in physiological studies on captive animals and, when it is infrequently addressed, the animals used are reared and housed at densities far above those in nature, making the translation of results from the laboratory to natural systems difficult. We survey the literature to highlight this important ecophysiological gap and bring attention to the possibility that conspecific density prior to experimentation may be a critical factor influencing results. Across three taxa: mammals, birds, and fish, we present evidence from ecology that density influences glucocorticoid levels, immune function, and body condition with the intention of stimulating discussion and increasing consideration of population density in physiology studies. We conclude with several directives to improve the applicability of insights gained in the laboratory to organisms in the natural environment.
authors.affiliation: Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada newman01@uoguelph.ca.
authors.forename: Amy E M
authors.initials: AE
authors.lastname: Newman
authors.affiliation: Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada.
authors.forename: Nicholas B
authors.initials: NB
authors.lastname: Edmunds
authors.affiliation: Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada.
authors.forename: Shannon
authors.initials: S
authors.lastname: Ferraro
authors.affiliation: Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada.
authors.forename: Quentin
authors.initials: Q
authors.lastname: Heffell
authors.affiliation: Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada.
authors.forename: Gillian M
authors.initials: GM
authors.lastname: Merritt
authors.affiliation: Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada.
authors.forename: Jesse J
authors.initials: JJ
authors.lastname: Pakkala
authors.affiliation: Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada.
authors.forename: Cory R
authors.initials: CR
authors.lastname: Schilling
authors.affiliation: Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada.
authors.forename: Sarah
authors.initials: S
authors.lastname: Schorno
mesh_terms: D000818:Animals; D000830:Animals, Laboratory / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D035843:Biomedical Research / Q000379:methods*; D001717:Birds / Q000502:physiology; D001823:Body Composition; D004463:Ecology; D005938:Glucocorticoids / Q000378:metabolism; D006799:Housing, Animal; D051379:Mice; D017686:Oncorhynchus mykiss / Q000502:physiology; D010827:Physiology; D011156:Population Density; D013312:Stress, Physiological; D013315:Stress, Psychological
chemical_list: D005938:Glucocorticoids
keywords: body condition; ecophysiology; glucocorticoids; immune function; stress