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Babic NL, Johnstone CP, Reljić S, Sergiel A, Huber Đ, Reina RD. Evaluation of physiological stress in free-ranging bears: current knowledge and future directions. Biol Rev Camb Philos Soc 2023; 98:168-190. [PMID: 36176191 PMCID: PMC10086944 DOI: 10.1111/brv.12902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 08/25/2022] [Accepted: 08/31/2022] [Indexed: 01/12/2023]
Abstract
Stress responses, which are mediated by the neurogenic system (NS) and hypothalamic-pituitary-adrenal (HPA) axis help vertebrates maintain physiological homeostasis. Fight-or-flight responses are activated by the NS, which releases norepinephrine/noradrenaline and epinephrine/adrenaline in response to immediate stressors, whilst the HPA axis releases glucocorticoid hormones (e.g. cortisol and corticosterone) to help mitigate allostatic load. There have been many studies on stress responses of captive animals, but they are not truly reflective of typical ranges or the types of stressors encountered by free-ranging wildlife, such as responses and adaptation to environmental change, which are particularly important from a conservation perspective. As stress can influence the composition of age and sex classes of free-ranging populations both directly and indirectly, ecological research must be prioritised towards more vulnerable taxa. Generally, large predators tend to be particularly at risk of anthropogenically driven population declines because they exhibit reduced behavioural plasticity required to adapt to changing landscapes and exist in reduced geographic ranges, have small population sizes, low fecundity rates, large spatial requirements and occupy high trophic positions. As a keystone species with a long history of coexistence with humans in highly anthropogenic landscapes, there has been growing concern about how humans influence bear behaviour and physiology, via numerous short- and long-term stressors. In this review, we synthesise research on the stress response in free-ranging bear populations and evaluate the effectiveness and limitations of current methodology in measuring stress in bears to identify the most effective metrics for future research. Particularly, we integrate research that utilised haematological variables, cardiac monitors and Global Positioning System (GPS) collars, serum/plasma and faecal glucocorticoid concentrations, hair cortisol levels, and morphological metrics (primarily skulls) to investigate the stress response in ursids in both short- and long-term contexts. We found that in free-ranging bears, food availability and consumption have the greatest influence on individual stress, with mixed responses to anthropogenic influences. Effects of sex and age on stress are also mixed, likely attributable to inconsistent methods. We recommend that methodology across all stress indicators used in free-ranging bears should be standardised to improve interpretation of results and that a wider range of species should be incorporated in future studies.
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Affiliation(s)
- Natarsha L Babic
- School of Biological Sciences, Monash University, 25 Rainforest Walk, Clayton, 3800, Victoria, Australia
| | - Christopher P Johnstone
- School of Biological Sciences, Monash University, 25 Rainforest Walk, Clayton, 3800, Victoria, Australia
| | - Slaven Reljić
- Faculty of Veterinary Medicine, University of Zagreb, Heinzelova 55, Zagreb, 10000, Croatia
| | - Agnieszka Sergiel
- Institute of Nature Conservation, Polish Academy of Sciences, Adama Mickiewicza 33, Krakow, 31120, Poland
| | - Đuro Huber
- Faculty of Veterinary Medicine, University of Zagreb, Heinzelova 55, Zagreb, 10000, Croatia.,Institute of Nature Conservation, Polish Academy of Sciences, Adama Mickiewicza 33, Krakow, 31120, Poland
| | - Richard D Reina
- School of Biological Sciences, Monash University, 25 Rainforest Walk, Clayton, 3800, Victoria, Australia
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Itoh Y, Sato Y. Genetic dissection of an alien chromosomal segment may enable the production of a rice (Oryza sativa L.) genotype showing shoot developmental instability. Dev Genes Evol 2015; 225:63-78. [PMID: 25677854 DOI: 10.1007/s00427-015-0490-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 01/13/2015] [Indexed: 10/24/2022]
Abstract
During the course of evolutionary history, organisms have acquired genes which cooperate harmoniously and subsequently express a stable pattern of development. In an earlier study we introduced a large chromosomal segment of chromosome 6 from a rice (Oryza sativa L.) ecotype, carrying the two flowering-time genes, which showed complex epistatic interactions in relation to environmental change, into a different ecotype by successive backcrossings. Four-near-isogenic lines (NILs) with respect to these two loci were obtained by subsequent hybridization with the recurrent parent. In the study reported here, these four NILs were the major plant material used to evaluate changes in days to leaf appearance (DLA) during shoot development using a quadratic-polynomial regression. The regressions were regarded as developmental norms because of the high values of R (2). Absolute Y-residuals (AYRs) (or size of deviation) of DLA from the norms were significantly affected by genotype. Dissections of the alien chromosomal segment resulted in one NIL that showed an increased level of AYR. Since this NIL also expressed a low survival rate in a stress environment, we suggest that the increased level of AYR during development might indicate an increased level of instability in shoot development.
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Affiliation(s)
- Youki Itoh
- Laboratory of Wildlife Ecology, Department of Environmental Symbiotic Science, College of Agriculture, Food and Environmental Sciences, Rakunogakuen University, Ebetsu, 069-8501, Hokkaido, Japan,
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McKenzie JA, Yen JL. Genotype, environment and the asymmetry phenotype. Dieldrin-resistance in Lucilia cuprina (the Australian sheep blowfly). Heredity (Edinb) 1995; 75 ( Pt 2):181-7. [PMID: 7558887 DOI: 10.1038/hdy.1995.122] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Dieldrin-resistant (Rdl/Rdl and Rdl/+) and susceptible (+/+) phenotypes of Lucilia cuprina were scored for departures from bilateral symmetry for bristle characters after development at different temperatures, larval densities or concentrations of dieldrin. The asymmetry phenotype of resistant flies was dominant and independent of developmental temperature and larval density. The asymmetry of susceptibles increased for temperatures and larval densities above and below standard rearing conditions. A positive correlation was observed between asymmetry score and dieldrin concentration for all genotypes. The susceptible phenotype did not attain the asymmetry score of resistant in any environment. Resistant phenotypes showed an antisymmetric pattern in each environment; fluctuating asymmetry was observed for susceptibles. The relevance of the results of genetic and general or specific environmental stresses to estimates of developmental perturbation is discussed.
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Affiliation(s)
- J A McKenzie
- Department of Genetics, University of Melbourne, Parkville, Victoria, Australia
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Freeman DC, Graham JH, Emlen JM. Developmental stability in plants: Symmetries, stress and epigenesis. Genetica 1993. [DOI: 10.1007/bf02424508] [Citation(s) in RCA: 111] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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