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Ebensperger LA, Tapia D, Ramírez-Estrada J, León C, Soto-Gamboa M, Hayes LD. Fecal cortisol levels predict breeding but not survival of females in the short-lived rodent, Octodon degus. Gen Comp Endocrinol 2013; 186:164-71. [PMID: 23524002 DOI: 10.1016/j.ygcen.2013.02.044] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 02/20/2013] [Accepted: 02/23/2013] [Indexed: 12/01/2022]
Abstract
The cort-adaptation hypothesis indicates that an association between glucocorticoid (cort) levels and fitness may vary with the extent to which reproduction or breeding effort is a major determinant of cort levels. Support for a context dependent association between cort and fitness comes mostly from relatively long-lived, bird species. We tested the hypothesis that there are gender and context (life-history) specific cort-fitness relationships in degus, a short-lived and generally semelparous social rodent. In particular, we used demographical records on a natural population to estimate adult survival through seasons and years and linked that to records of baseline cort (based on fecal cortisol metabolites). We found no evidence for a direct relationship between baseline cort and adult survival across seasons, and this lack of association was recorded irrespective of sex and life history stage. Yet, cort levels during early lactation predicted the probability that females produce a second litter during the same breeding season, supporting a connection between baseline cort levels and breeding effort. Overall, the differential effects of cort on survival and breeding supported that the extent of cort-fitness relationships depends on the fitness component examined.
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Affiliation(s)
- Luis A Ebensperger
- Centro de Estudios Avanzados en Ecología and Biodiversidad (CASEB), and Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile.
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Quirici V, Palma M, Sobrero R, Faugeron S, Ebensperger LA. Relatedness does not predict vigilance in a population of the social rodent Octodon degus. Acta Ethol 2012. [DOI: 10.1007/s10211-012-0131-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Burger JR, Chesh AS, Muñoz P, Fredes F, Ebensperger LA, Hayes LD. Sociality, exotic ectoparasites, and fitness in the plural breeding rodent Octodon degus. Behav Ecol Sociobiol 2012; 66:57-66. [PMID: 22328801 PMCID: PMC3277428 DOI: 10.1007/s00265-011-1252-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Social animals are susceptible to high infection levels by contact-transmitted parasites due to increased conspecific interaction. Exotic parasites are known to have adverse consequences on native hosts. We examined the relationship between social group size and exotic ectoparasite loads, and adult infection levels with per capita fitness and offspring survival in the plural breeding rodent Octodon degus in central Chile. Degus at our site were almost entirely infected by two exotic ectoparasites: the fleas Leptopsylla segnis and Xenopsylla cheopis. Neither group size nor number of females per group predicted the abundance of either exotic flea species. The per capita number of pups (per capita fitness) that emerged from burrow systems used by known social groups was negatively correlated with abundance of L. segnis but not X. cheopis. On adults, X. cheopis abundance was three times greater than L. segnis but was not significantly correlated with per capita fitness. In females, L. segnis abundance was negatively correlated with peak body mass during pregnancy. Adult ectoparasite load was not correlated with offspring survival. Based on these results, we hypothesize that high infection levels of L. segnis result in decreased reproductive fitness of adult female degus but are not a cost of sociality because parasite loads are not predicted by social group size. Further work is needed to experimentally test this hypothesis and to determine if L. segnis serves as a vector for a deleterious pathogen. Lastly, the lack of native ectoparasites may explain why a previous study at our site determined that behavioral adaptations needed to cope with high ectoparasite burdens (e.g., grooming) are not extensive in degus; they simply have not had the coevolutionary time needed for selection of these behaviors.
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Affiliation(s)
- Joseph R. Burger
- Department of Biology, University of Louisiana at Monroe, Monroe, LA 71209, USA
- Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Adrian S. Chesh
- Department of Biology, University of Louisiana at Monroe, Monroe, LA 71209, USA
| | - Pamela Muñoz
- Laboratorio de Parasitología Veterinaria, Facultad de Ciencias Veterinarias, Universidad Austral, Valdivia, Chile
| | - Fernando Fredes
- Departamento de Parasitología, Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Santiago, Chile
| | - Luis A. Ebensperger
- Centro de Estudios Avanzados en Ecología y Biodiversidad, Departmento de Ecología, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Loren D. Hayes
- Department of Biology, University of Louisiana at Monroe, Monroe, LA 71209, USA
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Ecological drivers of group living in two populations of the communally rearing rodent, Octodon degus. Behav Ecol Sociobiol 2011; 66:261-274. [PMID: 22344477 DOI: 10.1007/s00265-011-1274-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Intraspecific variation in sociality is thought to reflect a trade-off between current fitness benefits and costs that emerge from individuals' decision to join or leave groups. Since those benefits and costs may be influenced by ecological conditions, ecological variation remains a major, ultimate cause of intraspecific variation in sociality. Intraspecific comparisons of mammalian sociality across populations facing different environmental conditions have not provided a consistent relationship between ecological variation and group-living. Thus, we studied two populations of the communally rearing rodent Octodon degus to determine how co-variation between sociality and ecology supports alternative ecological causes of group living. In particular, we examined how variables linked to predation risk, thermal conditions, burrowing costs, and food availability predicted temporal and population variation in sociality. Our study revealed population and temporal variation in total group size and group composition that covaried with population and yearly differences in ecology. In particular, predation risk and burrowing costs are supported as drivers of this social variation in degus. Thermal differences, food quantity and quality were not significant predictors of social group size. In contrast to between populations, social variation within populations was largely uncoupled from ecological differences.
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Ebensperger LA, Ramírez-Estrada J, León C, Castro RA, Tolhuysen LO, Sobrero R, Quirici V, Burger JR, Soto-Gamboa M, Hayes LD. Sociality, glucocorticoids and direct fitness in the communally rearing rodent, Octodon degus. Horm Behav 2011; 60:346-52. [PMID: 21777588 DOI: 10.1016/j.yhbeh.2011.07.002] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Revised: 06/21/2011] [Accepted: 07/01/2011] [Indexed: 11/16/2022]
Abstract
While ecological causes of sociality (or group living) have been identified, proximate mechanisms remain less clear. Recently, close connections between sociality, glucocorticoid hormones (cort) and fitness have been hypothesized. In particular, cort levels would reflect a balance between fitness benefits and costs of group living, and therefore baseline cort levels would vary with sociality in a way opposite to the covariation between sociality and fitness. However, since reproductive effort may become a major determinant of stress responses (i.e., the cort-adaptation hypothesis), cort levels might also be expected to vary with sociality in a way similar to the covariation between sociality and fitness. We tested these expectations during three years in a natural population of the communally rearing degu, Octodon degus. During each year we quantified group membership, measured fecal cortisol metabolites (a proxy of baseline cort levels under natural conditions), and estimated direct fitness. We recorded that direct fitness decreases with group size in these animals. Secondly, neither group size nor the number of females (two proxies of sociality) influenced mean (or coefficient of variation, CV) baseline cortisol levels of adult females. In contrast, cortisol increased with per capita number of offspring produced and offspring surviving to breeding age during two out of three years examined. Together, our results imply that variation in glucocorticoid hormones is more linked to reproductive challenge than to the costs of group living. Most generally, our study provided independent support to the cort-adaptation hypothesis, according to which reproductive effort is a major determinant, yet temporally variable, influence on cort-fitness covariation.
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Affiliation(s)
- Luis A Ebensperger
- Centro de Estudios Avanzados en Ecología and Biodiversidad (CASEB), and Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile.
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Colonnello V, Iacobucci P, Fuchs T, Newberry RC, Panksepp J. Octodon degus. A useful animal model for social-affective neuroscience research: basic description of separation distress, social attachments and play. Neurosci Biobehav Rev 2011; 35:1854-63. [PMID: 21477615 DOI: 10.1016/j.neubiorev.2011.03.014] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Revised: 03/16/2011] [Accepted: 03/25/2011] [Indexed: 11/30/2022]
Abstract
A challenge for social-affective neuroscience programs is to identify simple and yet valid animal models for studying the expression of basic social emotions and their role during different developmental windows, from infancy to adulthood. For example, although laboratory rats are useful for studying juvenile social interactions, they are not ideal for studying infant attachment bonds. Here, we evaluate current understanding of the social behavior of Octodon degus, a diurnal precocial rodent, to elucidate the value of this species as a model for social-affective neuroscience research. After a synopsis of species-specific characteristics and brain susceptibility to changes of social environment, our behavioral findings on degu social proclivities are summarized. We then discuss why this pre-clinical model provides a valuable addition to the commonly available animal models for the study of human psychopathology.
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Affiliation(s)
- Valentina Colonnello
- Center for the Study of Animal Well-being, Department of Veterinary & Comparative Anatomy, Pharmacology and Physiology, Washington State University, Pullman, WA 99164-6520, USA.
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Colonnello V, Iacobucci P, Panksepp J. Analysis of the disruption of maternal social bonds in Octodon degus: Separation distress in restricted reunion tests. Dev Psychobiol 2011; 53:657-69. [DOI: 10.1002/dev.20539] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Accepted: 01/31/2011] [Indexed: 12/24/2022]
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Jekl V, Hauptman K, Knotek Z. Diseases in pet degus: a retrospective study in 300 animals. J Small Anim Pract 2011; 52:107-12. [DOI: 10.1111/j.1748-5827.2010.01028.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Ebensperger LA, Chesh AS, Castro RA, Tolhuysen LO, Quirici V, Burger JR, Sobrero R, Hayes LD. Burrow limitations and group living in the communally rearing rodent, Octodon degus. J Mammal 2011; 92:21-30. [PMID: 22328789 PMCID: PMC3277429 DOI: 10.1644/09-mamm-s-383.1] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Group living is thought to evolve whenever individuals attain a net fitness advantage due to reduced predation risk or enhanced foraging efficiency, but also when individuals are forced to remain in groups, which often occurs during high-density conditions due to limitations of critical resources for independent breeding. The influence of ecological limitations on sociality has been studied little in species in which reproduction is more evenly shared among group members. Previous studies in the caviomorph rodent Octodon degus (a New World hystricognath) revealed no evidence that group living confers an advantage and suggest that burrow limitations influence formation of social groups. Our objective was to examine the relevance of ecological limitations on sociality in these rodents. Our 4-year study revealed no association between degu density and use of burrow systems. The frequency with which burrow systems were used by degus was not related to the quality of these structures; only in 1 of the 4 years did the frequency of burrow use decrease with decreasing abundance of food. Neither the number of females per group nor total group size (related measures of degu sociality) changed with yearly density of degus. Although the number of males within social groups was lower in 2008, this variation was not related clearly to varying density. The percentage of females in social groups that bred was close to 99% and did not change across years of varying density. Our results suggest that sociality in degus is not the consequence of burrow limitations during breeding. Whether habitat limitations contribute to variation in vertebrate social systems is discussed.
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Affiliation(s)
- Luis A. Ebensperger
- Centro de Estudios Avanzados en Ecología y Biodiversidad, and Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, 6513677, Santiago, Chile (LAE, RAC, LOT, VQ, RS). Department of Biology, University of Louisiana at Monroe, Monroe, LA 71209, USA (ASC, JRB, LDH)
| | - Adrian S. Chesh
- Centro de Estudios Avanzados en Ecología y Biodiversidad, and Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, 6513677, Santiago, Chile (LAE, RAC, LOT, VQ, RS). Department of Biology, University of Louisiana at Monroe, Monroe, LA 71209, USA (ASC, JRB, LDH)
| | - Rodrigo A. Castro
- Centro de Estudios Avanzados en Ecología y Biodiversidad, and Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, 6513677, Santiago, Chile (LAE, RAC, LOT, VQ, RS). Department of Biology, University of Louisiana at Monroe, Monroe, LA 71209, USA (ASC, JRB, LDH)
| | - Liliana Ortiz Tolhuysen
- Centro de Estudios Avanzados en Ecología y Biodiversidad, and Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, 6513677, Santiago, Chile (LAE, RAC, LOT, VQ, RS). Department of Biology, University of Louisiana at Monroe, Monroe, LA 71209, USA (ASC, JRB, LDH)
| | - Verónica Quirici
- Centro de Estudios Avanzados en Ecología y Biodiversidad, and Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, 6513677, Santiago, Chile (LAE, RAC, LOT, VQ, RS). Department of Biology, University of Louisiana at Monroe, Monroe, LA 71209, USA (ASC, JRB, LDH)
| | - Joseph Robert Burger
- Centro de Estudios Avanzados en Ecología y Biodiversidad, and Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, 6513677, Santiago, Chile (LAE, RAC, LOT, VQ, RS). Department of Biology, University of Louisiana at Monroe, Monroe, LA 71209, USA (ASC, JRB, LDH)
| | - Raúl Sobrero
- Centro de Estudios Avanzados en Ecología y Biodiversidad, and Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, 6513677, Santiago, Chile (LAE, RAC, LOT, VQ, RS). Department of Biology, University of Louisiana at Monroe, Monroe, LA 71209, USA (ASC, JRB, LDH)
| | - Loren D. Hayes
- Centro de Estudios Avanzados en Ecología y Biodiversidad, and Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, 6513677, Santiago, Chile (LAE, RAC, LOT, VQ, RS). Department of Biology, University of Louisiana at Monroe, Monroe, LA 71209, USA (ASC, JRB, LDH)
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Hayes LD, Burger JR, Soto-Gamboa M, Sobrero R, Ebensperger LA. Towards an integrative model of sociality in caviomorph rodents. J Mammal 2011; 92:65-77. [PMID: 22328791 PMCID: PMC3277430 DOI: 10.1644/10-mamm-s-039.1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
In the late 1990s and early 2000s it was recognized that behavioral ecologists needed to study the sociality of caviomorph rodents (New World hystricognaths) before generalizations about rodent sociality could be made. Researchers identified specific problems facing individuals interested in caviomorph sociality, including a lack of information on the proximate mechanisms of sociality, role of social environment in development, and geographical or intraspecific variation in social systems. Since then researchers have described the social systems of many previously understudied species, including some with broad geographical ranges. Researchers have done a good job of determining the role of social environments in development and identifying the costs and benefits of social living. However, relatively little is known about the proximate mechanisms of social behavior and fitness consequences, limiting progress toward the development of integrative (evolutionary-mechanistic) models for sociality. To develop integrative models behavioral ecologists studying caviomorph rodents must generate information on the fitness consequences of different types of social organization, brain mechanisms, and endocrine substrates of sociality. We review our current understanding and future directions for research in these conceptual areas. A greater understanding of disease ecology, particularly in species carrying Old World parasites, is needed before we can identify potential links between social phenotypes, mechanism, and fitness.
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Affiliation(s)
- Loren D. Hayes
- Department of Biology, 700 University Avenue, University of Louisiana at Monroe, Monroe, LA 72109, USA
| | - Joseph Robert Burger
- Department of Biology, 700 University Avenue, University of Louisiana at Monroe, Monroe, LA 72109, USA
- Department of Biology, MSC03 2020/1, University of New Mexico, Albuquerque, NM 87131, USA
| | - Mauricio Soto-Gamboa
- Instituto de Ecología y Evolución, Facultad de Ciencias, Universidad Austral de Chile, Isla teja S/N, Casilla 567, Chile
| | - Raúl Sobrero
- Centro de Estudios Avanzados en Ecología y Biodiversidad and Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O’Higgins 340, Santiago, Chile
| | - Luis A Ebensperger
- Centro de Estudios Avanzados en Ecología y Biodiversidad and Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O’Higgins 340, Santiago, Chile
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Colonnello V, Iacobucci P, Anderson MP, Panksepp J. Brief periods of positive peer interactions mitigate the effects of total social isolation in young Octodon degus. Dev Psychobiol 2010; 53:280-90. [DOI: 10.1002/dev.20520] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2010] [Accepted: 10/18/2010] [Indexed: 11/11/2022]
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62
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Quirici V, Faugeron S, Hayes LD, Ebensperger LA. Absence of kin structure in a population of the group-living rodent Octodon degus. Behav Ecol 2010. [DOI: 10.1093/beheco/arq196] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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63
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Early fitness consequences and hormonal correlates of parental behaviour in the social rodent, Octodon degus. Physiol Behav 2010; 101:509-17. [DOI: 10.1016/j.physbeh.2010.07.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Revised: 07/10/2010] [Accepted: 07/27/2010] [Indexed: 11/18/2022]
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64
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Quirici V, Faugeron S, Hayes LD, Ebensperger LA. The influence of group size on natal dispersal in the communally rearing and semifossorial rodent, Octodon degus. Behav Ecol Sociobiol 2010. [DOI: 10.1007/s00265-010-1082-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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65
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Quirici V, Castro RA, Ortiz-Tolhuysen L, Chesh AS, Burger JR, Miranda E, Cortés A, Hayes LD, Ebensperger LA. Seasonal variation in the range areas of the diurnal rodent Octodon degus. J Mammal 2010; 91:458-466. [PMID: 22328788 DOI: 10.1644/08-mamm-a-337.1] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Both breeding activity and abundance and quality of available food are expected to influence daily movements of animals. Animals are predicted to range over large areas to meet high energy demands associated with reproduction (females) or to increase mating success (males). However, animals should expand their range areas whenever food conditions deteriorate. To examine the extent to which breeding activity versus food availability influence space use, we compared the size and location of range areas (home ranges) of the degu (Octodon degus), a diurnal rodent from semiarid environments of north-central Chile, during the austral winter and summer seasons. Degus produce young during the austral spring (September-October) when high-quality food is readily available. In contrast, degus do not breed during the austral summer (January-March) when food is scarce and of low quality. We predicted that degus would range over smaller areas in winter if the availability of food has a greater influence on space than breeding activity. Individuals were radiotracked in winter and the following summer over a 3-year period. Surveys of herbaceous cover were conducted during winter and summer to determine seasonal changes in the abundance and quality of primary food. In summer degus expanded and moved the location of their range areas to locations with available food. Given that preferred food was less abundant in summer than winter, we suggest that degu range areas are strongly influenced by food conditions.
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Affiliation(s)
- Verónica Quirici
- Centro de Estudios Avanzados en Ecología and Biodiversidad, and Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, 6513677, Santiago, Chile (VQ, RAC, LO-T, LAE) Department of Biology, University of Louisiana at Monroe, Louisiana 71209, USA (ASC, JRB, LDH) Departamento de Biología, Universidad de La Serena, La Serena, Chile (EM, AC)
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Wilson LAB, Schradin C, Mitgutsch C, Galliari FC, Mess A, Sánchez-Villagra MR. Skeletogenesis and sequence heterochrony in rodent evolution, with particular emphasis on the African striped mouse, Rhabdomys pumilio (Mammalia). ORG DIVERS EVOL 2010. [DOI: 10.1007/s13127-010-0020-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Previtali MA, Meserve PL, Kelt DA, Milstead WB, Gutierrez JR. Effects of more frequent and prolonged El Niño events on life-history parameters of the degu, a long-lived and slow-reproducing rodent. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2010; 24:18-28. [PMID: 20121838 DOI: 10.1111/j.1523-1739.2009.01407.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Global climate change (GCC) can have profound effects on species whose ecology is governed primarily by climatic factors. The ecology of small mammals inhabiting semiarid Chile is strongly affected by the El Niño Southern Oscillation (ENSO). During La Niña events in this area, dry conditions prevail and species may disappear from the thorn-scrub habitat. Conversely, El Niño events bring high rainfall, and associated pulses of food trigger small-mammal population increases. We used capture-mark-recapture to study responses of the degu (Octodon degus), a dominant small mammal, to variation in rainfall over 18 years. In response to a recent trend toward wetter conditions, degus reached record-high densities and maintained more stable numbers in the area. Underlying mechanisms involved variation in adult survival, juvenile persistence, and fecundity linked to rainfall changes during consecutive years (i.e., rainfall phases). During prolonged droughts, degus had low survival and produced fewer offspring, with low persistence. Following high rainfall, these parameters reversed; consecutive wet years resulted in further increases. Weak declines in fecundity and adult survival and high persistence of juveniles explained delayed responses to deteriorating conditions in initial dry years. If GCC leads to increased frequency of El Niño events, we anticipate greater numerical dominance of degus in semiarid Chile and possible range expansion. Furthermore, degus have strong impacts on other small mammal and some plant species, are important prey species, and are agricultural pests and disease reservoirs. Hence, GCC has the potential to dramatically influence their ecology in northern Chile and to have cascading effects on other components of this system.
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Affiliation(s)
- M Andrea Previtali
- Department of Biological Sciences, Northern Illinois University, DeKalb, IL 60115, USA.
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DUNCAN SARAHI, RIECHERT SUSANE, FITZPATRICK BENJAMINM, FORDYCE JAMESA. Relatedness and genetic structure in a socially polymorphic population of the spiderAnelosimus studiosus. Mol Ecol 2010; 19:810-8. [DOI: 10.1111/j.1365-294x.2010.04523.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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69
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Jesseau SA, Holmes WG, Lee TM. Communal nesting and discriminative nursing by captive degus, Octodon degus. Anim Behav 2009. [DOI: 10.1016/j.anbehav.2009.07.037] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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70
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Lagos PA, Meier A, Tolhuysen LO, Castro RA, Bozinovic F, Ebensperger LA. Flight initiation distance is differentially sensitive to the costs of staying and leaving food patches in a small-mammal prey. CAN J ZOOL 2009. [DOI: 10.1139/z09-089] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Escape theory predicts that a prey should flee from an approaching predator at a point in which the cost of staying equals the cost of escape. We manipulated the cost of fleeing upon approaching human predators by providing the small mammal Octodon degus (Molina, 1782) with varying amounts of supplementary food likely to disappear while the animals are not in the food patch (e.g., hidden in their burrows). Simultaneously, we manipulated the risk of remaining in the patch by providing supplementary food at varying distances from the nearest burrow. Degus fled at a shorter distance to approaching predators when foraging in patches closer to the nearest burrow and supplied with relatively high abundance of food, but only when these rodents were foraging socially. Also, degus fled at a greater distance to approaching predators when foraging in patches far from the nearest burrow. Thus, functions linked to the loss of feeding opportunities and the risk of predation interact to influence flight initiation distance after a simulated attack. This study represented one of the few demonstrations of an interactive effect between cost and risks on antipredator behavior in a small, social prey mammal.
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Affiliation(s)
- Patricio A. Lagos
- Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile
| | - Andrea Meier
- Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile
| | | | - Rodrigo A. Castro
- Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile
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71
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Villavicencio CP, Márquez IN, Quispe R, Vásquez RA. Familiarity and phenotypic similarity influence kin discrimination in the social rodent Octodon degus. Anim Behav 2009. [DOI: 10.1016/j.anbehav.2009.04.026] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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72
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Soto-Gamboa M, Gonzalez S, Hayes LD, Ebensperger LA. Validation of a radioimmunoassay for measuring fecal cortisol metabolites in the hystricomorph rodent,Octodon degus. ACTA ACUST UNITED AC 2009; 311:496-503. [DOI: 10.1002/jez.546] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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73
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Hayes LD, Chesh AS, Castro RA, Tolhuysen LO, Burger JR, Bhattacharjee J, Ebensperger LA. Fitness consequences of group living in the degu Octodon degus, a plural breeder rodent with communal care. Anim Behav 2009. [DOI: 10.1016/j.anbehav.2009.03.022] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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74
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Ebensperger LA, Chesh AS, Castro RA, Tolhuysen LO, Quirici V, Burger JR, Hayes LD. Instability Rules Social Groups in the Communal Breeder RodentOctodon degus. Ethology 2009. [DOI: 10.1111/j.1439-0310.2009.01635.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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75
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Long CV, Ebensperger LA. Pup Growth Rates and Breeding Female Weight Changes in Two Populations of Captive Bred Degus (Octodon degus), a Precocial Caviomorph Rodent. Reprod Domest Anim 2009; 45:975-82. [DOI: 10.1111/j.1439-0531.2009.01470.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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76
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Quispe R, Villavicencio CP, Cortés A, Vásquez RA. Inter-Population Variation in Hoarding Behaviour in Degus,Octodon degus. Ethology 2009. [DOI: 10.1111/j.1439-0310.2009.01621.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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77
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Favreau A, Richard-Yris MA, Bertin A, Houdelier C, Lumineau S. Social influences on circadian behavioural rhythms in vertebrates. Anim Behav 2009. [DOI: 10.1016/j.anbehav.2009.01.004] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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78
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QUAN YF, MACMANES MD, EBENSPERGER LA, LACEY EA, HAYES LD. Isolation and characterization of polymorphic microsatellite loci fromOctodon degus. Mol Ecol Resour 2009; 9:999-1001. [DOI: 10.1111/j.1755-0998.2009.02536.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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79
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Túnez JI, Guichón ML, Centrón D, Henderson AP, Callahan C, Cassini MH. Relatedness and social organization of coypus in the Argentinean pampas. Mol Ecol 2009; 18:147-55. [PMID: 19140969 DOI: 10.1111/j.1365-294x.2008.04006.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Behavioural and trapping studies of the social organization of coypus have suggested the occurrence of kin groups and a polygynous mating system. We used 16 microsatellite markers to analyse parentage and relatedness relationships in two populations (Jáuregui and Villa Ruiz) in the Argentinean Pampas. At Jáuregui, a dominant male monopolized most paternities, leading to a high variance in reproductive success between males and a high level of polygyny. At Villa Ruiz, variance in reproductive success was low among resident males and males were the fathers of zero to four offspring each. For females, no significant differences were found. Two different social groups in each study site were used to assess genetic relatedness within and between groups. These groups were neighbouring at Jáuregui but not at Villa Ruiz. At Villa Ruiz, coypus were significantly more related within than between groups, suggesting that behavioural groups were also genetic ones, and adult females were more related within than between groups, as should be expected for kin groups. This relationship was not found at Jáuregui. Our results provide support to previous studies based on behavioural and trapping data, which indicate that coypus form social groups and have a polygynous mating system. However, we found differences in social organization between the two populations. This is the first study to determine parentage and/or relatedness in coypus.
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Affiliation(s)
- J I Túnez
- Grupo de Estudios en Ecología de Mamíferos (GEMA), DCB & CONICET, Universidad Nacional de Luján, Rutas 5 y 7 (6700), Luján, Provincia de Buenos Aires, Argentina
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80
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Comparing composition of social groups, mating system and social behaviour in two populations of Microcavia australis. Mamm Biol 2009. [DOI: 10.1016/j.mambio.2008.08.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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81
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Verdolin JL, Slobodchikoff CN. Resources, not Kinship, Determine Social Patterning in the Territorial Gunnison’s prairie Dog (Cynomys gunnisoni). Ethology 2009. [DOI: 10.1111/j.1439-0310.2008.01590.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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82
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Suárez R, Mpodozis J. Heterogeneities of size and sexual dimorphism between the subdomains of the lateral-innervated accessory olfactory bulb (AOB) of Octodon degus (Rodentia: Hystricognathi). Behav Brain Res 2008; 198:306-12. [PMID: 19046995 DOI: 10.1016/j.bbr.2008.11.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2008] [Accepted: 11/02/2008] [Indexed: 11/27/2022]
Abstract
The vomeronasal system (VNS) of rodents participates in the regulation of a variety of social and sexual behaviours related to semiochemical communication. All rodents studied so far possess two parallel pathways from the vomeronasal organ (VNO) to the accessory olfactory bulb (AOB). These segregated afferences express either Gi2 or Go protein alpha-subunits and innervate the rostral or caudal half of the AOB, respectively. In muroid rodents, such as rats and mice, both subdivisions of the AOB are of similar proportions; as there is no anatomical feature indicative of the segregation, histochemical detection has been required to portray its boundary. We studied the AOB of Octodon degus, a diurnal caviomorph rodent endemic to central Chile, and found several distinctive traits not reported in a rodent before: (i) the vomeronasal nerve innervates the AOB from its lateral aspect, in opposition to the medial innervation described in rabbits and muroids, (ii) an indentation that spans all layers delimits the boundary between the rostral and caudal AOB subdivisions (rAOB and cAOB, respectively), (iii) the rAOB is twice the size of the cAOB and features more and larger glomeruli, and (iv) the rAOB, but not the cAOB, shows male-biased sexual dimorphisms in size and number of glomeruli, while the cAOB, but not the rAOB, shows a male-biased dimorphism in mitral cell density. The heterogeneities we describe here within AOB subdomains suggest that these segregated regions may engage in distinct operationalities. We discuss our results in relation to conspecific semiochemical communication in O. degus, and present it as a new animal model for the study of VNS neurobiology and evolution.
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Affiliation(s)
- Rodrigo Suárez
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Chile.
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83
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Naya D, Ebensperger L, Sabat P, Bozinovic F. Digestive and Metabolic Flexibility Allows Female Degus to Cope with Lactation Costs. Physiol Biochem Zool 2008; 81:186-94. [DOI: 10.1086/527453] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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85
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Female degus (Octodon degus) monitor their environment while foraging socially. Anim Cogn 2008; 11:441-8. [DOI: 10.1007/s10071-007-0134-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2007] [Revised: 08/31/2007] [Accepted: 12/19/2007] [Indexed: 10/22/2022]
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86
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Becker MI, De Ioannes AE, León C, Ebensperger LA. Females of the communally breeding rodent, Octodon degus, transfer antibodies to their offspring during pregnancy and lactation. J Reprod Immunol 2007; 74:68-77. [PMID: 17276515 DOI: 10.1016/j.jri.2007.01.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2006] [Revised: 10/30/2006] [Accepted: 01/03/2007] [Indexed: 11/24/2022]
Abstract
Females in numerous rodent species engage in communal nesting and breeding, meaning that they share a nest to rear their young together. One potential benefit to communally nesting mothers is that infants improve their immunocompetence. Thus, suckling from two or more females might provide newborns with a more diverse array of antibodies and defensive cells. As a first step toward testing the immunocompetence hypothesis, we assessed whether female degus (Octodon degus), a communally nesting and breeding caviomorph rodent, transfer immunoglobulins to their young through the yolk sac or placenta while in the uterus and, during lactation, through milk. With this aim, adult degu females were immunized with four antigens, including two mollusk hemocyanins from Concholepas and Megathura (CCH and KLH, respectively), porcine thyroglobulin and tetanus toxoid. Specific antibodies against the experimental antigens were used to track the origin of antibodies in the young. To establish the presence of specific antibodies of IgG and IgA isotypes in sera and milk of animals, an indirect enzyme-linked immunosorbent assay (ELISA) was developed. Degu females produced specific antibodies against antigens not found in their natural environment, and mothers were able to transfer the induced antibodies to their litters during pregnancy (IgG) and during lactation (IgA). However, we recorded only limited evidence of degu offspring acquiring antibodies from lactating mothers other than their own, giving little support to the increased immunocompetence hypothesis.
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Hayes LD, Chesh AS, Ebensperger LA. Ecological Predictors of Range Areas and Use of Burrow Systems in the Diurnal Rodent, Octodon degus. Ethology 2007. [DOI: 10.1111/j.1439-0310.2006.01305.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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88
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An experimental examination of the consequences of communal versus solitary breeding on maternal condition and the early postnatal growth and survival of degu, Octodon degus, pups. Anim Behav 2007. [DOI: 10.1016/j.anbehav.2006.06.004] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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90
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Ebensperger LA, Taraborelli P, Giannoni SM, José Hurtado M, León C, Bozinovic F. NEST AND SPACE USE IN A HIGHLAND POPULATION OF THE SOUTHERN MOUNTAIN CAVY (MICROCAVIA AUSTRALIS). J Mammal 2006. [DOI: 10.1644/05-mamm-a-407r2.1] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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91
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Ebensperger LA, Hurtado MJ, Ramos-Jiliberto R. Vigilance and Collective Detection of Predators in Degus (Octodon degus). Ethology 2006. [DOI: 10.1111/j.1439-0310.2006.01242.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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92
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Ebensperger LA, Hurtado MJ, Valdivia I. Lactating Females Do Not Discriminate Between Their Own Young and Unrelated Pups in the Communally Breeding Rodent, Octodon degus. Ethology 2006. [DOI: 10.1111/j.1439-0310.2006.01251.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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93
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Ebensperger LA, Blumstein DT. Sociality in New World hystricognath rodents is linked to predators and burrow digging. Behav Ecol 2006. [DOI: 10.1093/beheco/arj048] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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94
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Ebensperger LA, Hurtado MJ. On the Relationship between Herbaceous Cover and Vigilance Activity of Degus (Octodon degus). Ethology 2005. [DOI: 10.1111/j.1439-0310.2005.01084.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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95
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Urrejola D, Lacey EA, Wieczorek JR, Ebensperger LA. DAILY ACTIVITY PATTERNS OF FREE-LIVING CURUROS (SPALACOPUS CYANUS). J Mammal 2005. [DOI: 10.1644/bwg-222.1] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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96
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Soto-Gamboa M, Villalón M, Bozinovic F. Social cues and hormone levels in male Octodon degus (Rodentia): a field test of the Challenge Hypothesis. Horm Behav 2005; 47:311-8. [PMID: 15708760 DOI: 10.1016/j.yhbeh.2004.11.010] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2004] [Revised: 10/28/2004] [Accepted: 11/01/2004] [Indexed: 11/20/2022]
Abstract
Social interactions are important factors determining and regulating individual behaviors. Testosterone has been related to agonistic interactions, while glucocorticoids have been related to social stress, especially during interactions of dominance. We compared testosterone and cortisol concentrations in male degus (Octodon degus, Rodentia) under laboratory conditions without male social interactions, with data from wild males in nature. Under natural conditions, males should present higher levels of testosterone during the breeding season due to social interactions (Challenge Hypothesis). Alternatively, intense social instability could act as a stressing environment, raising glucocorticoids, which inhibit testosterone concentrations. Our results show a significant increase in agonistic interactions between males during the breeding season, and disappearance of non-agonistic male interactions during this period. Hormone levels in breeding season show nonsignificant differences between laboratory groups, but testosterone concentrations in field males were significantly higher than in laboratory males. Testosterone levels were similar among pre-breeding and breeding periods, but in field animals the concentration was approximately 30% higher than in laboratory degus. In field animals, we found two different mating strategies: resident males, with territorial behavior, and transient males, displayed an opportunistic approach to females. Finally, cortisol presents a similar pattern in both laboratory and field animals; pre-breeding values of cortisol are higher than during the breeding season. This suggests that social interactions in O. degus activate a rise in testosterone, supporting the Challenge Hypothesis, and could be considered as partial support of the Social Stress Hypothesis.
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Affiliation(s)
- Mauricio Soto-Gamboa
- Instituto de Zoología, Facultad de Ciencias, Universidad Austral de Chile, Casilla (Box) 567, Valdivia, Chile.
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