WWW.THESIS.XLIBX.INFO
FREE ELECTRONIC LIBRARY - Thesis, documentation, books
 
<< HOME
CONTACTS



Pages:     | 1 |   ...   | 14 | 15 || 17 | 18 |   ...   | 27 |

«Item type Thesis or dissertation Authors Davis, Nicolas Citation Davis, N., Schaffner, C. M., & Smith, T. E. (2005). Evidence that zoo visitors ...»

-- [ Page 16 ] --

5.4.4 The impact of social events on HPA activity in zoo-housed spider monkeys The present study investigated the impact of social factors on GC levels in a zoo-housed group of spider monkeys using a non-invasive measure of stress: urinary cortisol. Although stress research is used in the assessment of husbandry practices and social relationships in a number of primate species (Honess & Marin, 2006a), there have been only a handful of studies looking at various stressors within a zoo environment (Shepherdson, et al., 2004), and none previously reported in spider monkeys. Earlier research into social stress in primates has predominately examined it from the perspective of dominance hierarchy relationships, which is important in many species and considered a major source of psychological stress (Abbott, et al., 2003; Cavigelli, Dubovick, Levash, Jolly, & Pitts, 2003; Engh, et al., 2006).

However, spider monkeys are reputed to have low or no linear dominance hierarchies (Aureli & Schaffner, 2008) making them an interesting test case for assessing various social factors on their HPA axis responses. In addition, studies of primate aggression have been primarily carried out on species that are largely cohesive, such as macaques, squirrel monkeys, titi monkeys and callitrichids, whereas spider monkey social organisation is characterised by high fission-fusion dynamics (Aureli, et al.,

2008) and therefore the effects of various social factors may have different impacts on their HPA responses. Finally, no previous studies carried out on Ateles have examined the relationship between aggression and their GC response.

5.5 Aim

The aim of this study was to investigate the impact of social factors on GC levels in a zoo-housed group of spider monkeys using urinary cortisol as a noninvasive measure of stress. The particular categories of social events examined were aggression, reproduction and separation. Based on previous studies, it was believed that these particular events could be associated with an increase in cortisol in zoohoused spider monkeys.

5.5.1 Predictions Based on behaviour studies from the wild (Asensio, et al., 2008; Fedigan & Baxter, 1984; Slater, et al., 2008), and from a survey on aggression in spider monkeys in zoological parks (Chapter 4) I predicted the majority of minor aggression would be carried out by adult males towards receptive adult females when ovulating, or to a lesser extent by adult females to sub adult females as they approach maturity.

Aggression between adult females would not be expected. Any cases of severe or lethal aggression would be expected by adult males towards sub adult males.

Regarding cortisol it would be expected that the largest increases would be associated with the most severe cases of aggression (Ostner, et al., 2008), with severe and lethal aggression associated with the largest increased levels of cortisol. It would also be expected that the response would be dependent on the individuals’ role in the aggressive act with the targets of aggression experiencing the largest increase in urinary cortisol, followed by the actors of aggression and then the bystanders (Creel, 2001; T. E. Smith & French, 1997b). With respect to the timing of cortisol changes, I predicted that cortisol would be elevated the day following aggression and that the rate at which cortisol levels returned to pre-event levels would depend on the severity of the aggression.

Previous studies into reproductive events have shown increases in GCs associated with seasonality and increased competition by males for females (Manson, 2007). However, as spider monkeys are not seasonal breeders (Vick, 2008), and with only one adult male in the study group, competition for females would be at a minimum. Although minor, female-directed male aggression is reported in the wild (Slater et al., 2008; Fedigan & Baxter, 1984), it is unlikely that this would cause a pronounced stress response as it appears to be ritualised in spider monkeys.

However, because the spider monkeys investigated in the present study are zoohoused it may prove difficult for them to engage in species-specific secretive mating (Campbell & Gibson, 2008), therefore I predicted there would be increased GCs in the actors of sexual behaviour at the time of consortships. In addition, postpartum increases in GCs have also been seen in primates in captivity, which have been linked to maternal behaviour (Bahr, et al., 1998; Behringer, et al., 2009) and an increased sensitivity to a stress response from mothers with infants (Boccia, et al., 1995; Maestripieri, et al., 2008).

Severe stress responses have been associated with separations and reintroductions in a number of primate species in captivity (Brent, Kessel, & Barrera, 1997; Clarke, Harrison, & Didier, 1996; Honess & Marin, 2006a; Mendoza, et al., 2000). Therefore, I predicted that separating individuals from the social group would lead to an increase in cortisol levels in the separated individual and to a lesser extent in bystanders. In addition, I predicted that long-term separation would lead to higher cortisol levels than short term separations. Finally, I predicted that reintroduction of group members would also lead to increased cortisol responses for both targets of the separation and bystanders.

5.6 Method

5.6.1 Urine samples Urinary cortisol was used as an index of stress because the collection of samples was non invasive, it fitted in well with the daily routine of the group and is a proven method of measuring GCs in primates (Chapter 2). Levels of urinary cortisol were quantified in a total of 2140 samples from six adults present during the study between February 2000 and March 2005 (see Table 5.1).





–  –  –

5.6.2 Event categories For aggression I investigated the intensity, the role of the individual and the timing. Intensity included three levels: minor (aggression which included either no observed injuries or superficial injuries); severe (aggression which included single, or multiple wounds that required veterinary treatment) and lethal (aggression when the individual was killed outright or where the injuries were so serious they necessitated that the individual be euthanized). These levels could be characterised retrospectively following the event and did not rely on the aggression being observed. The role of the individual also included three levels: the target, the actor and bystanders. The role of actor and bystander could only be determined by direct observations of aggressive incidents either by me or by keeping staff which were subsequently recorded. Finally, I also examined the effect of time on aggressive events. This included: prior (samples seven days prior to the event); at (sample from the morning following the event); and post (samples from the following seven days after the event).

For reproduction I investigated the type of event, the role of the individual and the timing of the event. Reproduction included three events: ovulation (signalled on the day by (i) the presence of blood in urine or (ii) the male sniffing in the location of where a female was or had been sitting or (iii) the male handling and sniffing a female’s clitoris); mating (observed copulation between a female and the male) and birth (delivery of an infant following full term pregnancy). The role of the individual in each reproductive event included: the adult male; female target (adult female experiencing the event) and bystanders (other adult females). These events and roles were determined and recorded by myself or by keeping staff throughout the study period as and when they occurred. The sample collection protocol for assessment of reproductive events was identical to that for aggressive events.

For separation I investigated the effect of type of event, the role of the individual and the timing of the event. The type of event included: temporary separation (an individual was out of the group for 24 hr); separation (an individual was out of the group for ≥ 24 hr) and reintroduction (an individual or individuals were reintroduced back into the group following separation). During separations the individual was kept in a section of the enclosure at the back of the exhibit in visual and potential tactile contact with the rest of the group (see Chapter 2, section 2.1.6).

The role of the individual included only two levels: the separated individual and bystanders (individuals not separated from the group). Samples were analysed from the week before to the week after each event. Due to the delay in cortisol being excreted in the urine (see Chapter 1, section 1.4.10) each sample represented the cortisol value for the day prior to the day of collection.

5.6.3 Defrosted samples During storage, a number of samples (763 samples collected between November 2003 and July 2005) were accidentally defrosted over an unknown period of time (as persons unknown unplugged the freezer housing the samples) before they could be assayed. Of these samples, 458 were required for the present study.

Following the discovery of the defrosted event, samples were relabelled to reflect the thaw and then immediately frozen back to -20°C. Cortisol is a cholesterol based steroid hormone and is fairly robust to defrosting (Miki & Sudo, 1998), however due to the unknown time period of the defrosting its effect was investigated. To assess the potential for degradation of the cortisol and check for any potential interference from any other substances that may have formed during the defrosted period, a pool of the defrosted samples (Pool C) was taken and tested against the normal pool (Pool

B) for specificity (see Chapter 2, section 3.2). Pool C was comprised of six samples from each adult and five samples from each sub adult in this social impacts study, comprising a total of 45 samples. This equates to 24 samples from adult females, five from a sub adult female, six from an adult male and 10 from sub adult males. For details on Pool B see Chapter 2, section 3.2. To avoid confounding factors any lower level events which overlapped with any major events were not analysed.

5.6.4 Analyses Factors affecting levels of urinary cortisol were investigated by using linear mixed models (LMM’s). LMM’s allow both fixed and random variables to be fitted to a model, while controlling for variation due to repeated measures of individuals (Tabachnik & Fidell, 2007). The best model was selected by using Akaike’s information criteria (AIC). It compares the adequacy of several models, identifying the model that best explains the variance of the dependent variable as that with the lowest AIC value (Tabachnik & Fidell, 2007). This approach has been used previously in zoo based research on primates were sample size is limited (e.g. O. N.

Fraser, et al., 2008). Maximum likelihood (ML) method was used with fixed variables, and restricted maximum likelihood methods (RELM’s) were used with interactions of fixed variables. An alpha level of 0.05 was adopted for all statistical analysis. The cortisol level was entered as a continuous dependent variable, with identity as the random variable in the models.

The first analysis compared the data samples across types of social event to see whether there were any differences across the event categories (i.e. aggression, reproduction or separation). The subsequent analyses were performed on each type of social event. Post hoc tests used pairwise comparisons using Least Significant Difference. The timing categories for each event were the same as described previously for aggression.

–  –  –

Figure 5.1 % B/Bo of serial dilutions of the Pool B (none defrosted) and Pool C (defrosted) and two cortisol standards to demonstrated parallelism.

pool C at the working dilution of 1:512 and applied to the defrosted samples.

Applying such a conversion value has previously been carried out in a study in which a substance was found to consistently lower the measure of cortisol (Cross, Pines, & Rogers, 2004) I examined the impact of all the stress factors initially in a model to determine whether there were differences in how the different social factors of aggression, reproduction or separation events impacted cortisol values in the spider monkeys. Overall mean values of cortisol for the three categories were 2.408 ± 0.31 SEM, 1.899 ± 0.31 and 1.498 ± 0.35 for aggression, reproduction and separation, respectively. Analyses with LMM’s (ML) (see Table 5.2) revealed that, overall, aggression was responsible for the greatest degree of variance in cortisol levels [F (1, 3) = 10.191, P.0001, AIC = 25940.544] 5.7.1 Aggression A total of 60 aggressive incidents were recorded over the study period. When the actor of aggression could be identified the adult male (Ric) was largely responsible, accounting for 63% of minor cases and 44% of severe cases of Table 5.2 LMM results for the three event categories.

Dependent variables Continuous Cortisol Fixed explanatory variables Event 1 = Aggression, 2 = Reproduction, 3 = Separation Random variables ID

Event [F (1, 3) = 9.92, P.00005, AIC = 22707.01]

aggression. These were carried out predominately towards adult females although incidents of female-female aggression were also recorded, in particular towards the youngest adult female. Finally, there were two cases of lethal aggression which were both carried out by Ric towards juvenile males.

A total of 1709 samples were used in the analysis of 60 incidents of aggression (see Table 5.3). When I examined the impact of different intensities of aggression on the cortisol values for actors, targets, and bystanders the week prior to the day of and the week following the aggressive events a three way interaction of type, role and time provided the best fitting model with the lowest AIC value. [F (1, 23) = 9.772, P.0001, AIC = 9956.406]. The bystander values were calculated using the means of the individual animals so avoiding data pooling (see Table 5.4).

Each type of aggressive event was examined individually to determine where the differences across the three factors of the interaction lay. Cortisol levels for minor incidents (Figure 5.2A) showed very little variation across the role or time, with consistently low levels of cortisol throughout. Of the 29 incidences of minor aggression between adults where the actor was known, the adult male (Ric) was responsible for 20 events that were directed towards adult females. Of the 22 incidences between adults, where the target was known, the youngest adult female (Fay) was the recipient on 14 occasions.



Pages:     | 1 |   ...   | 14 | 15 || 17 | 18 |   ...   | 27 |


Similar works:

«Android Converter 2 © 2012 Engelmann Media GmbH Contents 3 Table of Contents Part I Android Converter 2 1 Programmbeschreibung 2 Packungsinhalt 3 Support 4 Systemvoraussetzungen Part II Einrichtung 1 Installation 2 Programmstart 3 Demoversion 4 Lizensierung 5 Updates Part III Kurzanleitung 1 Dateien laden 2 Einstellungen vornehmen 3 Medien konvertieren Part IV Anleitung 1 Die Programmoberfläche Die Hauptausw ahl Mediensuche_Oberfläche Herunterladen_Oberfläche Einstellungen_Oberfläche Die...»

«AP® Environmental Science Exam Regularly Scheduled Exam Date: Monday morning, May 2, 2016 Late-Testing Exam Date: Wednesday afternoon, May 18, 2016 Section I Total Time: 1 hr. 30 min. Section II Total Time: 1 hr. 30 min. Total Time: 1 hour 30 minutes Total Time: 1 hour 30 minutes Section I Section II Number of Questions: 100* Number of Questions: 4 Percent of Total Score: 60% Percent of Total Score: 40% Writing Instrument: Pencil required Writing Instrument: Pen with black or dark blue ink...»

«www.social-capital.net Empresa Social & Reservas de la Biosfera Estrategia de Desarrollo Sobre el Autor Colin Campbell es el fundador y Director Ejecutivo de Assit Social Capital, que utiliza el capital social como un recurso crítico para la innovación social y la resiliencia (capacidad de adaptación) de las comunidades. Ha trabajado en el campo de la empresa social desde 2001. En el año 2003, comenzó a utilizar la estrategia de capital social para el diseño y asesoramiento de una serie...»

«Social Media and Diffusion of Innovation:Examination of Applicability of Rogers Theory 1.1. Introduction Extant literature identifies that the diffusion of innovation is a social process and the adoption of a particular innovation by an individual is largely restricted by the behaviour of the social group (De Chowdhary et al., 2010; Lievrouw, 2002; Markus 1997). However, the degree of complexity associated with social networks and the associated heterogeneity of individuals make it more...»

«STEPHEN C. WHALEN Curriculum Vitae ADDRESS Department of Environmental Sciences and Engineering University of North Carolina, CB #7431 Chapel Hill, NC 27599-7400 Phone: (919) 966-9895 FAX: (919) 966-7911 RANK Associate Professor PLACE OF BIRTH Millbrook, NY CITIZENSHIP U.S.A. RESEARCH INTERESTS Biogeochemical cycling of N and C in aquatic, wetland and terrestrial environments. Exchange of radiatively and chemically important trace gases (CO2, CH4, N2O, CO) between the atmosphere and wetland and...»

«A slightly edited version of this article appeared in the 9 October issue of Nature (2003). The Nature version is available from http://www.nature.com Dodecahedral space topology as an explanation for weak wide-angle temperature correlations in the cosmic microwave background J.-P. Luminet Laboratoire Univers et Th´ories, CNRS-UMR 8102, Observatoire de Paris, e F-92195 Meudon Cedex (France) J. Weeks 15 Farmer St., Canton NY 13617-1120 (USA) A. Riazuelo Service de Physique Th´orique,...»

«PRESS RELEASE BY INSPECTOR-GENERAL OF POLICE IN RELATION TO INVESTIGATION ON THE ALLEGED PRODUCTION OF COMPONENTS FOR LIBYA'S URANIUM ENRICHMENT PROGRAMME INTRODUCTION On the evening of 10 Nov 2003, two intelligence representatives from the United States and Britain, i.e. the CIA and the MI6, met the Director of the Special Branch, Bukit Aman. The focus of their discussion was the ongoing investigation related to the international network that is suspected of being involved in the transfer of...»

«Selling or Selling Out?: An Exploration of Popular Music in Advertising Kimberly Kim Submitted to the Department of Music of Amherst College in partial fulfillment of the requirements for the degree of Bachelor of Arts with honors. Faculty Advisor: Professor Jason Robinson Faculty Readers: Professor Jenny Kallick Professor Jeffers Engelhardt Professor Klara Moricz 05 May 2011 Table of Contents Acknowledgments Chapter 1 – Towards an Understanding of Popular Music and Advertising Chapter 2 –...»

«GK Power Capsule June Month Current Affairs | 2016 Plastic is fantastic: Credit cards register highest growth in five years 1. Credit card issuances have recorded an impressive growth of 16 per cent year on year to 24.5 million in the financial year ended March 31, 2016 as banks added 3.4 million cards to the system. This was the highest growth in the number of cards added by banks after Reserve Bank of India (RBI) began sharing the data in 2012. Card spends too registered a 26.7-per cent...»

«INTERNATIONAL CONFERENCE ON ENGINEERING DESIGN ICED 03 STOCKHOLM, AUGUST 19-21, 2003 MASS CUSTOMISATION, CHANGE AND INSPIRATION – CHANGING DESIGNS TO MEET NEW NEEDS C M Eckert, U Pulm and T A W Jarratt Keywords: customisation, innovative products, change processes, product families, product platforms Abstract All design is a form of change, because all products are based on other designs or design ideas. This paper presents a classification of change processes occurring throughout the...»

«Virus structure in spherical space. Polyhedra, and beyond polyhedra. ‘for the present the reader may be content to draw his curves as common sense dictates’ (Hardy) Sten Andersson Sandforsk, Institute of Sandvik S-38074 Löttorp, Sweden www.sandforsk.se 6 april 2006 Abstract All the Platonic and Archimedean solids of pentagonal symmetry are used to describe capsids. Two different polyhedra, related to the icosi-dodecahedron, are also used to describe capsids. The capsids of complicated, or...»

«SPEEDING UP XML QUERYING Satisfiability Test & Containment Test of XPath Queries in the Presence of XML Schema Definitions Dissertation by Jinghua Groppe Lübeck, Germany, July 2008 Groppe, Jinghua: SPEEDING UP XML QUERYING : Satisfiability Test & Containment Test of XPath Queries in the Presence of XML Schema Definitions / Jinghua Groppe. – Als Ms. gedr. – Berlin : dissertation.de – Verlag im Internet GmbH, 2008 Zugl.: Lübeck, Univ., Diss., 2008 ISBN 978-3-86624-381-1 Bibliografische...»





 
<<  HOME   |    CONTACTS
2016 www.thesis.xlibx.info - Thesis, documentation, books

Materials of this site are available for review, all rights belong to their respective owners.
If you do not agree with the fact that your material is placed on this site, please, email us, we will within 1-2 business days delete him.