How many differences were accounted for in the selected minimal adequate model?

Of the total variance in the selected minimal adequate model (D AIC with a full model considering all up to 2nd order interaction effects = 14.31) 10.2% was accounted for by differences between individuals in a zoo, 56.9% by differences between zoos and, lastly, 32.9% by within-individual variation.

What was the effect of time of day on GC and androgen levels?

Since fecal samples were collected throughout the day, the authors tested for a potential effect of time of day on GC and androgen excretion.

What does the author think of the differences observed in field studies?

The authors predict differences observed in field studies are merely a flexible response to habitat quality and stability of food supply in the wild, there should be no species-specific differences in the endocrine physiology of zoohoused animals.

What was the effect of different stages of the ovarian cycle on GC levels?

Among the non-lactating females the authors investigated whether different stages of the ovarian cycle (follicular phase, fertile period, luteal phase) might have affected GC levels.

How many samples were collected from the Bornean and Sumatran populations?

Fecal samples from 16 Bornean (n = 105 samples) and 21 Sumatran orangutan males (n = 195) were collected and analyzed for androgen concentrations.

What is the effect of age on GC levels in females?

The positive effect of age (bMCMC = 0.012, PMCMC = 0.0072) suggests that transformed GC levels were slightly higher in older than in younger animals.

How long is the inter-birth interval in orangutans in the wild?

The mean inter-birth interval in orangutans living in captivity is shorter than in the wild (captivity: 4.5–5.5 years; wild 7–9 years, [1,73]).

What is the reason for the poor breeding success of the orangutan?

Although multiple proximate mechanisms may underlie the poor breeding success of captive orangutans, one important factor might be an increased level of stress as a consequence of the unnatural social housing conditions.

What did the authors do to investigate the behavior of the two species?

To investigate possible endocrine correlates underlying the observed behavioral variation documented for the two orangutan species under natural conditions, the authors carried out a crosssectional study on zoo-housed animals.

What is the reason for the higher stress levels in the orangutan?

The higher stress levels of orangutan mothers living in social housing conditions may also be caused by the perception that their infants are at risk from other group members.

What was the effect of species, age, and group size on GC levels in the female?

The authors also found a very small but significant linear increase in GC levels with increasing age in females, independent of sex and species.

Why did the authors not expect seasonal fluctuations in hormone levels?

Since orangutans are not seasonal breeders, the authors did not expect seasonal fluctuations in hormone levels and collected samples throughout the year.

What is the significance of the interaction effect between species and adult group size?

The negative sign of the significant interaction effect between species and (centered) adult group size (bMCMC = 0.221, PMCMC = 0.0226), indicates that the rate of increase of transformed GC values with increasing adult group size was significantly smaller in Sumatran than Bornean females (Fig. 3a).

What is the reason for the decline in orangutan hormone levels?

The authors suggest that these differences in hormone levels might be linked to differences in gregariousness of wild orangutans on the two islands, which are adaptations to local ecological conditions.

Open AccessJournal Article10.1016/J.YGCEN.2011.04.008

Species-specific patterns in fecal glucocorticoid and androgen levels in zoo-living orangutans (Pongo spp.)

Tony Weingrill, +4 more

- 01 Jul 2011

- General and Comparative Endocrinology

- Vol. 172, Iss: 3, pp 446-457

TL;DR: It is concluded that Sumatran zoo orangutans are better able to adjust to social housing conditions than their Bornean congeners, and differences in both glucocorticoid and androgen output between the two species of orangutan are presumably linked to ecological and behavioral differences.

About: This article is published in General and Comparative Endocrinology. The article was published on 01 Jul 2011. and is currently open access. The article focuses on the topics: Captivity.

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Most frequently asked questions

1. What are the contributions mentioned in the paper "Species-specific patterns in fecal glucocorticoid and androgen levels in zoo-living orangutans (pongo spp.)" ?

Weingrill et al. this paper found that male and female Bornean orangutans are more likely to associate with a female while she is sexually receptive than those from Sumatra.

2. What have the authors stated for future works in "Species-specific patterns in fecal glucocorticoid and androgen levels in zoo-living orangutans (pongo spp.)" ?

The authors suggest that the behavioral differences between the species found in the wild should be taken into account when orangutan social housing facilities are planned or restructured.

3. What is the reason for the low fertility rate of the Bornean orangutans?

Since the analysis of male samples showed a similar interaction between group size and GC levels, Bornean males in larger groups may also experience reduced fertility due to more social stress.

4. What is the common explanation for the decline in orangutans?

After reaching a plateau in adulthood, their study shows a decline in aging orangutans, a pattern found in other primates including great apes.

Fig. 1. Immunoreactive GC concentrations measured in the 3a, 11b dihydroxy-CM (top graphs), 11-oxoetiocholanolone (middle graphs) and cortisol (bottom graphs) EIA in feces before and after translocation of two female orangutans (left: female Astrid, right: female Tilda). Note: Day 0 represents the day of transport. The symbols before time point 0 in the profiles of Astrid represent the mean ± SD of pre-transport GC values (n = 8).

Table 4 Parameter estimates (bMCMC) and associated significance values (PMCMC) of all variables maintained in the selected minimal adequate linear mixed model of androgen levels in zoo-living orangutans. Significance values were estimated by Monte Carlo Markov Chain simulations (n = 10,000) taking Restricted Maximum Likelihood estimates of model parameters as priors cf. [3].

Fig. 4. Relationship between androgen metabolite levels and age of males. Sumatran orangutans are indicated by light gray circles, Bornean orangutans by dark gray circles. The 95% Highest Posterior Density Interval is light gray shaded for Sumatran and dark gray for Bornean orangutans.

Fig. 3. Relationship between fecal glucocorticoid metabolite levels and group size for females (a) and males (b). Sumatran orangutans are indicated by light gray circles, Bornean orangutans by dark gray circles. The 95% Highest Posterior Density Interval is shaded in light gray for Sumatran and dark gray for Bornean orangutans.

Table 3 Parameter estimates (bMCMC) and associated significance values (PMCMC) of all variables maintained in the selected minimal adequate linear mixed model of glucocorticoid levels in zoo-living male orangutans. Significance values were estimated by Monte Carlo Markov Chain simulations (n = 10,000) taking Restricted Maximum Likelihood estimates of model parameters as priors cf. [3].

Fig. 2. HPLC profiles of immunoreactivity detected with (a) the 3a, 11b dihydroxy-CM and (b) the EA assay in a fecal extract from a Borneon (closed circles) and a Sumatran (open triangles) male orangutan. Arrows indicate elution positions of 1 cortisol(14/15), 2 corticosterone (21/22), 3 11b-hydroxyetiocholanolone (25), 4 11oxoetiocholanolone, 5 testosterone (42), 6 androstenedione, dehydroepiandrosterone (55/56), 7 epiandrosterone, 5b-dihydrotestosterone (70–72), 8 5b-androstane-3a-ol-17one (82), 9 androsterone (100–102).

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References

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R: A language and environment for statistical computing.

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The Physiology of Reproduction

Ernst Knobil, +1 more

- 15 Jan 1994

TL;DR: The gametes, fertilization and early embryogenesis the reproductive systems - the female, the male the pituitary and the hypothalmus, and the reproductive processes and their control.

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Physiological Functions of Glucocorticoids in Stress and Their Relation to Pharmacological Actions

Allan Munck, +2 more

- 01 Jan 1984

- Endocrine Reviews

TL;DR: It is proposed that stress-induced increases in glucocorticoid levels protect not against the source of stress itself but rather against the body's normal reactions to stress, preventing those reactions from overshooting and themselves threatening homeostasis.

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The "Challenge Hypothesis": Theoretical Implications for Patterns of Testosterone Secretion, Mating Systems, and Breeding Strategies

John C. Wingfield, +3 more

- 29 Mar 1990

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TL;DR: This model indicates that there may be widely different hormonal responses to male-male and male-female interactions and presumably equally plastic neural mechanisms for the transduction of these signals into endocrine secretions.

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Species-specific patterns in fecal glucocorticoid and androgen levels in zoo-living orangutans (Pongo spp.)

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AI Agents for this Paper

Most frequently asked questions

1. What are the contributions mentioned in the paper "Species-specific patterns in fecal glucocorticoid and androgen levels in zoo-living orangutans (pongo spp.)" ?

2. What have the authors stated for future works in "Species-specific patterns in fecal glucocorticoid and androgen levels in zoo-living orangutans (pongo spp.)" ?

3. What is the reason for the low fertility rate of the Bornean orangutans?

4. What is the common explanation for the decline in orangutans?

5. How many differences were accounted for in the selected minimal adequate model?

6. What was the effect of time of day on GC and androgen levels?

7. What does the author think of the differences observed in field studies?

8. What was the effect of different stages of the ovarian cycle on GC levels?

9. How many samples were collected from the Bornean and Sumatran populations?

10. What is the effect of age on GC levels in females?

11. How long is the inter-birth interval in orangutans in the wild?

12. What is the reason for the poor breeding success of the orangutan?

13. What did the authors do to investigate the behavior of the two species?

14. What is the reason for the higher stress levels in the orangutan?

15. What was the effect of species, age, and group size on GC levels in the female?

16. Why did the authors not expect seasonal fluctuations in hormone levels?

17. What is the significance of the interaction effect between species and adult group size?

18. What is the reason for the decline in orangutan hormone levels?

Figures

Citations

Analyzing linguistic data: a practical introduction to statistics using R

Non-invasive monitoring of physiological stress in the Western lowland gorilla (Gorilla gorilla gorilla): Validation of a fecal glucocorticoid assay and methods for practical application in the field

Allostatic load and biological anthropology

Hair as a long-term retrospective cortisol calendar in orang-utans (Pongo spp.): new perspectives for stress monitoring in captive management and conservation.

Stereotypic head twirls, but not pacing, are related to a ‘pessimistic’-like judgment bias among captive tufted capuchins ( Cebus apella )

References

R: A language and environment for statistical computing.

The Physiology of Reproduction

Physiological Functions of Glucocorticoids in Stress and Their Relation to Pharmacological Actions

Analyzing linguistic data: a practical introduction to statistics using R

The "Challenge Hypothesis": Theoretical Implications for Patterns of Testosterone Secretion, Mating Systems, and Breeding Strategies

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