New method for testosterone determination in spotted hyenas

Date: June 24, 2015

Source: Forschungsverbund Berlin e.V. (FVB)

Summary: For the first-time, researchers have succeeded in measuring metabolites of testosterone excreted in the feces of spotted hyenas. This innovative non-invasive research method is essential to avoid disturbance of animals.

In male mammals, testosterone plays a key role in both development and reproduction. Thus, measures of changes in testosterone concentration both within an animal's lifespan and across populations provide information essential for an understanding of growth, reproductive strategies and aging. However, hormone research normally requires the taking of blood samples, which in wild animals is difficult, and not always possible, particularly in protected areas where the capture of wild animals is often prohibited. Additionally, capture and blood sampling may cause stress in wild animals, thereby inducing a change in the hormone concentration being measured. In contrast, the non-invasive monitoring of hormones avoids all these problems. Thus, physiological data of free-ranging animals can be collected easily, thereby allowing repeated sampling from the same animal in its natural environment throughout its lifespan.

Details and verification of the efficacy of the first antibody-based enzyme immunoassay to monitor fecal testosterone metabolites in spotted hyenas are published in PLOS ONE. It is now possible to investigate the influence of age, social status and reproductive behavioural strategies on testosterone concentrations in wild spotted hyenas.

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Males' Superior Spatial Ability Likely Is Not an Evolutionary Adaptation; Testosterone 'Side Effect'?

Feb. 19, 2013 — Males and females differ in a lot of traits (besides the obvious ones) and some evolutionary psychologists have proposed hypotheses to explain why. Some argue, for example, that males' slight, but significant, superiority in spatial navigation over females -- a phenomenon demonstrated repeatedly in many species, including humans -- is probably "adaptive," meaning that over the course of evolutionary history the trait gave males an advantage that led them to have more offspring than their peers.

A new analysis published in The Quarterly Review of Biology found no support for this hypothesis. The researchers, led by University of Illinois psychology professor Justin Rhodes, looked at 35 studies that included data about the territorial ranges and spatial abilities of 11 species of animals: cuttlefish, deer mice, horses, humans, laboratory mice, meadow voles, pine voles, prairie voles, rats, rhesus macaques and talastuco-tucos (a type of burrowing rodent). Rhodes and his colleagues found that in eight out of 11 species, males demonstrated moderately superior spatial skills to their female counterparts, regardless of the size of their territories or the extent to which males ranged farther than females of the same species.

The findings lend support to an often-overlooked hypothesis, Rhodes said. The average superiority of males over females in spatial navigation may just be a "side effect" of testosterone, he said. (Previous studies have shown that women who take testosterone tend to see an improvement in their spatial navigation skills, he said.)

Continued:  http://www.sciencedaily.com/releases/2013/02/130219121345.htm

Testosterone fuelled elephant Pathi Harn's Taronga Zoo attack

Injured elephant keeper returns to Taronga Zoo

THE woman keeper crushed by a two-year-old elephant at Taronga Zoo last October has returned to work following a full recovery and an inves...

A SPIKE in testosterone and two female elephants on heat are the likely reason a baby elephant pinned its trainer against a pole, says Taronga Zoo.

The findings of an investigation into the elephant attack which nearly crushed zoo keeper Lucy Melo to death last October were made public today.

Acting general manager of research and conservation, Dr Rebecca Spindler, said neither the zoo or the trainer or the elephant calf Pathi Harn had been at fault.

"We've confirmed two of our female elephants were coming into estrus at roughly the same time," Dr Spindler told reporters at the zoo.

"More surprising is that when we examined Pathi Harn's testosterone, he went through a spike in testosterone that day that was higher than any of our males, including our adult male."

Dr Spindler said the two-year-old calf had developed at a faster rate than most baby elephants.

"Pathi Harn, we now know, is a very unusual elephant," she said.

"He's developed much more quickly than anyone could have expected.

"It's entirely possible this spike in testosterone contributed to the sudden changes in behaviour we saw that day."

She said it appeared Pathi Harn had no ill will towards his trainer.

"We're not sure if the two females and the spike in testosterone caused him to act that way, but it was out of the ordinary for Pathi Harn and even for elephants his age to have those levels of testosterone."

Most elephants do not display any indications of testosterone until they are four years old, Dr Spindler said.

Read on:  http://www.theaustralian.com.au/news/nation/testosterone-fuelled-elephant-pathi-harns-taronga-zoo-attack/story-e6frg6nf-1226554176251?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+TheAustralianTheNationNews+%28The+Australian+%7C+The+Nation%29

Elaborate Bird Plumage Due to Testosterone?

ScienceDaily (Oct. 21, 2011) — In many bird species males have a more elaborate plumage than females. This elaborate plumage is often used to signal body condition, to intimidate rivals or to attract potential mates. In many cases plumage colouration also depends on the hormone testosterone. Christina Muck and Wolfgang Goymann from the Max Planck Institute for Ornithology in Seewiesen have now investigated whether this also holds true for sex role-reversed bird species.

In barred buttonquails that live in Southeast Asia, females are polygamous and pair with several males that incubate the eggs and raise the young. However, not only the behaviour, but also secondary sexual ornaments that depend on the male hormone testosterone are reversed between sexes.

Colourful plumage and long feathers allow a male to express its quality and/or condition without further physical demonstration of its strength. With such features they may be able to avoid physical fights which are costly with respect to energy expenditure and the risk of injuries. The size and intensity of some parts of the plumage, for example the so-called black bib in house sparrows, depends on the male sex hormone testosterone; males with high testosterone levels also possess a larger and more intensely coloured bib.

There is hardly anything known regarding function and regulation of plumage colouration in female birds: females mostly have a dull plumage with almost no variation between individuals. However, in a few bird species sex roles are reversed: here, the females aggressively defend territories and court males. The latter incubate the eggs and care for the young without any help from the females. Only very few species are known to show such sex role reversal in behaviour and the evolutionary background is still unsolved.

Christina Muck and Wolfgang Goymann now found a relationship between plumage colouration, body weight and testosterone concentrations in female barred buttonquail, a bird species that lives in Southeast Asia. The researchers kept the birds in pairs for one year in large breeding boxes and regularly took blood samples to monitor the time course of testosterone levels. In addition they weighed the birds and took photographs of the black throat patch of females to determine its size and colour intensity on the computer. Males of this species are smaller than females and do not possess such a patch.

The researchers could first show that testosterone levels were similar in males and females and did not exhibit large seasonal changes. Moreover, testosterone levels were rather low which is common is species that do not show a pronounced seasonality. Nevertheless they found a strong relationship between the size and the intensity of the black throat patch and the testosterone levels in females. Moreover, in females there was a correlation between testosterone levels and female body condition. No such correlations existed in males.

"It is really remarkable," states Christina Muck, "that the sex role reversal in behaviours is accompanied by a reversed hormone dependency in the expression of secondary sexual characters." Thus, female button quails succeed when they not only adopt male behavioural strategies but also use the underlying physiological mechanisms.

http://www.sciencedaily.com/releases/2011/10/111021074732.htm