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Competing for milk can be a stressful thing for hyena twin siblings

Date:
April 30, 2013
Source:
Forschungsverbund Berlin e.V. (FVB)
Summary:
Researchers have demonstrated for the first time in a free-ranging mammal that hunger and conflict for access to resources can be “stressful” for subordinate siblings and socially challenged dominant siblings, and hence increase their cost of maintaining homeostasis.
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Competing for milk can be a stressful thing for hyena twin siblings.
Credit: Photo IZW

Researchers from the German Leibniz Institute of Zoo and Wildlife Research (IZW) demonstrate for the first time in a free-ranging mammal that hunger and conflict for access to resources can be "stressful" for subordinate siblings and socially challenged dominant siblings, and hence increase their cost of maintaining homeostasis.

These findings were published in the science journal Biology Letters.

The researchers measured the concentration of metabolites of the 'stress' hormone cortisol in the faeces of young sibling and singleton spotted hyenas (Crocuta crocuta) in the Serengeti National Park, Tanzania, which depended on their mothers for milk. "It was not known whether sibling conflict over access to milk increased concentrations of cortisol metabolites in twin littermates -- we were now able to demonstrate that it significantly does," states Dr Sarah Benhaiem from the IZW, lead author of the study.

Surprisingly, hunger had little effect on the cortisol metabolite concentration of singletons, whether male or female. The picture was different for twin siblings -- both littermates had an elevated level when hungry. Interestingly, an even more important factor than hunger was the rivalry between twin littermates. In general, the less assertive (subordinate) cubs had higher cortisol metabolite levels than the more assertive (dominant) cubs.

More interestingly still, when hungry, subordinates competing against a sister were more assertive than subordinates competing against a brother. As a result, in such situations dominant sisters had higher cortisol metabolite levels than dominant brothers.

For the first time in a free-ranging wild mammal, the study shows how rivalry between twin siblings affects the cost of maintaining internal stability.


Story Source:

The above story is based on materials provided by Forschungsverbund Berlin e.V. (FVB). Note: Materials may be edited for content and length.


Journal Reference:

  1. S. Benhaiem, H. Hofer, M. Dehnhard, J. Helms, M. L. East. Sibling competition and hunger increase allostatic load in spotted hyaenas. Biology Letters, 2013; 9 (3): 20130040 DOI: 10.1098/rsbl.2013.0040

Cite This Page:

Forschungsverbund Berlin e.V. (FVB). "Competing for milk can be a stressful thing for hyena twin siblings." ScienceDaily. ScienceDaily, 30 April 2013. <www.sciencedaily.com/releases/2013/04/130430110031.htm>.
Forschungsverbund Berlin e.V. (FVB). (2013, April 30). Competing for milk can be a stressful thing for hyena twin siblings. ScienceDaily. Retrieved May 26, 2015 from www.sciencedaily.com/releases/2013/04/130430110031.htm
Forschungsverbund Berlin e.V. (FVB). "Competing for milk can be a stressful thing for hyena twin siblings." ScienceDaily. www.sciencedaily.com/releases/2013/04/130430110031.htm (accessed May 26, 2015).

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