Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Complex sex life of goats could have implications for wildlife management

15.12.2011
A new study of the mating habits of mountain goats reveals the vastly different strategies of males in different populations and could shed light on the unseen impacts of hunting.

A Durham University-led research team found that male chamois (a species of wild goat-antelope) adopt different strategies in different populations in order to succeed in the rut: some put a lot of energy in at a young age, while others wait until they are much older.

Researchers looking at neighbouring populations of chamois in Northern Italy found that males in one population delay their reproductive efforts until an older age when their size and experience allow them to dominate in the rut. They then put increasing effort into breeding until they die.

The study is the first to show clearly that this strategy of 'terminal investment', a pattern of higher reproductive effort in older age, is pursued by males in an animal population. The results, published in the journal PLoS One, show that reproductive strategies in animals are complex and can show surprising variation across neighbouring districts.

It's not clear why there is such variation but the way that these populations are managed through hunting could be a factor, according to the researchers. At present, 32 per cent of the hunting quota is made up of older males, even though these males make up only 23 per cent of the population.

If too many larger, older males are taken out of a population, younger males may be able to muscle in and start breeding. Years of rutting could exhaust these younger males, meaning that they are in poorer condition when they reach old age. If this reasoning is accurate, selectively hunting older males in populations such as this will have the effect of reducing the condition of older males in future.

This suggests that alternative hunting practices – such as hunting males in proportion to their age distribution – might be a better strategy.

Studies of bighorn sheep, a similarly hunted mountain species in America, have also suggested that selective hunting of older males can reduce genetic quality.

Researchers looked at three populations in detail and found that in neighbouring areas surprisingly different strategies prevailed; in one, the terminal investment strategy was dominant, in another, where older males were harvested at a slightly higher rate, the live fast/die younger strategy prevailed.

The group, led by Drs Stephen Willis and Philip Stephens, School of Biological and Biomedical Sciences, Durham University, in collaboration with ecologists at the University of Sassari, Italy, used data from 15,000 hunted male chamois, collected since 1973, to explore their breeding strategies. They looked at the amount of energy males of different ages expended during the annual rut at several sites in the Italian Alps and found unexpected variation across populations.

Co-author Dr Stephen Willis said: "It seems that chamois can have fun in their youth or enjoy their old age but they can't do both. In one valley, males left it until much later to get involved in the rut but, once involved, they showed a pattern of increasing effort, right up to the end of their lives."

The team was able to see how much energy was expended by rutting chamois by looking at how the body masses of males changed throughout the rut period. They were also able to establish the ages of shot individuals from the number of annual growth rings in their horns. The speed at which the animals lose body mass shows how much effort males put in to establishing and patrolling territories, and fighting to defend their harem.

At a site with more hunting and a 'faster' pace of life, the team found that male weight loss during the rut was high, that chamois began rutting at an earlier age and that life-expectancy was lower. By contrast, at a site with a 'slower' pace, lifespans were longer, the weight loss of males was less and males tended to increase the effort they put into reproduction as they got older.

Male chamois barely eat during the rut and use their non-rutting time for resting rather than foraging. They must put on weight prior to the rut in order to succeed and to survive the following winter months.

Co-author of the study, Tom Mason, a Durham University PhD student working on the project, said: "In most species, all males follow one or other of these strategies. It is intriguing that among chamois in different areas, males have different strategies, which might be related to resources, climate or competition."

Dr Philip Stephens added: "These patterns are consistent with two competing theories about how males should optimally allocate effort to reproduction during their lives, so you wouldn't normally expect to see them being displayed so differently by males in neighbouring populations of the same species."

The study is funded by the Natural Environment Research Council (NERC).

Carl Stiansen | EurekAlert!
Further information:
http://www.durham.ac.uk

More articles from Studies and Analyses:

nachricht The importance of biodiversity in forests could increase due to climate change
17.11.2017 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig

nachricht Win-win strategies for climate and food security
02.10.2017 | International Institute for Applied Systems Analysis (IIASA)

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Antarctic landscape insights keep ice loss forecasts on the radar

20.11.2017 | Earth Sciences

Filling the gap: High-latitude volcanic eruptions also have global impact

20.11.2017 | Earth Sciences

Water world

20.11.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>