Key to evolutionary fitness: Cut the calories

July 1, 2009

Charles Darwin and his contemporaries postulated that food consumption in birds and mammals was limited by resource levels, that is, animals would eat as much as they could while food was plentiful and produce as many offspring as this would allow them to. However, recent research has shown that, even when food is abundant, energy intake reaches a limit, even in animals with high nutrient demands, such as lactating females. Scientists at the Research Institute of Wildlife Ecology in Vienna suggest that this is due to active control of maternal investment in offspring in order to maintain long-term reproductive fitness.

The research, to be presented by Dr Teresa Valencak at the Society for Annual Meeting in Glasgow has shown that, when their energy reserves are low or when their offspring are kept in cooler temperatures, Brown hares are able to increase their energy turnover and rate of milk production above that normally observed. This indicates that, ordinarily, the hares are operating at below their maximum capacity and shows that this is not due to any kind of physiological constraint, such as length of digestive tract or maximum capacity of mammary glands. Also, as the hares were provided with plentiful food, there could be no limitation of energy turnover due to food availability.

The way that females regulated their energy expenditure according to pup demand and their own fat reserves but did not exceed certain levels fitted with the group's theory that using energy at close to the maximum rate has costs for animals which may compromise their ability to successfully reproduce in the future. If a hare puts most of its energy into a litter of pups then it will have little left over for growth and body repairs for example, which may shorten its life or make it less able to produce or care for young in the future. By actively limiting the rate of energy turnover, a mother can prevent this and maintain a higher level of over her lifetime.

Source: Society for Experimental Biology

Explore further: Mongoose pups work together to wheedle food out of carers

Related Stories

Mongoose pups work together to wheedle food out of carers

April 10, 2007

Mongoose pups use their littermates to gain more food from their carers. Researchers at the University of Cambridge found that a unique system of pup care reduces competition for adult help, allowing pups to collectively ...

The Building Blocks of Life

October 30, 2008

(PhysOrg.com) -- Ever wonder where all that food your teenager devoured was going? Not only does the food go into the teen's daily activities--running, doing homework, breathing and playing video games, but food converted ...

Want to monitor climate change? P-p-p-pick up a penguin!

April 4, 2007

We are used to hearing about the effects of climate change in terms of unusual animal behaviour, such as altering patterns of fish and bird migration. However, scientists at the University of Birmingham are trying out an ...

Burning extra calories with a 'futile protein cycle'

September 4, 2007

A new study in the September issue of Cell Metabolism points to a new method for burning off all those irresistible extra calories—by turning on an energy-draining, but otherwise futile, cycle of protein synthesis and breakdown.

Recommended for you

Mating induces sexual inhibition in female jumping spiders

October 18, 2017

After mating for the first time, most females of an Australian jumping spider are unreceptive to courtship by other males, and this sexual inhibition is immediate and often lasts for the rest of their lives, according to ...

Understanding the coevolving web of life as a network

October 18, 2017

Coevolution, which occurs when species interact and adapt to each other, is often studied in the context of pair-wise interactions between mutually beneficial symbiotic partners. But many species have mutualistic interactions ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.