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Why Are Bigger Offspring Better?

Credit: Eric Isselée/adobe

Bigger animals such as elephants use more energy, but they are also much more efficient users of energy. This allometric scaling of metabolism with mass may also occur with offspring size. Credit: Eric Isselée/adobe

By Amanda Pettersen

Bigger offspring have greater energy needs, so why do they survive and reproduce more successfully than their smaller siblings?

The full text of this article can be purchased from Informit.

We’ve all heard of the phrase: “A big baby is a healthy baby”, but this isn’t just an old wives’ tale. Larger offspring do perform better than smaller offspring, and this pattern has been observed by ecologists for decades. Across the many organisms that have been studied, including reptiles, birds, fish, insects and even in plants, we see that larger offspring are often “fitter” than smaller offspring. Larger offspring generally survive better, grow bigger, reproduce more and are less vulnerable to starvation and predation.

The effects of offspring size can pose consequences for later life. Not only do bigger offspring grow into fitter juveniles and adults; offspring size differences can affect later generations.

We wanted to know why this was the case. When it comes to offspring size, why is bigger, better?

Many studies have attempted to explain why this pattern occurs, and have tested some interesting theories. Some propose that larger offspring have more energy, which is a reasonable assumption. However, we must also consider that the energy required to maintain a larger size are also higher. Larger offspring may also be able to feed more successfully and therefore gain more energy than smaller offspring, or they might reach a size that gives them access to a refuge from predation.

Despite these intriguing insights into the advantages of...

The full text of this article can be purchased from Informit.