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Along Came a Spider

A large female golden orb-web spider

A large female golden orb-web spider is often surrounded by many small males competing for proximity to her on the web. But size isn’t the only factor determining who wins each fight.

By Michael Kasumovic

The comparative size and weight of two animals determines the outcome of 80% of fights. Now a small spider has revealed the physiological factors that help explain the other 20% of contests.

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

Predicting winners and outcomes in sporting events is a billion dollar industry. There are complex algorithms that use winning and loss percentages, the location of the game, the players playing and even personal player feelings. Given all the variables, it’s quite impressive that anyone can predict anything at all!

Yet predicting contest outcomes in the animal kingdom is relatively simple. Think of male lions brawling over a pride, elephant seals fighting over a harem or butterflies aggressively flitting over a sunny spot. In each of these instances you could predict the winner by simply measuring the size, weight or weaponry of each of the competitors before the contest. In fact, using any one of these traits alone gives you about 80% accuracy.

But if you’re like me you realise that this is only a part of the story, and wonder why these traits aren’t perfect predictors. Which factors explain the other 20%?

One of our recent studies provides some insight into these questions. When controlling for weight and size, we discovered that a male’s internal physiology plays an important role in winning competitions. What this means is that what our parents have been telling us is true: it really is what’s inside that counts.

Why Size Isn’t Everything

Along with navigating a world full of predators, individuals must acquire various resources...

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