Why youth is overrated

The youngest species do not always do better, it appears that evolutionarily ancient animals are better equipped to deal with future environmental stresses

There are many factors to consider when looking at the success of a species. Habitat, hunting prowess and how quickly it can reproduce, to name but a few.

It is now apparent that we can add evolutionary age into the mix.

A new study in the journal BMC Evolutionary Biology, finds that some of the most ancient vertebrate species alive today may in turn do better in future periods of dramatic climate change.

That's because they are better equipped to adapt to future environmental stresses, precisely because their ancient relatives have done so before.

The traits associated with their success could also predict how well other threatened species might survive.

Five years ago a team led by Sylvain Dubey of the University of Lausanne in Switzerland, started to look at the evolutionary age of vertebrate species to see if they could identify common features shared by old and young species.

They combed through the family trees of over 600 vertebrates to understand whether or not those features are specific to certain animal groups.

"We found a huge variety of patterns not specific to groups, not just birds or mammals," says Dubey.

That is, if a species of bird, mammal, amphibian or fish was viviparous - those that give birth to live young - it tended to have existed for longer than its egg-laying or "oviparous" counterparts.

But this effect was closely tied to which latitude they lived in.

Oviparous animals need to lay eggs in environments with a reasonably warm ambient temperature for their offspring to survive.

Viviparous animals on the other hand can move around to optimal environments before birth takes place, so they are better at surviving in cold regions, and better at coping with episodes of global cooling associated with ice ages.

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