What tigers and kiwi birds have in common

Species that lack significant levels of genetic diversity have a big problem. And it's not just about ending up with tiger and kiwi bird versions of Cletus the Slack-Jawed Yokel. Beyond the risk of inbreeding, genetic diversity supplies the tools that help a species adapt to change. If there's not enough of it, then the species is more likely to die out when subjected to stressful conditions ... like, say, climate change.