Describes a creature which, through
evolution or
experience, or lack of either one, has failed to develop
traits which are useful in its current
environment,
and/or has developed traits which are positively harmful.
For example, deer stand still and stare when they see headlights. This is bad for the car or train attached to those headlights, and worse for the deer.
Humans who have 'normal' blood (i.e. do not have sickle cell anaemia) are vulnerable to malaria. In an environment with malaria, the normally maladaptive trait of sickle cell anaemia becomes highly adaptive, and vice versa.
One recent problem for various species, especially migratory ones is that the hard-wired cues they use to choose when to migrate are going out of synch due to climate change. They arrive at their destination, only to find their food source gone, or not yet ready.
On a lighter note, creatures who have lived in AOL chat rooms are often maladapted to E2, though they can quickly readapt. On the other hand, people who piss off flamers are always maladapted. ;)