ABSTRACT
As fitness is a relative term, it is difficult to measure in nature. At present, longitudinal population studies and observations of resource allocation to different reproductive traits are the best sources of information for the development of theories to explain the evolution of life history tactics. Studies on terrestrial isopods suggest that tactics to maximise fitness are many and vary extensively even at the level of individual. Such flexibility, particularly in reproductive tactics, may be the key to the success of woodlice as terrestrial animals. In this review, we consider the available data on woodlice life histories from the evolutionary perspective of maintaining individual fitness. We consider the idea that proximate mechanisms must exist to allow the resource allocation 'decisions' within the overall reproductive pattern, and we discuss the constraints and limits to reproductive flexibility. These ideas are gathered into a suite of observations and testable hypotheses that we see as important for quantitative tests of reproductive flexibility as a strategy to maximise fitness in woodlice.
