1 - Introduction

Summary

And of every living thing of all flesh, two of every sort shalt thou bring into the ark.

Genesis

Definition: How much is enough?

Given biblical precedence, it is not surprising that for millennia, a pair (male and female) has been deemed sufficient to initiate, if not perpetuate, a population. In fact, there is more than scriptural authority behind this myth. With luck, two can indeed be a sufficient number of founders.

What is luck? Without going into theories of randomness and probability, luck implies a fortunate or unusual circumstance leading to a good result. The result of interest in this book is the survival of a population in a state that maintains its vigor and its potential for evolutionary adaptation. Such a population is a viable population. Legend does not question Noah's success with each of his multitudinous experiments. He must have been very lucky indeed. He also had some advantages over us, not the least of which was a fresh, well-watered planet.

The problem that we address in this book is ‘How much is enough?’. Put more concretely, it is: What are the minimum conditions for the long-term persistence and adaptation of a species or population in a given place? This is one of the most difficult and challenging intellectual problems in conservation biology.