INTRODUCTION

Conservation genetics is a maturing discipline. Since the millennium and with an established field-specific journal, large numbers of papers are published in the field and many relevant issues are debated widely in the literature. Perhaps still the most active of these debates centres on the longstanding issue of identifying and diagnosing units for conservation. The purpose of this short essay is to take up a few threads from this debate, dating back to 2000 when Crandall et al. (2000) published an article in Trends in Ecology and Evolution (TREE), suggesting the use of ecological and genetic exchangeability as criteria for diagnosing conservation units, an article that was pivotal in encouraging the debate towards adaptive variation in conservation, the general theme of this essay. I do not intend to exhaustively review earlier discussions on the issue, which most observers would agree dates back to Ryder's paper in the first issue of TREE in 1986. Here I will briefly overview recent opinions on diagnosing units for conservation and the role of neutral and adaptive genetic variation in this. I will focus a little on one controversial example, which serves to shed light on where some of the current debate is focused. I will then discuss perhaps the major recent development in conservation unit designation: the use of adaptive genetic markers, the concept of exchangeability and a recent proposal for a ‘Population Adaptive Index’. Finally, I will briefly discuss the issue of predictive conservation genetics and how geneticists and wildlife managers might coalesce around using new tools to take present-day molecular data and evaluate the likely changes in diversity under different management approaches that may be applied.

CURRENT SITUATION

One of the key elements of the current debate about how and whether adaptive genetic variation should be assayed when assessing conservation units is to what extent neutral genetic diversity can or should be used as a proxy for adaptive diversity or adaptive potential.