Genetic Considerations for Carnivore Conservation in the Greater Yellowstone Ecosystem

Introduction

With the recent reintroduction of the wolf, the Greater Yellowstone Ecosystem has logically recovered the carnivore community that persisted in the Northern Rockies since the end of the Pleistocene. This is to say that the species list of carnivores (see Table 1) is the same as one that might have be written 10,000 or 5,000 years ago. Having now managed to restore the preexisting alpha-level of carnivore diversity, conservationists and federal land managers face the problem of sustaining and conserving this system in a manner that can plausibly be represented as ³healthy.²

Ecological health can be looked within the varying time frames of ecological, community and population dynamic processes. It can also be looked at over various spatial scales, those of the landscape, ecosystem, community or that of populations of the individual species. Other chapters in this volume will consider some of these approaches.

In this chapter, we consider the question of conserving healthy biodiversity of the Greater Yellowstone Ecosystem carnivore community from the species viewpoint, at the level of genetics. Genetics cannot neatly be isolated from other levels of ecological process. However, as we argue below, maintaining genetic diversity is the necessary foundation for the successful resolution of these conservation issues at the higher levels of ecological organization. While concentrating mainly on population genetic processes, we try to point out connections to other levels in the discussion to follow.

There are many areas where genetical and population genetical knowledge can enlighten and inform conservation decision making. For instance, spatial patterns of allele frequencies can help fisheries scientists delineate distinct stocks that individually require different harvest quotas for sustainable yield. We focus on the salient feature that the GYE is an island ecosystem (or it soon will be) from the standpoint of the constituent carnivore species. On islands, a big management concern is extinction. In this chapter, we seek to explore the relationship between genetics and extinction probabilities.

A big genetic question is whether island populations can be maintained that are large enough to ensure long-term fitness and evolutionary potential (Soule 1980). Such populations should be able to adjust to long-term environmental change. As we shall soon argue, none of the GYE carnivore populations are large enough to sustain sufficient levels of genetic diversity over millennia. Given that they are not that large, the next genetic question becomes whether the present population size has captured and can sustain sufficient genetic diversity to avoid short-term (decades or generations) loss of fitness due to inbreeding and stochastic processes. This is the question that we will grapple with in this chapter.

The following sections of this chapter will discuss the relevant genetic theory, the molecular tools available for empirical genetic research, and current applications of those tools to carnivore populations. We shall explore what we feel are the most important genetical considerations for each species of carnivore, and we shall place these in the context of current best genetic management practice (e.g., Ralls and Ballou 1983, 1986), explaining aspects of data collection and associated uncertainties. We shall also briefly touch on the implications of recent results for carnivore management in the Greater Yellowstone Ecosystem.