Considering Local Adaptation in Issues of Lepidopteran Conservation-A Review and Recommendations

Article excerpt

ABSTRACT.-

Butterflies are among the most charismatic and alluring of invertebrate organisms. Their complex life histories and diverse habitat affiliations often produce regional variation and local adaptation among different populations. Unfortunately, numerous lepidopteran species are facing extinction. In this paper we address the importance of considering local adaptation in butterfly conservation and encourage investigations of regional specialization that may enhance the effectiveness of conservation strategies such as captive rearing, habitat restoration and the introduction of populations into new localities. We also give suggestions for dealing with problems arising from local adaptation in particular instances.

OVERVIEW

Preventing the loss of biodiversity is one of the most important challenges facing the scientific community (Wilson, 1992). Extinctions imperil the well-being of biological communities, diminish the effectiveness of ecosystem services and reduce the aesthetic value of the natural world for humans (Wilson, 1992; Luck et al, 2003). Recognition of these import contributions has resulted in a variety of programs aimed at slowing and reversing population declines.

Butterflies in particular have received a great deal of conservation attention, both for their scientific interest and for the appreciation they receive from the general public (PyIe, 1976). Protection of specific lepidopteran species can have far reaching, positive benefits for whole ecosystems and hence imperiled butterflies are worthy of both continued scientific inquiry and dedicated financial resources (Launer and Murphy, 1994; Emmel, 1995; Fleishman el al, 2000; Spitzer et al, 2009). Three of the most common and effective methods for protecting and enhancing butterfly populations are habitat restoration, captive rearing of individuals for release back into present populations and the establishment of new populations (New, 1991). This new establishment may be especially important with changes in climate permanently altering the long-term thermal landscape (Richardson et al, 2009). For each of these approaches, variation between populations and adaptation to specific local conditions can have a profound influence on the success of these efforts.

In species-specific conservation programs, the possibility of local adaptation is often only examined for one or a few potential impacts on survival and fitness (e.g., larval host-plant use; but see Pelini et al, 2009). Yet our work, and that of many others, shows that local adaptation across a wide array of life-history influences can be a very real concern for lepidopteran populations in decline. Adaptation, specifically evolutionary specialization driven by historical conditions, can hinder an organism's ability to adjust and propagate when conditions change (either naturally or because individuals are introduced to new locations; Yurk and Powell, 2009; Pelini et al, 2010). Likewise, selection that varies across space can create the formation of distinct ecotypes. As .a result, local adaptation and specialization is common among endangered butterflies and often hinders restoration efforts (Schultz et al, 2008; Nylin and Bergström, 2009).

Here we examine many of the factors that may generate local adaptation in lepidopteran populations in order to create awareness of potential problems that could impede recovery efforts. Our goal is to outline circumstances where local adaptation should be examined when plans to aid an imperiled species are initiated. Specifically, we address local adaptation in the context of captive rearing, habitat restoration and population introduction into new locations. We recognize that it would be impractical if not impossible for investigators to thoroughly research every component mentioned here for each species of concern. Rather, it is our hope that this review can suggest important avenues for inquiry and demonstrate why examination of local adaptation across many areas may be necessary for conservation success. …