Testing Surrogacy Assumptions: Can Threatened and Endangered Plants Be Grouped by Biological Similarity and Abundances?

Abstract

There is renewed interest in implementing surrogate species approaches in conservation planning due to the large number of species in need of management but limited resources and data. One type of surrogate approach involves selection of one or a few species to represent a larger group of species requiring similar management actions, so that protection and persistence of the selected species would result in conservation of the group of species. However, among the criticisms of surrogate approaches is the need to test underlying assumptions, which remain rarely examined. In this study, we tested one of the fundamental assumptions underlying use of surrogate species in recovery planning: that there exist groups of threatened and endangered species that are sufficiently similar to warrant similar management or recovery criteria. Using a comprehensive database of all plant species listed under the U.S. Endangered Species Act and tree-based random forest analysis, we found no evidence of species groups based on a set of distributional and biological traits or by abundances and patterns of decline. Our results suggested that application of surrogate approaches for endangered species recovery would be unjustified. Thus, conservation planning focused on individual species and their patterns of decline will likely be required to recover listed species.

Comparative Analysis of Plant Demographic Traits Across Species of Different Conservation Concern: Implications for Pesticide Risk Assessment

“…Previous studies have grouped listed species in the low end of such axes, implying poor population performance, low reproductive potential, and slow life histories. Although demographic traits of listed species have been suggested to be fairly localized within the continuum of life histories, other research has found no evidence of species clusters based on biological traits (e.g., maximum plant height, maximum flower size, life form, life‐history duration, reproductive mode, reproductive repetition, physiographic division, and range area) and abundance at listing, at and after recovery plan writing (Che‐Castaldo and Neel ).…”

Assessing the umbrella value of a range-wide conservation network for jaguars (Panthera onca)

“…Surrogates are used as short-cuts for monitoring biodiversity and ecosystem health, or for prioritizing areas for conservation, and thus are a key component of conservation efforts of a variety of organizations (Caro 2010). Despite their widespread usage, the effectiveness of the surrogate species strategy is contentious and faces theoretical (Saetersdal and Gjerde 2011) and empirical (Andelman and Fagan 2000, Bifolchi and Lodé 2005, Fleishman and Murphy 2009, Che-Castaldo and Neel 2012 challenges. This lack of certainty in the efficacy of surrogate species may contribute to the criticism of single species conservation efforts and increasing interest in more holistic ecosystem management approaches (Simberloff 1998, Mac Nally et al 2002, Lindenmayer et al 2007).…”

Actual and Potential Use of Population Viability Analyses in Recovery of Plant Species Listed under the U.S. Endangered Species Act

“…In this context, detailed demographic data for one species could be used to guide the formulation of recovery criteria for biologically similar species. Unfortunately, there is no evidence that listed plant species are sufficiently similar to form surrogate groups (Che‐Castaldo & Neel ), and even closely related or biologically similar species do not have similar population growth rates (Buckley et al ; Flather et al ). This lack of similarity and predictability is not surprising given demographic variations among populations within species, as we found here.…”