Accounting for non-independence of extinction probabilities in the derivation of conservation priorities based on Weitzman’s diversity concept

Abstract

In the original formulation of Weitzman's diversity concept, extinction probabilities of different operational taxonomic units (OTUs) are implicitly defined to be independent. In this study, it is shown, that dependencies like concurrence or synergistic relations between OTUs can be accounted for by assuming that joint extinction probabilities differ from the product of the extinction probabilities of the interacting OTUs. A fully analytical treatment is provided for the case of two interacting OTUs, and all cases are illustrated with an example data set. For the case of concurring OTUs, the following general results are derived: (a) concurrence between OTUs always reduces the amount of diversity expected to be conserved in the future; (b) concurrence has a more adverse effect on the more endangered OTUs involved; (c) concurrence can change conservation priorities between OTUs; and (d) with high levels of concurrence, investments in the conservation of some of the concurring OTUs can have a negative effect on the overall diversity conserved. In addition to conservation activities targeted towards some of the OTUs, reduction of the causes of concurrence may be a valid and cost-efficient alternative. For the case of synergistic dependencies between OTUs it was found, that such dependencies always increase the conservation potential of the involved OTUs but may lead to a change of priority ranking in extreme cases. Finally possible extensions and generalisations of the suggested approach are discussed and it is argued, that by adopting these extensions Weitzman's diversity concept becomes an even more powerful and flexible tool to derive conservation priorities both in an ecological and in a farm animal context.

A Cost–Benefit Approach for Prioritizing Invasive Species

“…Two key theoretical contributions are made: i) we explicitly model species interdependences allowing per se to apprehend the complexity of impacts resulting from invasive species, and ii) we assume a multi-component objective function combining ecological and economic considerations. It results that as in Weitzman's Noah's Arch approach (Weitzman, 1998) and related literature (Baumgärtner, 2004;van der Heide et al, 2005;Simianer, 2008;Courtois et al, 2014), a multi-component objective as well as species interrelations are accounted for in our optimization procedure. Finally, a last contribution and key motivation of this paper is to develop the the-3 It is currently being hailed for its success and adapted to other European countries, and may likely lead to the first continental-scale eradication of an invasive species .…”

“…12 Weitzman (1998) first studied conservation choices using this methodology and extensions of his work were proposed by Baumgärtner (2004), van der Heide et al (2005), Simianer (2008) and Courtois et al (2014). Other ecological objectives could be considered as for example preserving the ecological functions of the ecosystem.…”

Markovian log-supermodularity, and its applications in phylogenetics

“…1. The assumption that the events E x are independent is likely to be unrealistic in most settings (see, for example, [11,12]). For example, species 'close together' in T are more likely to share attributes that may put them at risk in a hostile future environment.…”

Trait-Dependent Extinction Leads to Greater Expected Biodiversity Loss

“…However, the assumption that the events E x are independent is likely to be unrealistic in most settings (see, for example, [8,14]). In particular, rates at which lineages become extinct may be influenced by some species traits [10,6].…”

“…It is easy to see that these conditions can be satisfied by some t-FOB model (together with its g-FOB) on T . Additionally, for any such t-FOB model, a value of λ a can be chosen that is large enough in relation to λ b and λ c so that λ 2 a Cov[Y a , Y a ] is the dominant term in (14), resulting in a greater total variance for the corresponding g-FOB.…”