An integrated framework to improve the concept of resource specialisation

Author(s)

Jorge, Leonardo R. ^[1] ; Prado, Paulo I. ^[2] ; Almeida-Neto, Mario ^[3] ; Lewinsohn, Thomas M. ^[1]

Affiliation

^[1] Univ Estadual Campinas UNICAMP, Inst Biol, Dept Biol Anim, BR-13083970 Campinas, SP - Brazil

^[2] Univ Sao Paulo, Inst Biociencias, Dept Ecol, LAGE, BR-05508900 Sao Paulo - Brazil

^[3] Univ Fed Goias, ICB, Dept Ecol, BR-74001970 Goiania, Go - Brazil

• Document type: Journal article
• Source: ECOLOGY LETTERS; v. 17, n. 11, p. 1341-1350, NOV 2014.
• Web of Science Citations: 17

Abstract

Resource specialisation, although a fundamental component of ecological theory, is employed in disparate ways. Most definitions derive from simple counts of resource species. We build on recent advances in ecophylogenetics and null model analysis to propose a concept of specialisation that comprises affinities among resources as well as their co-occurrence with consumers. In the distance-based specialisation index (DSI), specialisation is measured as relatedness (phylogenetic or otherwise) of resources, scaled by the null expectation of random use of locally available resources. Thus, specialists use significantly clustered sets of resources, whereas generalists use over-dispersed resources. Intermediate species are classed as indiscriminate consumers. The effectiveness of this approach was assessed with differentially restricted null models, applied to a data set of 168 herbivorous insect species and their hosts. Incorporation of plant relatedness and relative abundance greatly improved specialisation measures compared to taxon counts or simpler null models, which overestimate the fraction of specialists, a problem compounded by insufficient sampling effort. This framework disambiguates the concept of specialisation with an explicit measure applicable to any mode of affinity among resource classes, and is also linked to ecological and evolutionary processes. This will enable a more rigorous deployment of ecological specialisation in empirical and theoretical studies. (AU)

• FAPESP's process: 98/05085-2 - Species and interaction diversity in plants and phytophagous insects
• Grantee: Thomas Michael Lewinsohn
• Support Opportunities: BIOTA-FAPESP Program - Thematic Grants