Estimating changes in species abundance from occupancy and aggregation

Hui, Cang, Boonzaaier, Carmen, and Boyero, Luz (2012) Estimating changes in species abundance from occupancy and aggregation. Basic and Applied Ecology, 13 (2). pp. 169-177.

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Predicting the change in abundance is pivotal for evaluating species' current conservation status and population viability. Empirical works have suggested that species with an increasing abundance have a more aggregated distribution than those with a declining abundance (namely, the change-aggregation hypothesis, CAH). Here we introduced an improved negative binomial distribution model of the occupancy-abundance relationship (OAR) to estimate the change in abundance from changes in occupancy or aggregation. Analysis of the model suggests that (i) in general the change in abundance is synchronized with the change in occupancy when the level of environmental heterogeneity remains constant, and (ii) there could exist a threshold of the population density above which the CAH is no longer valid. Tests using data of epigaeic ants in Fynbos of South Africa collected from different seasons and macro-invertebrates from different localities in streams of central Spain verified these model propositions and thus support the use of this model as a monitoring method for assessing species persistence. Results suggest that the change in abundance can be estimated from the change in occupancy often obtained from cost-efficient presence-absence records, and a revision of the traditional CAH is necessary to capture the threshold phenomenon in the change-aggregation relationship. This work thus signifies the use of the three distinct but related concepts of population structure (i.e. occupancy, abundance and aggregation) in conservation biology.

Item ID: 22639
Item Type: Article (Research - C1)
ISSN: 1439-1791
Keywords: aggregation, occupancy-abundance relationship, spatiotemporal dynamics, change-aggregation hypothesis, epigaeic ants, stream invertebrates
Funders: NRF Blue Sky Programme, DST-NRF Centre of Excellence for Invasion Biology
Date Deposited: 01 Aug 2012 09:24
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060204 Freshwater Ecology @ 100%
SEO Codes: 96 ENVIRONMENT > 9609 Land and Water Management > 960999 Land and Water Management of Environments not elsewhere classified @ 100%
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