Comparative performance of species richness estimation methods

B. A. WALTHER a1c1p1 and S. MORAND a2
a1 Department of Zoology, Oxford University, Oxford OX1 3PS, UK
a2 Centre de Biologie et d'Écologie tropicale et méditerranéenne, Université de Perpignan, 66860 Perpignan, France


In most real-world contexts the sampling effort needed to attain an accurate estimate of total species richness is excessive. Therefore, methods to estimate total species richness from incomplete collections need to be developed and tested. Using real and computer-simulated parasite data sets, the performances of 9 species richness estimation methods were compared. For all data sets, each estimation method was used to calculate the projected species richness at increasing levels of sampling effort. The performance of each method was evaluated by calculating the bias and precision of its estimates against the known total species richness. Performance was evaluated with increasing sampling effort and across different model communities. For the real data sets, the Chao2 and first-order jackknife estimators performed best. For the simulated data sets, the first-order jackknife estimator performed best at low sampling effort but, with increasing sampling effort, the bootstrap estimator outperformed all other estimators. Estimator performance increased with increasing species richness, aggregation level of individuals among samples and overall population size. Overall, the Chao2 and the first-order jackknife estimation methods performed best and should be used to control for the confounding effects of sampling effort in studies of parasite species richness. Potential uses of and practical problems with species richness estimation methods are discussed.

(Received June 13 1997)
(Revised August 9 1997)
(Revised September 26 1997)
(Accepted September 26 1997)

Key Words: species richness; estimation methods; sampling methods; diversity; species accumulation curves; jackknife; bootstrap.

c1 Corresponding author: Hauptstrasse 25, 27432 Ebersdorf, Germany. Tel: +49 4765 431.
p1 Present address: Hauptstrasse 25, 27432 Ebersdorf, Germany.