Using empirical field data of aquatic insects to infer a cut-off slope value in asymptotic models to assess inventories completeness

Abstract

The selection of the most appropriate model is essential to predict the potential species richness of a site or landscape. Species accumulation curves have been used as a basic tool for comparing richness when different sampling protocols have been applied. Among the parameters generated by these models the slope has been cited as an indicator of completeness without regard to a defined cut-off value. In this work, we fit 12 field data sets of aquatic Coleoptera (Hidalgo) and Odonata larvae (Michoacán) to 2 asymptotic models (Clench and Linear Dependence) in order to calculate the slopes at the maximum effort and relate them with efficiency. Then, the theoretical effort needed to achieve the 95% of the lists was calculated for each data set in order to get the theoretical slopes. The average slope value found was 0.01 with a variance of <0.001, so we propose this value as indicative of a list reaching 95% of completeness for data obtained from similar sampling protocols. Additionally, we propose the use of number of rare species as an additional criterion to evaluate the inventories completeness. The effect of different sampling intensity on fitted models and estimation of parameters and the importance of a cut-off slope value in asymptotic models as a criterion to evaluate completeness of biological inventories are discussed.

Altitudinal and seasonal distribution of butterflies (Lepidoptera, Papilionoidea) in Cerro Bufa El Diente, Tamaulipas, Mexico

“…To complement the estimation of richness, and as a measure for the analysis of sampling efficiency, the linear dependence model was used. It assumes that as the list of species increases, the probability of adding new taxa decreases exponentially, and is an ideal model for studying small areas and known taxa (Gómez-Anaya et al 2014). The value obtained from the coefficient of determination (R 2 ) was used, as well as the slope value, which allows to measure the quality of the faunistic inventory.…”

Optimized grid representation of plant species richness in India—Utility of an existing national database in integrated ecological analysis

“…These curves attain asymptoteness when the probability of addition of new species approaches zero; they are non-asymptotic otherwise. Two parameters have been suggested for assessing sampling sufficiency: (i) the slope of the species accumulation curve, which describes the rate of addition of new species [ 18 ], [ 8 ], and (ii) the ratio of the total species richness expected from the richness estimators to the observed species richness [ 19 ], [ 20 ]. Recently Pardo et al [ 14 ] used FIDEGAM, which is based on species accumulation curves, under different scenarios of sampling exhaustiveness, with receiver operating characteristic (ROC) analyses to quantify sampling sufficiency.…”

Size-frequency distribution of coral assemblages in insular shallow reefs of the Mexican Caribbean using underwater photogrammetry

“…To model the relationship between the sampling effort and the number of species observed, the data were fitted to the asymptotic Clench model (Jiménez-Valverde & Hortal, 2003;Gómez-Anaya et al, 2014). The model equation used to estimate the number of predicted coral species for each reef was: S(x) = ax/(1 + bx), where x is a measure of sampling effort, S(x) is the predicted number of species at effort x, a represents the rate of increase at the beginning of sampling, b is a parameter related to the form of the accumulation curve and a/b is the asymptote.…”