Disentangling the effects of heterogeneity, stochastic dynamics and sampling in a community of aquatic insects

Reproducing static and dynamic biodiversity patterns in tropical forests: the critical role of environmental variance

“…It is also unclear a priori, because environmental variance results in substantial variations in the vital rates of different species and hence species evenness, and can also affect species richness by accelerating extinction of populations (Leigh 1981, Foley 1994, Halley and Iwasa 1998. Engen et al (2002Engen et al ( , 2011 and Lande et al (2003) made substantial contributions to answering the question posed by fitting a model with demographic and environmental variance (Engen and Lande 1996) to data from tropical butterfly communities in Amazonian Ecuador and riverine insect communities in Norway. Engen et al (2002Engen et al ( , 2011 and Lande et al (2003) made substantial contributions to answering the question posed by fitting a model with demographic and environmental variance (Engen and Lande 1996) to data from tropical butterfly communities in Amazonian Ecuador and riverine insect communities in Norway.…”

Analytical formulae for computing dominance from species-abundance distributions

“…200 and u 0.7 ). Given that many empirical SADs can be fitted by these three distributions (Fisher et al, 1943;Preston, 1948;Cohen 1968;Hubbell, 2001;Engen et al, 2002;Volkov et al, 2003;Forster and Warton, 2007;Engen et al, 2011; the lognormal distribution is typically mixed with a Poisson sampling distribution), the concentration of abundance in so few species that we typically found has important implications for community functioning and stability.…”

“…In this study, we examined four standard forms of SADs that together have commonly been fitted to empirical data (e.g, Fisher et al, 1943;Preston, 1948;Brian, 1953;Cohen, 1968;Hubbell, 2001;Engen et al, 2002;Plotkin and Muller-Landau, 2002;Volkov et al, 2003;Forster and Warton, 2007;Engen et al, 2011) and successfully derived analytical formulae quantifying dominance according to D u 1 p u , where p u is the minimum proportion of species required to account for a proportion u of all individuals (Table 1). We also examined the discrete broken-stick (MacArthur, 1957) and Zipf-Mandelbrot (Frontier, 1985) SADs, but due to the complexity of the SAD formulae, we were unable to derive corresponding analytical dominance formulae.…”

“…As u increases, more species are required for dominance of numerical abundance in the community considered. We examine four SAD forms that have been commonly studied and fitted to empirical data: the log-series (Fisher et al, 1943;Hubbell, 2001), exponential (Cohen, 1968), gamma (Brian, 1953;Plotkin and Muller-Landau, 2002;Forster and Warton, 2007) and lognormal (Preston, 1948;Engen et al, 2002;Volkov et al, 2003;Forster and Warton, 2007;Engen et al, 2011) forms. After deriving the dominance formulae, we 5 proceed to apply them to (i) gauge the levels of dominance expected in natural communities under biologically plausible scenarios; (ii) assess dominance in the metacommunity of tree species found in Amazonia, using the data of ter Steege et al (2013); and (iii) quantify how dominance is expected to change with increasing environmental variance, using the dynamic model of Engen and Lande (1996a).…”

How reliable are Malaise traps for biomonitoring? – A bivariate species abundance model evaluation using alpine Chironomidae (Diptera)

“…Engen et al . () showed that for assemblages of stoneflies and mayflies, the bivariate correlation between replicate samples was 0.935, and the over‐dispersion in the sampling accounted for 6.5% of the total variance. With a mean correlation for parallel samples of 0.967 for Diptera, the effect of over‐dispersion is very low (3.3% of the total variance) when using Malaise traps.…”