Beta Diversity in Spatially Implicit Neutral Models: A New Way to Assess Species Migration

Abstract

The spatially implicit neutral model (SINM) of S. P. Hubbell predicts species' abundance distributions at two levels: local communities where extinction balances immigration, characterized by the immigration number I, and the metacommunity, a source pool of migrants where speciation balances extinction. Previously, a plot's I was estimated from its species abundance distribution. Here, we relate neutral theory to the additive partitioning of species diversity and calculate the immigration rate into different plots from the variation in species composition among them. We revisit the G(ST) statistic of population genetics to introduce a new version, G(ST)(k), conditional on each community sample k. We derive an analytical expectation of G(ST)(k) as a function of the local immigration number, I(k), under a generalized version of the SINM, which allows the pool of migrants to deviate from the large-scale speciation-extinction balance. Simulations and field data suggest that G(ST)(k) provides reasonable estimates of immigration numbers, which were compared with the results from alternative likelihood-based estimations.

Zeta Diversity as a Concept and Metric That Unifies Incidence-Based Biodiversity Patterns

“…As a result, here we discuss only the implications of these two specific forms of z diversity decline for incidence-based biodiversity patterns. The exponential and power-law forms of z diversity decline are underpinned by distinct hypotheses about ecological process; that is, they represent species turnover as either largely stochastic (exponential z) or driven principally by niche differentiation processes (power-law z; Munoz et al 2008;Scheiner et al 2011).…”

Estimating immigration in neutral communities: theoretical and practical insights into the sampling properties

“…I(k) controls the probability of drawing a new individual that belongs to a lineage not represented in the sample (Etienne 2005, Munoz et al 2008, but which may be already present in the community.…”

“…Under the key assumption of 'ecological equivalence', namely that individuals have equal fitness whatever their species or habitat, Hubbell (2001) and followers (Etienne 2005) proposed a twolevel spatially implicit neutral model (so-called 2L-SINM by Munoz, Couteron, & Ramesh 2008; see a synthesis in Beeravolu et al 2009 and present Fig. 1a left) to decouple the dynamics of the large biogeographical background (i.e.…”

“…From a theoretical standpoint, neutral models can help us grasp how the interaction between limited immigration and local 'ecological drift' (Hubbell 2001) may influence taxonomic composition. Munoz, Couteron, & Ramesh (2008) have further proposed to relax the assumptions made by Hubbell (2001) at the upper level (i.e. the metacommunity) and to generalize the initial 2L-SINM into a 3L-SINM, by introducing an intermediate level, the regional pool of migrants, which may be shaped by non-neutral influences (Fig.…”

“…Although inferring Hubbell's parameters motivated a great deal of research in recent years leading to several estimation methods (Volkov et al 2003;Etienne 2005Etienne , 2009Munoz et al 2007;Munoz, Couteron, & Ramesh 2008), the rapidly growing number of applications to real-world data sets has raised questions about how to assess the reliability of the inference, even in the strictly neutral case. Furthermore, published methods have frequently led to substantially differing parameter estimates when applied to the same data sets (see for instance Latimer, Silander, & Cowling 2005;Etienne et al 2006;Etienne 2009, Table 1).…”