The neutral theory of biodiversity with random fission speciation

Abstract

The neutral theory of biodiversity and biogeography emphasizes the importance of dispersal and speciation to macro-ecological diversity patterns. While the influence of dispersal has been studied quite extensively, the effect of speciation has not received much attention, even though it was already claimed at an early stage of neutral theory development that the mode of speciation would leave a signature on metacommunity structure. Here, we derive analytical expressions for the distribution of abundances according to the neutral model with recruitment (i.e., dispersal and establishment) limitation and random fission speciation which seems to be a more realistic description of (allopatric) speciation than the point mutation mode of speciation mostly used in neutral models. We find that the two modes of speciation behave qualitatively differently except when recruitment is strongly limited. Fitting the model to six large tropical tree data sets, we show that it performs worse than the original neutral model with point mutation speciation but yields more realistic predictions for speciation rates, species longevities, and rare species. Interestingly, we find that the metacommunity abundance distribution under random fission is identical to the broken-stick abundance distribution

The Unified Neutral Theory of Biodiversity and Biogeography at Age Ten

“…The likelihood of each generated data set is then compared with the likelihood of the real data; if the likelihood of this empirical data is around the median of the artificially generated likelihoods, the fit is good. Similar procedures have since been developed for more complex versions of the model, such as when multiple local communities are linked to the same metacommunity [53,55] or when other speciation mechanisms are considered [34,36,37,98].…”

“…An apparently more realistic alternative is random fission speciation, in which populations split into two daughter species at random [2]. Etienne and Haegeman [34] recently noted that this produces identical results to MacArthur's broken stick model [35], which was motivated by random apportioning of limiting resources to niches that would then dictate relative species abundances. Surprisingly, point mutation speciation fits empirical data much better than do random fission and a variety of other alternatives [34,36,37].…”

Why abundant tropical tree species are phylogenetically old

“…In most NTB models, new species arise by a process analogous to mutation; every new offspring has a (low) probability of mutating into the first member of a new species (1)(2)(3)(4). In others, species randomly split into two new species with a probability proportional to population size (1,5,6). NTB models are remarkably successful in predicting distributions of species abundances, particularly with the assumption of mutation speciation (4,7,8).…”

Espaço e diversificação: uma perspectiva teórica

“…Muito embora a relação entre a multinomial de soma zero e a broken-stick já tenha sido explorada (Etienne and Haegeman 2011), ao que me consta essa é a primeira investigação em que elas emergem como distribuições alternativas para um único modelo.…”

“…Originally Hubbell conjectured that speciation modes would have little impact on the neutral theory's predictions (Hubbell 2001), but it was latter shown that the particularities of each speciation mode had drastic outcomes on the predicted biodiversity distributions (Rosindell, Hubbell, and Etienne 2011). Versions of the neutral theory were developed incorporating many speciation modes such as random fission of the parent species (Etienne and Haegeman 2011), emerging species with fixed size and emerging species with size drawn from a variety of distributions (Hubbell 2003). All of these implementations, however, are phenomenological models of speciation in that the criterions that establish fission, which could be drawn from the vast pool of species definitions (Coyne and Orr 2004), and the mechanisms by which these criterions could be achieved are never explicitated.…”