A simple spatially explicit neutral model explains the range size distribution of reef fishes

Abstract

Aim The great variation in range sizes among species has fascinated ecologists for decades. Reef‐associated fish species live in highly spatially structured habitats and adopt a wide range of dispersal strategies. We consequently expect species with greater dispersal ability to occupy larger ranges. However, empirical evidence for such a positive relationship between dispersal and range size remains scarce. Here, we unveil the role of dispersal on the range size distribution of reef‐associated fishes using empirical data and a novel spatially explicit model. Location Tropical Eastern Pacific. Major taxa studied Reef‐associated fishes. Time period Underlying records are from the 20th and 21st centuries. Methods We estimated range size distributions for all reef‐associated fishes separated into six guilds, each with different dispersal abilities. We used a one‐dimensional spatially explicit neutral model, which simulates the distribution of species along a linear and contiguous coastline, to explore the effect of dispersal, speciation and sampling on the distribution of range sizes. Our model incorporates biologically important long‐distance dispersal events with a fat‐tailed dispersal kernel and also adopts a more realistic gradual “protracted” speciation process than originally used in neutral theory. We fitted the model to the empirical data using an approximate Bayesian computation approach, with a sequential Monte Carlo algorithm. Results Stochastic birth, death, speciation and dispersal events alone can accurately explain empirical range size distributions for six different guilds of tropical, reef‐associated fishes. Variation in range size distributions among guilds are explained purely by differences in dispersal ability with the best dispersers being distributed over larger ranges. Main conclusions Neutral processes and guild‐specific dispersal ability provide a general explanation for both within‐ and across‐guild range size variation. Our results support the theoretically expected, but empirically much debated, hypothesis that high dispersal capacity promotes the establishment of large range size.

Spatial genetic differentiation correlates with species assemblage turnover across tropical reef fish lineages

“…It is also worth noting that divergence times for most species belonging to the studied families (e.g., Gaboriau et al, 2018; Hodge et al, 2014) pre‐date the period of establishment of the Monsoon Drift (circa 13 million years ago) in response to the onset of the Indian Monsoon (see Betzler et al, 2013). Overall, these findings add weight to previous results derived from neutral process‐based models, which show that dispersal processes, by mediating vicariance, accurately predict α‐ and β‐diversity patterns (Leprieur et al, 2016) as well as range size variation (Alzate et al, 2019) in tropical reef fishes. More generally, our results highlight the importance of dispersal barriers and neutral processes in the maintenance of both genetic and community structure, as expected by recent theoretical developments (see Baselga et al, 2022).…”

gen3sis: A general engine for eco-evolutionary simulations of the processes that shape Earth’s biodiversity

“…The first landscape class contains (i) the geographic coordinates of the landscape sites; (ii) the corresponding information on which sites are generally suitable for a clade (e.g., land or ocean); and (iii) the environmental conditions (e.g., temperature and aridity). The landscape may be simplified into a single geographic axis (e.g., [72]) for theoretical experiments, or it may consider realistic configurations aimed at reproducing real local or global landscapes [26,73,74]. The second landscape class defines the connectivity of the landscape, used for computing dispersal and consequently isolation of populations.…”

Species‐range‐size distributions: Integrating the effects of speciation, transformation, and extinction

“…These include studies with a particular focus on inferring speciation modes (Cardillo, 2015;Phillimore & Price, 2008;Skeels & Cardillo, 2019), phylogenesis (Albert et al, 2017;Pigot et al, 2010), niche evolution (Rangel et al, 2007(Rangel et al, , 2018, size-age relationship of geographic ranges (Pigot et al, 2012), and the heritability of range size (Borregaard et al, 2012). In addition to the focus on individual species-range sizes, previous studies also shed light on the shape and the underlying mechanisms of the emergent distributions of range size across many species (e.g., Alzate et al, 2019;Anderson, 1985;Gaston & He, 2002;Pigot et al, 2010;Rangel et al, 2007). In early work, Anderson (1985) focused on range-size distributions using an algorithm with nine different scenarios for range dynamics (speciation is associated with an extinction event in the algorithms) to generate range-size distributions resembling faunal data for North American vertebrates.…”