Evaluating the influence of connectivity and distance on biogeographical patterns in the south‐western deserts of North America

Abstract

Aim To examine the role of geological history, connectivity and distance in shaping the biogeographical structure of North American desert clades that are restricted to habitat islands (sand dunes and relictual aquatic habitats), using statistical model choice on old and new probabilistic biogeographical models.Location North America, Mojave, Sonoran and Chihuahuan Deserts.Materials and methods Dated phylogenies were estimated for three fieldsampled insect clades (Trigonoscuta, Rhaphiomidas and sand treader crickets), and five other literature-sampled clades (the snails Assiminea, Pyrgulopsis and Tryonia; the desert fringe-toed lizard Uma; and the desert pupfish Cyprinodon).BioGeoBEARS was used to statistically compare biogeographical models assuming unconstrained or connectivity-constrained dispersal, with or without founder-event speciation (jump dispersal) permitted. Finally, we introduce and test a novel distance-based dispersal model (+x) where dispersal probability is multiplied by distance to the power x.Results We observed little concordance between biogeographical patterns and timing of geological events. Model comparisons were decidedly in favour of inclusion of founder-event speciation in the models for most taxa, with only a small taxon, Uma, showing support for the model favouring vicariance. The inclusion of a constrained-dispersal matrix was favoured by three of the eight taxa examined (Cyprinodon, sand treader crickets, and Trigonoscuta). Surprisingly, tests for distance influencing dispersal probability were mostly negative. Main conclusionsOur results do not show support for any one geological event shaping the biogeographical patterns of these desert taxa. Instead, the histories of desert dune and aquatic taxa are largely products of rare jump dispersal events, and can be considered island-like systems. Although results are negative for the distance-based dispersal model, this in itself demonstrates the superiority of explicit statistical model testing over a priori assumption of fixed models in historical biogeography.

Multiple colonizations, hybridization and uneven diversification in Cyrtandra (Gesneriaceae) lineages on Hawai'i Island

“…() found the BayArea‐like+j+x model (Bayesian Inference of Historical Biogeography for Discrete Areas; Landis, Matzke, Moore, & Huelsenbeck, ) to be the best model for describing biogeographic patterns in Hawaiian Cyrtandra , thus we used this model to estimate ancestral areas in the present study. This model includes anagenetic dispersal and extinction as base parameters, as well as the free parameters “ j ” (founder events; Matzke, ) and “ x ” (dispersal distance; Van Dam & Matzke, ), which are likely important for understanding biogeographic patterns on islands. The ultrametric SNAPP tree was pruned to remove outgroup taxa and used to reconstruct ancestral areas.…”

“…Tree topology and node ages were visualized in Figtree. as well as the free parameters "j" (founder events; Matzke, 2014) and "x" (dispersal distance; Van Dam & Matzke, 2016), which are likely important for understanding biogeographic patterns on islands. The ultrametric SNAPP tree was pruned to remove outgroup TA B L E 2 Collection details for Cyrtandra taxa across the main Hawaiian Islands, including island, sampling locality, species and number of individuals sampled.…”

Biodiversity and Topographic Complexity: Modern and Geohistorical Perspectives

“…The Pliocene peak in rodent diversity within the active and passive regions also fits this model, since warming should stimulate geographic-range shifts into both regions. More elaborate scenarios, such as speciation following range expansion along specific dispersal routes (e.g., [50]), can also be tested.…”

“…In SSE models, speciation or extinction rate can vary as a function of a character state (or geographic region) that itself is evolving on the tree [88]. The complexity and flexibility of SSE models also raise challenges [89,90], with some already being addressed [50,91]. …”

Long distance dispersal in the assembly of floras: A review of progress and prospects in North America

“…In addition to investigating founder effects, spatially explicit models represent an alternative way to test dispersal hypotheses for widespread, disjunctive temperate forest species (Cain et al, ). These models represent expectations about the geographic patterns resulting from a combination of different parameters, including dispersal (Dunning et al, ; Cain et al, ; van Dam & Matzke, ). Thus, it is possible to test whether models that integrate dispersal are a better fit for the demographics of disjunctively distributed species.…”