The Biogeography of Adaptive Radiations and the Geographic Overlap of Sister Species

Abstract

Originally published at: Pontarp, Mikael; Ripa, Jörgen; Lundberg, Per (2015). The biogeography of adaptive radiations and the geographic overlap of sister species. The American Naturalist, 186(5):565-581. DOI: https://doi.org/10.1086/683260The University of Chicago Online enhancement: appendix.abstract: The biogeography of speciation and what can be learned about the past mode of speciation from current biogeography of sister species are recurrent problems in evolution. We used a trait-and individual-based, eco-evolutionary model to simulate adaptive radiations and recorded the geographical overlap of species during and after evolutionary branching (speciation). We compared the spatial overlap among sister species in the fully saturated community with the overlap at the speciation event. The mean geographic overlap at speciation varied continuously from complete (sympatry) to none (allopatry), depending on local and regional environmental heterogeneity and the rate of dispersal. The distribution of overlap was, however, in some cases considerably bimodal. This tendency was most expressed at large values of regional heterogeneity, corresponding to sharp environmental contrasts. The mean geographic overlap also varied during the course of a radiation, sometimes with a consistent negative trend over time. The speciations that resulted in currently observable end community sister species were therefore not an unbiased sample of all speciations throughout the radiation. Postspeciation range shifts (causing increased overlap) occurred most frequently when dispersal was high or when local habitat heterogeneity was low. Our results help us understand how the patterns of geographic mode of speciation emerge. We also show the difficulty in inferring the geographical speciation mode from phylogenies and the biogeography of extant species.

Ecological opportunity and predator–prey interactions: linking eco-evolutionary processes and diversification in adaptive radiations

“…Similar to, for example, Doebeli & Dieckmann [ 36 ] we assume that consumer–resource and consumer–consumer trait matching dictates resource utilization and competition respectively. Given these general assumptions and similar to previous community models [ 9 , 10 , 38 ], the per capita growth (fitness) of a focal competitor individual associated with a given population is thus a function of its resource utilization trait, the abundance of the individual's own population, the local resource distribution and the abundance of all other populations competing for the same resources. The fitness of a predator is a function of its trait, the traits and abundance of its prey and the traits and abundance of other predators to which the focal predator competes.…”

“…For each evolutionary step, we also assigned each population to a species ID using a trait-based speciation definition (see also [ 9 , 10 ]). We define species as populations having common descent and a continuous distribution of traits (no gaps in the trait distribution > 3* σ µ ).…”

“…If σ α is larger than or close to the width of the resource distribution σ K (here set as a constant = 1), competition strength will be high even among populations using opposite ends of the local resource spectrum. Consequently, there will only be room (regarding niche space) for one population and no branching will occur in the local community [ 9 , 10 ]. If, on the other hand, the biotic niche width is narrower ( σ α < σ K ), then local evolutionary branching is facilitated, driving prey speciation [ 6 , 7 ].…”

Testing the role of climate in speciation: New methods and applications to squamate reptiles (lizards and snakes)

“…Our study represents the first large‐scale analysis of geographic modes of squamate speciation. We recognize that current geographic distributions of sister species may not always reflect the geographic mode by which they originated (e.g., Pontarp, Ripa, & Lundberg, ), but the impossibility of inferring geographic modes from present‐day range overlaps may be overstated (see Cardillo, ; Phillimore et al., ). Furthermore, there are methods for inferring the potential impact of postspeciational dispersal on the inference of geographic modes, such as testing for increasing range overlap over time (e.g., Barraclough & Vogler, ).…”

The Latitudinal Diversity Gradient: Novel Understanding through Mechanistic Eco-evolutionary Models

“…After making decisions about what speciation mode to model (e.g., sympatric versus allopatric), modelers face a range of implementation choices from purely phenomenological models of point mutation speciation as in Box 1 to more mechanistic models, where species diversification emerges from evolved trait divergence [48,[68][69][70], or the accumulation of genetic differences that arise as a function of vicariant events or divergent selection ( Figure I). These implementation decisions can impact emergent phylogenetic patterns.…”