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

Abstract

Much of life's diversity has arisen through ecological opportunity and adaptive radiations, but the mechanistic underpinning of such diversification is not fully understood. Competition and predation can affect adaptive radiations, but contrasting theoretical and empirical results show that they can both promote and interrupt diversification. A mechanistic understanding of the link between microevolutionary processes and macroevolutionary patterns is thus needed, especially in trophic communities. Here, we use a trait-based eco-evolutionary model to investigate the mechanisms linking competition, predation and adaptive radiations. By combining available micro-evolutionary theory and simulations of adaptive radiations we show that intraspecific competition is crucial for diversification as it induces disruptive selection, in particular in early phases of radiation. The diversification rate is however decreased in later phases owing to interspecific competition as niche availability, and population sizes are decreased. We provide new insight into how predation tends to have a negative effect on prey diversification through decreased population sizes, decreased disruptive selection and through the exclusion of prey from parts of niche space. The seemingly disparate effects of competition and predation on adaptive radiations, listed in the literature, may thus be acting and interacting in the same adaptive radiation at different relative strength as the radiation progresses.

A multi‐platform package for the analysis of intra‐ and interspecific trait evolution

“…Here, the steep topography of Hispaniola might have reduced exchanges between populations and subsequently competition. Ecological release theory posits that there are several phases to adaptive radiation (Ackermann & Doebeli, 2004;Aguilée et al, 2018;Pontarp & Petchey, 2018). A first phase, dominated by disruptive competition, increases intraspecific variation (Bolnick, 2001) F I G U R E 4 (a) Posterior density curves of the estimated optima for 'cybotes' (θ H , blue density curve) and 'sagrei' (θ C , green density curve) clades under the best model (mBM-vOUM).…”

“…The increase in intraspecific phenotypic variance is then expected to slow down and eventually reverse as phenotypic diversification and subsequent speciation events progressively fill niche space (Ackermann & Doebeli, 2004;Aguilée et al, 2018;Pontarp & Petchey, 2018). This effect of interspecific competition has been shown to greatly reduce intraspecific variation in prey diversity, thus affecting phenotypic variation (Costa-Pereira, Araújo, Souza, & Ingram, 2019;Schluter, 2000).…”

“…Empirical and theoretical studies clearly suggest that the evolution of intraspecific variation of a trait is informative of the underlying phenotypic evolutionary dynamics and their causes. Theoretical models demonstrate that intraspecific phenotypic variance is expected to increase with disruptive competition for resources in an empty niche space (Ackermann & Doebeli, 2004; Aguilée, Gascuel, Lambert, & Ferriere, 2018; Pontarp & Petchey, 2018). In the presence of a new resource, Drosophila populations subject to more competition displayed a faster niche expansion towards the new resource associated with an increase of intraspecific phenotypic variance (Bolnick, 2001).…”

Inferring community assembly processes from macroscopic patterns using dynamic eco‐evolutionary models and Approximate Bayesian Computation (ABC)

“…Lack of information about the underlying mechanisms can lead to misinterpretations of patterns. For example, trophic interactions and evolution are seldom considered in process inference (Pausas & Verdu, ) despite evidence of major effects on both trait distributions and phylogenetic patterns (Pontarp & Petchey, , ).…”

“…). By assigning a species identity to individuals, for example, using a trait‐based species definition (see also Pontarp, Ripa, & Lundberg, ; Pontarp et al., ), we can follow trait evolution, diversity, and phylogenetic and phenotypic community structure throughout evolutionary history (see also Pontarp & Petchey, ). Code for the model implementation is provided at https://zenodo.org/badge/latestdoi/158187026 and a guide to model modification is found in Appendix S5.…”