Understanding the effect of competition during evolutionary radiations: an integrated model of phenotypic and species diversification

Abstract

Competition can drive macroevolutionary change, for example during adaptive radiations. However, we still lack a clear understanding of how it shapes diversification processes and patterns. To better understand the macroevolutionary consequences of competition, as well as the signal left on phylogenetic data, we developed a model linking trait evolution and species diversification in an ecological context. We find four main results: first, competition spurs trait diversity but not necessarily species richness; second, competition produces slowdowns in species diversification even in the absence of explicit ecological limits, but not in phenotypic diversification even in the presence of such limits; third, early burst patterns do not provide a reliable way of testing for adaptive radiations; and fourth, looking for phylogenetic signal in trait data and support for phenotypic models incorporating competition is a better alternative. Our results clarify the macroevolutionary consequences of competition and could help design more powerful tests of adaptive radiations in nature.

Assessing the causes of diversification slowdowns: temperature‐dependent and diversity‐dependent models receive equivalent support

“…However only 18% truly support diversity‐dependent models when compared to time‐ and temperature‐dependent ones. Therefore, our results caution against comparing constant‐rate models with only time‐dependent models and interpreting speciation slowdowns as niche filling processes (Moen & Morlon ; Aristide & Morlon ). A little less than a quarter (23%) of phylogenies supporting a speciation slowdown were indeed explained by diversity‐dependence, but more than half (52%) were in fact better supported by models with a positive dependence of speciation rate on temperature, while the rest were explained by neither one nor the other.…”

“…However, there is increasing empirical (Adams et al ; Cantalapiedra et al . ) and theoretical (Aristide & Morlon ) evidence that this coupling might not be so straightforward. Developing a model where both diversification and phenotypic evolution are influenced by competition for limited resources, Aristide & Morlon () found that niche packing limits speciation and increases extinctions rates, but does not reduce trait evolutionary rates, as frequent extinctions free up ecological space that is rapidly reoccupied.…”

“…) and theoretical (Aristide & Morlon ) evidence that this coupling might not be so straightforward. Developing a model where both diversification and phenotypic evolution are influenced by competition for limited resources, Aristide & Morlon () found that niche packing limits speciation and increases extinctions rates, but does not reduce trait evolutionary rates, as frequent extinctions free up ecological space that is rapidly reoccupied. If such a model applies in nature, with increased availability of resources under warm climates, we expect that speciation rates will be lower during low productivity, cool geological periods, but that this will not impact trait evolutionary rates.…”

High-throughput sequencing for community analysis: the promise of DNA barcoding to uncover diversity, relatedness, abundances and interactions in spider communities

“…Analysis of the community phylogenies provides a deeptime lens on community structure which can be used to estimate speciation and extinction rates (Manceau et al 2015) and make inferences about diversification processes (Emerson and Gillespie 2008;Morlon 2014;Pearse et al 2014). Recent methods have also been developed to simultaneously model trait evolution and species diversification (Weber et al 2017) to investigate the importance of competition in shaping evolutionary radiations (Aristide and Morlon 2019), and the joint contribution of competition and environmental filtering in structuring ecological communities (Ruffley et al 2019). Community-scale trait data can also be analyzed along with metabarcoding data in a hierarchical modeling framework to further account for feedbacks among processes happening at disparate timescales (Overcast et al n.d.).…”

The rise of angiosperms pushed conifers to decline during global cooling

“…However, such a double-wedge pattern could conceivably be produced by differential responses to physical change or differential clade interactions (9). Identifying which abiotic and/or biotic factors control diversity changes is a key challenge in macroevolution (7,10), and macroevolutionary models involving competition as a major driving factor remain disputed (1,11).…”