Imprints of tropical niche conservatism and historical dispersal in the radiation of Tyrannidae (Aves: Passeriformes)

Abstract

Speciation events occurring within biogeographic regions, and historical dispersal between regions influence diversity patterns observed in present-day assemblages. Such assessment has been often performed based on the phylogenetic structure of local assemblages. We underline some issues with that approach, and show that more reliable evaluation of historical events influencing present-day diversity can be achieved by combining phylogenetic diversity to an estimate of species assemblage age based on ancestral range estimation. We apply the new approach to test two concurrent hypotheses—Tropical Niche Conservatism (TNC) and Out of The Tropics (OTT)—which provide alternative explanations to species richness gradients, as possible explanations to higher species richness in tropical assemblages of Tyrannidae birds in relation to temperate ones across the American continent. Tropical assemblages tended to be older and to show higher phylogenetic diversity than temperate ones, suggesting that recent events of historical dispersal carried out by few lineages likely drove species assembly in younger temperate assemblages. This finding provides support to TNC as the most probable explanation to species richness variation in tyrannid assemblages across the Americas. Combining phylogenetic structure measures with a flexible assemblage age metric calculated from ancestral range estimation allows deeper understanding of current diversity gradients.

Herodotools: An R package to integrate macroevolution, biogeography and community ecology

“…The contribution of different regions to lineage dispersal events is shown in the supplementary material, Figure S6, and the online vignette (https://gabri elnak amura.github.io/Herod otool s/artic les/Intro_Herod otools_vigne tte.html). Results on trait evolution metrics (transition rates, stasis time and last transition time) in sigmodontine rodent assemblages can also be found in Although some of the metrics presented here are not new in biogeographical literature (Luza et al, 2021;Maestri & Duarte, 2020;Van Dijk et al, 2021), by wrapping them into a single platform, we provide an easy and unified tool to investigate questions in historical biogeography. As far as we know, the Herodotools R package is the first computational infrastructure of analysis that considers historical variables (macroevolution) at community and assemblage levels.…”

Herodotools: An R package to integrate macroevolution, community ecology, and biogeography

“…Specifically, functions implemented in Herodotools allows for manipulation of data from common macroevolutionary analyses (e.g., ancestral area reconstruction models in BioGeoBears (Matzke, 2013), and ancestral traits reconstruction (Bollback 2006)), converting the output of these analyses to matrices and data frames, which allows calculating macroevolutionary metrics at assemblage level (Table 1). These metrics can be used to map the effects of historical factors at different scales or as variables in common modeling frameworks allowing to test hypotheses in ecology, macroevolution, biogeography, and community ecology (e.g., Luza et al, 2021;Van Dijk et al, 2021). Additionally, Herodotools perform phylogenetic regionalization methods, map transition zones (Maestri & Duarte, 2020), and detect source and sink regions (functions evoregions, affiliation, and dispersal_from, respectively).…”

“…The in-situ diversification component comprises the evolutionary history that emerged due to in-situ speciation, i.e., all the events that occurred since each lineage's arrival and establishment time in the region where an assemblage is situated. In other words, it represents the path from tip to root between the species current occurrence in an assemblage to the oldest ancestor in which the range was estimated to occur in the same region as the assemblage, estimated through ancestral area reconstruction (Van Dijk et al, 2021). This tree component is used to calculate assemblage level metrics, for example, age of assemblages, in-situ diversification, the amount of phylogenetic diversity, and endemism that emerged as a process of in-situ diversification in a region.…”

“…First, when macroevolutionary dynamics are ignored at a local scale, we assume that only contemporary factors are important, ending up with a limited picture regarding the role of evolution in shaping local communities (Cavender-Bares et al, 2009). Second, by assuming unreliable premises regarding macroevolutionary dynamics and by adopting a pattern-to-process approach of trait evolution to interpret community phylogenetic patterns (e.g., static occurrence area was static during lineage evolution or phylogenetic clustering as a proxy of in-situ diversification), we may reach wrong conclusions about the imprints of diversification, and historical dispersal as neither occurrence area is likely to be static nor phylogenetic clustering be produced by diversification (Van Dijk et al, 2021). Finally, we can reach wrong estimates of assemblage characteristics such as the age of assemblages or the role of in situ diversification and historical dispersal (e.g., as shown by Van Dijk et al, 2021).…”

“…Second, by assuming unreliable premises regarding macroevolutionary dynamics and by adopting a pattern-to-process approach of trait evolution to interpret community phylogenetic patterns (e.g., static occurrence area was static during lineage evolution or phylogenetic clustering as a proxy of in-situ diversification), we may reach wrong conclusions about the imprints of diversification, and historical dispersal as neither occurrence area is likely to be static nor phylogenetic clustering be produced by diversification (Van Dijk et al, 2021). Finally, we can reach wrong estimates of assemblage characteristics such as the age of assemblages or the role of in situ diversification and historical dispersal (e.g., as shown by Van Dijk et al, 2021). These three general problems limit our ability to reach reliable results and conclusions regarding the importance of macroevolutionary events shaping the distribution of biodiversity at multiple spatial scales.…”