Tempo and mode of morphological evolution are decoupled from latitude in birds

Abstract

The latitudinal diversity gradient is one of the most striking patterns in nature, yet its implications for morphological evolution are poorly understood. In particular, it has been proposed that an increased intensity of species interactions in tropical biota may either promote or constrain trait evolution, but which of these outcomes predominates remains uncertain. Here, we develop tools for fitting phylogenetic models of phenotypic evolution in which the impact of species interactions—namely, competition—can vary across lineages. Deploying these models on a global avian trait dataset to explore differences in trait divergence between tropical and temperate lineages, we find that the effect of latitude on the mode and tempo of morphological evolution is weak and clade- or trait dependent. Our results indicate that species interactions do not disproportionately impact morphological evolution in tropical bird families and question the validity of previously reported patterns of slower trait evolution in the tropics.

Conceptual and empirical bridges between micro- and macroevolution

“…Species competing for the same niche are expected to show signs of character displacement, which should be detectable with coexistence experiments 105 , disparity through time analysis of phenotypes (DTT 137 ) or other models of phenotypic evolution (diversity-dependent, matching competition and early burst models 119 ). These types of analyses permit the detection of interspecific phenotypic interaction during species coexistence 138 and across the latitudinal gradient 139 . Interactions beyond temporal co-occurrence, such as predation and spatial competition can be observed directly in the fossil record 140 and could potentially be incorporated in modeling frameworks.…”

“…The appearance and persistence of populations should in turn be linked to the probability of speciation and extinction at larger time scales 9,129 . Recently developed comparative models 139 have the potential to be used to study a large variety of positive and negative species interactions (such as competition, mutualisms, symbiosis) 126 .…”

Genome and life-history evolution link bird diversification to the end-Cretaceous mass extinction

“…The aftermath of mass extinctions, especially those of short duration, may present all three classes of opportunities, resulting in recovery faunas that experience "early bursts" of lineage and character diversification (51,52). If diversification becomes constrained as niches fill [e.g., (53)], rates of morphological evolution and lineage accumulation should decline, with the fastest rates of change restricted to a short interval following the mass extinction event (54,55). Accordingly, we expect initially high rates of evolution to generate outsized disparity (e.g., trait variance or heterogeneity) early in post-extinction adaptive radiations.…”

A bird in the hand: Global‐scale morphological trait datasets open new frontiers of ecology, evolution and ecosystem science

“…Similarly, methods using traits to quantify niche differences among species are no longer limited to smaller samples (e.g. Pigot & Tobias, 2013) and can now be applied across all birds (Drury et al, 2021; Freeman et al, 2022; Pigot et al, 2018).…”