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Extinction rates of non-avian dinosaur species are uncorrelated with the rate of evolution of phylogenetically informative characters.

ABSTRACT: Determining the factors that shape temporal variation in species diversity is an ongoing challenge. One theory is that species exhibiting lower rates of phenotypic evolution should be more likely to go extinct as they are more susceptible to changing environmental conditions. However, little work has been done to assess whether this process shapes comparatively few lineages, or is a common mechanism shaping changes in species diversity. Here, I analyse the correlation between rates of morphological evolution and extinction at the species level using six published morphological matrices of non-avian dinosaurs. I find no correlation between the two rates at different taxonomic scales, suggesting that extinction in these groups is better described by other factors. As there is a strong prior expectation of correlated rates, I suggest that traditional morphological matrices are inappropriate for addressing this question and that the characters governing lineage persistence are independent of those with high phylogenetic signal. This may be comprehensively determined with continued development of phenomic matrices.

SUBMITTER: Crouch NMA

PROVIDER: S-EPMC7336841 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Large-scale adaptive radiations might explain the runaway success of a minority of extant vertebrate clades. This hypothesis predicts, among other things, rapid rates of morphological evolution during the early history of major groups, as lineages invade disparate ecological niches. However, few studies of adaptive radiation have included deep time data, so the links between extant diversity and major extinct radiations are unclear. The intensively studied Mesozoic dinosaur record provides a model system for such investigation, representing an ecologically diverse group that dominated terrestrial ecosystems for 170 million years. Furthermore, with 10,000 species, extant dinosaurs (birds) are the most speciose living tetrapod clade. We assembled composite trees of 614-622 Mesozoic dinosaurs/birds, and a comprehensive body mass dataset using the scaling relationship of limb bone robustness. Maximum-likelihood modelling and the node height test reveal rapid evolutionary rates and a predominance of rapid shifts among size classes in early (Triassic) dinosaurs. This indicates an early burst niche-filling pattern and contrasts with previous studies that favoured gradualistic rates. Subsequently, rates declined in most lineages, which rarely exploited new ecological niches. However, feathered maniraptoran dinosaurs (including Mesozoic birds) sustained rapid evolution from at least the Middle Jurassic, suggesting that these taxa evaded the effects of niche saturation. This indicates that a long evolutionary history of continuing ecological innovation paved the way for a second great radiation of dinosaurs, in birds. We therefore demonstrate links between the predominantly extinct deep time adaptive radiation of non-avian dinosaurs and the phenomenal diversification of birds, via continuing rapid rates of evolution along the phylogenetic stem lineage. This raises the possibility that the uneven distribution of biodiversity results not just from large-scale extrapolation of the process of adaptive radiation in a few extant clades, but also from the maintenance of evolvability on vast time scales across the history of life, in key lineages.

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Extinction rates of non-avian dinosaur species are uncorrelated with the rate of evolution of phylogenetically informative characters.

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