Phylogenomic Analysis of Placental Mammal Evolution

Phylogenomic analysis of placental mammals harnesses whole-genome data, rare genomic markers and advanced statistical models to reconstruct the evolutionary history and timing of diversification within the largest clade of living mammals. By integrating vast alignments of protein-coding genes, transposable element insertion patterns and expanded fossil calibrations, researchers now trace the early branching events that gave rise to Afrotheria, Xenarthra and Boreoeutheria. Improved coalescent-based methods address conflicts among individual gene trees arising from incomplete lineage sorting and rapid radiations around the Cretaceous–Palaeogene (K-Pg) boundary. Bayesian molecular-clock frameworks, calibrated with probabilistic interpretations of the fossil record, have narrowed estimates for the origin of crown Placentalia to the Late Cretaceous and clarified the pace of ordinal divergences both before and after the K-Pg mass extinction. Complementary studies of retroposon insertion presence/absence have provided virtually homoplasy-free evidence for deep splits, reinforcing molecular findings and resolving the root of the placental tree. Together, these phylogenomic advances offer a robust timescale for mammalian evolution, illuminate the drivers of adaptive radiation after mass extinction and furnish a scaffold for comparative analyses in ecology, physiology and conservation biology.

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Phylogenomic Analysis of Placental Mammal Evolution publication trend

The graph below shows the total number of articles in phylogenomic analysis of placental mammal evolution across all publications each year (not limited to Nature Index journals).

Technical terms

Phylogenomics: The integration of whole-genome sequence data into phylogenetic analyses to infer evolutionary relationships and divergence times.

Molecular clock: A method that uses the rate of genetic mutations to estimate the timing of species divergences, often calibrated by fossil constraints.

Retroposon insertion: A type of transposable element whose presence or absence at orthologous genomic sites provides virtually homoplasy-free markers for phylogenetic reconstruction.

Incomplete lineage sorting (ILS): The retention of ancestral genetic variants across successive speciation events, leading to discordance among gene trees.

Bayesian inference: A statistical framework that estimates phylogenetic trees and divergence times by integrating prior information with observed data to calculate posterior probability distributions.

References

1. A timescale for placental mammal diversification based on Bayesian modeling of the fossil record. Current Biology (2023).
2. Inferring the mammal tree: Species-level sets of phylogenies for questions in ecology, evolution, and conservation. PLOS Biology (2019).
3. Retroposed Elements as Archives for the Evolutionary History of Placental Mammals. PLOS Biology (2006).
4. Coalescent-Based Genome Analyses Resolve the Early Branches of the Euarchontoglires. PLOS ONE (2013).
5. Eutherians experienced elevated evolutionary rates in the immediate aftermath of the Cretaceous–Palaeogene mass extinction. Proceedings of the Royal Society B (2016).