ArticleBiology letters2020
An irregular hourglass pattern describes the tempo of phenotypic development in placental mammal evolution.
Article in Biology letters, 2020. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 6 papers.
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6 citing papers in PubMed, 15 citations in OpenAlex.
- The Interplay of Ontogeny and Phylogeny at the Transcriptome Level of the Tetrapod Heart.Journal of experimental zoology. Part B, Molecular and developmental evolution · 2025Article
- From Circuits to Lifespan: Translating Mouse and Human Timelines with Neuroimaging-Based Tractography.The Journal of neuroscience : the official journal of the Society for Neuroscience · 2025Article
- Evolutionary mechanisms modulating the mammalian skull development.Philosophical transactions of the Royal Society of London. Series B, Biological sciences · 2023Review
- Timing of organogenesis underscores the evolution of neonatal life histories and powered flight in bats.Proceedings. Biological sciences · 2023Article
- Turtle Shell Kinesis Underscores Constraints and Opportunities in the Evolution of the Vertebrate Musculoskeletal System.Integrative organismal biology (Oxford, England) · 2023Review
- Shifts in growth, but not differentiation, foreshadow the formation of exaggerated forms under chicken domestication.Proceedings. Biological sciences · 2021Article
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Authors and funding
3 authors at 2 institutions in 2 countries.
Funding
No grant is acknowledged in the PubMed record.
Abstract
Organismal development is defined by progressive transformations that ultimately give rise to distinct tissues and organs. Thus, temporal shifts in ontogeny often reflect key phenotypic differences in phylogeny. Classical theory predicts that interspecific morphological divergence originates towards the end of embryonic or fetal life stages, i.e. the early conservation model. By contrast, the hourglass model predicts interspecific variation early and late in prenatal ontogeny, though with a phylogenetically similar mid-developmental period. This phylotypic period, however, remains challenging to define within large clades such as mammals. Thus, molecular and morphological tests on a mammalian hourglass have not been entirely congruent. Here, we report an hourglass-like pattern for mammalian developmental evolution. By comparing published data on the timing of 74 homologous characters across 51 placental species, we demonstrated that variation in the timing of development decreased late in embryogenesis--when organ formation is highly active. Evolutionary rates of characters related to this timeframe were lowest, coinciding with a phylotypic period that persisted well beyond the pharyngula 'stage'. The trajectory culminated with elevated variation in a handful of fetal and perinatal characters, yielding an irregular hourglass pattern. Our study invites further quantification of ontogeny across diverse amniotes and thus challenges current ideas on the universality of developmental patterns.
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