Convergent genome streamlining accompanies independent miniaturization in the world's smallest fishes.
8 affiliations
- 1Natural History Museum Bern, Bern 3005, Switzerland.
- 2Division of Evolutionary Ecology, Institute of Ecology and Evolution, University of Bern, Bern 3012, Switzerland.
- 3Faculty of Biology, Ludwig Maximilian University of Munich, Planegg 82152, Germany.
- 4Senckenberg Natural History Collections, Dresden 01109, Germany.
- 5Department of Ecology and Conservation Biology and Biodiversity Research and Teaching Collections, Texas A&M University, College Station, TX 77843.
- 6Lee Kong Chian Natural History Museum, National University of Singapore, Singapore 117377, Singapore.
- 7Department of Environmental Sciences, Zoological Institute, University of Basel, Basel 4051, Switzerland.
- 8Division of Aquatic Ecology and Evolution, Institute of Ecology and Evolution, University of Bern, Bern 3012, Switzerland.
Abstract
Miniaturization, the reduction of adult body size to an extreme degree, has evolved repeatedly across vertebrates. Yet its genomic underpinnings remain poorly understood. Cypriniformes, the most species-rich order of freshwater fishes, contains multiple miniaturized lineages that have evolved via contrasting developmental processes. Proportioned dwarfs are tiny-bodied but otherwise morphologically similar to larger relatives, while progenetic miniatures exhibit developmental truncation and retain larval-like anatomical features into adulthood. Using a new time-calibrated phylogeny of 309 cypriniform species and comparative genomic analyses of 33 high-quality genome assemblies, we investigated the evolutionary history and genomic correlates of miniaturization across this order. Ancestral state reconstruction revealed multiple independent origins of both miniature types, with reversals to the nonminiature state rarely recovered and miniature origins nonrandomly distributed across the phylogeny. The origins of the two types of miniatures differed in their timing. Progenetic miniatures arose predominantly in the Eocene whereas proportioned dwarfs arose mainly within the Miocene period. Genome size variation across Cypriniformes has been overwhelmingly driven by polyploidy. However, progenetic miniatures showed a directionally consistent, though nonsignificant, trend toward genome size reduction. Comparative genomic analyses revealed that all three independently evolved progenetic miniature lineages share convergent signatures of repeat loss alongside genome-wide intron shortening, patterns absent in proportioned dwarfs. Our study provides the broadest evidence to date that progenetic miniaturization, despite independent origins, is underpinned by predictable structural genomic changes, revealing a fundamental link between developmental truncation and genome architecture in vertebrates.
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BibTeX
@article{sudasinghe2026convergent,
title = {{Convergent genome streamlining accompanies independent miniaturization in the world's smallest fishes.}},
author = {Hiranya Sudasinghe and Michael Matschiner and Ralf Britz and Kevin W Conway and Heok Hui Tan and Walter Salzburger and Catherine L Peichel and Lukas Rüber},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
year = {2026},
month = oct,
doi = {10.1073/pnas.2614605123},
url = {https://europepmc.org/article/MED/42873784},
note = {CC BY},
}
RIS
TY - JOUR
TI - Convergent genome streamlining accompanies independent miniaturization in the world's smallest fishes.
AU - Hiranya Sudasinghe
AU - Michael Matschiner
AU - Ralf Britz
AU - Kevin W Conway
AU - Heok Hui Tan
AU - Walter Salzburger
AU - Catherine L Peichel
AU - Lukas Rüber
PY - 2026
DA - 2026/10/14
JO - Proceedings of the National Academy of Sciences of the United States of America
DO - 10.1073/pnas.2614605123
UR - https://europepmc.org/article/MED/42873784
AB - Miniaturization, the reduction of adult body size to an extreme degree, has evolved repeatedly across vertebrates. Yet its genomic underpinnings remain poorly understood. Cypriniformes, the most species-rich order of freshwater fishes, contains multiple miniaturized lineages that have evolved via contrasting developmental processes. Proportioned dwarfs are tiny-bodied but otherwise morphologically similar to larger relatives, while progenetic miniatures exhibit developmental truncation and retain larval-like anatomical features into adulthood. Using a new time-calibrated phylogeny of 309 cypriniform species and comparative genomic analyses of 33 high-quality genome assemblies, we investigated the evolutionary history and genomic correlates of miniaturization across this order. Ancestral state reconstruction revealed multiple independent origins of both miniature types, with reversals to the nonminiature state rarely recovered and miniature origins nonrandomly distributed across the phylogeny. The origins of the two types of miniatures differed in their timing. Progenetic miniatures arose predominantly in the Eocene whereas proportioned dwarfs arose mainly within the Miocene period. Genome size variation across Cypriniformes has been overwhelmingly driven by polyploidy. However, progenetic miniatures showed a directionally consistent, though nonsignificant, trend toward genome size reduction. Comparative genomic analyses revealed that all three independently evolved progenetic miniature lineages share convergent signatures of repeat loss alongside genome-wide intron shortening, patterns absent in proportioned dwarfs. Our study provides the broadest evidence to date that progenetic miniaturization, despite independent origins, is underpinned by predictable structural genomic changes, revealing a fundamental link between developmental truncation and genome architecture in vertebrates.
SN - 0027-8424
SN - 1091-6490
ER -