Platypus and echidna genomes reveal mammalian biology and evolution

Date

2021

Authors

Zhou, Yang
Shearwin-Whyatt, Linda
Li, Jing
Song, Zhenzhen
Hayakawa, Takashi
Stevens, David
Fenelon, Jane C.
Peel, Emma
Cheng, Yuanyuan
Pajpach, Filip

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Volume Title

Publisher

Macmillan Publishers Ltd

Abstract

Egg-laying mammals (monotremes) are the only extant mammalian outgroup to therians (marsupial and eutherian animals) and provide key insights into mammalian evolution1,2. Here we generate and analyse reference genomes of the platypus (Ornithorhynchus anatinus) and echidna (Tachyglossus aculeatus), which represent the only two extant monotreme lineages. The nearly complete platypus genome assembly has anchored almost the entire genome onto chromosomes, markedly improving the genome continuity and gene annotation. Together with our echidna sequence, the genomes of the two species allow us to detect the ancestral and lineage-specific genomic changes that shape both monotreme and mammalian evolution. We provide evidence that the monotreme sex chromosome complex originated from an ancestral chromosome ring configuration. The formation of such a unique chromosome complex may have been facilitated by the unusually extensive interactions between the multi-X and multi-Y chromosomes that are shared by the autosomal homologues in humans. Further comparative genomic analyses unravel marked differences between monotremes and therians in haptoglobin genes, lactation genes and chemosensory receptor genes for smell and taste that underlie the ecological adaptation of monotremes.

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Source

Nature

Type

Journal article

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Access Statement

Open Access

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Creative Commons Attribution licence

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