Chromosome-level Echidna Genome Illuminates Evolution of Multiple Sex Chromosome System in Monotremes

Overview

Journal Gigascience

Publisher Oxford University Press

Date 2025 Jan 8

PMID 39778707

Authors

Yang Zhou

Jiazheng Jin

Xuemei Li

Gregory Gedman

Sarah Pelan

Arang Rhie

Chuan Jiang

Olivier Fedrigo

Kerstin Howe

Adam M Phillippy

Erich D Jarvis

Frank Grutzner

Qi Zhou

Guojie Zhang

Affiliations

Soon will be listed here.

Abstract

Background: A thorough analysis of genome evolution is fundamental for biodiversity understanding. The iconic monotremes (platypus and echidna) feature extraordinary biology. However, they also exhibit rearrangements in several chromosomes, especially in the sex chromosome chain. Therefore, the lack of a chromosome-level echidna genome has limited insights into genome evolution in monotremes, in particular the multiple sex chromosomes complex.

Results: Here, we present a new long reads-based chromosome-level short-beaked echidna (Tachyglossus aculeatus) genome, which allowed the inference of chromosomal rearrangements in the monotreme ancestor (2n = 64) and each extant species. Analysis of the more complete sex chromosomes uncovered homology between 1 Y chromosome and multiple X chromosomes, suggesting that it is the ancestral X that has undergone reciprocal translocation with ancestral autosomes to form the complex. We also identified dozens of ampliconic genes on the sex chromosomes, with several ancestral ones expressed during male meiosis, suggesting selective constraints in pairing the multiple sex chromosomes.

Conclusion: The new echidna genome provides an important basis for further study of the unique biology and conservation of this species.

Citing Articles

Chromosome-level echidna genome illuminates evolution of multiple sex chromosome system in monotremes.

Zhou Y, Jin J, Li X, Gedman G, Pelan S, Rhie A Gigascience. 2025; 14.

PMID: 39778707 PMC: 11710854. DOI: 10.1093/gigascience/giae112.

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