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A spectacular bear assembly

The spectacled bear (Tremarctos ornatus) is the only bear native to South America. It is the last remaining short-faced bear (subfamily Tremarctinae). The species is classified as Vulnerable by the IUCN because of habitat loss.

Handsome Chester, photo by Valerie [CC BY-NC-ND 2.0], via

The species is of course famous in literary circles as much as in conservation ones thanks to Michael Bond's much-loved Paddington, whose adventures have featured in twenty books, three TV series and two feature films to date. (Interestingly, Bond originally imagined Paddington to have 'travelled all the way from darkest Africa', before being advised that there were no bear species in Africa! So the bear became one from 'darkest Peru').

Today, we share the chromosome-length genome assembly for the spectacled bear, based on a sample provided to us by the San Antonio Zoo. This is a $1K-model genome assembly, with contig N50=117kb and scaffold N50=105Mb. Read more about the $1K genomes on our Methods page.

This is our 5th genome in the Ursidae family (bears), after the Malayan sun bear, the American black bear, grizzly and polar bear. Unlike all the other bears who all have a karyotype of 2n=74, the spectacled bear is 2n=52. See below how the chromosomes of the spectacled bear relate to the very conservative karyotype of all other bears, suggesting multiple fusion events associated with the spectacled bear chromosomes as compared to the 'main' Ursidae karyotype!

Whole-genome alignment plots between the chromosome-length spectacled bear assembly and those of other bears in the DNA Zoo collection: left to right, Ursus americanus, Ursus arctos, Helarctos malayanus and Ursus maritimus. The Helarctos malayanus alignments are filtered at a higher threshold to account for shorter phylogenetic distance between the species.

Don't forget to check out the interactive map for the 2n=52 chromosomes below and on the corresponding assembly page!

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