Baiji genomes reveal low genetic variability and new insights into secondary aquatic adaptations

Nat Commun. 2013;4:2708. doi: 10.1038/ncomms3708.

Abstract

The baiji, or Yangtze River dolphin (Lipotes vexillifer), is a flagship species for the conservation of aquatic animals and ecosystems in the Yangtze River of China; however, this species has now been recognized as functionally extinct. Here we report a high-quality draft genome and three re-sequenced genomes of L. vexillifer using Illumina short-read sequencing technology. Comparative genomic analyses reveal that cetaceans have a slow molecular clock and molecular adaptations to their aquatic lifestyle. We also find a significantly lower number of heterozygous single nucleotide polymorphisms in the baiji compared to all other mammalian genomes reported thus far. A reconstruction of the demographic history of the baiji indicates that a bottleneck occurred near the end of the last deglaciation, a time coinciding with a rapid decrease in temperature and the rise of eustatic sea level.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biological Evolution
  • China
  • Conservation of Natural Resources
  • Dolphins / genetics*
  • Extinction, Biological
  • Female
  • Gene Library
  • Genetic Variation*
  • Genome*
  • Heterozygote
  • Male
  • Phylogeny
  • Polymorphism, Single Nucleotide
  • Rivers
  • Sequence Analysis, DNA