Adaptations and Diversity of Antarctic Fishes: A Genomic Perspective

Abstract

Antarctic notothenioid fishes are the classic example of vertebrate adaptive radiation in a marine environment. Notothenioids diversified from a single common ancestor ∼25 Mya to more than 140 species today, and they represent ∼90% of fish biomass on the continental shelf of Antarctica. As they diversified in the cold Southern Ocean, notothenioids evolved numerous traits, including osteopenia, anemia, cardiomegaly, dyslipidemia, and aglomerular kidneys, that are beneficial or tolerated in their environment but are pathological in humans. Thus, notothenioids are models for understanding adaptive radiations, physiological and biochemical adaptations to extreme environments, and genetic mechanisms of human disease. Since 2014, 16 notothenioid genomes have been published, which enable a first-pass holistic analysis of the notothenioid radiation and the genetic underpinnings of novel notothenioid traits. Here, we review the notothenioid radiation from a genomic perspective and integrate our insights with recent observations from other fish radiations. Expected final online publication date for the Annual Review of Animal Biosciences, Volume 10 is February 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Comparative Analysis of the pIgR Gene from the Antarctic Teleost Trematomus bernacchii Reveals Distinctive Features of Cold Adapted Notothenioidei

“…TEs account for a significant portion of vertebrate genomes and are known to play a role in genome modifications [36,37]. Hotspots of retrotransposons (Rex-like) and DNA transposons (Tc1-like) elements have been reported in multiple teleost fishes, including Notothenioidei [31,38,39]. These findings support the idea that TEs could have contributed to the evolutionary process that led to the elongation of introns observed in Antarctic pIgR genes.…”

Tissue-Specific and Differential Cold Responses in the Domesticated Cold Tolerant Fugu

“…There must be some sort of cold compensation allowing higher rates of metabolism at low temperatures [31,32]. Thus, high rates of oxygen uptake have been observed in isolated brain slices of teleost fishes, and enzymes from the brains of Antarctic teleosts are more active at very low temperatures than those from animals adapted to warmer temperatures [31,[33][34][35], suggesting that partial compensation to temperature may exist in ATP producing pathways in fish brains. A study on green sunfish (Lepomis cyanellus) demonstrates that activities of glycolytic enzymes such as glucose phosphate isomerase, glyceraldehyde phosphate dehydrogenase, and pyruvate kinase are elevated in the brain during cold exposure [15,36].…”

Comparative Analysis of the pIgR Gene from the Antarctic Teleost Trematomus bernacchii Reveals Distinctive Features of Cold-Adapted Notothenioidei

“…TEs account for a significant portion of vertebrate genomes and are known to play a role in genome modifications [ 31 , 32 ]. Hotspots of retrotransposons (Rex-like) and DNA transposons (Tc1-like) elements have been reported in multiple teleost fishes, including Notothenioidei [ 26 , 33 , 34 ]. These findings support the idea that TEs could have contributed to the evolutionary process that led to the elongation of introns observed in Antarctic pIgR genes.…”