Cold Fusion: Massive Karyotype Evolution in the Antarctic Bullhead Notothen Notothenia coriiceps

Half of all vertebrate species share a series of chromosome fusions that preceded the teleost genome duplication (TGD), but we do not understand the causative evolutionary mechanisms. The Robertsonian-translocation hypothesis suggests a regular fusion of each ancestral acro- or telocentric chromosom...

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Published in:G3 Genes|Genomes|Genetics
Main Authors: Amores, Angel, Wilson, Catherine A, Allard, Corey AH, Dietrich, William H, III
Format: Text
Language:unknown
Published: Dartmouth Digital Commons 2017
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Online Access:https://digitalcommons.dartmouth.edu/facoa/165
https://doi.org/10.1534/g3.117.040063
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spelling ftdartmouthcoll:oai:digitalcommons.dartmouth.edu:facoa-1166 2023-07-16T03:53:23+02:00 Cold Fusion: Massive Karyotype Evolution in the Antarctic Bullhead Notothen Notothenia coriiceps Amores, Angel Wilson, Catherine A Allard, Corey AH Dietrich, William H, III 2017-07-01T07:00:00Z text/html https://digitalcommons.dartmouth.edu/facoa/165 https://doi.org/10.1534/g3.117.040063 unknown Dartmouth Digital Commons https://digitalcommons.dartmouth.edu/facoa/165 doi:10.1534/g3.117.040063 https://doi.org/10.1534/g3.117.040063 Dartmouth Scholarship Notothenioid Antarctica Robertsonian translocation teleost genome duplication karyotype reduction Earth Sciences Environmental Sciences Physical Sciences and Mathematics text 2017 ftdartmouthcoll https://doi.org/10.1534/g3.117.040063 2023-06-28T10:42:43Z Half of all vertebrate species share a series of chromosome fusions that preceded the teleost genome duplication (TGD), but we do not understand the causative evolutionary mechanisms. The Robertsonian-translocation hypothesis suggests a regular fusion of each ancestral acro- or telocentric chromosome to just one other by centromere fusions, thus halving the karyotype. An alternative genome-stirring hypothesis posits haphazard and repeated fusions, inversions, and reciprocal and nonreciprocal translocations. To study large-scale karyotype reduction, we investigated the decrease of chromosome numbers in Antarctic notothenioid fish. Most notothenioids have 24 haploid chromosomes, but bullhead notothen (Notothenia coriiceps) has 1. To understand mechanisms, we made a RAD-tag meiotic map with approximate to 10,000 polymorphic markers. Comparative genomics aligned about a thousand orthologs of platyfish and stickleback genes along bullhead chromosomes. Results revealed that 9 of 11 bullhead chromosomes arose by fusion of just two ancestral chromosomes and two others by fusion of three ancestral chromosomes. All markers from each ancestral chromosome remained contiguous, implying no inversions across fusion borders. Karyotype comparisons support a history of: (1) Robertsonian fusions of 22 ancestral chromosomes in pairs to yield 11 fused plus two small unfused chromosomes, like N. angustata; (2) fusion of one of the remaining two ancestral chromosomes to a preexisting fused pair, giving 12 chromosomes like N. rossii; and (3) fusion of the remaining ancestral chromosome to another fused pair, giving 11 chromosomes in N. coriiceps. These results raise the question of what selective forces promoted the systematic fusion of chromosomes in pairs and the suppression of pericentric inversions in this lineage, and provide a model for chromosome fusions in stem teleosts. Text Antarc* Antarctic Antarctica Dartmouth Digital Commons (Dartmouth College) Antarctic The Antarctic G3 Genes|Genomes|Genetics 7 7 2195 2207
institution Open Polar
collection Dartmouth Digital Commons (Dartmouth College)
op_collection_id ftdartmouthcoll
language unknown
topic Notothenioid
Antarctica
Robertsonian translocation
teleost genome duplication
karyotype reduction
Earth Sciences
Environmental Sciences
Physical Sciences and Mathematics
spellingShingle Notothenioid
Antarctica
Robertsonian translocation
teleost genome duplication
karyotype reduction
Earth Sciences
Environmental Sciences
Physical Sciences and Mathematics
Amores, Angel
Wilson, Catherine A
Allard, Corey AH
Dietrich, William H, III
Cold Fusion: Massive Karyotype Evolution in the Antarctic Bullhead Notothen Notothenia coriiceps
topic_facet Notothenioid
Antarctica
Robertsonian translocation
teleost genome duplication
karyotype reduction
Earth Sciences
Environmental Sciences
Physical Sciences and Mathematics
description Half of all vertebrate species share a series of chromosome fusions that preceded the teleost genome duplication (TGD), but we do not understand the causative evolutionary mechanisms. The Robertsonian-translocation hypothesis suggests a regular fusion of each ancestral acro- or telocentric chromosome to just one other by centromere fusions, thus halving the karyotype. An alternative genome-stirring hypothesis posits haphazard and repeated fusions, inversions, and reciprocal and nonreciprocal translocations. To study large-scale karyotype reduction, we investigated the decrease of chromosome numbers in Antarctic notothenioid fish. Most notothenioids have 24 haploid chromosomes, but bullhead notothen (Notothenia coriiceps) has 1. To understand mechanisms, we made a RAD-tag meiotic map with approximate to 10,000 polymorphic markers. Comparative genomics aligned about a thousand orthologs of platyfish and stickleback genes along bullhead chromosomes. Results revealed that 9 of 11 bullhead chromosomes arose by fusion of just two ancestral chromosomes and two others by fusion of three ancestral chromosomes. All markers from each ancestral chromosome remained contiguous, implying no inversions across fusion borders. Karyotype comparisons support a history of: (1) Robertsonian fusions of 22 ancestral chromosomes in pairs to yield 11 fused plus two small unfused chromosomes, like N. angustata; (2) fusion of one of the remaining two ancestral chromosomes to a preexisting fused pair, giving 12 chromosomes like N. rossii; and (3) fusion of the remaining ancestral chromosome to another fused pair, giving 11 chromosomes in N. coriiceps. These results raise the question of what selective forces promoted the systematic fusion of chromosomes in pairs and the suppression of pericentric inversions in this lineage, and provide a model for chromosome fusions in stem teleosts.
format Text
author Amores, Angel
Wilson, Catherine A
Allard, Corey AH
Dietrich, William H, III
author_facet Amores, Angel
Wilson, Catherine A
Allard, Corey AH
Dietrich, William H, III
author_sort Amores, Angel
title Cold Fusion: Massive Karyotype Evolution in the Antarctic Bullhead Notothen Notothenia coriiceps
title_short Cold Fusion: Massive Karyotype Evolution in the Antarctic Bullhead Notothen Notothenia coriiceps
title_full Cold Fusion: Massive Karyotype Evolution in the Antarctic Bullhead Notothen Notothenia coriiceps
title_fullStr Cold Fusion: Massive Karyotype Evolution in the Antarctic Bullhead Notothen Notothenia coriiceps
title_full_unstemmed Cold Fusion: Massive Karyotype Evolution in the Antarctic Bullhead Notothen Notothenia coriiceps
title_sort cold fusion: massive karyotype evolution in the antarctic bullhead notothen notothenia coriiceps
publisher Dartmouth Digital Commons
publishDate 2017
url https://digitalcommons.dartmouth.edu/facoa/165
https://doi.org/10.1534/g3.117.040063
geographic Antarctic
The Antarctic
geographic_facet Antarctic
The Antarctic
genre Antarc*
Antarctic
Antarctica
genre_facet Antarc*
Antarctic
Antarctica
op_source Dartmouth Scholarship
op_relation https://digitalcommons.dartmouth.edu/facoa/165
doi:10.1534/g3.117.040063
https://doi.org/10.1534/g3.117.040063
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container_title G3 Genes|Genomes|Genetics
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