1
|
Preising GA, Faber-Hammond JJ, Renn SCP. Correspondence of aCGH and long-read genome assembly for detection of copy number differences: A proof-of-concept with cichlid genomes. PLoS One 2021; 16:e0258193. [PMID: 34618847 PMCID: PMC8496808 DOI: 10.1371/journal.pone.0258193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 09/21/2021] [Indexed: 11/18/2022] Open
Abstract
Copy number variation is an important source of genetic variation, yet data are often lacking due to technical limitations for detection given the current genome assemblies. Our goal is to demonstrate the extent to which an array-based platform (aCGH) can identify genomic loci that are collapsed in genome assemblies that were built with short-read technology. Taking advantage of two cichlid species for which genome assemblies based on Illumina and PacBio are available, we show that inter-species aCGH log2 hybridization ratios correlate more strongly with inferred copy number differences based on PacBio-built genome assemblies than based on Illumina-built genome assemblies. With regard to inter-species copy number differences of specific genes identified by each platform, the set identified by aCGH intersects to a greater extent with the set identified by PacBio than with the set identified by Illumina. Gene function, according to Gene Ontology analysis, did not substantially differ among platforms, and platforms converged on functions associated with adaptive phenotypes. The results of the current study further demonstrate that aCGH is an effective platform for identifying copy number variable sequences, particularly those collapsed in short read genome assemblies.
Collapse
Affiliation(s)
| | | | - Suzy C. P. Renn
- Department of Biology, Reed College, Portland, OR, United States of America
| |
Collapse
|
2
|
Renn SC, Hurd PL. Epigenetic Regulation and Environmental Sex Determination in Cichlid Fishes. Sex Dev 2021; 15:93-107. [PMID: 34433170 PMCID: PMC8440468 DOI: 10.1159/000517197] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2021] [Accepted: 05/12/2021] [Indexed: 12/14/2022] Open
Abstract
Studying environmental sex determination (ESD) in cichlids provides a phylogenetic and comparative approach to understand the evolution of the underlying mechanisms, their impact on the evolution of the overlying systems, and the neuroethology of life history strategies. Natural selection normally favors parents who invest equally in the development of male and female offspring, but evolution may favor deviations from this 50:50 ratio when environmental conditions produce an advantage for doing so. Many species of cichlids demonstrate ESD in response to water chemistry (temperature, pH, and oxygen concentration). The relative strengths of and the exact interactions between these factors vary between congeners, demonstrating genetic variation in sensitivity. The presence of sizable proportions of the less common sex towards the environmental extremes in most species strongly suggests the presence of some genetic sex-determining loci acting in parallel with the ESD factors. Sex determination and differentiation in these species does not seem to result in the organization of a final and irreversible sexual fate, so much as a life-long ongoing battle between competing male- and female-determining genetic and hormonal networks governed by epigenetic factors. We discuss what is and is not known about the epigenetic mechanism behind the differentiation of both gonads and sex differences in the brain. Beyond the well-studied tilapia species, the 2 best-studied dwarf cichlid systems showing ESD are the South American genus Apistogramma and the West African genus Pelvicachromis. Both species demonstrate male morphs with alternative reproductive tactics. We discuss the further neuroethology opportunities such systems provide to the study of epigenetics of alternative life history strategies and other behavioral variation.
Collapse
Affiliation(s)
| | - Peter L Hurd
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, CA
- Department of Psychology, University of Alberta, Edmonton, AB, CA
| |
Collapse
|
3
|
Modak TH, Literman R, Puritz JB, Johnson KM, Roberts EM, Proestou D, Guo X, Gomez-Chiarri M, Schwartz RS. Extensive genome-wide duplications in the eastern oyster ( Crassostrea virginica). Philos Trans R Soc Lond B Biol Sci 2021; 376:20200164. [PMID: 33813893 DOI: 10.1098/rstb.2020.0164] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Genomic structural variation is an important source of genetic and phenotypic diversity, playing a critical role in evolution. The recent availability of a high-quality reference genome for the eastern oyster, Crassostrea virginica, and whole-genome sequence data of samples from across the species range in the USA, provides an opportunity to explore structural variation across the genome of this species. Our analysis shows significantly greater individual-level duplications of regions across the genome than that of most model vertebrate species. Duplications are widespread across all ten chromosomes with variation in frequency per chromosome. The eastern oyster shows a large interindividual variation in duplications as well as particular chromosomal regions with a higher density of duplications. A high percentage of duplications seen in C. virginica lie completely within genes and exons, suggesting the potential for impacts on gene function. These results support the hypothesis that structural changes may play a significant role in standing genetic variation in C. virginica, and potentially have a role in their adaptive and evolutionary success. Altogether, these results suggest that copy number variation plays an important role in the genomic variation of C. virginica. This article is part of the Theo Murphy meeting issue 'Molluscan genomics: broad insights and future directions for a neglected phylum'.
Collapse
Affiliation(s)
- Tejashree H Modak
- Department of Biological Sciences, University of Rhode Island, 120 Flagg Road, Kingston, RI 02881, USA
| | - Robert Literman
- Department of Biological Sciences, University of Rhode Island, 120 Flagg Road, Kingston, RI 02881, USA
| | - Jonathan B Puritz
- Department of Biological Sciences, University of Rhode Island, 120 Flagg Road, Kingston, RI 02881, USA
| | - Kevin M Johnson
- Center for Coastal Marine Sciences, California Polytechnic State University, 1 Grand Avenue, San Luis Obispo, CA 93407, USA.,Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.,California Sea Grant, University of California San Diego, La Jolla, CA 92093-0232, USA
| | - Erin M Roberts
- Department of Fisheries, Animal and Veterinary Sciences, University of Rhode Island, 120 Flagg Road, Kingston, RI 02881, USA
| | - Dina Proestou
- USDA Agricultural Research Service, National Cold Water Marine Aquaculture Center, 469 CBLS, 120 Flagg Road, Kingston, RI 02881, USA
| | - Ximing Guo
- Haskin Shellfish Research Laboratory, Department of Marine and Coastal Sciences, Rutgers University, 6959 Miller Avenue, Port Norris, NJ 08349, USA
| | - Marta Gomez-Chiarri
- Department of Fisheries, Animal and Veterinary Sciences, University of Rhode Island, 120 Flagg Road, Kingston, RI 02881, USA
| | - Rachel S Schwartz
- Department of Biological Sciences, University of Rhode Island, 120 Flagg Road, Kingston, RI 02881, USA
| |
Collapse
|
4
|
Liu S, Gao G, Layer RM, Thorgaard GH, Wiens GD, Leeds TD, Martin KE, Palti Y. Identification of High-Confidence Structural Variants in Domesticated Rainbow Trout Using Whole-Genome Sequencing. Front Genet 2021; 12:639355. [PMID: 33732289 PMCID: PMC7959816 DOI: 10.3389/fgene.2021.639355] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 02/08/2021] [Indexed: 12/14/2022] Open
Abstract
Genomic structural variants (SVs) are a major source of genetic and phenotypic variation but have not been investigated systematically in rainbow trout (Oncorhynchus mykiss), an important aquaculture species of cold freshwater. The objectives of this study were 1) to identify and validate high-confidence SVs in rainbow trout using whole-genome re-sequencing; and 2) to examine the contribution of transposable elements (TEs) to SVs in rainbow trout. A total of 96 rainbow trout, including 11 homozygous lines and 85 outbred fish from three breeding populations, were whole-genome sequenced with an average genome coverage of 17.2×. Putative SVs were identified using the program Smoove which integrates LUMPY and other associated tools into one package. After rigorous filtering, 13,863 high-confidence SVs were identified. Pacific Biosciences long-reads of Arlee, one of the homozygous lines used for SV detection, validated 98% (3,948 of 4,030) of the high-confidence SVs identified in the Arlee homozygous line. Based on principal component analysis, the 85 outbred fish clustered into three groups consistent with their populations of origin, further indicating that the high-confidence SVs identified in this study are robust. The repetitive DNA content of the high-confidence SV sequences was 86.5%, which is much higher than the 57.1% repetitive DNA content of the reference genome, and is also higher than the repetitive DNA content of Atlantic salmon SVs reported previously. TEs thus contribute substantially to SVs in rainbow trout as TEs make up the majority of repetitive sequences. Hundreds of the high-confidence SVs were annotated as exon-loss or gene-fusion variants, and may have phenotypic effects. The high-confidence SVs reported in this study provide a foundation for further rainbow trout SV studies.
Collapse
Affiliation(s)
- Sixin Liu
- National Center for Cool and Cold Water Aquaculture, Agricultural Research Service, United States Department of Agriculture, Kearneysville, WV, United States
| | - Guangtu Gao
- National Center for Cool and Cold Water Aquaculture, Agricultural Research Service, United States Department of Agriculture, Kearneysville, WV, United States
| | - Ryan M Layer
- BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, United States.,Department of Computer Science, University of Colorado Boulder, Boulder, CO, United States
| | - Gary H Thorgaard
- Center for Reproductive Biology, School of Biological Sciences, Washington State University, Pullman, WA, United States
| | - Gregory D Wiens
- National Center for Cool and Cold Water Aquaculture, Agricultural Research Service, United States Department of Agriculture, Kearneysville, WV, United States
| | - Timothy D Leeds
- National Center for Cool and Cold Water Aquaculture, Agricultural Research Service, United States Department of Agriculture, Kearneysville, WV, United States
| | | | - Yniv Palti
- National Center for Cool and Cold Water Aquaculture, Agricultural Research Service, United States Department of Agriculture, Kearneysville, WV, United States
| |
Collapse
|
5
|
Xiong P, Hulsey CD, Fruciano C, Wong WY, Nater A, Kautt AF, Simakov O, Pippel M, Kuraku S, Meyer A, Franchini P. The comparative genomic landscape of adaptive radiation in crater lake cichlid fishes. Mol Ecol 2021; 30:955-972. [PMID: 33305470 PMCID: PMC8607476 DOI: 10.1111/mec.15774] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Revised: 11/21/2020] [Accepted: 11/30/2020] [Indexed: 12/13/2022]
Abstract
Factors ranging from ecological opportunity to genome composition might explain why only some lineages form adaptive radiations. While being rare, particular systems can provide natural experiments within an identical ecological setting where species numbers and phenotypic divergence in two closely related lineages are notably different. We investigated one such natural experiment using two de novo assembled and 40 resequenced genomes and asked why two closely related Neotropical cichlid fish lineages, the Amphilophus citrinellus species complex (Midas cichlids; radiating) and Archocentrus centrarchus (Flyer cichlid; nonradiating), have resulted in such disparate evolutionary outcomes. Although both lineages inhabit many of the same Nicaraguan lakes, whole-genome inferred demography suggests that priority effects are not likely to be the cause of the dissimilarities. Also, genome-wide levels of selection, transposable element dynamics, gene family expansion, major chromosomal rearrangements and the number of genes under positive selection were not markedly different between the two lineages. To more finely investigate particular subsets of the genome that have undergone adaptive divergence in Midas cichlids, we also examined if there was evidence for 'molecular pre-adaptation' in regions identified by QTL mapping of repeatedly diverging adaptive traits. Although most of our analyses failed to pinpoint substantial genomic differences, we did identify functional categories containing many genes under positive selection that provide candidates for future studies on the propensity of Midas cichlids to radiate. Our results point to a disproportionate role of local, rather than genome-wide factors underlying the propensity for these cichlid fishes to adaptively radiate.
Collapse
Affiliation(s)
- Peiwen Xiong
- Department of BiologyUniversity of KonstanzKonstanzGermany
| | - C. Darrin Hulsey
- Department of BiologyUniversity of KonstanzKonstanzGermany
- School of Biology and Environmental ScienceUniversity College DublinDublinIreland
| | - Carmelo Fruciano
- Department of BiologyUniversity of KonstanzKonstanzGermany
- National Research Council (CNR) – IRBIMMessinaItaly
| | - Wai Y. Wong
- Department of Molecular Evolution and DevelopmentUniversity of ViennaViennaAustria
| | | | - Andreas F. Kautt
- Department of BiologyUniversity of KonstanzKonstanzGermany
- Department of Organismic and Evolutionary BiologyHarvard UniversityCambridgeMAUSA
| | - Oleg Simakov
- Department of Molecular Evolution and DevelopmentUniversity of ViennaViennaAustria
| | - Martin Pippel
- Max Planck Institute of Molecular Cell Biology and GeneticsDresdenGermany
| | - Shigehiro Kuraku
- Laboratory for PhyloinformaticsRIKEN Center for Biosystems Dynamics Research (BDR)KobeJapan
| | - Axel Meyer
- Department of BiologyUniversity of KonstanzKonstanzGermany
| | | |
Collapse
|