Surprising amount of stasis in repetitive genome content across the Brassicales

2020 ◽  
Author(s):  
Aleksandra Beric ◽  
Makenzie E Mabry ◽  
Alex E Harkess ◽  
M. Eric Schranz ◽  
Gavin C Conant ◽  
...  
Keyword(s):  
Genome Size ◽  
Contributing Factors ◽  
Plant Genomes ◽  
New Methods ◽  
Whole Genome Duplications ◽  
Genome Size Evolution ◽  
Size Evolution ◽  
Genome Duplications ◽  
Genome Content ◽  
Low Coverage

Genome size of plants has long piqued the interest of researchers due to the vast differences among organisms. However, the mechanisms that drive size differences have yet to be fully understood. Two important contributing factors to genome size are expansions of repetitive elements, such as transposable elements (TEs), and whole-genome duplications (WGD). Although studies have found correlations between genome size and both TE abundance and polyploidy, these studies typically test for these patterns within a genus or species. The plant order Brassicales provides an excellent system to test if genome size evolution patterns are consistent across larger time scales, as there are numerous WGDs. This order is also home to one of the smallest plant genomes, Arabidopsis thaliana - chosen as the model plant system for this reason - as well as to species with very large genomes. With new methods that allow for TE characterization from low-coverage genome shotgun data and 71 taxa across the Brassicales, we find no correlation between genome size and TE content, and more surprisingly we identify no significant changes to TE landscape following WGD.

scholarly journals Comparative phylogenetics of repetitive elements in a diverse order of flowering plants (Brassicales)

2021 ◽  
Author(s):  
Aleksandra Beric ◽  
Makenzie E Mabry ◽  
Alex E Harkess ◽  
Julia Brose ◽  
M Eric Schranz ◽  
...  
Keyword(s):  
Genome Size ◽  
Repetitive Elements ◽  
Contributing Factors ◽  
New Methods ◽  
Whole Genome Duplications ◽  
Genome Size Evolution ◽  
Size Evolution ◽  
Genome Duplications ◽  
Comparative Phylogenetics ◽  
Low Coverage

Abstract Genome sizes of plants have long piqued the interest of researchers due to the vast differences among organisms. However, the mechanisms that drive size differences have yet to be fully understood. Two important contributing factors to genome size are expansions of repetitive elements, such as transposable elements (TEs), and whole-genome duplications (WGD). Although studies have found correlations between genome size and both TE abundance and polyploidy, these studies typically test for these patterns within a genus or species. The plant order Brassicales provides an excellent system to further test if genome size evolution patterns are consistent across larger time scales, as there are numerous WGDs. This order is also home to one of the smallest plant genomes, Arabidopsis thaliana—chosen as the model plant system for this reason—as well as to species with very large genomes. With new methods that allow for TE characterization from low-coverage genome shotgun data and 71 taxa across the Brassicales, we confirm correlation between genome size and TE content, however, we are unable to reconstruct phylogenetic relationships and do not detect any shift in TE abundance associated with WGD.

scholarly journals Size is not everything: rates of genome size evolution, not C -value, correlate with speciation in angiosperms

2015 ◽  
Vol 282 (1820) ◽  
pp. 20152289 ◽  
Author(s):  
Mark N. Puttick ◽  
James Clark ◽  
Philip C. J. Donoghue
Keyword(s):  
Genome Size ◽  
Sister Group ◽  
Land Plants ◽  
Whole Genome ◽  
Whole Genome Duplications ◽  
Rates Of Evolution ◽  
Genome Size Evolution ◽  
Size Evolution ◽  
Genome Duplications ◽  
Duplication Events

Angiosperms represent one of the key examples of evolutionary success, and their diversity dwarfs other land plants; this success has been linked, in part, to genome size and phenomena such as whole genome duplication events. However, while angiosperms exhibit a remarkable breadth of genome size, evidence linking overall genome size to diversity is equivocal, at best. Here, we show that the rates of speciation and genome size evolution are tightly correlated across land plants, and angiosperms show the highest rates for both, whereas very slow rates are seen in their comparatively species-poor sister group, the gymnosperms. No evidence is found linking overall genome size and rates of speciation. Within angiosperms, both the monocots and eudicots show the highest rates of speciation and genome size evolution, and these data suggest a potential explanation for the megadiversity of angiosperms. It is difficult to associate high rates of diversification with different types of polyploidy, but it is likely that high rates of evolution correlate with a smaller genome size after genome duplications. The diversity of angiosperms may, in part, be due to an ability to increase evolvability by benefiting from whole genome duplications, transposable elements and general genome plasticity.

scholarly journals Comparative Analysis of Transposable Elements in Genus Calliptamus Grasshoppers Revealed That Satellite DNA Contributes to Genome Size Variation

Insects ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 837
Author(s):  
Muhammad Majid ◽  
Huang Yuan
Keyword(s):  
Comparative Analysis ◽  
Transposable Elements ◽  
Genome Size ◽  
Structural Changes ◽  
Evolutionary Dynamics ◽  
Size Variation ◽  
Genome Size Variation ◽  
Genome Size Evolution ◽  
Size Evolution ◽  
Low Coverage

Transposable elements (TEs) play a significant role in both eukaryotes and prokaryotes genome size evolution, structural changes, duplication, and functional variabilities. However, the large number of different repetitive DNA has hindered the process of assembling reference genomes, and the genus level TEs diversification of the grasshopper massive genomes is still under investigation. The genus Calliptamus diverged from Peripolus around 17 mya and its species divergence dated back about 8.5 mya, but their genome size shows rather large differences. Here, we used low-coverage Illumina unassembled short reads to investigate the effects of evolutionary dynamics of satDNAs and TEs on genome size variations. The Repeatexplorer2 analysis with 0.5X data resulted in 52%, 56%, and 55% as repetitive elements in the genomes of Calliptamus barbarus, Calliptamus italicus, and Calliptamus abbreviatus, respectively. The LINE and Ty3-gypsy LTR retrotransposons and TcMar-Tc1 dominated the repeatomes of all genomes, accounting for 16–35% of the total genomes of these species. Comparative analysis unveiled that most of the transposable elements (TEs) except satDNAs were highly conserved across three genomes in the genus Calliptamus grasshoppers. Out of a total of 20 satDNA families, 17 satDNA families were commonly shared with minor variations in abundance and divergence between three genomes, and 3 were Calliptamus barbarus specific. Our findings suggest that there is a significant amplification or contraction of satDNAs at genus phylogeny which is the main cause that made genome size different.

PATTERNS OF GENOME SIZE EVOLUTION IN TETRAODONTIFORM FISHES

Evolution ◽  
2001 ◽  
Vol 55 (11) ◽  
pp. 2363 ◽  
Author(s):  
Elizabeth L. Brainerd ◽  
Sandra S. Slutz ◽  
Edward K. Hall ◽  
Randall W. Phillis
Keyword(s):  
Genome Size ◽  
Genome Size Evolution ◽  
Size Evolution

Polyploidization and Genome Size Evolution in Australian Billy Buttons (Craspedia, Asteraceae: Gnaphalieae)

2017 ◽  
Vol 178 (5) ◽  
pp. 352-361 ◽  
Author(s):  
Meghan Castelli ◽  
Cathy H. Miller ◽  
Alexander N. Schmidt-Lebuhn
Keyword(s):  
Genome Size ◽  
Genome Size Evolution ◽  
Size Evolution

scholarly journals Comparative analysis reveals within-population genome size variation in a rotifer is driven by large genomic elements with highly abundant satellite DNA repeat elements

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
C. P. Stelzer ◽  
J. Blommaert ◽  
A. M. Waldvogel ◽  
M. Pichler ◽  
B. Hecox-Lea ◽  
...  
Keyword(s):  
Genome Size ◽  
Satellite Dna ◽  
Gc Content ◽  
Size Variation ◽  
Isolated Populations ◽  
Genome Size Variation ◽  
Variable Regions ◽  
Geographic Population ◽  
Genome Size Evolution ◽  
Size Evolution

Abstract Background Eukaryotic genomes are known to display an enormous variation in size, but the evolutionary causes of this phenomenon are still poorly understood. To obtain mechanistic insights into such variation, previous studies have often employed comparative genomics approaches involving closely related species or geographically isolated populations within a species. Genome comparisons among individuals of the same population remained so far understudied—despite their great potential in providing a microevolutionary perspective to genome size evolution. The rotifer Brachionus asplanchnoidis represents one of the most extreme cases of within-population genome size variation among eukaryotes, displaying almost twofold variation within a geographic population. Results Here, we used a whole-genome sequencing approach to identify the underlying DNA sequence differences by assembling a high-quality reference genome draft for one individual of the population and aligning short reads of 15 individuals from the same geographic population including the reference individual. We identified several large, contiguous copy number variable regions (CNVs), up to megabases in size, which exhibited striking coverage differences among individuals, and whose coverage overall scaled with genome size. CNVs were of remarkably low complexity, being mainly composed of tandemly repeated satellite DNA with only a few interspersed genes or other sequences, and were characterized by a significantly elevated GC-content. CNV patterns in offspring of two parents with divergent genome size and CNV patterns in several individuals from an inbred line differing in genome size demonstrated inheritance and accumulation of CNVs across generations. Conclusions By identifying the exact genomic elements that cause within-population genome size variation, our study paves the way for studying genome size evolution in contemporary populations rather than inferring patterns and processes a posteriori from species comparisons.

scholarly journals The hidden elasticity of avian and mammalian genomes

2016 ◽  
Author(s):  
Aurélie Kapusta ◽  
Alexander Suh ◽  
Cédric Feschotte
Keyword(s):  
Genome Size ◽  
Interspecific Variation ◽  
Size Spectrum ◽  
Computational Pipeline ◽  
Substantial Variation ◽  
Avian Evolution ◽  
Genome Size Evolution ◽  
Size Evolution ◽  
Mammalian Genomes ◽  
Dna Loss

AbstractGenome size in mammals and birds shows remarkably little interspecific variation compared to other taxa. Yet, genome sequencing has revealed that many mammal and bird lineages have experienced differential rates of transposable element (TE) accumulation, which would be predicted to cause substantial variation in genome size between species. Thus, we hypothesize that there has been co-variation between the amount of DNA gained by transposition and lost by deletion during mammal and avian evolution, resulting in genome size homeostasis. To test this model, we develop a computational pipeline to quantify the amount of DNA gained by TE expansion and lost by deletion over the last 100 million years (My) in the lineages of 10 species of eutherian mammals and 24 species of birds. The results reveal extensive variation in the amount of DNA gained via lineage-specific transposition, but that DNA loss counteracted this expansion to various extent across lineages. Our analysis of the rate and size spectrum of deletion events implies that DNA removal in both mammals and birds has proceeded mostly through large segmental deletions (>10 kb). These findings support a unified ‘accordion’ model of genome size evolution in eukaryotes whereby DNA loss counteracting TE expansion is a major determinant of genome size. Furthermore, we propose that extensive DNA loss, and not necessarily a dearth of TE activity, has been the primary force maintaining the greater genomic compaction of flying birds and bats relative to their flightless relatives.

scholarly journals An enormous Paris polyphylla genome sheds light on genome size evolution and polyphyllin biogenesis

2020 ◽  
Author(s):  
Jing Li ◽  
Meiqi Lv ◽  
Lei Du ◽  
A Yunga ◽  
Shijie Hao ◽  
...  
Keyword(s):  
Genome Size ◽  
Single Molecule ◽  
Repetitive Sequences ◽  
Plant Genome ◽  
Growth Stages ◽  
Evolutionary Trend ◽  
Rna Seq ◽  
Genome Size Evolution ◽  
Size Evolution ◽  
Paris Polyphylla

AbstractThe monocot family Melanthiaceae with varying genome sizes in a range of 230-fold is an ideal model to study the genome size fluctuation in plants. Its family member Paris genus demonstrates an evolutionary trend of bearing huge genomes characterized by an average c-value of 49.22 pg. Here, we report a 70.18 Gb genome assembly out of the 82.55 Gb genome of Paris polyphylla var. yunnanensis (PPY), which represents the biggest sequenced genome to date. We annotate 69.53% repetitive sequences in this genome and 62.50% of which are long-terminal repeat (LTR) transposable elements. Further evolution analysis indicates that the giant genome likely results from the joint effect of common and species-specific expansion of different LTR superfamilies, which might contribute to the environment adaptation after speciation. Moreover, we identify the candidate pathway genes for the biogenesis of polyphyllins, the PPY-specific medicinal saponins, by complementary approaches including genome mining, comprehensive analysis of 31 next-generation RNA-seq data and 55.23 Gb single-molecule circular consensus sequencing (CCS) RNA-seq reads, and correlation of the transcriptome and phytochemical data of five different tissues at four growth stages. This study not only provides significant insights into plant genome size evolution, but also paves the way for the following polyphyllin synthetic biology.

scholarly journals The dynamic evolutionary history of genome size in North American woodland salamanders

Genome ◽  
2017 ◽  
Vol 60 (4) ◽  
pp. 285-292 ◽  
Author(s):  
Catherine E. Newman ◽  
T. Ryan Gregory ◽  
Christopher C. Austin
Keyword(s):  
Genome Size ◽  
Evolutionary History ◽  
Future Studies ◽  
Plethodontid Salamanders ◽  
Genome Size Evolution ◽  
Size Evolution ◽  
History Of ◽  
Large Genome Size ◽  
Uncertain Future ◽  
Phylogeographic Study

The genus Plethodon is the most species-rich salamander genus in North America, and nearly half of its species face an uncertain future. It is also one of the most diverse families in terms of genome sizes, which range from 1C = 18.2 to 69.3 pg, or 5–20 times larger than the human genome. Large genome size in salamanders results in part from accumulation of transposable elements and is associated with various developmental and physiological traits. However, genome sizes have been reported for only 25% of the species of Plethodon (14 of 55). We collected genome size data for Plethodon serratus to supplement an ongoing phylogeographic study, reconstructed the evolutionary history of genome size in Plethodontidae, and inferred probable genome sizes for the 41 species missing empirical data. Results revealed multiple genome size changes in Plethodon: genomes of western Plethodon increased, whereas genomes of eastern Plethodon decreased, followed by additional decreases or subsequent increases. The estimated genome size of P. serratus was 21 pg. New understanding of variation in genome size evolution, along with genome size inferences for previously unstudied taxa, provide a foundation for future studies on the biology of plethodontid salamanders.

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