Genome Size and Chromosome Number Relationship Contradicts the Principle of Darwinian Evolution from Common Ancestor

El-Shehawi, Ahmed M.; Elseehy, Mona M.

doi:10.4172/2329-9002.1000179

Cited by 4 publications

(3 citation statements)

References 32 publications

(38 reference statements)

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“…Dysploidy, chromatin elimination or expansion, nested polyploidizations, introgression, and hybridization can confound the evolutionary dynamics between chromosome number and genome size over time [60][61][62]. Consequently, these two genomic parameters show independent evolution and no clear correlation, especially in older polyploids, such as meso-and paleopolyploids [61,63,64]. Nevertheless, some correlation can still be observed in neopolyploids [6,61].…”

Section: Chromosome and Genome Size Evolutionmentioning

confidence: 99%

Disentangling Crocus Series Verni and Its Polyploids

Raca

Blattner

Waminal

et al. 2023

Biology

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Spring crocuses, the eleven species within Crocus series Verni (Iridaceae), consist of di- and tetraploid cytotypes. Among them is a group of polyploids from southeastern Europe with yet-unclear taxonomic affiliation. Crocuses are generally characterized by complex dysploid chromosome number changes, preventing a clear correlation between these numbers and ploidy levels. To reconstruct the evolutionary history of series Verni and particularly its polyploid lineages associated with C. heuffelianus, we used an approach combining phylogenetic analyses of two chloroplast regions, 14 nuclear single-copy genes plus rDNA spacers, genome-wide genotyping-by-sequencing (GBS) data, and morphometry with ploidy estimations through genome size measurements, analysis of genomic heterozygosity frequencies and co-ancestry, and chromosome number counts. Chromosome numbers varied widely in diploids with 2n = 8, 10, 12, 14, 16, and 28 and tetraploid species or cytotypes with 2n = 16, 18, 20, and 22 chromosomes. Crocus longiflorus, the diploid with the highest chromosome number, possesses the smallest genome (2C = 3.21 pg), while the largest diploid genomes are in a range of 2C = 7–8 pg. Tetraploid genomes have 2C values between 10.88 pg and 12.84 pg. Heterozygosity distribution correlates strongly with genome size classes and allows discernment of di- and tetraploid cytotypes. Our phylogenetic analyses showed that polyploids in the C. heuffelianus group are allotetraploids derived from multiple and partly reciprocal crosses involving different genotypes of diploid C. heuffelianus (2n = 10) and C. vernus (2n = 8). Dysploid karyotype changes after polyploidization resulted in the tetraploid cytotypes with 20 and 22 chromosomes. The multi-data approach we used here for series Verni, combining evidence from nuclear and chloroplast phylogenies, genome sizes, chromosome numbers, and genomic heterozygosity for ploidy estimations, provides a way to disentangle the evolution of plant taxa with complex karyotype changes that can be used for the analysis of other groups within Crocus and beyond. Comparing these results with morphometric analysis results in characters that can discern the different taxa currently subsumed under C. heuffelianus.

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Section: Chromosome and Genome Size Evolutionmentioning

confidence: 99%

Disentangling Crocus Series Verni and Its Polyploids

Raca

Blattner

Waminal

et al. 2023

Biology

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“…Variation in genome size of polychaete taxa is not evenly distributed, as species inhabiting interstitial environments have smaller size (0.06–1.1 pg), whereas macrobenthic species are larger (0.4–7.2 pg), and the difference has been considered to adaptation of different environments (Soldi et al 1994, Gambi et al 1997, Gregory 2018). In addition, the DNA content among different species was also found to be independent of chromosome numbers, which was also concluded by EI-Shehawi and Elseehy (2017) that no correlation between genome size and chromosome number after the comparison of more than 6000 records. In echiurans, there has been no report of the nuclear genome size up to now.…”

Section: Discussionmentioning

confidence: 65%

Analysis of chromosome karyotype and genome size in echiuran Urechis unicinctus Drasche, 1880 (Polychaeta, Urechidae)

Qin

Liu

et al. 2019

CCG

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Karyotype and genome size are two primary cytogenetic characteristics of species, which are of great significance to the study of cytogenetics, taxonomy, phylogenesis, evolution as well as molecular biology. However, this basic cytogenetic information in echiurans is lacking. Therefore, we analyzed characteristics of karyotype and genome size in the echiuran worm Urechisunicinctus Drasche, 1880. In this study, coelomic cells of U.unicinctus were used for analyzing the genome size by a flow cytometry with chicken erythrocytes as DNA standard, and the 2C DNA content was determined to be 1.85 pg, which was corresponded to the genome size of 904.58 Mbp approximately. Furthermore, trochophores of U.unicinctus were dissociated and cells were utilized for preparing the chromosomes stained with DAPI, and the karyotype was determined as 2n = 30 (10m + 6sm + 6st + 8t), FN=52. Our data provided the basic cytogenetic information of U.unicinctus, which could be utilized in taxonomic study and whole-genome sequencing in future.

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“…The change of chromosome counts provides a chance for us to understand the evolution of polyploidization during the process of speciation (Levin & Wilson, 1976; EI‐Shehawi & Elseehy, 2017). The variation of chromosome counts of angiosperms is large ranging from 2 n = 4 to 2 n = 178 for global angiosperms and from 2 n = 4 to 2 n = 90 for Chinese angiosperms, with the highest frequency of 2 n gamete from 14 to 28 (Fig.…”

Section: Discussionmentioning

confidence: 99%

Biogeographic patterns of polyploid species for the angiosperm flora in China

Wang

Deng

Yao

et al. 2022

J of Sytematics Evolution

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Exploring the frequency and distribution pattern of polyploid species in geographic parameters is of significance in understanding the mechanisms of polyploid speciation and evolutionary drivers of biodiversity. We here explored polyploid and paleopolyploid incidence frequency in a scale of 100 × 100 km grids in China. We found 33% of angiosperm species are polyploidy in China, and 23% of polyploid speciation. Western China and eastern China showed a significantly different polyploid and paleopolyploid frequency, with an evolutionary cradle of polyploid angiosperms in the Qinghai–Tibetan plateau. Herbaceous species exhibited higher polyploid frequency but lower paleopolyploid frequency than woody species, indicating the former experienced more rapid differentiation and speciation than the latter. Our results indicate that western China is an evolutionary cradle for polyploid angiosperms where harsh environment facilitates the establishment and survival of polyploids, while polyploid lineages tend to rediploidize to be diploids with sufficient time in suitable environment.

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Genome Size and Chromosome Number Relationship Contradicts the Principle of Darwinian Evolution from Common Ancestor

Cited by 4 publications

References 32 publications

Disentangling Crocus Series Verni and Its Polyploids

Disentangling Crocus Series Verni and Its Polyploids

Analysis of chromosome karyotype and genome size in echiuran Urechis unicinctus Drasche, 1880 (Polychaeta, Urechidae)

Biogeographic patterns of polyploid species for the angiosperm flora in China

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