Evolution of genome size and genomic GC content in carnivorous holokinetics (Droseraceae)

Endoreplication-Why Are We Not Using Its Full Application Potential?

Endoreplication-a process that is common in plants and also accompanies changes in the development of animal organisms-has been seen from a new perspective in recent years. In the paper, we not only shed light on this view, but we would also like to promote an understanding of the application potential of this phenomenon in plant cultivation. Endoreplication is a pathway for cell development, slightly different from the classical somatic cell cycle, which ends with mitosis. Since many rounds of DNA synthesis take place within its course, endoreplication is a kind of evolutionary compensation for the relatively small amount of genetic material that plants possess. It allows for its multiplication and active use through transcription and translation. The presence of endoreplication in plants has many positive consequences. In this case, repeatedly produced copies of genes, through the corresponding transcripts, help the plant acquire the favorable properties for which proteins are responsible directly or indirectly. These include features that are desirable in terms of cultivation and marketing: a greater saturation of fruit and flower colors, a stronger aroma, a sweeter fruit taste, an accumulation of nutrients, an increased resistance to biotic and abiotic stress, superior tolerance to adverse environmental conditions, and faster organ growth (and consequently the faster growth of the whole plant and its biomass). The two last features are related to the nuclear-cytoplasmic ratio-the greater the content of DNA in the nucleus, the higher the volume of cytoplasm, and thus the larger the cell size. Endoreplication not only allows cells to reach larger sizes but also to save the materials used to build organelles, which are then passed on to daughter cells after division, thus ending the classic cell cycle. However, the content of genetic material in the cell nucleus determines the number of corresponding organelles. The article also draws attention to the potential practical applications of the phenomenon and the factors currently limiting its use.

Microsatellite diversity in four cultivated species of Actinidiaceae and Rutaceae

Microsatellites or Simple Sequence Repeats (SSRs) are short iterations of 1-6 bp in the genomes of almost all living organisms. Our study aimed to explore the microsatellite diversity in four cultivated species, namely Actinidia chinensis, Actinidia eriantha, Citrus maxima, and Citrus sinensis of the Actinidiaceae and Rutaceae families. We present a comprehensive analysis of microsatellite abundance, distribution, and motif composition in the genomes of these species. The association of microsatellite abundance with genomic features such as genome size, GC content, number of microsatellites, relative abundance, and relative density was also examined. The results revealed significant variations in the frequency and distribution of microsatellites across the genomes of these four species. Notably, a positive correlation was observed between genome size and microsatellite number as well as with GC content, indicating that larger genomes provide more opportunities for the accumulation of microsatellites. Furthermore, a negative correlation of genome size with relative microsatellite abundance and relative density was observed. These findings provide new insights into the microsatellite landscape of Actinidiaceae and Rutaceae, which could be explored for the development of microsatellite markers for diverse applications in the characterization of genetic diversity, molecular plant breeding, and phylogenetic analysis.

Complex patterns of ploidy in a holocentric plant clade (Schoenus, Cyperaceae) in the Cape biodiversity hotspot

BACKGROUND AND AIMS

It is unclear how widespread polyploidy is throughout the largest holocentric plant family - the Cyperaceae. Because of the prevalence of chromosomal fusions and fissions, which affect chromosome number but not genome size, it can be impossible to distinguish if individual plants are polyploids in holocentric lineages based on chromosome count data alone. Furthermore, it is unclear how differences in genome size and ploidy levels relate to environmental correlates within holocentric lineages, such as the Cyperaceae.

METHODS

We focus our analyses on tribe Schoeneae, and more specifically the southern African clade of Schoenus. We examine broad-scale patterns of genome size evolution in tribe Schoeneae and focus more intensely on determining the prevalence of polyploidy across the southern African Schoenus by inferring ploidy level with the program ChromEvol, as well as interpreting chromosome number and genome size data. We further investigate whether there are relationships between genome size/ploidy level and environmental variables across the nutrient-poor and summer-arid Cape biodiversity hotspot.

KEY RESULTS

Our results show a large increase in genome size, but not chromosome number, within Schoenus compared to other species in tribe Schoeneae. Across Schoenus, there is a positive relationship between chromosome number and genome size, and our results suggest that polyploidy is a relatively common process throughout the southern African Schoenus. At the regional scale of the Cape, we show that polyploids are more often associated with drier locations that have more variation in precipitation between dry and wet months, but these results are sensitive to the classification of ploidy level.

CONCLUSIONS

Polyploidy is relatively common in the southern African Schoenus, where a positive relationship is observed between chromosome number and genome size. Thus, there may be a high incidence of polyploidy in holocentric plants, whose cell division properties differ from monocentrics.

Chromosome size matters: genome evolution in the cyperid clade

BACKGROUND AND AIMS

While variation in genome size and chromosome numbers and their consequences are often investigated in plants, the biological relevance of variation in chromosome size remains poorly known. Here, we examine genome and mean chromosome size in the cyperid clade (families Cyperaceae, Juncaceae and Thurniaceae), which is the largest vascular plant lineage with predominantly holocentric chromosomes.

METHODS

We measured genome size in 436 species of cyperids using flow cytometry, and augment these data with previously published datasets. We then separately compared genome and mean chromosome sizes (2C/2n) amongst the major lineages of cyperids and analysed how these two genomic traits are associated with various environmental factors using phylogenetically informed methods.

KEY RESULTS

We show that cyperids have the smallest mean chromosome sizes recorded in seed plants, with a large divergence between the smallest and largest values. We found that cyperid species with smaller chromosomes have larger geographical distributions and that there is a strong inverse association between mean chromosome size and number across this lineage.

CONCLUSIONS

The distinct patterns in genome size and mean chromosome size across the cyperids might be explained by holokinetic drive. The numerous small chromosomes might function to increase genetic diversity in this lineage where crossovers are limited during meiosis.

The ecological adaptation of the unparalleled plastome character evolution in slipper orchids

Plastomes may have undergone adaptive evolution in the process of plant adaptation to diverse environments, whereby species may differ in plastome characters. Cypripedioideae successfully colonized distinct environments and could be an ideal group for studying the interspecific variation and adaptive evolution of plastomes. Comparative study of plastomes, ancestral state reconstruction, phylogenetic-based analysis, ecological niche modelling, and selective pressure analysis were conducted to reveal the evolutionary patterns of plastomes in Cypripedioideae and their relationship with environmental factors. The plastomes of the three evolved genera had reduced plastome size, increased GC content, and compacted gene content compared to the basal group. Variations in plastome size and GC content are proved to have clear relationships with climate regions. Furthermore, ecological niche modelling revealed that temperature and water factors are important climatic factors contributing to the distributional difference which is directly correlated with the climate regions. The temperature-sensitive genes ndh genes, infA, and rpl20 were found to be either lost/pseudogenized or under positive selection in the evolved groups. Unparalleled plastome character variations were discovered in slipper orchids. Our study indicates that variations in plastome characters have adaptive consequences and that temperature and water factors are important climatic factors that affect plastome evolution. This research highlights the expectation that plants can facilitate adaptation to different environmental conditions with the changes in plastome and has added critical insight for understanding the process of plastome evolution in plants.

Transcriptional differences between major Fusarium pathogens of maize, Fusarium verticillioides and Fusarium graminearum with different optimum growth temperatures

Fusarium verticillioides and Fusarium graminearum are important pathogens causing disease in maize (Zea mays) worldwide. The distributions of these fungal pathogens vary greatly in different regions and in different years, and are influenced by environmental and climatic conditions. Temperature has significant effects on the growth and mycotoxin production of Fusarium species. In this study, the effects of temperature on the growth and pathogenicity of F. verticillioides and F. graminearum were investigated. F. verticillioides grew fastest and exhibited the strongest pathogenicity to maize stems and grains at 30°C, while F. graminearum grew best at 20°C. Both species produced more toxins at 20°C than at 30°C. To explain the interspecific differences in the relationship of growth and temperature, RNA-seq was used to compare F. verticillioides and F. graminearum cultivated for 4 d at the optimum temperatures of 30°C and 20°C, respectively. Samples of F. verticillioides were also cultivated for 9 d (to maximize toxin production) at 20°C and 30°C and analyzed by RNA-seq to investigate the influence of temperature for different growth stages. The differently expressed genes (DEGs) were identified by comparison of cultures grown for the same amount of time but at different temperatures. GO enrichment analysis showed high enrichment of DEGs in categories of membrane part, catalytic activity, metabolic process, and growth at warmer temperature resulted in more down-regulated DEGs enriched in membrane components in all groups. KEGG analysis revealed enrichment of DEGs related to different temperatures in carbohydrate and amino acid metabolism pathways. For both species, there was decreased expression of many DEGs related to amino acid metabolism when cultivated at warm temperature, such as genes related to beta-alanine metabolism and arginine and proline metabolism. However, changes in genes related to glyoxylate and dicarboxylate metabolism and fatty acid degradation were more related to the growth state. The results showing different responses pattern of these pathways provides a foundation for further investigation of the molecular mechanisms underlying distinct thermal ecological niches of F. verticillioides and F. graminearum.

The Evolution of Cytogenetic Traits in Cuscuta (Convolvulaceae), the Genus With the Most Diverse Chromosomes in Angiosperms

Karyotypes are characterized by traits such as chromosome number, which can change through whole-genome duplication and dysploidy. In the parasitic plant genus Cuscuta (Convolvulaceae), chromosome numbers vary more than 18-fold. In addition, species of this group show the highest diversity in terms of genome size among angiosperms, as well as a wide variation in the number and distribution of 5S and 35S ribosomal DNA (rDNA) sites. To understand its karyotypic evolution, ancestral character state reconstructions were performed for chromosome number, genome size, and position of 5S and 35S rDNA sites. Previous cytogenetic data were reviewed and complemented with original chromosome counts, genome size estimates, and rDNA distribution assessed via fluorescence in situ hybridization (FISH), for two, seven, and 10 species, respectively. Starting from an ancestral chromosome number of x = 15, duplications were inferred as the prevalent evolutionary process. However, in holocentric clade (subgenus Cuscuta), dysploidy was identified as the main evolutionary mechanism, typical of holocentric karyotypes. The ancestral genome size of Cuscuta was inferred as approximately 1C = 12 Gbp, with an average genome size of 1C = 2.8 Gbp. This indicates an expansion of the genome size relative to other Convolvulaceae, which may be linked to the parasitic lifestyle of Cuscuta. Finally, the position of rDNA sites varied mostly in species with multiple sites in the same karyotype. This feature may be related to the amplification of rDNA sites in association to other repeats present in the heterochromatin. The data suggest that different mechanisms acted in different subgenera, generating the exceptional diversity of karyotypes in Cuscuta.

Recent ecophysiological, biochemical and evolutional insights into plant carnivory

BACKGROUND

Carnivorous plants are an ecological group of approx. 810 vascular species which capture and digest animal prey, absorb prey-derived nutrients and utilize them to enhance their growth and development. Extant carnivorous plants have evolved in at least ten independent lineages, and their adaptive traits represent an example of structural and functional convergence. Plant carnivory is a result of complex adaptations to mostly nutrient-poor, wet and sunny habitats when the benefits of carnivory exceed the costs. With a boost in interest and extensive research in recent years, many aspects of these adaptations have been clarified (at least partly), but many remain unknown.

SCOPE

We provide some of the most recent insights into substantial ecophysiological, biochemical and evolutional particulars of plant carnivory from the functional viewpoint. We focus on those processes and traits in carnivorous plants associated with their ecological characterization, mineral nutrition, cost-benefit relationships, functioning of digestive enzymes and regulation of the hunting cycle in traps. We elucidate mechanisms by which uptake of prey-derived nutrients leads to stimulation of photosynthesis and root nutrient uptake.

CONCLUSIONS

Utilization of prey-derived mineral (mainly N and P) and organic nutrients is highly beneficial for plants and increases the photosynthetic rate in leaves as a prerequisite for faster plant growth. Whole-genome and tandem gene duplications brought gene material for diversification into carnivorous functions and enabled recruitment of defence-related genes. Possible mechanisms for the evolution of digestive enzymes are summarized, and a comprehensive picture on the biochemistry and regulation of prey decomposition and prey-derived nutrient uptake is provided.

Reference standards for flow cytometric estimation of absolute nuclear DNA content in plants

The estimation of nuclear DNA content has been by far the most popular application of flow cytometry in plants. Because flow cytometry measures relative fluorescence intensities of nuclei stained by a DNA fluorochrome, ploidy determination, and estimation of the nuclear DNA content in absolute units both require comparison to a reference standard of known DNA content. This implies that the quality of the results obtained depends on the standard selection and use. Internal standardization, when the nuclei of an unknown sample and the reference standard are isolated, stained, and measured simultaneously, is mandatory for precise measurements. As DNA peaks representing G₁/G₀ nuclei of the sample and standard appear on the same histogram of fluorescence intensity, the quotient of their position on the fluorescence intensity axis provides the quotient of DNA amounts. For the estimation of DNA amounts in absolute units, a number of well‐established standards are now available to cover the range of known plant genome sizes. Since there are different standards in use, the standard and the genome size assigned to it has always to be reported. When none of the established standards fits, the introduction of a new standard species is needed. For this purpose, the regression line approach or simultaneous analysis of the candidate standard with several established standards should be prioritized. Moreover, the newly selected standard organism has to fulfill a number of requirements: it should be easy to identify and maintain, taxonomically unambiguous, globally available, with known genome size stability, lacking problematic metabolites, suitable for isolation of sufficient amounts of nuclei, and enabling measurements with low coefficients of variation of DNA peaks, hence suitable for the preparation of high quality samples.

Repeat proliferation and partial endoreplication jointly shape the patterns of genome size evolution in orchids

Although the evolutionary drivers of genome size change are known, the general patterns and mechanisms of plant genome size evolution are yet to be established. Here we aim to assess the relative importance of proliferation of repetitive DNA, chromosomal variation (including polyploidy), and the type of endoreplication for genome size evolution of the Pleurothallidinae, the most species-rich orchid lineage. Phylogenetic relationships between 341 Pleurothallidinae representatives were refined using a target enrichment hybrid capture combined with high-throughput sequencing approach. Genome size and the type of endoreplication were assessed using flow cytometry supplemented with karyological analysis and low-coverage Illumina sequencing for repeatome analysis on a subset of samples. Data were analyzed using phylogeny-based models. Genome size diversity (0.2-5.1 Gbp) was mostly independent of profound chromosome count variation (2n = 12-90) but tightly linked with the overall content of repetitive DNA elements. Species with partial endoreplication (PE) had significantly greater genome sizes, and genomic repeat content was tightly correlated with the size of the non-endoreplicated part of the genome. In PE species, repetitive DNA is preferentially accumulated in the non-endoreplicated parts of their genomes. Our results demonstrate that proliferation of repetitive DNA elements and PE together shape the patterns of genome size diversity in orchids.

Chromosome-level genome assembly of the aphid parasitoid Aphidius gifuensis using Oxford Nanopore sequencing and Hi-C technology

Aphidius gifuensis is a parasitoid wasp that has been commercially bred and released in large scale as a biocontrol agent for the management of aphid pests. As a highly efficient endoparasitoid, it is also an important model for exploring mechanisms of parasitism. Currently, artificially bred populations of this wasp are facing rapid decline with undetermined cause, and mechanisms underlying its parasitoid strategy remain poorly understood. Exploring the mechanism behind its population decline and the host–parasitoid relationship is impeded partly due to the lack of a comprehensive genome data for this species. In this study, we constructed a high‐quality reference genome of A. gifuensis using Oxford Nanopore sequencing and Hi‐C (proximity ligation chromatin conformation capture) technology. The final genomic assembly was 156.9 Mb, with a contig N50 length of 3.93 Mb, the longest contig length of 10.4 Mb and 28.89% repetitive sequences. 99.8% of genome sequences were anchored onto six linkage groups. A total of 11,535 genes were predicted, of which 90.53% were functionally annotated. Benchmarking Universal Single‐Copy Orthologs (BUSCO) analysis showed the completeness of assembled genome is 98.3%. We found significantly expanded gene families involved in metabolic processes, transmembrane transport, cell signal communication and oxidoreductase activity, in particular ATP‐binding cassette (ABC) transporter, Cytochrome P450 and venom proteins. The olfactory receptors (ORs) showed significant contraction, which may be associated with the decrease in host recognition. Our study provides a solid foundation for future studies on the molecular mechanisms of population decline as well as host–parasitoid relationship for parasitoid wasps.

Substantial intraspecific genome size variation in golden-brown algae and its phenotypic consequences

BACKGROUND AND AIMS

While nuclear DNA content variation and its phenotypic consequences have been well described for animals, vascular plants and macroalgae, much less about this topic is known regarding unicellular algae and protists in general. The dearth of data is especially pronounced when it comes to intraspecific genome size variation. This study attempts to investigate the extent of intraspecific variability in genome size and its adaptive consequences in a microalgal species.

METHODS

Propidium iodide flow cytometry was used to estimate the absolute genome size of 131 strains (isolates) of the golden-brown alga Synura petersenii (Chrysophyceae, Stramenopiles), identified by identical internal transcribed spacer (ITS) rDNA barcodes. Cell size, growth rate and genomic GC content were further assessed on a sub-set of strains. Geographic location of 67 sampling sites across the Northern hemisphere was used to extract climatic database data and to evaluate the ecogeographical distribution of genome size diversity.

KEY RESULTS

Genome size ranged continuously from 0.97 to 2.02 pg of DNA across the investigated strains. The genome size was positively associated with cell size and negatively associated with growth rate. Bioclim variables were not correlated with genome size variation. No clear trends in the geographical distribution of strains of a particular genome size were detected, and strains of different genome size occasionally coexisted at the same locality. Genomic GC content was significantly associated only with genome size via a quadratic relationship.

CONCLUSIONS

Genome size variability in S. petersenii was probably triggered by an evolutionary mechanism operating via gradual changes in genome size accompanied by changes in genomic GC content, such as, for example, proliferation of transposable elements. The variation was reflected in cell size and relative growth rate, possibly with adaptive consequences.

Is the evolution of carnivory connected with genome size reduction?

PREMISE

As repeatedly shown, the remarkable variation in the genome size of angiosperms can be shaped by extrinsic selective pressures, including nutrient availability. Carnivory has evolved independently in 10 angiosperm clades, but all carnivorous plants share a common affinity to nutrient-poor habitats. As such, carnivory and genome reduction could be responses to the same environmental pressure. Indeed, the smallest genomes among flowering plants are found in the carnivorous family Lentibulariaceae, where a unique mutation in cytochrome c oxidase (COX) is suspected to promote genome miniaturization. Despite these hypotheses, a phylogenetically informed test of genome size and nutrient availability across carnivorous clades has so far been missing.

METHODS

Using linear mixed models, we compared genome sizes of 127 carnivorous plants from 7 diverse angiosperm clades with 1072 of their noncarnivorous relatives. We also tested whether genome size in Lentibulariaceae reflects the presence of the COX mutation.

RESULTS

The genome sizes of carnivorous plants do not differ significantly from those of their noncarnivorous relatives. Based on available data, no significant association between the COX mutation and genome miniaturization could be confirmed, not even when considering polyploidy.

CONCLUSIONS

Carnivory alone does not seem to significantly affect genome size decrease. Plausibly, it might actually counterbalance the effect of nutrient limitation on genome size evolution. The role of the COX mutation in genome miniaturization needs to be evaluated by analysis of a broader data set because current knowledge of its presence across Lentibulariaceae covers less than 10% of the species diversity in this family.

Functional insights from the GC-poor genomes of two aphid parasitoids, Aphidius ervi and Lysiphlebus fabarum

BACKGROUND

Parasitoid wasps have fascinating life cycles and play an important role in trophic networks, yet little is known about their genome content and function. Parasitoids that infect aphids are an important group with the potential for biological control. Their success depends on adapting to develop inside aphids and overcoming both host aphid defenses and their protective endosymbionts.

RESULTS

We present the de novo genome assemblies, detailed annotation, and comparative analysis of two closely related parasitoid wasps that target pest aphids: Aphidius ervi and Lysiphlebus fabarum (Hymenoptera: Braconidae: Aphidiinae). The genomes are small (139 and 141 Mbp) and the most AT-rich reported thus far for any arthropod (GC content: 25.8 and 23.8%). This nucleotide bias is accompanied by skewed codon usage and is stronger in genes with adult-biased expression. AT-richness may be the consequence of reduced genome size, a near absence of DNA methylation, and energy efficiency. We identify missing desaturase genes, whose absence may underlie mimicry in the cuticular hydrocarbon profile of L. fabarum. We highlight key gene groups including those underlying venom composition, chemosensory perception, and sex determination, as well as potential losses in immune pathway genes.

CONCLUSIONS

These findings are of fundamental interest for insect evolution and biological control applications. They provide a strong foundation for further functional studies into coevolution between parasitoids and their hosts. Both genomes are available at https://bipaa.genouest.org.

Super-Resolution Microscopy Reveals Diversity of Plant Centromere Architecture

Centromeres are essential for proper chromosome segregation to the daughter cells during mitosis and meiosis. Chromosomes of most eukaryotes studied so far have regional centromeres that form primary constrictions on metaphase chromosomes. These monocentric chromosomes vary from point centromeres to so-called "meta-polycentromeres", with multiple centromere domains in an extended primary constriction, as identified in Pisum and Lathyrus species. However, in various animal and plant lineages centromeres are distributed along almost the entire chromosome length. Therefore, they are called holocentromeres. In holocentric plants, centromere-specific proteins, at which spindle fibers usually attach, are arranged contiguously (line-like), in clusters along the chromosomes or in bands. Here, we summarize findings of ultrastructural investigations using immunolabeling with centromere-specific antibodies and super-resolution microscopy to demonstrate the structural diversity of plant centromeres. A classification of the different centromere types has been suggested based on the distribution of spindle attachment sites. Based on these findings we discuss the possible evolution and advantages of holocentricity, and potential strategies to segregate holocentric chromosomes correctly.

Characteristics analysis of the complete Wurfbainia villosa chloroplast genome

Wurfbainia villosa, which belongs to the huge family Zingiberaceae, is used in the clinic for the treatment of spleen and stomach diseases in southern China. The complete chloroplast genome of W. villosa was sequenced and analyzed using next-generation sequencing technology in the present work. The results showed that the W. villosa chloroplast genome is a circular molecule with 163,608 bp in length. It harbors a pair of inverted repeat regions (IRa and IRb) of 29,820 bp in length, which separate the large single copy (LSC, 88,680 bp) region and the small single copy (SSC, 15,288 bp) region. After annotation, 134 genes were identified in this plastome in total, comprising of 87 protein-coding genes, 38 transfer RNA genes, 8 ribosomal RNA genes and one pseudogene (ycf1). Codon usage, RNA editing sites and single/long sequence repeats were investigated to understand the structural characteristics of the W. villosa chloroplast genome. Furthermore, IR contraction and expansion were analyzed by comparison of complete chloroplast genomes of W. villosa and four other Zingiberaceae species. Finally, a phylogeny study based on the chloroplast genome of W. villosa, along with that of 15 different species, was conducted to further investigate the relationship among these lineages. Overally, our results represented the first insight into the chloroplast genome of W. villosa, and could serve as a significant reference for species identification, genetic diversity analysis and phylogenetic research between W. villosa and other species within Zingiberaceae.

Diversity in genome size and GC content shows adaptive potential in orchids and is closely linked to partial endoreplication, plant life-history traits and climatic conditions

In angiosperms, genome size and nucleobase composition (GC content) exhibit pronounced variation with possible adaptive consequences. The hyperdiverse orchid family possessing the unique phenomenon of partial endoreplication (PE) provides a great opportunity to search for interactions of both genomic traits with the evolutionary history of the family. Using flow cytometry, we report values of both genomic traits and the type of endoreplication for 149 orchid species and compare these with a suite of life-history traits and climatic niche data using phylogeny-based statistics. The evolution of genomic traits was further studied using the Brownian motion (BM) and Ornstein-Uhlenbeck (OU) models to access their adaptive potential. Pronounced variation in genome size (341-54 878 Mb), and especially in GC content (23.9-50.5%), was detected among orchids. Diversity in both genomic traits was closely related to the type of endoreplication, plant growth form and climatic conditions. GC content was also associated with the type of dormancy. In all tested scenarios, OU models always outperformed BM models. Unparalleled GC content variation was discovered in orchids, setting new limits for plants. Our study indicates that diversity in both genome size and GC content has adaptive consequences and is tightly linked with evolutionary transitions to PE.

Do holocentric chromosomes represent an evolutionary advantage? A study of paired analyses of diversification rates of lineages with holocentric chromosomes and their monocentric closest relatives

Despite most of the cytogenetic research is focused on monocentric chromosomes, chromosomes with kinetochoric activity localized in a single centromere, several studies have been centered on holocentric chromosomes which have diffuse kinetochoric activity along the chromosomes. The eukaryotic organisms that present this type of chromosomes have been relatively understudied despite they constitute rather diversified species lineages. On the one hand, holocentric chromosomes may present intrinsic benefits (chromosome mutations such as fissions and fusions are potentially neutral in holocentrics). On the other hand, they present restrictions to the spatial separation of the functions of recombination and segregation during meiotic divisions (functions that may interfere), separation that is found in monocentric chromosomes. In this study, we compare the diversification rates of all known holocentric lineages in animals and plants with their most related monocentric lineages in order to elucidate whether holocentric chromosomes constitute an evolutionary advantage in terms of diversification and species richness. The results showed that null hypothesis of equal mean diversification rates cannot be rejected, leading us to surmise that shifts in diversification rates between holocentric and monocentric lineages might be due to other factors, such as the idiosyncrasy of each lineage or the interplay of evolutionary selections with the benefits of having either monocentric or holocentric chromosomes.