BACKGROUND: Despite progress in genomic analysis of spiders, their chromosome evolution is not satisfactorily understood. Most information on spider chromosomes concerns the most diversified clade, entelegyne araneomorphs. Other clades are far less studied. Our study focused on haplogyne araneomorphs, which are remarkable for their unusual sex chromosome systems and for the co-evolution of sex chromosomes and nucleolus organizer regions (NORs); some haplogynes exhibit holokinetic chromosomes. To trace the karyotype evolution of haplogynes on the family level, we analysed the number and morphology of chromosomes, sex chromosomes, NORs, and meiosis in pholcids, which are among the most diverse haplogyne families. The evolution of spider NORs is largely unknown. RESULTS: Our study is based on an extensive set of species representing all major pholcid clades. Pholcids exhibit a low 2n and predominance of biarmed chromosomes, which are typical haplogyne features. Sex chromosomes and NOR patterns of pholcids are diversified. We revealed six sex chromosome systems in pholcids (X0, XY, X1X20, X1X2X30, X1X2Y, and X1X2X3X4Y). The number of NOR loci ranges from one to nine. In some clades, NORs are also found on sex chromosomes. CONCLUSIONS: The evolution of cytogenetic characters was largely derived from character mapping on a recently published molecular phylogeny of the family. Based on an extensive set of species and mapping of their characters, numerous conclusions regarding the karyotype evolution of pholcids and spiders can be drawn. Our results suggest frequent autosome-autosome and autosome-sex chromosome rearrangements during pholcid evolution. Such events have previously been attributed to the reproductive isolation of species. The peculiar X1X2Y system is probably ancestral for haplogynes. Chromosomes of the X1X2Y system differ considerably in their pattern of evolution. In some pholcid clades, the X1X2Y system has transformed into the X1X20 or XY systems, and subsequently into the X0 system. The X1X2X30 system of Smeringopus pallidus probably arose from the X1X20 system by an X chromosome fission. The X1X2X3X4Y system of Kambiwa probably evolved from the X1X2Y system by integration of a chromosome pair. Nucleolus organizer regions have frequently expanded on sex chromosomes, most probably by ectopic recombination. Our data suggest the involvement of sex chromosome-linked NORs in achiasmatic pairing.

Arachnida Section Alexander Koenig Zoological Research Museum Adenauerallee 160 53113 Bonn Germany

Invertebrate Zoology Unit Department of Zoology Faculty of Science Charles University Viničná 7 128 44 Prague 2 Czech Republic

Laboratory of Arachnid Cytogenetics Department of Genetics and Microbiology Faculty of Science Charles University Viničná 5 128 44 Prague 2 Czech Republic

Laboratory of Molecular Cytogenetics Department of Molecular Biology and Genetics Faculty of Science University of South Bohemia Branišovská 31 370 05 České Budějovice Czech Republic

Laboratory of Molecular Cytogenetics Department of Molecular Biology and Genetics Institute of Entomology Biology Centre CAS Branišovská 31 370 05 České Budějovice Czech Republic

Prague 1 Czech Republic

Research Group of Arachnid Systematics and Ecology Department of Zoology and Entomology Faculty of Natural and Agricultural Sciences University of the Free State P O Box 339 Bloemfontein 9300 Republic of South Africa

Research Team of Plant Stress Biology and Biotechnology Division of Crop Genetics and Breeding Crop Research Institute Drnovská 507 73 161 00 Prague 6 Czech Republic

Erratum v

BMC Ecol Evol. 2021 May 21;21(1):93. doi: 10.1186/s12862-021-01828-3. PubMed

Zobrazit více v PubMed

Traut W, Ahola V, Smith DAS, Gordon IJ, ffrench-Constant RH. Karyotypes versus genomes: the nymphalid butterflies Melitaea cinxia, Danaus plexippus, and D. chrysippus. Cytogenet Genome Res. 2017;153:46–53. PubMed

Tomaszkiewicz M, Medvedev P, Makova KD. Y and W chromosome assemblies: approaches and discoveries. Trends Genet. 2017;33:266–282. PubMed

Deakin JE, Ezaz T. Understanding the evolution of reptile chromosomes through applications of combined cytogenetics and genomics approaches. Cytogenet Genome Res. 2019;157:7–20. PubMed

Schwager E, Sharma PP, Thomas C, Leite DJ, Wierschin T, Pechmann M, et al. The house spider genome reveals an ancient whole-genome duplication during arachnid evolution. BMC Biol. 2017;15:62. PubMed PMC

Král J, Kořínková T, Forman M, Krkavcová L. Insights into the meiotic behavior and evolution of multiple sex chromosome systems in spiders. Cytogenet Genome Res. 2011;133:43–66. PubMed

Král J, Kořínková T, Krkavcová L, Musilová J, Forman M, Ávila Herrera IM, et al. Evolution of karyotype, sex chromosomes, and meiosis in mygalomorph spiders (Araneae: Mygalomorphae) Biol J Linnean Soc. 2013;2:377–408.

Král J. Evolution of multiple sex chromosomes in the spider genus Malthonica (Araneae: Agelenidae) indicates unique structure of the spider sex chromosome systems. Chromosome Res. 2007;15:863–879. PubMed

Garb JE, Sharma PP, Ayoub NA. Recent progress and prospects for advancing arachnid genomics. Curr Opin Insect Sci. 2018;25:51–57. PubMed PMC

Král J, Musilová J, Šťáhlavský F, Řezáč M, Akan Z, Edwards RL, et al. Evolution of the karyotype and sex chromosome systems in basal clades of araneomorph spiders (Araneae: Araneomorphae) Chromosome Res. 2006;14:859–880. PubMed

Wheeler WC, Coddington JA, Crowley LM, Dimitrov D, Goloboff PA, Griswold CE, et al. The spider tree of life: phylogeny of Araneae based on target-gene analyses from an extensive taxon sampling. Cladistics. 2017;33:574–616. PubMed

Shao L, Li S. Early Cretaceous greenhouse pumped higher taxa diversification in spiders. Mol Phylogenet Evol. 2018;127:146–155. PubMed

Michalik P, Kallal R, Dederichs TM, Labarque FM, Hormiga G, Giribet G, et al. Phylogenomics and genital morphology of cave raptor spiders (Araneae, Trogloraptoridae) reveal an independent origin of a flow-through female genital system. J Zool Syst Evol Res. 2019;57:737–747.

World Spider Catalog. Version 20.5. Natural History Museum, Bern. 2020. http://wsc.nmbe.ch. Accessed 4 Jan 2020.

Král J, Forman M, Kořínková T, Reyes Lerma AC, Haddad CR, Musilová J, et al. Insights into the karyotype and genome evolution of haplogyne spiders indicate a polyploid origin of lineage with holokinetic chromosomes. Sci Rep. 2019;9:3001. PubMed PMC

Ávila Herrera IM, Carabajal Paladino LZ, Musilová J, Palacios Vargas JG, Forman M, Král J. Evolution of karyotype and sex chromosomes in two families of haplogyne spiders, Filistatidae and Plectreuridae. In: Martins C, Pedrosa-Harand A, Houben A, Sullivan B, Martelli L, O´Neil R. editors. 21st international chromosome conference, Foz do Iguaçu, Brazil. Cytogenet Genome Res. 2016;148:104.

Paula-Neto E, Cella DM, Araujo D, Brescovit AD, Schneider MC. Comparative cytogenetic analysis among filistatid spiders (Araneomorphae: Haplogynae) J Arachnol. 2017;45:123–128.

Araujo D, Schneider MC, Zacaro AA, de Oliveira EG, Martins R, Brescovit AD. Venomous Loxosceles species (Araneae, Haplogynae, Sicariidae) from Brazil: 2n♂ = 23 and X1X2Y sex chromosome system as shared characteristics. Zool Sci. 2020;37:128–139. PubMed

Kořínková T, Král J. Karyotypes, sex chromosomes, and meiotic division in spiders. In: Nentwig W, editor. Spider ecophysiology. Berlin: Springer; 2013. pp. 159–172.

McStay B. Nucleolar organizer regions: genomic 'dark matter' requiring illumination. Genes Dev. 2016;30:1598–1610. PubMed PMC

Eberle J, Dimitrov D, Valdez-Mondragón A, Huber BA. Microhabitat change drives diversification in pholcid spiders. BMC Evol Biol. 2018;18:141. PubMed PMC

Huber BA, Eberle J, Dimitrov D. The phylogeny of pholcid spiders: a critical evaluation of relationships suggested by molecular data (Araneae, Pholcidae). ZooKeys. 2018;789:51–101. PubMed PMC

Huber BA. Phylogeny and classification of Pholcidae (Araneae): an update. J Arachnol. 2011;39:211–222.

Huber BA. Pholcidae. In: Roig-Juñent S, Claps LE, Morrone JJ, editors. Biodiversidad de Artrópodos Argentinos. Buenos Aires: Sociedad Entomológica Argentina; 2014. pp. 131–140.

Araujo D, Schneider MC, Paula-Neto E, Cella DM. The spider cytogenetic database. 2020. http://www.arthropodacytogenetics.bio.br/spiderdatabase. Accessed 30 Jan 2020.

Lomazi RL, Araujo D, Carvalho LS, Schneider MC. Small pholcids (Araneae: Synspermiata) with big surprises: the lowest diploid number in spiders with monocentric chromosomes. J Arachnol. 2018;46:45–49.

Araujo D, Brescovit A, Rheims C, Cella D. Chromosomal data of two pholcids (Araneae, Haplogynae): a new diploid number and the first cytogenetical record for the New World clade. J Arachnol. 2005;2:591–596.

Ramalho M, Araujo D, Schneider M, Brescovit A, Cella D. Mesabolivar brasiliensis (Moenkhaus 1898) and Mesabolivar cyaneotaeniatus (Keyserling 1891) (Araneomorphae, Pholcidae): close relationship reinforced by cytogenetic analyses. J Arachnol. 2008;36:453–456.

Bole-Gowda B. A study of the chromosomes during meiosis in twenty-two species of Indian spiders. Proc Zool Soc Bengal. 1958;2:69–108.

Srivastava M, Shukla S. Chromosome number and sex-determining mechanism in forty-seven species of Indian spiders. Chromos Inf Serv. 1986;41:23–26.

Oliveira RM, Jesus AC, Brescovit AD, Cella DM. Chromosomes of Crossopriza lyoni (Blackwall 1867), intraindividual numerical chromosome variation in Physocyclus globosus (Taczanowski 1874), and the distribution pattern of NORs (Araneomorphae, Haplogynae, Pholcidae) J Arachnol. 2007;35:293–306.

Golding AE, Paliulis LV. Karyotype, sex determination, and meiotic chromosome behavior of two pholcid (Araneomorphae, Pholcidae) spiders: implications for karyotype evolution. PLoS ONE. 2011;9:e24748. PubMed PMC

Arunkumar S, Jayaprakash Chromosomal studies of two spider species of Pholcidae (Aranae: Haplogynae) Int J Curr Res. 2015;2:2650–2653.

Parida B, Sharma N. Chromosome number, sex mechanism and genome size in 27 species of Indian spiders. Chromos Inf Serv. 1987;43:11–13.

Sharma N, Parida BB. Study of chromosomes in spiders from Orissa. Pranikee. 1987;8:71–76.

Wang X, Cui S, Yang Z, Wang J, Wang Y. On karyotype of the Pholcus affinis (Araneida: Pholcidae) Acta Arachnol Sin. 1997;1:19–22.

Garrison NL, Rodriguez J, Agnarsson I, Coddington JA, Griswold CE, Hamilton CA, et al. Spider phylogenomics: untangling the spider tree of life. PeerJ. 2016;4:e1719. PubMed PMC

Fernández R, Kalla RJ, Dimitrov D, Ballesteros JA, Arnedo M, Giribet G, et al. Phylogenomics, diversification dynamics, and comparative transcriptomics across the spider tree of life. Curr Biol. 2018;13:2190–2193. PubMed

Suzuki S. Cytological studies in spiders. III. Studies on the chromosomes of fifty-seven species of spiders belonging to seventeen families, with general considerations on chromosomal evolution. J Sci Hiroshima Univ Ser B. 1954;2:23–136.

Sharma S, Ramakrishna S. Cytological studies on three species of Indian spiders. Int J Adv Sci Res Manag. 2019;4:1–6.

Rieseberg LH. Chromosomal rearrangements and speciation. Trends Ecol Evol. 2001;7:351–358. PubMed

Ayala F, Coluzzi M. Chromosome speciation: humans, Drosophila, and mosquitoes. Proc Natl Acad Sci USA. 2005;1:6535–6542. PubMed PMC

Silva D. Estudio cariotípico de Loxosceles laeta (Araneae: Loxoscelidae) Rev Perú Ent. 1988;31:9–12.

Silva RW, Klisiowicz DR, Cella DM, Mangili OC, Sbalqueiro IJ. Differential distribution of constitutive heterochromatin in two species of brown spider: Loxosceles intermedia and L. laeta (Araneae, Sicariidae), from the metropolitan region of Curitiba, PR (Brazil) Acta Biol Par Curitiba. 2002;31:123–136.

Selden PA, Penney D. Fossil spiders. Biol Rev Camb Philos Soc. 2009;85:171–206. PubMed

Araujo D, Schneider MC, Paula-Neto E, Cella DM. Sex chromosomes and meiosis in spiders: a review. In: Swan A, editor. Meiosis: molecular mechanisms and cytogenetic diversity. Rijeka: InTech; 2012. pp. 87–108.

Řezáč M, Král J, Musilová J, Pekár S. Unusual karyotype diversity in the European spiders of the genus Atypus (Araneae: Atypidae) Hereditas. 2006;143:123–129. PubMed

Souza LB, Brescovit AD, Araujo DS. A new species of Synotaxus and the first chromosomal study on Synotaxidae, presenting a rare XY sex chromosome system in spiders (Araneae, Araneoidea) Zootaxa. 2017;4303:140–150.

Araujo D, Oliveira EG, Giroti AM, Mattos VF, Paula-Neto E, Brescovit AD, et al. Comparative cytogenetics of seven Ctenidae species (Araneae) Zool Sci. 2014;31:83–88. PubMed

Datta SN, Chatterjee K. Chromosomes and sex determination in 13 araneid spiders of North-Eastern India. Genetica. 1988;76:91–99.

Mahadevaiah SK, Lovell-Badge R, Burgoyne PS. Tdy-negative XY, XXY and XYY female mice: breeding data and synaptonemal complex analysis. J Reprod Fertil. 1993;97:151–60. PubMed

Maddison WP. XXXY sex chromosomes in males of the jumping spider genus Pellenes (Araneae: Salticidae) Chromosoma. 1982;5:23–37.

Rowell DM. Complex sex-linked fusion heterozygosity in the Australian huntsman spider Delena cancerides (Araneae: Sparassidae) Chromosoma. 1985;93:169–176.

Maddison WP, Leduc RG. Multiple origins of sex chromosome fusions correlated with chiasma localization in Habronattus jumping spiders (Araneae: Salticidae) Evolution. 2013;67:2258–2272. PubMed PMC

Martin LT. Sex chromosome translocations in the evolution of reproductive isolation. Genetics. 1972;72:317–333. PubMed PMC

Presgraves DC. Sex chromosomes and speciation in Drosophila. Trends Genet. 2008;24:336–343. PubMed PMC

Kitano J, Ross JA, Mori S, Kume M, Jones FC, Chan YF, et al. A role for a neo-sex chromosome in stickleback speciation. Nature. 2009;461:1079–1083. PubMed PMC

Hooper DM, Griffith SC, Price TD. Sex chromosome inversions enforce reproductive isolation across an avian hybrid zone. Mol Ecol. 2019;28:1246–1262. PubMed

Lima TG. Higher levels of sex chromosome heteromorphism are associated with markedly stronger reproductive isolation. Nat Commun. 2014;5:4743. PubMed

Miller DA, Dev VG, Tantravahi R, Miller OJ. Suppression of human nucleolus organizer activity in mouse-human somatic hybrid cells. Exp Cell Res. 1976;101:235–243. PubMed

Dunlop JA, Penney D, Jekel D. A summary list of fossil spiders and their relatives. In: World Spider Catalog. Natural History Museum Bern. version 20.0. 2019. http://wsc.nmbe.ch. Accessed 4 Jan 2020.

Dimitrov D, Astrin JJ, Huber BA. Pholcid spider molecular systematics revisited, with new insights into the biogeography and the evolution of the group. Cladistics. 2013;29:132–146. PubMed

McKee BD, Karpen GH. Drosophila ribosomal RNA genes function as an X-Y pairing site during male meiosis. Cell. 1990;61:61–72. PubMed

Mandrioli M, Bizzaro D, Giusti M, Manicardi GC, Bianchi U. The role of rDNA genes in X chromosome association in the aphid Acyrthosiphon pisum. Genome. 1999;42:381–386. PubMed

Roy V, Monti-Dedieu L, Chaminade N, Siljak-Yakovlev S, Aulard S, Lemeunier F, et al. Evolution of the chromosomal location of rDNA genes in two Drosophila species subgroups: ananassae and melanogaster. Heredity. 2005;94:388–395. PubMed

Forman M, Nguyen P, Hula P, Král J. Sex chromosome pairing and extensive NOR polymorphism in Wadicosa fidelis (Araneae: Lycosidae) Cytogenet Genome Res. 2013;1:43–49. PubMed

Mittal OP. Karyological studies on the Indian spiders VI. Chromosome number and sex-determining mechanism in the family Araneidae. Res Bull Panjab Univ Sci. 1966;17:335–351.

Benavente R, Wettstein R. Ultrastructural characterization of the sex chromosomes during spermatogenesis of spiders having holocentric chromosomes and a long diffuse stage. Chromosoma. 1980;77:69–81. PubMed

John B. Meiosis. 3. Cambridge: Cambridge University Press; 1990.

Lukaszewski AJD, Kopecky G. Inversions of chromosome arms 4AL and 2BS in wheat invert the patterns of chiasma distribution. Chromosoma. 2012;121:201–208. PubMed

Alberti G, Weinmann C. Fine structure of spermatozoa of some labidognath spiders (Filistatidae, Segestriidae, Dysderidae, Oonopidae, Scytodidae, Pholcidae; Araneae; Arachnida) with remarks on spermiogenesis. J Morphol. 1985;185:1–35. PubMed

Sokolow II. Endomitotic polyploidy in testicular epithelial cells of spiders (Araneina). II. Cytology. 1967;9:257–264. PubMed

Gregory TR, Shorthouse DP. Genome sizes of spiders. J Hered. 2003;94:285–290. PubMed

Hackman W. Chromosomenstudien an Araneen mit besonderer Berücksichtigung der Geschlechtschromosomen. Acta Zool Fennica. 1948;54:1–101.

Huber BA. Southern African pholcid spiders: revision and cladistic analysis of Quamtana gen. nov. and Spermophora Hentz (Araneae: Pholcidae), with notes on male-female covariation. Zool J Linn Soc. 2003;139:477–527.

Brignoli PM. Beitrag zur Kenntnis der mediterranen Pholcidae (Arachnida, Araneae) Mitt Zool Mus Berlin. 1971;47:255–267.

Brignoli PM. Ragni di Grecia IX. Specie nuove o interessanti delle famiglie Leptonetidae, Dysderidae, Pholcidae ed Agelenidae (Araneae) Rev Suisse Zool. 1976;83:539–578.

Brignoli PM. Spiders from Lebanon, V. On Hoplopholcuscecconii Kulczynski, 1908 (Pholcidae) Bull Br Arachnol Soc. 1979;4:350–352.

Huber BA. New World pholcid spiders (Araneae: Pholcidae): a revision at generic level. Bull Am Mus Nat Hist. 2000;254:1–348.

Huber BA. Revision and cladistic analysis of the Afrotropical endemic genus Smeringopus Simon, 1890 (Araneae: Pholcidae) Zootaxa. 2012;3461:1–138.

Dolejš P, Kořínková T, Musilová J, Opatová V, Kubcová L, Buchar J, et al. Karyotypes of central European spiders of the genera Arctosa, Tricca and Xerolycosa (Araneae: Lycosidae) Eur J Entomol. 2011;108:1–16.

Levan AK, Fredga K, Sandberg AA. Nomenclature for centromeric position on chromosomes. Hereditas. 1964;52:201–220.

Cokendolpher JC. Karyotypes of three spider species (Araneae: Pholcidae: Physocyclus) J N Y Entomol Soc. 1989;97:475–478.

Cokendolpher JC, Brown JD. Air-dry method for studying chromosomes of insects and arachnids. Entomol News. 1985;3:114–118.

Galián J, Proenca SJR, Vogler AP. Evolutionary dynamics of autosomal-heterosomal rearrangements in a multiple-X chromosome system of tiger beetles (Cicindelidae) BMC Evol Biol. 2007;7:158. PubMed PMC

Graves JAM, Wakefield MJ, Toder R. The origin and evolution of pseudoautosomal regions of human sex chromosomes. Hum Mol Genet. 1998;7:1991–1996. PubMed

Bačovský V, Čegan R, Šimoníková D, Hřibová E, Hobza R. The formation of sex chromosomes in Silene latifolia and S. dioica was accompanied by multiple chromosomal rearrangements. Front Plant Sci. 2020;11:205. PubMed PMC

Kejnovský E, Hobza R, Čermák T, Kubát Z, Vyskot B. The role of repetitive DNA in structure and evolution of sex chromosomes in plants. Heredity. 2009;102:533–541. PubMed

Schartl M, Schmid M, Nanda I. Dynamics of vertebrate sex chromosome evolution: from equal size to giants and dwarfs. Chromosoma. 2016;125:553–571. PubMed

Advances in Understanding the Karyotype Evolution of Tetrapulmonata and Two Other Arachnid Taxa, Ricinulei and Solifugae

Karyotype differentiation and male meiosis in European clades of the spider genus Pholcus (Araneae, Pholcidae)

Atypus karschi Dönitz, 1887 (Araneae: Atypidae): An Asian purse-web spider established in Pennsylvania, USA

Insights into the Karyotype Evolution of Charinidae, the Early-Diverging Clade of Whip Spiders (Arachnida: Amblypygi)

Correction to: Evolutionary pattern of karyotypes and meiosis in pholcid spiders (Araneae: Pholcidae): implications for reconstructing chromosome evolution of araneomorph spiders