Evolutionary trends in chromosome number changes iiiiiiiiiiii ®B»((l(llillfl Basic chromosome number (x) a relative concept [x has to be related to a certain taxonomie unit, e.g. genus or (sub)family] monobasic taxa (single x number), dibasic taxa (two x nos.) and polybasic taxa (>2 x nos.) are there any evolutionary trends in chromosome number changes? are the same chromosome number and similar karyotype structure indicative of close phylogenetic relationship? can polybasic taxa be regarded as monophyletic? is the most common basic chromosome number automatically the ancestral one? Asferaceae- example of a polybasic family Table 4. Tri- and polybasic genera in the Astereae. Genus Region Uasic" chromosome numbers Ameltus L, Aphanostephus DC. Aster L. Astranthium Nutt. Brachyscome Cass. Ca tor is R. Br. Chrysopsis Nutt. Felicia Cass. Haphpappus Cass, sensu lato Machaewnthem Nees Psiiüctis A, Gray (Africa) (N. Am.-Mex.) (cosmopolitan) (N, Am,-Mex.) (Austr,n N,Z., N.C.) x = 6, 8, 9 (diploid) a: = 3, 4t 5 (diploid) ;c = (4_)5, 7, 8, 9, 13 (polyploid to 16.T) x = 3, 4, 5, 6, 8, 9, etc. (dysploid; polyploid to óx?) x =2, 3,4,5, 6, 7,8, 9, 10, 11, 12, 13, etc. (dysploid; poly- ploid to ISjc?) (New Zealand) x = 4, 7, 8, 9, etc. (polyploid to 14.V?) (N, Am.) x = 4, 5, 9 (polyploid to 6x) (Africa) x = 5, 6, 8, 9 (diploid and tetra- ploid) (N, Am.-S. Am.) * = 2, 3, 4, 5,6, 7, 8, 9, etc. (dys- ploid; polyploid to I8.r?) (N, Am.-Mex.) x = 2, 4, 5, 8, 97 (dysploid; dip- loid and telraploid) (N. Am.-S. Am.) x = 4, 5, 9 (perhaps dibasic with dysploidy; diploid) Evolutionary changes of basic chromosome number I. allopolyploidy / / \ Note: B. campestris = B. rapa II. aneuploidy descending aneuploidy ascending aneuploidy Changes in chromosome number Ö Alteration of diploid chromosome number by mis-segregation from meiotic multivalents of an individual that is heterozygous for two translocations between a metacentric and two acrocentric chromosomes. y i n=4 Descending aneuploidy due to unequal reciprocal translocation (centric fusion) 2n = 8 chromosome number reduction 2n = 8 or 7 or 6 I ! t i B IS —* i\\ u B i Most 2N*8 2N-7 2N=6 81 8 Descending aneuploidy due to Robertsonian translocation (centric fusion) Acrocentric chromosomes Large metacentric chromosome Small chromosome 1 lost Ascending aneuploidy 1. Centric fission -^ el a & 2. Meiotic misdivision • misdivision resulting in a tetrasomic plant (2n+2) (or first trisomy: 2n+l followed by tetrasomy, 2n+2) • the extra chromosome can diverge from their homologues through a translocation with non-homologous chromosomes Chromosome number pattern congruent with phylogenetic relationships: Ranunculaceae • Langlet (1927, 1932) recognized two subfamilies of Ranunculaceae {Ranunculoideae and Thalictroideae) on the basis of cytological characters, including chromosome size and basic number • the Ranunculus group of genera (R-chromosome group) has large and long chromosomes with a basic number of 8 • the Thalictrum group (T-chromosome group) has short and small chromosomes with a basic number of 7 or 9 Mwwwwtm T-iype :■:»::;■»::■:: Uncertain x = bas« number (A) • Ro et al. (1997): chromosome type and base number are congruent with the inferred molecular (rDNA) phylogeny ,- $ • fruit type (often used for the higher classification) was not congruent with karyological data and phylogenetic patterns Cúfísositss amtngua D&pftMivm exaltation NigeHadamsiscenii Actee? sit?* Cimicifuga amerlcana Eranttils hyematls Heflebonss tortious Calina palustris Trotllua laxus Aüo/tia vemaíls TrautvettĚrtá caiotlnensta Ranunculus recurvatus Hepatica ametlcana Pulsatilla so. Anemone trifolia Anemone tfutňqueíůtta Clematis albltoma ClemnUs itvntontti Thallctmm thaltotroides Jhpllctrvm dlolcvm Thsltctnim corlgceum TJjpitctrvfTi rBvtrtutufn ThBiictrvm dasyearpum Trtallctrum cooteyl Aquilegia ecatcarata Aquilegia vulgaris Aquilegia canadensis Enemion blternatum xantftorhlza simplfclsslma COfitis tritQlla Hydvstls cpnßdensls Descending aneuploidy in Hypochaeris (Asferaceae) H. acauli.i H. apargiaides ff. piiiuytrii ŕľ. apatiwlata Wp h 4 H. psnwsscs H. tiůritxMiíies —I H. apargKHOts H. fňrtKJaŕfllŕs H. «U» h paAisMa H. aoauts ff. i&mdjiiöne ff. w-ssUWtefa H mepSpĎŕamteS <• : i v.'.'ťi 'siL ^ ŕf jiťigijs]i(t]liít ) Setí. ActyraflfiWUä n=4 Somh America t H. oľipocsfVíalls ---------rf. maculate -W ura*jrj &S 1 Sad. -1 n= 1 Emn Je I n=5 n=3 98 +t 8sT"I H. '----H. 5í araenneftfea H cii..-!.í.) ---------- H. aCnJiDflÜCfUS M tamiwjiafa 5«ct. H^pKriaarfs n=4, 5 n=6 -----------------LAosŕäimurti daAMftampn Ľuigrr.ip — 0.0Ů1 5i*sWiHkin5.íi1c Descending aneuploidy in Podolepis (Asferaceae) • the extraordinary series of chromosome numbers, n = 12, 11, 10, 9, 8, 7 and 3 (dysploidy) • chromosome number of n = 10 is the most common in the genus, and thus, x = 10 was regarded as the ancestral chromosome base number for the genus Descending aneuploidy in Podolepis (Asferaceae) • the haploid chromosome number of n = 12 is the most common in the related genera (Chrysocephalum, Waitzia, Leptorhynchos, Pterochaeta) • according to the phylogenetic analysis, the ancestral chromosome base number in the genus Podolepis may be x = 12 • chromosome number reduction has occurred in three lineages: - from n = 12 to n = 10 and 9 in the subclade A - from n = 12 to n = 8 and 7 in the subclade B1 - from n = 12 to n = 11 and 3 in the subclade B2 • the low chromosome numbers of n = 8,7 and 3 were found only in annual species which were distributed in sem i-arid regions • comparing the karyotypes between the taxa with n = 12 (in Waitzia and Chrysocephalum) and n = 10 (perennial Podolepis), the increase in the number of large chromosomes accompanies the decrease in the number of medium-sized chromosomes in Podolepis -^ the reduction in chromosome number has been achieved by the unequal reciprocal translocations, followed by the loss of the short translocation product Podolepis Podolepis (jrwhnviiku rugaiu robtata neghcta iiierucioidcs jaceoides monäcota canescens gracilis davislanc mucllcri tcssonti tepperi Citpillaris microapkala Axteriilea u\tert>iiies Asta idea alhiixioides PierOChatUl panic vlata /.tyvrjr/i ynchtix Mfttumiitv* Leptorhynchos mt't/itis H LťHcochtysiim molíť S Leucochrysum stipitutttm Tijptilodiscus pygmaeus Waitzia acuminata var. albicans Waitiiu suuveolens mr stiuveolens Podolepis kendailii Chrysotvpfhtitm apicutatum Chrysocephalum .icmifkiptms urn Podolepis georgei Sckoeitki casstnkota Descending aneuploidy in Houston/a (Rubiaceae) Proposed phylogenetic hypotheses for the Hedyotis/ Houstonia lineage in North America eutsm scurtwesl ceulCiiL SSSBm c :i. i. N.Am. . /Bsja Calif.) N.Am. N Am N.Am. N.Am. liedyůtisl HfíÁymis J Hedy otis Hedyotis Hedyotis. Hedyotis ji-6 \ . í- 1? / 1-11 x-%\ i eastern NA. eastern N.A. central U.S. 11 1 11 11 11 11 . southwestern U.S. & Mexico molecular phylogeny based on ITS (nrDNA) and trnL (cpDNA) sequences Descending and ascending aneuploidy in Calochorfus\Liliaceae) • c. 67 spp. • chromosome numbers n = 6, 7, 8, 9, and 10 • molecular phylogenetic study carried out to test the monophyly of the three sections and 12 subsections erected by Ownbey (1940) based on morphology and chromosome number n^-/. yjc 3Í te VteTZ s? 38 f W^ li-3 E:. 3Bh Descending and ascending aneuploidy in Calochortus (Liliaceae) Has* rÍHiilllíKiilllt: ni ii n I n-i the ancestral chromosome number of Calochortus is x = 9 descending aneuploidy (9 -» 8, 7, 6) ascending aneuploidy (9 ^ 10) m Patterson and Givnish (2003) I puk h f ŕŕtfj I umJi-rfitilui I .'.''míi :■■,:.-j, j- | ivithfi | Jiŕ'ľi'i .-■ ■■.'■ l olbvt l uJfccu San Diep> I JnilmĚť: I umĽffrzui I ÚJHCUJúnU ID I ppifij-llfiiiiij MN I wEtfcfef turycarpbs I nwrafrui I ffljňJrTiůi mAarafrämf £ŕŕŕHŕŕ l J>trf/ŕ ŕ I wrjífťppij | Jrjnjefojr/hJňJi I HTíÍDIíŕŕ | H'fťrfH MVfíiTÍ | UWtfM k'ŕJJliff I ílPflÍNŕŕltfŕ | j;:i/i/i:.'rn-i l am» l NHíŕflŕftiNV l nmuMUI I ii/ĎBŕŕiJfflii CA l frmnfami5 NV i caiicgípr | fALĽ7VÍ3ľlAJ | čttľvzíriM l itichtlinii | ■■ iV'.jr.'L r | caTuíiriai* | ŕuíŕuJ | Vr JfüC l david&otut I fíevucjta I spí rn dera I ig'ynnif ŕúŕlfiníU wnuj:ŕuŕi£T fATfŕff pwpww ipütufaiui onabeyi ľousLhI twtfrpyŕ iateriw 77 Descending and ascending aneuploidy Siderifis (Lamiaceae) • bimodal pattern of chromosomal change • Clade 1 shows decreasing aneuploid series, with 2n=44 being the ancestral number • Clade 2 (with some ambiguity): 2n=36 is the ancestral number and ascending aneuploidy has occurred m rJ44J I]«) ^cE PĚ I® Karyotype formula 44 44 34 (8m 7wn ZT) 36 (9m 4am 3at a T) 44 40 (7m 7am 6T) 44 '42 - 42 (4™ 7am 2»t ST) Sťujl-------3* (llmeam) 44 j-------44 '-------44 h=iěEí (7m Mm ZT) 44 (4m earn 2at 10T) 44,4« n| I— r® r® iB E -@- ■ 44 (4m4am4«tl0T) -44 -38-42 Bfl 36 36 36 (7m 9am 2T) ■aiz: «SE Ě 38 (7m Ssm i si ST) 44 (Sm Bam latlOTj 36 (11m Sam 21) 28 30 24 32 6 S.Lürbcllüta StbarbellalB S-srlTiCephala S.breulcaulls S.cysloalphDii S.lntomallB S. canadensis S.kuaglariana S. nervosa S.BOi.BBp.BOl uta S.ĽrB.asp.crolICB S.ere. x nar. S.canadensis S.ferrsnBls S.latsyl S.cre.rtf). spicala S.gom,wp,g(wnsree S.nutanu S-canarianaJa S.oro.v.arayB« S-Ono.v.OralaiWiltfBa S.aol.aap.guQl marls Sdandrochahorra S.daaygnaphala S.dasygriapliala Sdlacolor šavantanll a.cůnrJlearlĚ S.pumlla S.pumlla ä.up.nov. S.maimoreB S.göm.aap.fKillBlII 5. macros tachya Z^ Sromana jO S.hyaaspllolla /^ S.iyriaca ýí S.acordtoa ií"/ S raorrtana Reconstructing the ancestral • the reconstructed ancestral base chromosome number is x=6 • x=6 is a theoretical reconstructed base number, it can be said that the ancestral number was low - between x=6 nad 9 Soltis et al. 2005 base number for angiosperms 300 CHAPTER 13 FIGURE 13,8 MacCEade reconstruction of bascchramo* some nunibc-r diversification in angtpspemis obtained using tlit1 "nil must parsimonious states" option. This reconstruction use? the actual numbers reported in the literature for many of tnu genera and families indicated. However there is evidence for ancient polyploidy in many basal lineages. For those taxa thought to be ancient polyploids, a hypothetical original base number has been substituted (see text). Most gyittnosperms (outgroups) have n — 11 or 12. This figure represents a simplified version of a larger recrtnslruction involving 172 taxa, The large rusid, astetid, CmyüphyUaleft SanlaJales, and Sasifragalcs clades harve been reduced to a single terminal. The ancestral,state shown tor each of these clades is that reconstructed using the larger matrix. ftasť chwintMomc n umber [x =) (unontaed) H? IZZI id rr/j 11 H !2 raa Polymorphic Ľ-:' 1 Equivocal x=6