Cytogenetics and spore morphology of Struthiopteris spicant var. fallax Jóhannes Bjarki Urbancic Tómasson Líf- og umhverfisvísindadeild Háskóli Íslands 2017 Cytogenetics and spore morphology of Struthiopteris spicant var. fallax Jóhannes Bjarki Urbancic Tómasson 12 eininga ritgerð sem er hluti af Baccalaureus Scientiarum gráðu í líffræði Leiðbeinandi Kesara Margrét Anamthawat-Jónsson Líf- og umhverfisvísindadeild Verkfræði- og náttúruvísindasvið Háskóli Íslands Reykjavík, maí 2017 Cytogenetics and spore morphology of Struthiopteris spicant var. fallax 12 eininga ritgerð sem er hluti af Baccalaureus Scientiarum gráðu í líffræði Höfundarréttur © 2017 Jóhannes Bjarki Urbancic Tómsson Öll réttindi áskilin Líf- og umhverfisvísindadeild Verkfræði- og náttúruvísindasvið Háskóli Íslands Sturlugötu 7 101 Reykjavík Sími: 525 4000 Skráningarupplýsingar: Jóhannes Bjarki Urbancic Tómasson, 2016, Cytogenetics and spore morphology of Struthiopteris spicant var. fallax., BS-ritgerð, Líf- og umhverfisvísindadeild, Háskóli Íslands, 24 bls. Prentun: Svansprent Reykjavík, maí 2017 Útdráttur Ofan við Deildartunguhver vex tunguskollakambur (Struthiopteris spicant var. fallax), afbrigði burkna sem hvergi er að finna annars staðar í heiminum. Þrátt fyrir sérstöðu tunguskollakambs hefur hann lítið verið rannsakaður, sérstaklega eftir að kjarngerð hans var birt árið 1968. Á síðustu árum hefur komið í ljós að gera þarf nýjar rannsóknir á tunguskollakambinum og er þessi ritgerð fyrsta birtingin í því verkefni. Sýnum fyrir litningagreiningu og rannsóknir á gróum var safnað af tunguskollakambi, spicant- og homophyllum-afbrigðum skollakambs (Struthiopteris spicant). Niðurstöður úr kjarngerðarrannsókn sýna að tunguskollakambur er tvílitna en ekki fjórlitna eins og áður var talið. Önnur afbrigði skollakambs eru fjórlitna og önnur sýni í rannsókninni en þau af tunguskollakambi höfðu fjórlitna erfðamengi. Gró tunguskollakambs báru einstök mynstur á grókápunni sem kom á óvart þar sem hingað til hefur verið talið að gró skollakambs séu áreiðanleg flokkunareinkenni. Niðurstöðurnar úr báðum hlutum rannsóknarinnar gefa til kynna að tunguskollakambur gæti flokkunarfræðilegrar sérstöðu. Þær opna dyr fyrir rannsóknum á sviði stofnvistfræði og þróun tunguskollakambs og varpa nýju ljósi á tegundamyndun. Abstract On top of the most powerful hotspring in Europe grows a variety of fern that is local to Iceland. The sporadic studies of this variety, S. spicant var. fallax, came to an end in 1968 after its karyotype was published. For various reasons the need to reinvestigate S. spicant var. fallax has recently become evident. Samples for karyotyping and spore morphology were collected and examined for S. spicant var. fallax, var. spicant and var. homophyllum. Results from the karyotype analysis show that S. spicant var. fallax is diploid rather than tetraploid, which is the prevalent ploidy level in S. spicant and which was observed in S. spicant var. spicant samples. Under a scanning electron microscope, the spores of S. spicant var. fallax showed unique features in ornamentation when compared to spores of other S. spicant varieties. The karyotype results and the unique spore morphology of S. spicant var. fallax challenge the current taxonomy of S. spicant var. fallax. This opens up numerous questions regarding the population ecology and evolution of S. spicant var. fallax and the the process of speciation. Table of contents Útdráttur ............................................................................................................................. iii Abstract ............................................................................................................................... iii Table of contents ..................................................................................................................iv List of figures ........................................................................................................................ v List of tables .........................................................................................................................vi Abbreviations ..................................................................................................................... vii Þakkir ...................................................................................................................................ix 1 Introduction ..................................................................................................................... 1 2 Material and methods ..................................................................................................... 4 2.1 Karyotype analysis ................................................................................................... 4 2.2 Spore morphology .................................................................................................... 4 3 Results ............................................................................................................................... 7 3.1 Karyotype analysis ................................................................................................... 7 3.2 Spore morphology .................................................................................................... 9 4 Discussion ....................................................................................................................... 12 4.1 Karyotype analysis ................................................................................................. 12 4.2 Spore size and ornamentation ................................................................................ 13 4.3 Spore abortion ........................................................................................................ 14 4.4 Considerations about S. Spicant var. fallax population dynamics ......................... 16 4.5 Models of differentiation between S. spicant var. fallax and S. spicant var. spicant .................................................................................................................... 17 References ........................................................................................................................... 19 Supplement ......................................................................................................................... 22 iv List of figures Figure 1: A composite image of some representative cellular elements of various S. spicant samples observed with a fluorescent microscope and DAPI.. .................... 9 Figure 2: SEM images of S. spicant spores from different S. spicant varieties bear different ornamental patterns. ................................................................................ 11 Figure 3: A SEM image of spores of S. spicant var. spicant in the open sporangium. ............ 14 v List of tables Table 1: Samples used for spore morphology imaging. ............................................................. 5 Table 2: Microscopic evidence for various ploidy levels of S. spicant chromosome samples assorted by their origin. 7 Table 3: Results of an ANOVA of equitorial spore length in relation to sample groups. ......... 9 Table 4: Results of a Tukey‘s honest significance test for equitorial spore length in relation to the sample groups. ................................................................................ 10 Table 5: Summarization of spore discriptions from each sample. ........................................... 10 vi Abbreviations °C Degrees celcius °N Degrees north °W Degrees west μm Microlitre B. Blechnum cm Centimetre ml Millilitre Inc. sed. Incertae sedis P:E ratio Polar-Equitorial raito S. Struthiopteris SEM Scanning electron microscope var. variety vii viii Þakkir Ég vil þakka Kesöru fyrir þolinmæðina og öll þau tækifæri sem hún hefur boðið mér. Ég vil einnig þakka samnemendum mínum í líffræðinni fyrir frábærar stundir í BS-náminu. Engu síður vil ég þakka öllum þeim sem hafa þurft að hlusta á burknatalið í mér síðastliðið ár. ix 1 Introduction On top of the most powerful hotspring in Europe grows a little known variety of an otherwise common fern, Struthiopteris spicant (L.) F.W.Weiss., or deer fern. This hotspring is Deildartunguhver and the plant variety is S. spicant var. fallax, which taxonomical status has, perhaps erroneously, remained mostly uncontested since 1968. Struthiopteris spicant belongs to the Blechnaceae family of leptosporangiate ferns. The classification of S. spicant is not well established and has remained especially disarranged after the sequencing of cpDNA of some Blechnaceae species. Traditionally S. spicant belonged to the genus Blechnum (L.), as Blechnum spicant (L.) Sm., which was divided into 8, 9 or 12 subgenera by taxanomists based on spores, frond morphology, rhizomes, dimorphism and habit (Passarelli et al., 2010; Gabriel y Galán et al., 2013). According to this classification, B. spicant was placed in the penna-marina group of Blechnaceae ferns. Sequencing of the cpDNA of some American ferns by Gabriel y Galán et al. (2013) revealed a position for B. spicant at the base of the tree, while the penna-marina group was highly supported and nested deep within the tree. It was therefore suggested that B. spicant were placed in a separate clade, apart from other Blechnum species (Gabriel y Galán et al. 2013). Subsequently, a similar study of ferns of Australasia by Perrie et al. (2014) found a similar position for B. spicant on the evolutionary tree. The paper mentioned the possibility of placing B.