Spelling suggestions: "subject:"knoxdaviesia protean"" "subject:"knoxdaviesia protea""
1 |
Diversity and dispersal of the ophiostomatoid fungus, Knoxdaviesia proteae, within Protea repens infructescencesAylward, Janneke 04 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Two genera of ophiostomatoid fungi occur in the seed-bearing structures of serotinous
Protea species in the Cape Floristic Region. These fungi are dispersed by arthropods,
including mites and beetles that visit the Protea host plants. Although the vectors of Proteaassociated
ophiostomatoid fungi are known, their dispersal patterns remain unknown –
especially the manner in which recently burnt fynbos vegetation is recolonized. Additionally,
their reproduction strategy has not previously been investigated. The focus of this study was,
therefore, to determine the extent of within- and between-plant dispersal of Proteaassociated
ophiostomatoid fungi at the population level and to investigate their reproductive
strategy. One Protea-associated ophiostomatoid fungus, Knoxdaviesia proteae, is found
exclusively in the fruiting structures of P. repens and was the focus of this study. In order to
interrogate natural populations of this fungus, 12 polymorphic microsatellite markers
specific to K. proteae were developed with an ISSR-PCR enrichment strategy and
pyrosequencing. These markers were amplified in two distantly separated populations of K.
proteae. The genetic and genotypic diversities of both populations were exceptionally high
and neither showed significant population differentiation. The lack of population structure in
both populations implies that K. proteae individuals within a P. repens stand are in
panmixia. As one of the sampling sites had burnt recently, the process whereby young
fynbos is recolonized could be investigated. Compared to the adjacent, unburnt area, K.
proteae individuals in the burnt area of this population had significantly less private alleles,
suggestive of a young population that had experienced a genetic bottleneck. Knoxdaviesia
proteae individuals that did not originate from the adjacent unburnt area were encountered
within the burnt site and, additionally, isolation-by-distance could not be detected. The
parsimony-based haplotype networks and the tests for linkage disequilibrium indicated that
recombination is taking place within as well as between the two distantly separated
populations. The observed panmixia in P. repens stands, widespread recolonization and the high genetic similarity and number of migrants between the two populations emphasizes
long-distance dispersal and therefore the role of beetles in the movement of K. proteae. This
cohesive genetic structure and connection across large distances is likely a result of multiple
migration events facilitated by beetles carrying numerous phoretic mites. / AFRIKAANSE OPSOMMING: Twee genera ophiostomatoid swamme kom in die saad-draende strukture van bloeiende
Protea spesies in the Kaapse Floristiese Streek voor. Hierdie Protea-verwante
ophiostomatoid swamme word gekenmerk deur hul assosiasie met geleedpotige vektore –
spesifiek die myt en kewer besoekers van die Protea gasheer plante. Alhoewel die
geleedpotige vektore van Protea-verwante ophiostomatoid swamme bekend is, is die wyse
waarop hierdie swamme versprei onbekend; veral die manier waarop onlangse gebrande
fynbos geherkoloniseer word. Verder is die voortplantings-strategie van hierdie swamme
nog nie voorheen ondersoek nie. Die fokus van hierdie studie was dus om die omvang van
binne- en tussen-plant verspreiding van Protea-verwante ophiostomatoid swamme te bepaal
op die populasie vlak en om hul voorplantings-strategie te ondersoek. Een Protea-verwante
ophiostomatoid swam, Knoxdaviesia proteae, word uitsluitlik in die vrugdraende strukture
van P. repens aangetref en was die fokus van hierdie studie. Om natuurlike populasies van
hierdie swam te ondersoek is 12 mikrosatelliet-merkers spesifiek vir K. proteae ontwerp
deur ‘n ISSR-PCR strategie en “pyro”-basisvolgorde bepaling te gebruik. Hierdie merkers is
geamplifiseer in twee K. proteae populasies wat ver van mekaar geskei is. Die genetiese en
genotipiese diversiteit van beide populasies was uitsonderlik hoog en nie een het beduidende
populasie-differensiasie getoon nie. Die gebrek aan populasie struktuur in beide populasies
veronderstel dat K. proteae individue binne ‘n P. repens stand in panmiksia is. Aangesien
een van die steekproef terreine onlangs gebrand het, kon die herkolonisasie proses van jong
fynbos ondersoek word. In vergelyking met die aangrensende, ongebrande area, het K.
proteae individue in die gebrande area beduidend minder private allele gehad. Dit dui op ‘n
jong populasie wat ‘n genetiese bottelnek beleef het. Knoxdaviesia proteae individue wat nie
van die aangrensende, ongebrande area afkomstig is nie is ook binne die gebrande terrein
aangetref. Verder is afsondering-deur-afstand nie aangetref nie. Die parsimonie-gebaseerde haplotiepe-netwerke en die toetse vir koppeling-onewewigtigheid het aangedui dat
rekombinasie binne sowel as tussen die twee populasies plaasvind. Die panmiksia wat
waargeneem is in P. repens populasies, wydverspreide herkolonisasie en die hoë genetiese
ooreenkoms en hoeveelheid immigrante tussen die twee populasies beklemtoon lang afstand
verspreiding en dus die rol van kewers in die beweging van K. proteae. Hierdie
samehangende genetiese struktuur en die verband oor groot afstande is waarskynlik ‘n
gevolg van verskeie migrasies gefasiliteer deur kewers wat talle foretiese myte dra.
|
Page generated in 0.0511 seconds