Thesis (MSc)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: The species Haliotis midae is the only abalone species of commercial importance to the
South African fisheries industry. The species is currently under substantial pressure due
to commercial harvest and illegal poaching, to the extent that genetic and biodiversity
may be under threat. The species is also being cultured in commercial systems for
supply to international markets. The South African production for 2002 amounted to
350 tons. The commercial production of abalone may also have implications with
regard to genetic diversity of natural and commercial populations.
The aim of this project was to assess the genetic diversity of the natural and commercial
populations of abalone at the I&J Abalone Farm, Danger Point, Gansbaai, in South
Africa, in order to make recommendation with regard to possible impact on natural
diversity as well as internal management systems. Distortion of natural genetic diversity
or a loss of internal diversity will have detrimental consequences.
Representative samples have been obtained from the surrounding natural population, as
well as the commercial populations, including the broodstock and various progeny
groups. Both mtDNA and AFLP molecular techniques were used to assess genetic
diversity.
Data analysis showed that the genetic profile of the commercial population display
sufficient genetic variation. The genetic structure of the commercial population also
displays no significant deviation from that of the surrounding natural population, i.e. the
population of origin. The results through give indication of a small, though
unsignificant loss of genetic variation from the broodstock to the subsequent progeny
groups.
The investigation conclude that the commercial populations of abalone at the I&J
Abalone Farm, Danger Point, Gansbaai, in its current format holds no threat to the
disruption of the genetic diversity of the surrounding natural population. Further, the
commercial population possesses sufficient genetic variation in view of future genetic
development. There is signs of a slight loss of genetic variation in the change over from
the broodstock to the progeny groups. This would necessitate careful and controlled
replacement of the original broodstock with new animals from the commercial progeny
groups as part of an ongoing process of domestication. / AFRIKAANSE OPSOMMING: Die spesie Haliotis midae is die enigste perlemoen spesie van kommersiële belang vir
Suid Afrikaanse visserye. Die spesie verkeer tans onder toenemende druk as gevolg van
kommersiële en onwettige vangste, tot so 'n mate dat genetiese en biodiversiteit
daardeur geaffekteer kan word. Die spesie word in toenemende mate kunsmatig
gekweek vir voorsiening aan internasionale markte. Suid Afrikaanse produksie vir 2002
beloop reeds sowat 350 ton per jaar. Die kunsmatige produksie van perlemoen het ook
moontlike implikasies op die genetiese diversiteit van natuurlike en kommersiële
populasies van die perlemoen, Haliotis midae.
Die doel van die projek was om die aard van genetiese diversiteit van die natuurlike en
kommersiële populasies van perlemoen by die I&J Perlemoen Plaas, Danger Point,
Gansbaai in Suid Afrika te ondersoek, ten einde aanbevelings te maak ten opsigte van
moontlike impak op natuurlike diversiteit asook ten opsigte van interne genetiese
bestuurstelsels. Versteuring van natuurlike diversiteit of verlies van interne diversiteit
hou nadelige gevolge in.
Verteenwoordigende monsters is versamel vanuit die omliggende natuurlike populasies,
sowel as van die kommersiële populasie op die plaas, insluitend die teelmateriaal en
verskillende nageslaggroepe. Beide mtDNA en AFLP-molekulêre tegnieke is gebruik
tydens die ontleding van genetiese diversiteit.
Dataontleding het aangetoon dat die genetiese profiel van die kommersiële populasie
voldoende genetiese variasie demonstreer. Die genetiese struktuur van die kommersiële
populasie toon verder geen betekenisvolle verskil met die omliggende natuurlike
populasie nie, dit wil sê met die populasie van oorsprong nie. Die resultate toon verder
'n geringe, dog nie betekenisvolle verlies van genetiese variasie wat waargeneem word
met oorgang van die teelmateriaal na die onderskeie nageslaggroepe.
Die bevindinge van die ondersoek is dus dat die kommersiële populasie op die I&J
Perlemoen Plaas, Danger Point, Gansbaai, in die huidige formaat, geen bedreiging
inhou vir die versteuring van die omliggende natuurlike genetiese diversiteit nie.
Verdere bevindinge is dat die kommersiële populasie oor voldoende genetiese
diversiteit beskik met die oog op toekomstige genetiese ontwikkeling. Daar is tekens
van 'n geringe afname in genetiese diversiteit met die oorgang vanaf die teelmateriaal
na die nageslaggroepe. Dit beklemtoon die belang van 'n gekontroleerde vervanging
van die oorspronklike teelmateriaal met nuwe teeldiere vanuit die kommersiële
populasie as deel van die domestikasieproses.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/52943 |
| Date | 12 1900 |
| Creators | Lambrechts, Daneel |
| Contributors | Brink, D., D' Amato, M. E., Stellenbosch University. Faculty of AgriSciences. Dept. of Genetics. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 99 pages : illustrations |
| Rights | Stellenbosch University |
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