Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Comparative analyses of genetic diversity, population structure and evolutionary relationships
among co–distributed species can provide useful insights into fisheries management. In this
study, mitochondrial DNA control region (mtCR) sequences were used to investigate genetic
population structure and recruitment patterns of three co–occurring shallow water penaeid prawn
species; Penaeus monodon, Fenneropenaeus indicus and Metapenaeus monoceros. These taxa
dominate artisanal and commercial prawn catches in the Malindi–Ungwana Bay in Kenya, where
juvenile prawns inhabit estuarine habitats, and adults occur further offshore, on mudbanks in the
bay. A total of 296 [i.e. (P. monodon; n = 129), (F. indicus; n = 96), (M. monoceros; n = 71)]
specimens were sampled from five sites; two estuarine nursery areas (juveniles), a nearshore
mid–station (adults), and two offshore areas (adults). The sites were chosen to represent the bulk
of the Kenyan fishery activities, and to include juvenile and adult cohorts that are presumably
connected to each other through larval dispersal processes and migrations. Juveniles were
obtained during 2010 from local fishermen, and adult prawns during 2011 using a commercial
prawn trawler. Analysis of the mtCR sequences indicated high haplotype diversity (P. monodon;
h = 0.9996 ± 0.0010; F. indicus; h = 0.9998 ± 0.0015; M. monoceros; h = 0.9815 ± 0.0110) for
all three species. Genetic differentiation results for each species using AMOVA indicated no
significant population differentiation (P. monodon; ΦST = 0.000, = p > 0.05; F. indicus; ΦST =
0.000, = p > 0.05; M. monoceros; ΦST = 0.0164, = p > 0.05) and pairwise ΦST statistics among
sampling sites indicated the complete absence of spatial differentiation of female genes for all
three species. In addition, the mtDNA data of P. monodon (i.e. n = 103) was augmented by using
six polymorphic nuclear microsatellite loci. The pattern of panmixia was supported by the microsatellite analyses of P. monodon where AMOVA (i.e. RST = 0.00113, = p > 0.05), pairwise
RST statistics (i.e. RST = 0.0000–0.0223, = p > 0.05) and STRUCTURE all confirmed the
complete absence of genetic differentiation, among all sampled localities. Based on the absence
of genetic population structure, each of the three species can be regarded as a single management
unit throughout the Malindi–Ungwana Bay area. Spatial management strategies for prawn
fisheries in the bay should therefore rely on factors other than genetic metapopulations, such as
seasonal prawn recruitment and distribution patterns, ecosystem functioning and socio–economic
implications to fishing communities and commercial trawl fishing companies. / AFRIKAANSE OPSOMMING: Vergelykende analise van genetiese diversiteit, bevolkings stuktuur en evolutionêre
verwantskappe tussen spesies wat 'n verspreidingsgebied deel kan nuttige insigte lewer oor
vissery bestuur. In hierdie studie was die mitokondriale DNS kontrole area (mtCR)
volgordebepalings gebruik om die bevolkings genetiese stuktuur en werwingspatrone van drie
mede-verspreide vlak water penaeid garnaal spesies; Penaeus monodon, Fenneropenaeus indicus
and Metapenaeus monoceros te ondersoek. Hierdie taksa domineer die ambagtelike en
kommersiële vangste in die Malindi-Ungwanabaai in Kenya waar, onvolwasse garnale in
riviermondings voorkom en volwassenes in dieper waters op modderbanke in die baai voorkom.
'n Totaal van 296 [(P. monodon; n = 129), (F. indicus; n = 96), (M. monoceros; n = 71)]
monsters was geneem vanaf vyf lokaliteite; twee in riviermondings (onvolwassenes), 'n nabykus
mid stasie (volwasse) en twee diep water (volwasse) areas. Hierdie lokaliteite was gekies
om die oorgrote meerderheid van Kenya se vissery aktiwiteite, asook die onvolwasses en
volwassene kohorte te verteenwoordig wat vermoedelik geneties verbind is aan mekaar deur
larwale verspreidingsprosesse en migrasies. Onvolwasse diere was verkry in 2010 vanaf
plaaslike vissermanne en volwasse diere was in 2011 gekollekteer deur gebruik te maak van 'n
kommersiële garnaal vissersboot. Analise van die mtCR volgorde bepaling het gewys dat daar
'n hoë haplotipiese diversiteit (P. monodon; h = 0.9996 ± 0.0010; F. indicus; h = 0.9998 ±
0.0015; M. monoceros; h = 0.9815 ± 0.0110) vir al drie spesies bestaan. Genetiese differensiasie
resultate vir elke spesie, bepaal deur 'n AMOVA toets, dui op geen beduidende bevolking
differensiasie nie (P. monodon; ΦST = 0.000, = p > 0.05; F. indicus; ΦST = 0.000, = p > 0.05; M.
monoceros; ΦST = 0.0164, = p > 0.05) en paarsgewyse ΦST statistiek tussen die lokaliteite waar monsters geneem was, dui op geen ruimtelike differensiasie van die vroulike gene in al drie
spesies nie. Hierbenewens is die mtDNS datastel van P. monodon (i.e. n = 103) uitgebrei deur
ses polimorfiese kern mikrosatelliete in te sluit. Die patroon van mtCR panmixia was ondersteun
deur die mikro-satelliet analise van P. monodon waar die AMOVA (i.e. RST = 0.00113, = p >
0.05), paarsgewyse RST statistiek (i.e. RST = 0.0000-0.0223, = p > 0.05) en STRUCTURE
bevestig het dat daar totale afwesigheid is van genetiese differensiasie tussen alle vergelyk-te
lokaliteite. Gebaseer op die afwesigheid van genetiese bevolking-struktuur kan elk van die drie
spesies beskou word as 'n enkele bestuurseenheid deur die Malindi-Ungwanabaai area. Die
bestuurstrategieë vir garnaal vissery aktiwiteite in die baai moet dus steun op ander faktore as
genetiese meta-bevolking. Belangrike faktore om in ag te neem is seisoenale garnaal werwing en
verspreidings patrone, ekosisteem funksionering en sosio-ekonomiese implikasies van vissers
gemeenskappe en kommersiële visserymaatskappye.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/79798 |
| Date | 03 1900 |
| Creators | Mkare, Thomas Kalama |
| Contributors | Matthee, Conrad A., Groeneveld, Johan C., Von der Heyden, Sophie, Stellenbosch University. Faculty of Science. Dept. of Botany and Zoology. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | xv, 75 p. : ill. |
| Rights | Stellenbosch University |
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