The scalloped spiny lobster, Panulirus homarus has a subspecies trio that are widely
distributed in shallow-water habitats in the South West Indian Ocean. Subspecies are
defined by differences in colour and abdominal sculptural pattern. A red variety with the
megasculptural carapace pattern, P. h. rubellus is distributed along the south east coast
of Africa and Madagascar, where they are endemic. Along the African coast P. h.
rubellus stocks traverse political boundaries, Mozambique and South Africa. This
project aimed to facilitate regional fisheries management of shared stocks by employing
genetic tools to determine whether stocks (or populations) are indeed shared between
countries. Lobster samples were collected from seven localities throughout the east
African coast. The mitochondrial cyctochrome c oxidase subunit 1 region was
sequenced to assess the genetic diversity 1) between different subspecies, P. h. homarus
and P. h. rubellus and 2) between populations of P. h. rubellus across its African
distribution range. Using DNA barcoding methods, genetic diversity was also found
between morphologically distinct subspecies, Panulirus homarus homarus and P. h.
rubellus which differed genetically by ca. 2-3% in sequence divergence. Both
subspecies were monophyletic relative to the out-group taxa and formed well supported
sister clades (BI: 1.00, ML: 93%, P: 100%, NJ: 100%). The distribution of P. h.
rubellus along the African coast occurs adjacent to different current regimes and
therefore varied larval transport modes (i.e. Agulhas Current and inshore countercurrents
along the Eastern Cape). This may have driven the formation of subpopulations
(ΦPT = 0.104, p = 0.010) which differ by ca. 1.7% in sequence difference. The pattern of
gene flow of populations of P. h. rubellus lends support to the Agulhas Current being a
major mode of larval transport as well as corroborates previous abundance and
distribution records. Time since population expansion estimates for the P. h. homarus
and P. h. rubellus subspecies as well as for the P. h. rubellus subpopulations dated back
to the mid-Holocene Epoch in accordance with a warmer, more stable marine
environment. Genetically distinct subspecies of P. homarus as well as differentiated
subpopulations of P. h. rubellus calls for a re-visit of the current collective management
of P. homarus as well as P. h. rubellus as a single genetic stock along the south east
African coast. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2013.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ukzn/oai:http://researchspace.ukzn.ac.za:10413/10131 |
| Date | 29 November 2013 |
| Creators | Reddy, Mageshnee Mayshree. |
| Contributors | MacDonald, Angus Hector Harold., Schleyer, Michael H. |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
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