Abstract
M.Sc.
Two species of multimammate mice occur in South Africa, namely Mastomys
natalensis and M. coucha. These species, both reservoirs for different and
equally important disease pathogens, are morphologically identical with variations
described in chromosome number, sperm morphology, pheromones, ultrasound
and allozyme and isozyme markers. Their identical macro morphologies also
raise problems where habitat and distribution is concerned. The need to identify
various disease threats based on the carrier organism makes their identification
important because they occur sympatrically in many areas of South Africa. Both
species were expected to occur within the Roan Camp, Kruger National Park,
South Africa and therefore toe samples were obtained from D. MacFadyen who
was able to capture the Mastomys genus during his biodiversity survey of the
area. He was unable to assign species designations to the captured individuals
based on external morphology, but identification would allow exploration into the
habitat preferences of each species when compared to the vegetation data
gathered by MacFadyen using cross tabulation methods. DNA was extracted
from 90 toe samples obtained during August 2003 (30 samples) and 2004 (60
samples) and the cytochrome-b region was amplified using the polymerase chain
reaction (PCR). Amplified PCR products were cut using the restriction enzyme
BsmAI to produce restriction fragment length polymorphism (RFLP) profiles from
which the two species were identified. Once identified, the species were
associated to vegetation data received from MacFadyen and samples were
selected for further analysis using 5 microsatellite loci. Mastomys natalensis was
found in very low numbers, as expected, based on the average rainfall and
altitude of the sample area, which is preferred by M. coucha. Further insight was
gained into the preferences of each species concerning habitat and their
respective status as pioneer species in habitat recolonisation. Genetic
differences were obtained within the two species with 100% and 80% polymorphic
loci for M. coucha and M. natalensis respectively. Allele classes at most of the
loci deviated from Hardy-Weinberg equilibrium, probably due to small sample
sizes, null alleles and/or heterozygote deficiencies with average heterozygosities
of 0.754 for M. coucha and 0.526 for M. natalensis. The genetic distance between
the two species was 0.465 and an Rst value of 0.503 indicated a significant
differentiation between the two species. Fixed allele differences between the
species were not obtained, but private alleles were found at four loci in M. coucha
and one locus in M. natalensis. This study therefore contributes to the global
information on species identification, genetic variation and ecology of the two
cryptic Mastomys species; the three pillars on which the Convention of Biological
Diversity (of which South Africa is a signatory) rests upon.