A phylogeographic study of the circumtropical glasseye Heteropriacanthus cruentatus was conducted... more A phylogeographic study of the circumtropical glasseye Heteropriacanthus cruentatus was conducted. Molecular analyses indicate two mitochondrial cytochrome c oxidase subunit I (coI) lineages that are 10·4% divergent: one in the western Atlantic (Caribbean) and another that was detected across the Indo-Pacific. A fixed single nucleotide polymorphism (SNP) was detected at a nuclear locus (S7 ribosomal protein) and is consistent with this finding. There is evidence of recent dispersal from the Atlantic to the Indian Ocean with individuals of mixed lineages detected in South Africa and the Mozambique Channel. Using coalescent analyses of the mitochondrial dataset, time of divergence between lineages was estimated to be c. 15·3 million years. The deep divergence between these two lineages indicates distinct evolutionary units, however, due to the lack of morphological differences and evidence of hybridization between lineages, taxonomic revision is not suggested at this time.
ABSTRACT The slinger, Chrysoblephus puniceus, a seabream of the family Sparidae, is an important ... more ABSTRACT The slinger, Chrysoblephus puniceus, a seabream of the family Sparidae, is an important commercial linefish species in South Africa and Mozambique. Despites its fisheries importance little is known about the population structure of the species and it is currently managed separately by both countries. The genetic connectivity between localities throughout C. puniceus’ core distributional range was investigated using the mitochondrial control region and ten microsatellite loci. The majority of pairwise population comparisons were not significant (P > 0.05) and none remained significant after Bonferroni corrections. While one AMOVA grouping using mtDNA found weak levels of structure separating Gaza and Inhaca in southern Mozambique from other localities, all other groupings for both data sets found no significant among group variation. Similarly, SAMOVA, Mantel tests (P > 0.05) and STRUCTURE analysis using—ln likelihoods were unable to identify genetic structuring through C. puniceus’ distribution. MIGRATE-n analysis showed asymmetrical migration between sites with net migration probably influenced by the prevailing oceanographic feature. The results of the study failed to reject panmixia suggesting a single C. puniceus stock. The transboundary nature of a single stock coupled with the uneven temporal and spatial distribution of historical fishing effort likely made the species resilient to exploitation. This raises concerns as current management strategies are not aligned and the species is now harvested throughout most of its core distribution excluding the Ponta do Ouro, Maputaland, St Lucia marine protected areas.KeywordsLinefishGeneticsStock structureTransboundaryManagement
The reproductive biology and distribution of two species of Syngnathus (S. temminckii and S. wate... more The reproductive biology and distribution of two species of Syngnathus (S. temminckii and S. watermeyeri) were investigated using information from museum specimens, published data, survey data and samples collected during mouth-breaching events of temporarily open/closed estuaries over the period 1950-2011. Distribution records indicate that the two species are restricted to specific habitats and bioregions in southern Africa. Although S. temminckii has marine and estuarine populations, the species is most prevalent in warm and cool temperate estuarine systems. Syngnathus watermeyeri has limited dispersal capabilities owing to life-history characteristics and is completely dependent on shallow vegetated habitat in mesosaline estuarine systems in the warm temperate region, where it co-occurs with S. temminckii. The presence of breeding individuals and juveniles indicated that the spawning period of both species occurs in spring and summer, coinciding with warmer water temperatures and enhanced food resources, with reproductive activity of S. temminckii peaking in November. The estimated lengths (standard length) at 50% maturity of males and females of S. temminckii (129 and 120 mm respectively), were larger than those of S. watermeyeri (118 and 102 mm) and similar to those for other syngnathids. Although the observed sex ratios for S. temminckii (0.5:1.0, M:F) and S. watermeyeri (0.7:1.0), were biased towards females and similar to those observed among congeners, only S. temminckii was significantly different from the expected 1:1 ratio. The mean number of mature oocytes in the females (n = 379; 95% CI = 244-658) of S. temminckii was not significantly different from the mean number of eggs/embryos in the male brood pouch (n = 451; 95% CI = 270-486). The relationship between carrying capacity and size was linear and positively correlated, implying that fecundity, and hence reproductive efficiency, increases with the size of the individual. Comparative analyses indicated that these species have different life-history strategies and dispersal capabilities. However, they are both highly vulnerable as a result of anthropogenic threats to the unstable estuarine environment.
The marble notothen, Notothenia rossii, is widely distributed around the waters of sub-Antarctic ... more The marble notothen, Notothenia rossii, is widely distributed around the waters of sub-Antarctic islands in the Southern Ocean and is exposed to different temperatures that range from -1.5 to 8°C. This study investigates whether the different environmental conditions experienced by N. rossii at different latitudes in the Southern Ocean affect the levels of its blood serum antifreeze glycoprotein (AFGP). N. rossii specimens were collected from four localities, including the Ob' Seamount in the Indian Ocean sector, and South Georgia Island, South Shetland Islands and Dallman Bay in the Atlantic Ocean sector. Serum AFGP activity was determined in terms of thermal hysteresis, i.e. the difference between the equilibrium melting and non-equilibrium freezing points (f.p.s.). Among the four populations, the Ob' Seamount specimen had the lowest serum AFGP activity (0.44°C) and concentration (4.88 mg/mL), and the highest nonequilibrium f.p. (-1.39°C). These results are consistent with the warmer, ice-free waters around the Ob' Seamount. The other three higher latitude populations have 2-3 times greater serum AFGP activity and concentration, and much lower non-equilibrium f.p.s. In contrast, the physiological profiles of serum AFGP size isoforms revealed that all N. rossii populations, including the Ob' Seamount specimen, possess an extensive complements of AFGP proteins. Isoform variation was observed, especially in the large size isoforms (AFGPs 1-5), when compared to AFGP of the high Antarctic Dissostichus mawsoni. The lower levels of AFGP and the absence of some of the large isoforms are likely responsible for higher non-equilibrium f.p.s. of the Ob' seamount specimen.
The reef fish Myripristis berndti (Jordan & Everman 1903) is a pantropical species. A genetic ana... more The reef fish Myripristis berndti (Jordan & Everman 1903) is a pantropical species. A genetic analysis was conducted on 353 individuals from 10 localities distributed across the SW Indian Ocean (SWIO) in order to determine patterns of connectivity in the SWIO. Both the mtDNA sequences (711-bp cytochrome b sequences) and the microsatellites (8 newly developed loci) reveal spatial patterns of differentiation within the SWIO. There is, however, a discrepancy between the structure observed with each kind of marker. MtDNA revealed that 3 peripheral populations (NW Kenya, SE Reunion, and SW Europa) were isolated from the 7 more central populations, which form a more densely connected population network, while microsatellite data indicated a more restricted connectivity with significant differentiation between most pairs of localities. Higher genetic differences between Reunion and Europa were found, which might be explained by geography and isolation by distance pattern. In contrast, the genetic signature of Kenya -the most divergent locality identified by mtDNA basis but not with microsatellite -was probably the consequence of a particular colonisation history. These results indicate a much more restricted connectivity than previously thought for this species.
The first record of the Cape hagfish Myxine capensis in Mozambican waters is reported based on a ... more The first record of the Cape hagfish Myxine capensis in Mozambican waters is reported based on a single 356 mm total length specimen taken by bottom trawl off Maputo, 25° 52·9' S; 34° 42·7' E - 25° 54·1' S; 34° 41·0' E, at depths from 557 to 564 m. This account also represents the northernmost record of a hagfish in the western Indian Ocean. Morphometric and meristic data are provided and compared with those of 27 specimens (including the holotype) caught off Namibia and South Africa.
The taxonomic status of two southern African coastal pipefish species, Syngnathus temminckii and ... more The taxonomic status of two southern African coastal pipefish species, Syngnathus temminckii and Syngnathus watermeyeri , was investigated using a combination of morphological and genetic data. Morphological data showed that S. temminckii is distinct from the broadly distributed European pipefish Syngnathus acus, and a molecular phylogeny reconstructed using mitochondrial DNA recovered S. temminckii and S. watermeyeri as sister taxa. The southern African species share an evolutionary origin with north-eastern Atlantic Ocean and Mediterranean Sea species, including S. acus. These data support the existence of a distinct southern African clade of Syngnathus pipefishes that has diverged in situ to form the two species present in the region today.
JAIDS Journal of Acquired Immune Deficiency Syndromes, 2008
To estimate oral disease prevalence among Zimbabwean women by HIV serostatus and CD4 cell count a... more To estimate oral disease prevalence among Zimbabwean women by HIV serostatus and CD4 cell count and to assess accuracy of oral disease diagnoses made by nurses as compared with an oral surgeon. Standardized oral mucosa examinations were performed by trained nurse-examiners and by an oral surgeon among women recruited in Harare, Zimbabwe. A total of 461 women (320 HIV-infected, 141 uninfected) were seen by nurses and an oral surgeon within a 2-week period. Oral candidiasis (OC) was the most common lesion diagnosed in nearly one quarter of HIV-infected women, whereas hairy leukoplakia and Kaposi sarcoma were found in <3%. The prevalence of OC diagnosed by nurses or the surgeon was significantly higher among women with a CD4 count <200 cells/mm than in women with a CD4 count from 200 to 499 cells/mm3 or a CD4 count >499 cells/mm3. The sensitivity of nurse examinations compared with examinations by the oral surgeon among HIV-infected women for the diagnosis of OC was 73%, the specificity was 95%, and the kappa-statistic was 0.71. OC was the most common lesion in HIV-infected women and was strongly associated with a low CD4 cell count. Interexaminer agreement was good for the diagnosis of OC among HIV-infected women. This study suggests that OC may play a role, in combination with other clinical indicators as a marker of disease progression in resource-poor settings.
A cross-sectional study was conducted on women attending family planning clinics in Harare, Zimba... more A cross-sectional study was conducted on women attending family planning clinics in Harare, Zimbabwe to determine the prevalence of cervical neoplasia among HIV-1 positive women relative to an HIV-1 negative control group. Five hundred and fifty four women were recruited and the prevalence of HIV-1 was 36.8%. Cervical cytology was abnormal in 25.6% of HIV-infected women compared to only 6.7% HIV-1 seronegative women. Cervical neoplasia was significantly associated with HIV infection (chi(2)=42.4, P<0.001). Cellular changes typical of HPV infection (koilocytocis) were recorded in 6.4% of HIV infected women compared with 1.7% of HIV-1-uninfected women (chi(2)=8.43, P=0.004). HIV-1-positive women had twice the risk of having abnormal cervical cells than HIV-negative women (relative risk 2.47, odds ratio 10.14, P<0.001). Therefore the introduction of national cervical screening programme in HIV-1 endemic countries like Zimbabwe where the highest burden of pre-malignant lesions is among HIV-1-infected women needs careful planning because these women have other competing health needs including high rates of opportunistic infections.
Glossogobius callidus exhibits broad salinity tolerance and is distributed in both estuarine and ... more Glossogobius callidus exhibits broad salinity tolerance and is distributed in both estuarine and freshwater environments in southern Africa. Previous studies revealed substantial morphological and molecular variation among populations, suggesting they constitute a species complex. The present study utilised phylogenetic and population structure analyses of molecular sequence data from mitochondrial (cytochrome b) and nuclear (S7 intron 1) DNA markers to evaluate the genetic structure of the species. Two reproductively isolated lineages, 8.7% and 1.1% divergent, respectively, were identified. Lineage 1 represented the true G. callidus distributed mainly among estuarine systems including the type locality (Bushmans River, Eastern Cape, South Africa). Lineage 2 probably represents a cryptic species that is likely to be widespread in tropical and subtropical regions. Pairwise comparisons of both genetic markers within lineages detected high genetic diversity and numbers of private haplotypes. Mozambican haplotypes were divergent (2.7%, cyt b) and restricted to Lineage 2. Both datasets identified a shallow but consistent phylogeographic break between warm-temperate/subtropical and tropical regions. Analysis of Lineage 1 recovered three geographic groups in the warm-temperate region that could be associated with isolation of upper reaches resulting from past river capture and sea level changes. These results are indicative of a complex history of isolation and reconnection in river drainages and/or multiple colonisation events.
A phylogeographic study of the circumtropical glasseye Heteropriacanthus cruentatus was conducted... more A phylogeographic study of the circumtropical glasseye Heteropriacanthus cruentatus was conducted. Molecular analyses indicate two mitochondrial cytochrome c oxidase subunit I (coI) lineages that are 10·4% divergent: one in the western Atlantic (Caribbean) and another that was detected across the Indo-Pacific. A fixed single nucleotide polymorphism (SNP) was detected at a nuclear locus (S7 ribosomal protein) and is consistent with this finding. There is evidence of recent dispersal from the Atlantic to the Indian Ocean with individuals of mixed lineages detected in South Africa and the Mozambique Channel. Using coalescent analyses of the mitochondrial dataset, time of divergence between lineages was estimated to be c. 15·3 million years. The deep divergence between these two lineages indicates distinct evolutionary units, however, due to the lack of morphological differences and evidence of hybridization between lineages, taxonomic revision is not suggested at this time.
ABSTRACT The slinger, Chrysoblephus puniceus, a seabream of the family Sparidae, is an important ... more ABSTRACT The slinger, Chrysoblephus puniceus, a seabream of the family Sparidae, is an important commercial linefish species in South Africa and Mozambique. Despites its fisheries importance little is known about the population structure of the species and it is currently managed separately by both countries. The genetic connectivity between localities throughout C. puniceus’ core distributional range was investigated using the mitochondrial control region and ten microsatellite loci. The majority of pairwise population comparisons were not significant (P > 0.05) and none remained significant after Bonferroni corrections. While one AMOVA grouping using mtDNA found weak levels of structure separating Gaza and Inhaca in southern Mozambique from other localities, all other groupings for both data sets found no significant among group variation. Similarly, SAMOVA, Mantel tests (P > 0.05) and STRUCTURE analysis using—ln likelihoods were unable to identify genetic structuring through C. puniceus’ distribution. MIGRATE-n analysis showed asymmetrical migration between sites with net migration probably influenced by the prevailing oceanographic feature. The results of the study failed to reject panmixia suggesting a single C. puniceus stock. The transboundary nature of a single stock coupled with the uneven temporal and spatial distribution of historical fishing effort likely made the species resilient to exploitation. This raises concerns as current management strategies are not aligned and the species is now harvested throughout most of its core distribution excluding the Ponta do Ouro, Maputaland, St Lucia marine protected areas.KeywordsLinefishGeneticsStock structureTransboundaryManagement
The reproductive biology and distribution of two species of Syngnathus (S. temminckii and S. wate... more The reproductive biology and distribution of two species of Syngnathus (S. temminckii and S. watermeyeri) were investigated using information from museum specimens, published data, survey data and samples collected during mouth-breaching events of temporarily open/closed estuaries over the period 1950-2011. Distribution records indicate that the two species are restricted to specific habitats and bioregions in southern Africa. Although S. temminckii has marine and estuarine populations, the species is most prevalent in warm and cool temperate estuarine systems. Syngnathus watermeyeri has limited dispersal capabilities owing to life-history characteristics and is completely dependent on shallow vegetated habitat in mesosaline estuarine systems in the warm temperate region, where it co-occurs with S. temminckii. The presence of breeding individuals and juveniles indicated that the spawning period of both species occurs in spring and summer, coinciding with warmer water temperatures and enhanced food resources, with reproductive activity of S. temminckii peaking in November. The estimated lengths (standard length) at 50% maturity of males and females of S. temminckii (129 and 120 mm respectively), were larger than those of S. watermeyeri (118 and 102 mm) and similar to those for other syngnathids. Although the observed sex ratios for S. temminckii (0.5:1.0, M:F) and S. watermeyeri (0.7:1.0), were biased towards females and similar to those observed among congeners, only S. temminckii was significantly different from the expected 1:1 ratio. The mean number of mature oocytes in the females (n = 379; 95% CI = 244-658) of S. temminckii was not significantly different from the mean number of eggs/embryos in the male brood pouch (n = 451; 95% CI = 270-486). The relationship between carrying capacity and size was linear and positively correlated, implying that fecundity, and hence reproductive efficiency, increases with the size of the individual. Comparative analyses indicated that these species have different life-history strategies and dispersal capabilities. However, they are both highly vulnerable as a result of anthropogenic threats to the unstable estuarine environment.
The marble notothen, Notothenia rossii, is widely distributed around the waters of sub-Antarctic ... more The marble notothen, Notothenia rossii, is widely distributed around the waters of sub-Antarctic islands in the Southern Ocean and is exposed to different temperatures that range from -1.5 to 8°C. This study investigates whether the different environmental conditions experienced by N. rossii at different latitudes in the Southern Ocean affect the levels of its blood serum antifreeze glycoprotein (AFGP). N. rossii specimens were collected from four localities, including the Ob' Seamount in the Indian Ocean sector, and South Georgia Island, South Shetland Islands and Dallman Bay in the Atlantic Ocean sector. Serum AFGP activity was determined in terms of thermal hysteresis, i.e. the difference between the equilibrium melting and non-equilibrium freezing points (f.p.s.). Among the four populations, the Ob' Seamount specimen had the lowest serum AFGP activity (0.44°C) and concentration (4.88 mg/mL), and the highest nonequilibrium f.p. (-1.39°C). These results are consistent with the warmer, ice-free waters around the Ob' Seamount. The other three higher latitude populations have 2-3 times greater serum AFGP activity and concentration, and much lower non-equilibrium f.p.s. In contrast, the physiological profiles of serum AFGP size isoforms revealed that all N. rossii populations, including the Ob' Seamount specimen, possess an extensive complements of AFGP proteins. Isoform variation was observed, especially in the large size isoforms (AFGPs 1-5), when compared to AFGP of the high Antarctic Dissostichus mawsoni. The lower levels of AFGP and the absence of some of the large isoforms are likely responsible for higher non-equilibrium f.p.s. of the Ob' seamount specimen.
The reef fish Myripristis berndti (Jordan & Everman 1903) is a pantropical species. A genetic ana... more The reef fish Myripristis berndti (Jordan & Everman 1903) is a pantropical species. A genetic analysis was conducted on 353 individuals from 10 localities distributed across the SW Indian Ocean (SWIO) in order to determine patterns of connectivity in the SWIO. Both the mtDNA sequences (711-bp cytochrome b sequences) and the microsatellites (8 newly developed loci) reveal spatial patterns of differentiation within the SWIO. There is, however, a discrepancy between the structure observed with each kind of marker. MtDNA revealed that 3 peripheral populations (NW Kenya, SE Reunion, and SW Europa) were isolated from the 7 more central populations, which form a more densely connected population network, while microsatellite data indicated a more restricted connectivity with significant differentiation between most pairs of localities. Higher genetic differences between Reunion and Europa were found, which might be explained by geography and isolation by distance pattern. In contrast, the genetic signature of Kenya -the most divergent locality identified by mtDNA basis but not with microsatellite -was probably the consequence of a particular colonisation history. These results indicate a much more restricted connectivity than previously thought for this species.
The first record of the Cape hagfish Myxine capensis in Mozambican waters is reported based on a ... more The first record of the Cape hagfish Myxine capensis in Mozambican waters is reported based on a single 356 mm total length specimen taken by bottom trawl off Maputo, 25° 52·9' S; 34° 42·7' E - 25° 54·1' S; 34° 41·0' E, at depths from 557 to 564 m. This account also represents the northernmost record of a hagfish in the western Indian Ocean. Morphometric and meristic data are provided and compared with those of 27 specimens (including the holotype) caught off Namibia and South Africa.
The taxonomic status of two southern African coastal pipefish species, Syngnathus temminckii and ... more The taxonomic status of two southern African coastal pipefish species, Syngnathus temminckii and Syngnathus watermeyeri , was investigated using a combination of morphological and genetic data. Morphological data showed that S. temminckii is distinct from the broadly distributed European pipefish Syngnathus acus, and a molecular phylogeny reconstructed using mitochondrial DNA recovered S. temminckii and S. watermeyeri as sister taxa. The southern African species share an evolutionary origin with north-eastern Atlantic Ocean and Mediterranean Sea species, including S. acus. These data support the existence of a distinct southern African clade of Syngnathus pipefishes that has diverged in situ to form the two species present in the region today.
JAIDS Journal of Acquired Immune Deficiency Syndromes, 2008
To estimate oral disease prevalence among Zimbabwean women by HIV serostatus and CD4 cell count a... more To estimate oral disease prevalence among Zimbabwean women by HIV serostatus and CD4 cell count and to assess accuracy of oral disease diagnoses made by nurses as compared with an oral surgeon. Standardized oral mucosa examinations were performed by trained nurse-examiners and by an oral surgeon among women recruited in Harare, Zimbabwe. A total of 461 women (320 HIV-infected, 141 uninfected) were seen by nurses and an oral surgeon within a 2-week period. Oral candidiasis (OC) was the most common lesion diagnosed in nearly one quarter of HIV-infected women, whereas hairy leukoplakia and Kaposi sarcoma were found in <3%. The prevalence of OC diagnosed by nurses or the surgeon was significantly higher among women with a CD4 count <200 cells/mm than in women with a CD4 count from 200 to 499 cells/mm3 or a CD4 count >499 cells/mm3. The sensitivity of nurse examinations compared with examinations by the oral surgeon among HIV-infected women for the diagnosis of OC was 73%, the specificity was 95%, and the kappa-statistic was 0.71. OC was the most common lesion in HIV-infected women and was strongly associated with a low CD4 cell count. Interexaminer agreement was good for the diagnosis of OC among HIV-infected women. This study suggests that OC may play a role, in combination with other clinical indicators as a marker of disease progression in resource-poor settings.
A cross-sectional study was conducted on women attending family planning clinics in Harare, Zimba... more A cross-sectional study was conducted on women attending family planning clinics in Harare, Zimbabwe to determine the prevalence of cervical neoplasia among HIV-1 positive women relative to an HIV-1 negative control group. Five hundred and fifty four women were recruited and the prevalence of HIV-1 was 36.8%. Cervical cytology was abnormal in 25.6% of HIV-infected women compared to only 6.7% HIV-1 seronegative women. Cervical neoplasia was significantly associated with HIV infection (chi(2)=42.4, P<0.001). Cellular changes typical of HPV infection (koilocytocis) were recorded in 6.4% of HIV infected women compared with 1.7% of HIV-1-uninfected women (chi(2)=8.43, P=0.004). HIV-1-positive women had twice the risk of having abnormal cervical cells than HIV-negative women (relative risk 2.47, odds ratio 10.14, P<0.001). Therefore the introduction of national cervical screening programme in HIV-1 endemic countries like Zimbabwe where the highest burden of pre-malignant lesions is among HIV-1-infected women needs careful planning because these women have other competing health needs including high rates of opportunistic infections.
Glossogobius callidus exhibits broad salinity tolerance and is distributed in both estuarine and ... more Glossogobius callidus exhibits broad salinity tolerance and is distributed in both estuarine and freshwater environments in southern Africa. Previous studies revealed substantial morphological and molecular variation among populations, suggesting they constitute a species complex. The present study utilised phylogenetic and population structure analyses of molecular sequence data from mitochondrial (cytochrome b) and nuclear (S7 intron 1) DNA markers to evaluate the genetic structure of the species. Two reproductively isolated lineages, 8.7% and 1.1% divergent, respectively, were identified. Lineage 1 represented the true G. callidus distributed mainly among estuarine systems including the type locality (Bushmans River, Eastern Cape, South Africa). Lineage 2 probably represents a cryptic species that is likely to be widespread in tropical and subtropical regions. Pairwise comparisons of both genetic markers within lineages detected high genetic diversity and numbers of private haplotypes. Mozambican haplotypes were divergent (2.7%, cyt b) and restricted to Lineage 2. Both datasets identified a shallow but consistent phylogeographic break between warm-temperate/subtropical and tropical regions. Analysis of Lineage 1 recovered three geographic groups in the warm-temperate region that could be associated with isolation of upper reaches resulting from past river capture and sea level changes. These results are indicative of a complex history of isolation and reconnection in river drainages and/or multiple colonisation events.
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Papers by M. Mwale