SUNScholar - Browsing by Author "Matthee, Conrad A."

Browsing by Author "Matthee, Conrad A."

Now showing 1 - 12 of 12

Comparative phylogeography between two generalist flea species reveal a complex interaction between parasite life history and host vicariance : parasite-host association matters
(BioMed Central, 2015-06) Van der Mescht, Luther; Matthee, Sonja; Matthee, Conrad A.
Background: In parasitic taxa, life history traits such as microhabitat preference and host specificity can result in differential evolutionary responses to similar abiotic events. The present study investigates the influence of vicariance and host association on the genetic structure of two generalist flea species, Listropsylla agrippinae, and Chiastopsylla rossi. The taxa differ in the time spent on the host (predominantly fur vs. nest) and level of host specificity. Results: A total of 1056 small mammals were brushed to collect 315 fleas originating from 20 geographically distinct localities in South Africa. Phylogeographic genetic structure of L. agrippinae and C. rossi were determined by making use of 315 mitochondrial COII and 174 nuclear EF1-α sequences. Both parasites show significant genetic differentiation among the majority of the sampling sites confirming limited dispersal ability for fleas. The generalist fur flea with a narrower host range, L. agrippinae, displayed geographic mtDNA spatial genetic structure at the regional scale and this pattern is congruent with host vicariance. The dating of the divergence between the L. agrippinae geographic clades co-insides with paleoclimatic changes in the region approximately 5.27 Ma and this provides some evidence for a co-evolutionary scenario. In contrast, the more host opportunistic nest flea, C. rossi, showed a higher level of mtDNA and nDNA spatial genetic structure at the inter-populational scale, most likely attributed to comparatively higher restrictions to dispersal. Conclusions: In the present study, the evolutionary history of the flea species could best be explained by the association between parasite and host (time spent on the host). The phylogeographic pattern of the fur flea with a narrower host range correspond to host spatial genetic structures, while the pattern in the host opportunistic nest flea correspond to higher genetic divergences between sampling localities that may also be associated with higher effective population sizes. These findings suggest that genetic exchange amon
Comparative phylogeography of parasitic Laelaps mites contribute new insights into the specialist-generalist variation hypothesis (SGVH)
(BMC (part of Springer Nature), 2018-09-03) Matthee, Conrad A.; Engelbrecht, Adriaan; Matthee, Sonja
Background: The specialist-generalist variation hypothesis (SGVH) in parasites suggests that, due to patchiness in habitat (host availability), specialist species will show more subdivided population structure when compared to generalist species. In addition, since specialist species are more prone to local stochastic extinction events with their hosts, they will show lower levels of intraspecific genetic diversity when compared to more generalist. Results: To test the wider applicability of the SGVH we compared 337 cytochrome oxidase I mitochondrial DNA and 268 nuclear tropomyosin DNA sequenced fragments derived from two co-distributed Laelaps mite species and compared the data to 294 COI mtDNA sequences derived from the respective hosts Rhabdomys dilectus, R. bechuanae, Mastomys coucha and M. natalensis. In support of the SGVH, the generalist L. muricola was characterized by a high mtDNA haplotypic diversity of 0.97 (±0.00) and a low level of population differentiation (mtDNA Fst= 0.56, p < 0.05; nuDNA Fst = 0.33, P < 0.05) while the specialist L. giganteus was overall characterized by a lower haplotypic diversity of 0.77 (±0.03) and comparatively higher levels of population differentiation (mtDNA Fst = 0.87, P < 0.05; nuDNA Fst = 0.48, P < 0.05). When the two specialist L. giganteus lineages, which occur on two different Rhabdomys species, are respectively compared to the generalist parasite, L. muricola, the SGVH is not fully supported. One of the specialist L. giganteus species occurring on R. dilectus shows similar low levels of population differentiation (mtDNA Fst= 0.53, P < 0. 05; nuDNA Fst= 0.12, P < 0.05) than that found for the generalist L. muricola. This finding can be correlated to differences in host dispersal: R. bechuanae populations are characterized by a differentiated mtDNA Fst of 0.79 (P < 0.05) while R. dilectus populations are less structured with a mtDNA Fst= 0.18 (P < 0.05). Conclusions: These findings suggest that in ectoparasites, host specificity and the vagility of the host are both important drivers for parasite dispersal. It is proposed that the SGHV hypothesis should also incorporate reference to host dispersal since in our case only the specialist species who occur on less mobile hosts showed more subdivided population structure when compared to generalist species.
Correlated genetic and ecological diversification in a widespread Southern African horseshoe bat
(Public Library of Science (PLoS), 2012-02) Stoffberg, Samantha; Schoeman, M. Corrie; Matthee, Conrad A.
The analysis of molecular data within a historical biogeographical framework, coupled with ecological characteristics can provide insight into the processes driving diversification. Here we assess the genetic and ecological diversity within a widespread horseshoe bat Rhinolophus clivosus sensu lato with specific emphasis on the southern African representatives which, although not currently recognized, were previously described as a separate species R. geoffroyi comprising four subspecies. Sequence divergence estimates of the mtDNA control region show that the southern African representatives of R. clivosus s.l. are as distinct from samples further north in Africa than they are from R. ferrumequinum, the sister-species to R. clivosus. Within South Africa, five genetically supported geographic groups exist and these groups are corroborated by echolocation and wing morphology data. The groups loosely correspond to the distributions of the previously defined subspecies and Maxent modelling shows a strong correlation between the detected groups and ecoregions. Based on molecular clock calibrations, it is evident that climatic cycling and related vegetation changes during the Quaternary may have facilitated diversification both genetically and ecologically.
Evidence for panmixia despite barriers to gene flow in the southern African endemic, Caffrogobius caffer (Teleostei: Gobiidae)
(BioMed Central, 2008-12) Neethling, Marlene; Matthee, Conrad A.; Bowie, Rauri C. K.; Von der Heyden, Sophie
Background: Oceanography and life-history characteristics are known to influence the genetic structure of marine species, however the relative role that these factors play in shaping phylogeographic patterns remains unresolved. The population genetic structure of the endemic, rocky shore dwelling Caffrogobius caffer was investigated across a known major oceanographic barrier, Cape Agulhas, which has previously been shown to strongly influence genetic structuring of South African rocky shore and intertidal marine organisms. Given the variable and dynamic oceanographical features of the region, we further sought to test how the pattern of gene flow between C. caffer populations is affected by the dominant Agulhas and Benguela current systems of the southern oceans. Results: The variable 5' region of the mtDNA control region was amplified for 242 individuals from ten localities spanning the distributional range of C. caffer. Fifty-five haplotypes were recovered and in stark contrast to previous phylogeographic studies of South African marine species, C. caffer showed no significant population genetic structuring along 1300 km of coastline. The parsimony haplotype network, AMOVA and SAMOVA analyses revealed panmixia. Coalescent analyses reveal that gene flow in C. caffer is strongly asymmetrical and predominantly affected by the Agulhas Current. Notably, there was no gene flow between the east coast and all other populations, although all other analyses detect no significant population structure, suggesting a recent divergence. The mismatch distribution suggests that C. caffer underwent a population expansion at least 14 500 years ago. Conclusion: We propose several possible life-history adaptations that could have enabled C. caffer to maintain gene flow across its distributional range, including a long pelagic larval stage. We have shown that life-history characteristics can be an important contributing factor to the phylogeography of marine species and that the effects of oceanography do not necessarily suppress its influence on effective dispersal.
The influence of interspecific competition and host preference on the phylogeography of two African ixodid tick species
(Public Library of Science -- PLoS, 2013-10) Cangi, Nídia; Horak, Ivan G.; Apanaskevich, Dmitry A.; Matthee, Sonja; Das Neves, Luis C. B. G.; Estrada-Pena, Agustin; Matthee, Conrad A.
A comparative phylogeographic study on two economically important African tick species, Amblyomma hebraeum and Hyalomma rufipes was performed to test the influence of host specificity and host movement on dispersion. Pairwise AMOVA analyses of 277 mtDNA COI sequences supported significant population differentiation among the majority of sampling sites. The geographic mitochondrial structure was not supported by nuclear ITS-2 sequencing, probably attributed to a recent divergence. The three-host generalist, A. hebraeum, showed less mtDNA geographic structure, and a lower level of genetic diversity, while the more host-specific H. rufipes displayed higher levels of population differentiation and two distinct mtDNA assemblages (one predominantly confined to South Africa/Namibia and the other to Mozambique and East Africa). A zone of overlap is present in southern Mozambique. A mechanistic climate model suggests that climate alone cannot be responsible for the disruption in female gene flow. Our findings furthermore suggest that female gene dispersal of ticks is more dependent on the presence of juvenile hosts in the environment than on the ability of adult hosts to disperse across the landscape. Documented interspecific competition between the juvenile stages of H. rufipes and H. truncatum is implicated as a contributing factor towards disrupting gene flow between the two southern African H. rufipes genetic assemblages.
The influence of life history characteristics on flea (Siphonaptera) species distribution models
(BioMed Central, 2016) Van der Mescht, Luther; Le Roux, Peter C.; Matthee, Conrad A.; Raath, Morgan J.; Matthee, Sonja
Background: Ectoparasites exhibit pronounced variation in life history characteristics such as time spent on the host and host range. Since contemporary species distribution (SD) modelling does not account for differences in life history, the accuracy of predictions of current and future species’ ranges could differ significantly between life history groups. Results SD model performance was compared between 21 flea species that differ in microhabitat preferences and level of host specificity. Distribution models generally performed well, with no significant differences in model performance based on either microhabitat preferences or host specificity. However, the relative importance of predictor variables was significantly related to host specificity, with the distribution of host-opportunistic fleas strongly limited by thermal conditions and host-specific fleas more associated with conditions that restrict their hosts’ distribution. The importance of temperature was even more pronounced when considering microhabitat preference, with the distribution of fur fleas being strongly limited by thermal conditions and nest fleas more associated with variables that affect microclimatic conditions in the host nest. Conclusions Contemporary SD modelling, that includes climate and landscape variables, is a valuable tool to study the biogeography and future distributions of fleas and other parasites taxa. However, consideration of life history characteristics is cautioned as species may be differentially sensitive to environmental conditions.
The influence of pleistocene climatic changes and ocean currents on the phylogeography of the Southern African Barnacle, Tetraclita serrata (Thoracica; Cirripedia)
(Public Library of Science, 2014-07) Reynolds, Terry V.; Matthee, Conrad A.; Von der Heyden, Sophie
Abstract The evolutionary effects of glacial periods are poorly understood for Southern Hemisphere marine intertidal species, particularly obligatory sessile organisms. We examined this by assessing the phylogeographic patterns of the southern African volcano barnacle, Tetraclita serrata, a dominant species on rocky intertidal shores. Restricted gene flow in some geographical areas was hypothesized based on oceanic circulation patterns and known biogeographic regions. Barnacle population genetic structure was investigated using the mitochondrial cytochrome oxidase subunit 1 (COI) region for 410 individuals sampled from 20 localities spanning the South African coast. The mtDNA data were augmented by generating nuclear internal transcribed spacer 1 (ITS1) sequences from a subset of samples. Phylogenetic and population genetic analyses of mitochondrial DNA data reveal two distinct clades with mostly sympatric distributions, whereas nuclear analyses reveal only a single lineage. Shallow, but significant structure (0.0041–0.0065, P,0.01) was detected for the mtDNA data set, with the south-west African region identified as harbouring the highest levels of genetic diversity. Gene flow analyses on the mtDNA data show that individuals sampled in south-western localities experience gene flow primarily in the direction of the Benguela Current, while south and eastern localities experience bi-directional gene flow, suggesting an influence of both the inshore currents and the offshore Agulhas Current in the larval distribution of T. serrata. The mtDNA haplotype network, Bayesian Skyline Plots, mismatch distributions and time since expansion indicate that T. serrata population numbers were not severely affected by the Last Glacial Maximum (LGM), unlike other southern African marine species. The processes resulting in the two morphologically cryptic mtDNA lineages may be the result of a recent historical allopatric event followed by secondary contact or could reflect selective pressures due to differing environmental conditions.
Natural hosts of the larvae of Nuttalliella sp. (N. namaqua?) (Acari: Nuttalliellidae)
(AOSIS Publishing, 2012-02-02) Horak, Ivan G.; Lutermann, Heike; Medger, Katarina; Apanaskevich, Dmitry A.; Matthee, Conrad A.
The first collection of unengorged and fully engorged larvae of Nuttalliella sp. (N. namaqua?) from the murid rodents Micaelamys namaquensis, Aethomys chrysophilus and Acomys spinosissimus in Limpopo Province and from M. namaquensis in the Northern Cape Province, South Africa, is documented. A total of nine larvae were collected from two M. namaquensis in the Soutpansberg mountain range in the Limpopo Province during April 2009. During the last week of September 2011, 221 larvae were collected from rodents at the same locality and 10 of 48 M. namaquensis, 6 of 12 Ae. chrysophilus and 3 of 14 Ac. spinosissimus were infested. One of the M. namaquensis harboured 53 larvae. Five larvae were collected from two M. namaquensis in the Northern Cape Province. Total genomic DNA was extracted from two larvae and a region of the 18S rRNA gene was sequenced for these. BLASTn searches revealed similarity between these specimens and the Nuttalliella sequences published on GenBank. © 2012. The Authors.
Signatures of seaway closures and founder dispersal in the phylogeny of a circumglobally distributed seahorse lineage
(BioMed Central, 2007-08) Teske, Peter R.; Hamilton, Healy; Matthee, Conrad A.; Barker, Nigel P.
Background: The importance of vicariance events on the establishment of phylogeographic patterns in the marine environment is well documented, and generally accepted as an important cause of cladogenesis. Founder dispersal (i.e. long-distance dispersal followed by founder effect speciation) is also frequently invoked as a cause of genetic divergence among lineages, but its role has long been challenged by vicariance biogeographers. Founder dispersal is likely to be common in species that colonize remote habitats by means of rafting (e.g. seahorses), as long-distance dispersal events are likely to be rare and subsequent additional recruitment from the source habitat is unlikely. In the present study, the relative importance of vicariance and founder dispersal as causes of cladogenesis in a circumglobally distributed seahorse lineage was investigated using molecular dating. A phylogeny was reconstructed using sequence data from mitochondrial and nuclear markers, and the well-documented closure of the Central American seaway was used as a primary calibration point to test whether other bifurcations in the phylogeny could also have been the result of vicariance events. The feasibility of three other vicariance events was explored: a) the closure of the Indonesian Seaway, resulting in sister lineages associated with the Indian Ocean and West Pacific, respectively; b) the closure of the Tethyan Seaway, resulting in sister lineages associated with the Indo-Pacific and Atlantic Ocean, respectively, and c) continental break-up during the Mesozoic followed by spreading of the Atlantic Ocean, resulting in pairs of lineages with amphi-Atlantic distribution patterns. Results: Comparisons of pairwise genetic distances among the seahorse species hypothesized to have diverged as a result of the closure of the Central American Seaway with those of published teleost sequences having the same distribution patterns show that the seahorses were among the last to diverge. This suggests that their cladogenesis was associated with the final closure of this seaway. Although two other divergence events in the phylogeny could potentially have arisen as a result of the closures of the Indonesian and Tethyan seaways, respectively, the timing of the majority of bifurcations in the phylogeny differed significantly from the dates of vicariance events suggested in the literature. Moreover, several divergence events that resulted in the same distribution patterns of lineages at different positions in the phylogeny did not occur contemporaneously. For that reason, they cannot be the result of the same vicariance events, a result that is independent of molecular dating. Conclusion: Interpretations of the cladogenetic events in the seahorse phylogeny based purely on vicariance biogeographic hypotheses are problematic. We conclude that the evolution of the circumglobally distributed seahorse lineage was strongly influenced by founder dispersal, and suggest that this mode of speciation may be particularly important in marine organisms that lack a pelagic dispersal phase and instead disperse by means of rafting.
Suprafamilial relationships among Rodentia and the phylogenetic effect of removing fast-evolving nucleotides in mitochondrial, exon and intron fragments
(BioMed Central, 2008-11) Montgelard, Claudine; Forty, Ellen; Arnal, Veronique; Matthee, Conrad A.
Background: The number of rodent clades identified above the family level is contentious, and to date, no consensus has been reached on the basal evolutionary relationships among all rodent families. Rodent suprafamilial phylogenetic relationships are investigated in the present study using ~7600 nucleotide characters derived from two mitochondrial genes (Cytochrome b and 12S rRNA), two nuclear exons (IRBP and vWF) and four nuclear introns (MGF, PRKC, SPTBN, THY). Because increasing the number of nucleotides does not necessarily increase phylogenetic signal (especially if the data is saturated), we assess the potential impact of saturation for each dataset by removing the fastest-evolving positions that have been recognized as sources of inconsistencies in phylogenetics. Results: Taxonomic sampling included multiple representatives of all five rodent suborders described. Fast-evolving positions for each dataset were identified individually using a discrete gamma rate category and sites belonging to the most rapidly evolving eighth gamma category were removed. Phylogenetic tree reconstructions were performed on individual and combined datasets using Parsimony, Bayesian, and partitioned Maximum Likelihood criteria. Removal of fast-evolving positions enhanced the phylogenetic signal to noise ratio but the improvement in resolution was not consistent across different data types. The results suggested that elimination of fastest sites only improved the support for nodes moderately affected by homoplasy (the deepest nodes for introns and more recent nodes for exons and mitochondrial genes). Conclusion: The present study based on eight DNA fragments supports a fully resolved higher level rodent phylogeny with moderate to significant nodal support. Two inter-suprafamilial associations emerged. The first comprised a monophyletic assemblage containing the Anomaluromorpha (Anomaluridae + Pedetidae) + Myomorpha (Muridae + Dipodidae) as sister clade to the Castorimorpha (Castoridae + Geomyoidea). The second suprafamilial clustering identified a novel association between the Sciuromorpha (Gliridae + (Sciuridae + Aplodontidae)) and the Hystricomorpha (Ctenodactylidae + Hystricognathi) which together represents the earliest dichotomy among Rodentia. Molecular time estimates using a relaxed Bayesian molecular clock dates the appearance of the five suborders nearly contemporaniously at the KT boundary and this is congruent with suggestions of an early explosion of rodent diversity. Based on these newly proposed phylogenetic relationships, the evolution of the zygomasseteric pattern that has been used for a long time in rodent systematics is evaluated.
Western Zambian sable : are they a geographic extension of the giant sable antelope
(South African Wildlife Management Association, 2010-04) Jansen van Vuuren, Bettine; Robinson, Terence J.; VazPinto, Pedro; Estes, Richard; Matthee, Conrad A.
The giant sable (Hippotragus niger variani) is one of Africa's most spectacular large antelope. Years of civil unrest in Angola, a highly localized distribution and Interbreeding with its congener the roan antelope (H. equinus) has led to this subspecies being considered as critically endangered. Sable antelope occurring ∼600 km to the east in western Zambia superficially resemble giant sable in phenotype, prompting speculation in the popular media that the distribution of giant sable may be larger than currently documented. Our aim here was to Investigate the evolutionary placement of western Zambian sable using mitochondrial DNA control region data. Phylogenese analyses (maximum likelihood and Bayesian analyses) supported the monophyly of H. n. variant (Bayesian posterior probability of >0.95, bootstrap support >80%) and nested the western Zambian sable within H. n. niger. This finding was supported by an analysis of molecular variance that discretely grouped western Zambian sable from giant sable (ΦST = 0.645, P = 0.001). Significant genetic structure was also found across the range of H. n. nigera as Indicated by our phylogenetic analyses and analysis of molecular variance (ΦST = 0.418, P = 0.001). We conclude that although the western Zambian sable antelope and those of H. n. variani resemble one another in morphology, particularly with respect to facial markings, significant genetic differences underpin these two evolutionary lineages. Our findings hold Implications for the conservation of sable and highlight the need for active management Intervention.
When homoplasy mimics hybridization : a case study of Cape hakes (Merluccius capensis and M. paradoxus)
(PeerJ, 2016) Henriques, Romina; Von der Heyden, Sophie; Matthee, Conrad A.
In the marine environment, an increasing number of studies have documented introgression and hybridization using genetic markers. Hybridization appears to occur preferentially between sister-species, with the probability of introgression decreasing with an increase in evolutionary divergence. Exceptions to this pattern were reported for the Cape hakes (Merluccius capensis and M. paradoxus), two distantly related Merluciidae species that diverged 3–4.2 million years ago. Yet, it is expected that contemporary hybridization between such divergent species would result in reduced hybrid fitness. We analysed 1,137 hake individuals using nine microsatellite markers and control region mtDNA data to assess the validity of the described hybridization event. To distinguish between interbreeding, ancestral polymorphism and homplasy we sequenced the flanking region of the most divergent microsatellite marker. Simulation and empirical analyses showed that hybrid identification significantly varied with the number of markers, model and approach used. Phylogenetic analyses based on the sequences of the flanking region of Mmerhk-3b, combined with the absence of mito-nuclear discordance, suggest that previously reported hybridization between M. paradoxus and M. capensis cannot be substantiated. Our findings highlight the need to conduct a priori simulation studies to establish the suitability of a particular set of microsatellite loci for detecting multiple hybridization events. In our example, the identification of hybrids was severely influenced by the number of loci and their variability, as well as the different models employed. More importantly, we provide quantifiable evidence showing that homoplasy mimics the effects of heterospecific crossings which can lead to the incorrect identification of hybridization.

Browsing by Author "Matthee, Conrad A."

Results Per Page

Sort Options