Ecology, systematics and evolutionary biology of frog blood parasites in northern KwaZulu-Natal

["Anurans","amphibians","Haemoparasites","frog blood parasites","Hepatozoon","Dactylosoma","Haemococcidia","Trypanosoma","filarial nematode","phylogenetics","parasite ecology","life cycle"]

Netherlands, Edward Charles

North-West University

Others  :  https://repository.nwu.ac.za:443/bitstream/10394/32835/1/Netherlands_EC_21714363.pdf

瑞士|英语

来源: North-West University

【 摘 要 】

Blood parasites have been recorded in a variety of vertebrate and invertebrate hosts,inhabiting both aquatic and terrestrial environments. Until this study, only a few bloodparasite surveys had been carried out on frogs in sub-Saharan Africa. Thus information onthe diversity of these parasites remained limited. To increase our knowledge of frog bloodparasites, a large multi-approach study on the diversity, evolutionary biology, and ecology offrog blood parasites was undertaken. The majority of the fieldwork took place in northernKwaZulu-Natal (KZN), South Africa, focussing specifically on the area adjacent to thePhongolo River and its associated floodplain. However, samples also included thosecollected from frogs in the southern regions of the Kruger National Park, South Africa, andfrom frogs in Belgium. The latter was fortuitous, as Europe is the type locality for many frogblood parasite species and genera. These samples provided essential data for phylogeneticcomparisons between the African and European species.Presently this is the largest multi-species, generic and family amphibian bloodparasite survey to be completed, including a total of 643 anurans of 38 species, 20 generaand 13 families. The study was divided into three main components for the collection,analysis and reporting of data. The first component was to determine the frog blood parasitediversity, the second to determine phylogenetic relationships in conjunction with the formercomponent, and lastly the ecological and host-vector-parasite relationships. Blood sampleswere drawn from the femoral artery of each frog and thin blood smears prepared forscreening and morphometrics; the remaining blood fixed in 70% molecular grade EtOH forlater molecular analysis. Giemsa stained blood smears were screened microscopically forthe presence of any blood inhabiting organisms. Positive infections were then furtheranalysed according to the aims of the respective chapters. Analyses included bothmorphological and molecular aspects. Morphology was used for the description andidentification of species, and molecular analyses were used to assist with the morphologybaseddescriptions, as well as to allow for phylogenetic relationship comparisons of theblood parasites with one another.In the present study, three new species of Hepatozoon were described fromhyperoliid frogs (Afrixalus fornasini, Hyperolius argus, and Hyperolius marmoratus), namelyHepatozoon involucrum Netherlands, Cook & Smit, 2018; Hepatozoon tenuis Netherlands,Cook & Smit, 2018; and Hepatozoon thori Netherlands, Cook & Smit, 2018. Phylogeneticrelationships show that species of Hepatozoon isolated from African frogs form as amonophyletic group, separate from the species of Hepatozoon isolated from European andNorth American frogs.Two species of Dactylosoma Labbé, 1894, were found parasitising three species offrogs namely, Ptychadena anchietae and Sclerophrys gutturalis from South Africa, as well asPelophylax lessonae from Belgium. Based on morphometrics and molecular findings a newdactylosomatid, Dactylosoma sp. 1, is described form Pty. anchietae and Scl. gutturalis. Thespecies of Dactylosoma isolated from Pel. lessonae conforms morphologically withDactylosoma splendens Labbé 1894, thus placing in question the validity of D. splendenssynonymy with D. ranarum (Kruse, 1890). Phylogenetic analysis shows species of anuranDactylosoma as a monophyletic group, separate from the other haemogregarine groups.Five species of frogs from South Africa and two from Belgium were found parasitisedwith haemococcidia. Based on morphological, morphometric and molecular findingsLankesterella minima (Chaussat 1850) is redescribed from Pelophylax kl. esculentus(Linnaeus, 1758) and Pel. lessonae (Camerano, 1882) from Belgium. Additionally, two newspecies of Lankesterella were described, namely Lankesterella sp. 1 in Pel. lessonae fromBelgium, and Lankesterella sp. 2 in Afr. delicates and Afr. fornasini from South Africa.Furthermore, a new genus of haemococcidia, with a new species combination, is describedfrom Phr. mababiensis, Pty. anchietae, and Pyx. edulis from South Africa; as well as a newspecies, haemococcidia sp. 2, described from Afr. fornasini from South Africa. This is thefirst study to provide molecular data for species of haemococcidia from African andEuropean anurans.A new species of amphibian filarial nematode (Onchocercidae: Waltonellinae) wasdescribed from the toads Scl. gutturalis and Scl. garmani. The life history of this nematodewas elucidated from its natural mosquito vectors Uranotaenia (Pseudoficalbia)mashonaensis and Uranotaenia (Pfc.) montana. All stages of development werecharacterised using morphological and molecular methods. This study is the first to elucidatethe life history of an amphibian filarial nematode from southern Africa, and provide data onits phylogenetic placement within the Onchocercidae.In addition to the taxonomic and phylogenetic perspective of this study, this studyalso aimed at exploring the potential of frog blood parasites as indicators of environmentalhealth. For this, blood parasites infecting grass frogs (Ptychadena Boulenger, 1917) from thePhongolo River system in South Africa were used as a case study. In general, findingsindicate that frogs from more impacted sites harboured more blood parasites than from lessimpactedsites.In summary, this study explored the efficacy of a large multi-species, multi-approachsurvey on the diversity of frog blood parasites from northern KwaZulu-Natal, South Africa.Based on the results several new species of frog blood parasites from different taxa werediscovered and described, greatly contributing to knowledge and species records on theoverall diversity of frog blood parasites from South Africa. Furthermore, this study providesthe first molecular data for species of Dactylosoma and Lankesterella for frogs from Africa,as well as the first molecular data for a filarial nematode for frogs from South Africa. Thephylogenetic relationships of species of Hepatozoon, Dactylosoma, Lankesterella, and thefilarial nematode were also characterised based on comparisons to other availablemolecular data. From an ecological perspective, blood parasites from this study adhere toseveral criteria of what is considered a good indicator and thus demonstrate potential asindicators for healthy ecosystems and intact food webs. The results of this study establish afoundation for future research into the blood parasite biodiversity in northern KZN, an areathat this study has highlighted as not only rich in anuran diversity, but also rich in anuranblood parasite diversity. Furthermore, this study provides a baseline for future taxonomicand ecological studies on these parasite groups, not only in South Africa but globally as well.