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From what likely ancestry do the Gymnostomata descend?
Where do researchers suggest the primate plasmodia originated?
What do many parasitologists believe about the transmission of primate malarias to the New World?
What is the primary focus of the fruitful approach to phylogenetic problems of ciliates?
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What is suggested to have happened as man became more separated from non-human primates?
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Which trypanosome develops in the mid-gut of its insect vector?
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What is a unique characteristic of T.equiperdum compared to other trypanosomes?
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What is the main ecological characteristic of T.cruzi?
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Which group of flagellates evolved from Monocercomonas?
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Which organism is considered to have arisen from the Sarcomastigophora?
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What feature distinguishes Devescovina from Monocercomonas?
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What process exemplifies the transformation of tsetse-borne trypanosomes to mechanical transmission?
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Which amoeba is known for having both amoeboid and flagellate stages?
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What is one proposed origin of entozoic protozoa?
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Which genera are known to contain both ectozoic and entozoic species?
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What advantage does the intestine provide to ingested protozoa?
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The origin of parasitic habits among protozoa is believed to arise from which of the following?
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What characteristic is shared by species of the Euglenida in relation to hosts?
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What method was used to study the phylogenetic relationships of opalinids?
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What role does Baker play in the study of parasitic protozoa?
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What type of organisms are primarily implicated as initial hosts for sporadic invasions by protozoa?
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What is significant about the adaptation of Apicomplexa, Myxospora, and Microspora?
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From what types of organisms did the sporozoans and cnidosporans likely adapt to parasitism?
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Which of the following is true about Haemosporina and their evolutionary history?
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Which feature is retained by modern gregarines?
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What does the presence of merozoites and flagellated microgametes in Apicomplexa suggest?
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What likely influences the pathogenicity of Haemosporina in their hosts?
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Which aspect makes a re-evaluation of amoeba evolution necessary?
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What is a possible origin of the coccidia?
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What defines the Sporozoa in the context of the Sarcomastigophora?
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What type of organism is Amphileptus branchiarum described as?
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What significant change is occurring with Amphileptus branchiarum in its life cycle?
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Which genus was found in the gut of Spirobolus marginatus during Wenrich's study?
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What was the purpose of Wenrich's attempt to feed Euglena gracilis to millipedes?
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Which of the following correctly describes the relationship between free-living and parasitic protozoa as suggested by Wenrich's findings?
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Which statement is NOT true regarding the evolution of Ciliophora from the Sarcomastigophora?
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What likely triggered the specialization observed in the Sarcomastigophora?
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Study Notes
Origin of Parasitic Protozoa
- Entozoic protozoa likely originated from ectoparasites, evolving from casual commensals to established parasites.
- Early protozoa may have attached to hosts' skin or openings, gaining survival advantages by transitioning into their hosts' intestines.
- Parasitism appears to have evolved independently from various free-living protozoa across different groups, indicating multiple evolutionary origins.
- Temporary associations between free-living protozoa and hosts serve as initial steps toward developing endoparasitic behaviors.
Evidence from Specific Protozoa
- Amphileptus branchiarum, found on tadpole gills, exemplifies a transition towards parasitism by displaying both predatory and adhesive behaviors.
- Euglenids, like Menoidium, show potential for successful temporary entozoic survival, but don't establish permanent parasitic relationships.
- Trypanosomes, such as T. vivax and T. congolense, demonstrate evolutionary stages in their relationship with insect vectors, moving from midgut to salivary glands.
- The varying infection rates in triatomid bugs versus tsetse flies for different trypanosomes signal evolutionary adaptations and differences in host relationships.
Evolution of Specific Protozoan Groups
- Sarcomastigophora (ameboflagellates) are viewed as modern representatives of early protozoa, leading to the evolution of Sporozoa and Ciliophora.
- The Trichomonadidae evolved greater complexity from simpler Monocercomonas-like organisms, adapting unique structures for their ecological niches.
- Sarcodinians evolved from Sarcomastigophora, indicating the development of amoeboid characteristics from previously flagellated ancestors.
- Lines of evolution encompass both amoeboid and flagellate transitions, illustrated by the relationships among Tetramitus, Vahlkampfia, and Naegleria.
Adaptations and Phylogenetic Relationships
- Examining the life cycles of protozoa provides insight into phylogenetic relationships and evolutionary pathways.
- Apicomplexa and related groups possess features from both flagellates and ameboflagellates, adapting first to aquatic invertebrates before invading vertebrate hosts.
- The relationship between coccidians and Haemosporina (e.g., malarial parasites) remains debated, with evidence supporting dual evolutionary pathways.
- Primate malarias possibly originated in Southeast Asia, with the close ecological relationship between humans and non-human primates facilitating the exchange of malaria parasites.
Ciliates and Phylogenetic Approaches
- The phylogeny of ciliates utilizes structural elements like basal granules and infraciliature, crucial for understanding ciliate evolution.
- Gymnostomata represents a foundational lineage in the ciliate evolutionary tree, signifying the diversity rooted in protozoan origins.
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Description
Explore the evolution of entozoic protozoa and their origins from ectoparasites. Discover how these organisms transitioned from free-living forms to becoming commensals and eventually parasitic. Understand the various theories proposed by authors regarding their adaptation and associations with hosts.
