Factors of Parasitic Virulence ABSTRACT Why do some parasites kill the military they plain upon slice others coexist with their host? ii prime factors determine parasitic glumness: the modality in which the parasite is transmitted, and the developmentary history of the parasite and its host. Parasites which have annex a new host species flow to be to a greater extent irate than parasites which have coevolved with their hosts. Parasites which ar transmitted horizontally tend to be to a greater extent acetous than those transmitted vertically. It has been assumed that parasite-host interactions inescapably evolve toward lower tartness. This is contradicted by studies in which asperity is hold or increases over time. A precedent which encompasses the disagreement of parasite-host interactions by synthesizing spacial (transmission) and temporal (evolutionary) factors is examined. Lenski and May (1994) and Antia et al. (1993) predict the conversion of virulence in parasite-host systems by integrating evolutionary and transmissibility factors. INTRODUCTION Why do certain(prenominal) parasites bear witness steep levels of virulence within their host populations while others exhibit low virulence? The two prime factors most frequently cited (Esch and Fernandez 1993, Toft et al. 1991) are evolutionary history and temper of transmission. Incongruently evolved parasite-host associations are characterized by high virulence, while congruent evolution may conduce in reduced virulence (Toft et al. 1991).
Parasites transmitted vertically (from parent to offspring) tend to be little virulent than parasites transmitted horizontally (between orthogonal individuals of the homogeneous or different species). Studies in which virulence is shown to increase during parasite-host interaction, as in Eberts (1994) prove with Daphnia magna, postulate a price reduction of traditionally discrete factors to predict a coevolutionary outcome. Authors given to habitually use the account book decrease before the sacred scripture virulence are encouraged to replace the motive with modulate, which emphasizes the need for an inclusive, predictive paradigm for parasite-host interaction. Evolutionary history... If you desire to name a integral essay, order it on our website: Ordercustompaper.com
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