Factors of Parasitic Virulence.

Factors of Parasitic Virulence ABSTRACT why do round parasites kill the multitude they opine upon while others coexist with their host? Two prime factors determine parasitic sourness: the mode 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 more irate than parasites which have coevolved with their hosts. Parasites which are transmitted horizontally race to be more acetous than those transmitted vertically. It has been assumed that parasite-host interactions needfully evolve toward lower tartness. This is contradicted by studies in which asperity is hold or increases over time. A model which encompasses the disagreement of parasite-host interactions by synthesizing spatial (transmission) and temporal (evolutionary) factors is examined. Lenski and May (1994) and Antia et al. (1993) predict the modulation of virulence in parasite-host systems by integrating e volutionary and transmissibility factors. INTRODUCTION Why do certain(prenominal) parasites bear witness high levels of virulence inwardly their host populations while others exhibit low virulence? The cardinal prime factors most frequently cited (Esch and Fernandez 1993, Toft et al. 1991) are evolutionary history and mode of transmission. Incongruently evolved parasite-host associations are characterized by high virulence, while congruent evolution may result in reduced virulence (Toft et al. 1991).

Parasites transmitted vertically (from parent to offspring) tend to be slight virulent than parasites transmitt ed horizontally (between unrelated individua! ls of the homogeneous or different species). Studies in which virulence is shown to increase during parasite-host interaction, as in Eberts (1994) experiment with Daphnia magna, postulate a synthesis of traditionally discrete factors to predict a coevolutionary outcome. Authors given to habitually employ the word decrease before the word virulence are encouraged to replace the former with modulate, which emphasizes the need for an inclusive, predictive figure of speech for parasite-host interaction. Evolutionary history... If you want to name a full essay, ramble it on our website: OrderCustomPaper.com

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