Expansion of host range as a driving force in the evolution of Toxoplasma

Adaptive host manipulation by Toxoplasma gondii: fact or fiction?

“…Having multiple routes of transmission and such a wide host range make T. gondii unique and successful [14,22], perhaps eliminating the need for this parasite to enhance transmission by adaptive manipulation.…”

“…This increase in fitness may be in the form of short-term benefits (by increasing transmission to new hosts) and/or long-term benefits of sexual reproduction (which could be difficult to define, see [11,12] for discussions). However, there is a growing belief (e.g., [13,14]) that cats and sexual reproduction are not essential for the survival, transmission, and maintenance of T. gondii in a population, bringing into question the importance of the sexual cycle.…”

“…Theoretically, T. gondii could be maintained in a population, in the absence of cats, via repeated vertical transmission [16] and/or repeated carnivory [14], resulting in clonal reproduction of the parasite. The clonal population genetic structure suggests that these 'non-cat' routes of transmission happen often (Box 2), and that sexual reproduction occurs only rarely.…”

The Life Cycle of Toxoplasma gondii in the Natural Environment

“…This could result in a high opportunity to ingest T. gondii infected preys. So, despite the fact that the ecology of T. gondii in the wild tropical environment has been poorly studied, the different behaviour of wild felids compared to that of domestic cats and the number of possible IHs suggest a complex ecology of this parasite in this environment leading to a high genetic diversity [160].…”

“…gondii would have developed a plurality of alleles to increase its colonization potential [160,162]. In addition, the larger home ranges of wild felids compared to domestic cats can also strongly influence hybridization patterns and gene flow of the parasite and thus the genetic structure of pathogen populations.…”