@entity3204 is a wide spread protozoan parasite belonging to the phylum Apicomplexa. Members of this group of @entity4801 cause economically and medically important diseases in a variety of animals, including @entity1 . @entity3204 is notable among this group for the fact that it readily infects virtually all warm-blooded vertebrates, while most apicomplexans are typically restricted in their host range. Individual strains of @entity3204 are genetically quite similar and molecular studies indicate that the vast majority (>95%) of strains can be grouped into one of three distinct clonal lineages. Remarkably, these three lineages are comprised of different combinations of two parental alleles, indicating they arose from a single genetic cross. The unusual population structure of @entity3204 originated within the last 10,000 years, while the genus itself is approximately 10 million years old. The remarkable success of the three lineages following their recent origin is likely attributable to a dramatic change in the life cycle that greatly facilitated transmission. Prior to the cross that gave rise to the clonal lineages, and in all closely related @entity4801 , transmission occurred by an obligatory two-host life cycle that alternated between definitive (carnivorous) and intermediate (herbivorous) hosts. The reassortment of genes that occurred in the cross allowed direct oral transmission between many different intermediate hosts. These findings illustrate that complex biological life cycles can change rapidly and dramatically, thus presenting a constant source of new @entity2927 .

Recent origins among ancient XXXX .

@entity4801 :: ('MESH:D010272', 'Disease') :: ['parasites'] @entity1 :: ('9606', 'Species') :: ['humans'] @entity2927 :: ('MESH:D015047', 'Disease') :: ['zoonotic infections'] @entity3204 :: ('5811', 'Species') :: ['T. gondii', 'Toxoplasma gondii']
@entity4801 :: (MESH:D010272,Disease) :: ['parasites']
