Unrooted distance phylogram generated from a neighbor-joining analysis of small subunit ribosomal genes. Organisms were chosen to illustrate relationships among the Alveolata with an emphasis on the Apicomplexa. The organisms chosen for study here include the three major branches of the Apicomplexa: Plasmodium falciparum representing the Haemosporidia; Toxoplasma gondii, Neospora caninum,Sarcocystis neurona representing the tissue-dwelling coccidia;Eimeria tenella representing the enteric coccidia; andBabesia microti, Babesia bovis, Theileria parva, and Theileria annulata representing the Piroplasms;Symbiodinium microadriaticum and Prorocentrum micansrepresenting the Dinloflagellata; and Parameceum tetraureliaand Oxytricha nova representing the ciliates. O. novawas designated as the outgroup. Bootstrap percentages ≥50% are noted above the branches. The scale is as indicated.