Fig. 5.

Diagram showing presumed divergence of species and reproductive strategies (ovulation rate/litter size) among members of the Suiforme suborder together with the Hippopotamidae and Ruminatia. Ovulation rates (<2 or >4 follicles/oocytes) and the number of genes encoding for aromatase cytochrome P450 (CYP19) are also shown for all species of the Tayassuidae and Suidae families where known. To date, full-length sequences for aromatases cloned from over a dozen other mammals representing seven orders including the artiodactyla suggest the existence of a single functional CYP19 gene in these species.