The study is the first to assess genetic ancestry of primate hybrids inhabiting a natural hybrid zone using molecular data to explain morphological variation.
Between 1998 and 2008, the researchers sampled 135 adult howler monkeys from Tabasco, Mexico, along with 76 others from Veracruz, Campeche, Chiapas and Quintana Roo states in Mexico and Peten in Guatemala. The field team collected blood, hair and morphometric measurements from the anesthetized animals before releasing them in the same locations. Sample collection from wild monkeys was carried out in accordance with U-M's University Committee on Use and Care of Animals protocol #09319, and in collaboration with researchers at the Universidad Veracruzana in Mexico.
The animals were weighed, and 16 body-part measurements were made: trunk, tail, leg, foot, arm and hand length; chest and abdominal girth; head circumference and breadth; head, mandible and ear length; interorbital breadth; internasal distance; and testicular volume.
Howler monkeys are among the largest of New World monkeys, with male mantled howlers weighing up to 22 pounds. Fourteen species of howler monkeys are currently recognized. They are native to Central and South American forests, in addition to southeastern Mexico.
|Contact: Jim Erickson|
University of Michigan