菊花视频

Study in Congo protected area helps researchers understand selective factors in gorilla behavior and reproduction

NEW YORK (May 1, 2012)鈥�Conservationists with the 菊花视频 and the Max Planck Institute for Evolutionary Anthropology have found that larger male gorillas living in the rainforests of Congo seem to be more successful than smaller ones at attracting mates and even raising young.

The study鈥攃onducted over a 12-year period in Nouabal茅-Ndoki National Park in the Republic of Congo鈥攈elps to illuminate the selective pressures that influence the evolution of great apes.

The study appears in a recent edition of Journal of Human Evolution. The authors of the study include: Thomas Breuer of the 菊花视频 and the Max Planck Institute for Evolutionary Anthropology; and Andrew M. Robbins, Christophe Boesch, and Martha M. Robbins of the Max Planck Institute for Evolutionary Anthropology.

In assessing the role of size in the reproductive success of 鈥渟ilverback鈥� gorillas, the researchers selected three physical factors for measurement: overall body length; the size of the adult male鈥檚 head crest (also known as a sagittal crest which is absent in females); and the size of an individual鈥檚 gluteal muscles on the animal鈥檚 posterior. The researchers then compared data on individual size with information on group dynamics to explore possible correlations between physical characteristics of adult males, the number of female gorillas connected to males, and the survival rates of an adult gorilla鈥檚 offspring.

The results of the study revealed that all three characteristics were positively correlated to an adult male鈥檚 average number of mates. In other words, the bigger the adult male, the more mates it had. An unexpected finding was that only head-crest size and gluteal muscles were strongly related to offspring survival (measured as infants that survived to weaning age) and overall reproductive success, measured as the number of surviving offspring.

鈥淥ur findings of correlations between physical traits and male reproductive success could be considered evidence of a selection process in gorillas, but it is not yet proof,鈥� said Breuer, the lead author of the study. 鈥淢ore studies would be necessary to determine the links between morphology and fitness in this and other long-lived species.鈥�

The research is the latest of several studies of gorillas made from the ideal research conditions of Nouabal茅-Ndoki National Park鈥檚 Mbeli Bai, a large, swampy forest clearing where gorillas (and scientists studying them) gather for long periods. From 1995 until 2007, the team followed the lives of 19 adult male western lowland gorillas and their family groups from observation platforms with telescopes and cameras. Over that time, the researchers were able to track the number of females each male mated with, and the number and survival rate of offspring produced by each adult male.

The gorilla group data was complemented by physical measurements of adult male gorillas by using a novel, non-invasive method called digital photogrammetry, which produces accurate measurements of individual gorillas and their characteristics from digital images (converting pixel size to actual lengths).

鈥淏y using non-invasive methods for measuring the size of individual male gorillas and their features, we are gaining insights about the factors that could be driving mate selection in our closest relatives,鈥� added Breuer.

鈥淪tudies such as these鈥攐nes that examine the subtle dynamics of gorilla interactions鈥攁re only possible in the stable conditions created in protected areas such as Nouabal茅-Ndoki National Park,鈥� said Dr. James Deutsch, Executive Director for WCS鈥檚 Africa Program.

This study was made possible through funding from the Brevard Zoo, Columbus Zoo and Aquarium, Cincinnati Zoo and Botanical Garden, Cleveland Zoological Society, Disney Worldwide Conservation Fund, Dublin Zoo, SeaWorld & Busch Gardens Conservation Fund, The Toronto Zoo, the 菊花视频, and The Woodland Park Zoo.