Conservationists with the Wildlife Conservation Society 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.
This is an adult male gorilla -- also known as a "silverback" (far right) -- with a family group in Nouabalé-Ndoki National Park in the Republic of Congo. Conservationists from WCS and the Max Planck Institute for Evolutionary Anthropology recently discovered that larger male gorillas are more successful than smaller ones at attracting mates and raising young.
Credit: Thomas Breuer/WCS
The study—conducted over a 12-year period in Nouabalé-Ndoki National Park in the Republic of Congo—helps 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 Wildlife Conservation Society 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 "silverback" gorillas, the researchers selected three physical factors for measurement: overall body length; the size of the adult male's head crest (also known as a sagittal crest which is absent in females); and the size of an individual's gluteal muscles on the animal's 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's offspring.
The results of the study revealed that all three characteristics were positively correlated to an adult male's 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.
"Our 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," said Breuer, the lead author of the study. "More studies would be necessary to determine the links between morphology and fitness in this and other long-lived species."
The research is the latest of several studies of gorillas made from the ideal research conditions of Nouabalé-Ndoki National Park's 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).
"By 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," added Breuer.
"Studies such as these—ones that examine the subtle dynamics of gorilla interactions—are only possible in the stable conditions created in protected areas such as Nouabalé-Ndoki National Park," said Dr. James Deutsch, Executive Director for WCS's 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 Wildlife Conservation Society, and The Woodland Park Zoo.
John Delaney | EurekAlert!
Species may appear deceptively resilient to climate change
24.11.2017 | University of California - Davis
Scientists team up on study to save endangered African penguins
16.11.2017 | Florida Atlantic University
High-precision measurement of the g-factor eleven times more precise than before / Results indicate a strong similarity between protons and antiprotons
The magnetic moment of an individual proton is inconceivably small, but can still be quantified. The basis for undertaking this measurement was laid over ten...
Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...
The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.
Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
24.11.2017 | Physics and Astronomy
24.11.2017 | Health and Medicine
24.11.2017 | Earth Sciences