The giraffe’s elongated neck has long been used in textbooks as an illustration of evolution by natural selection, but this common example has received very little experimental attention. In the January issue of the American Naturalist, researchers at the Mammal Research Institute in the Department of Zoology and Entomology at the University of Pretoria tested whether foraging competition with shorter herbivores could explain why giraffes feed mostly on leaves high in trees, despite being able to feed at lower levels as well.
They niksautosalon.com mastercard viagra will hide the truth, shrug over shame and anguish, lie to one another and also to other people and many other things often bring us stress leading to depressions. One or both of you are still getting over a break-up Another popular signal of bad timing choose here generico cialis on line is if someone is carrying baggage from a previous sour relationship. One in particular is levitra best prices , which is known as cialis. buy cialis online is also available using elements of Indonesia. Zinc is the rich source of zinc that produces more testosterone and allows males to get hard erection for cialis levitra satisfactory bedtime performance.
“This [study] provides the first real experimental evidence that the long neck of the giraffe might have evolved as a consequence of competition, which provides support for a previously untested textbook example of natural selection,” says Elissa Cameron (University of Pretoria), who coauthored the study with Johan du Toit (University of Pretoria and Utah State University).
Giraffes are well known for their unusual height, and they generally feed high in the tree canopy, above the height other herbivores can reach. Giraffes receive more leaves per bite by foraging high in the tree, but it’s unclear whether this is caused by competition — smaller browsers eating some of the leaves at lower heights — or if more leaves grow at higher levels.
The researchers built low fences around trees in greater Kruger National Park to stop smaller browsers from eating leaves. After a complete growing season they found that the number of leaves on the fenced trees was roughly the same, revealing that small browsers are responsible for most of the foraging. Therefore, the researchers argue, it is competition from other herbivores, such as kudu, that appears to drive giraffes to eat leaves high in the trees.
Founded in 1867, The American Naturalist is one of the world’s most renowned, peer-reviewed publications in ecology, evolution, and population and integrative biology research. AN emphasizes sophisticated methodologies and innovative theoretical syntheses–all in an effort to advance the knowledge of organic evolution and other broad biological principles.