Phylogeny

The Origin of Orangutansphylogeny

Using a combination of molecular phylogentics and classical taxinomic comparisons we can construct a phylogenetic tree representing the points of divergence in the Great Apes clade (3). The Pongo clade diverged early relative to the other Great Apes (Figure to the right).

Some uncertainty still exists within the Pongo clade as to whether or not there has been speciation among the Sumatran and Bornean populations. On this website, I have decided to present the hypothesis that Pongo is divided into two distinct species with Pongo pygmaeus having three subspecies.

 

Phylogenetic comparisons in feeding behavior

As you might expect, orangutans have different feeding behavior from the other great apes (8). Orangutans are rarely observed feeding in groups, wheras in other great apes this is a common behavior. One hypothesis suggests that orangutan isolation results from the highly dispersed nature of fruiting trees in Borneo and Sumatra, forcing orangutans to disperse.comparison

Orangutans and Chimpanzees

Another comparison between orangutans and chimpanzees suggests that orangutans are adapted to larger variance in fruit availability than other primates (12). This particular study shows the energy intake per month is greater in orangutans than in chimpanzees (Figure to the right). This sort of feeding behavior depends on an efficient mechanism for storing energy.

Further comparisons among apes might prove useful for understanding the origins of orangutan feeding behavior.