Homology/Analogy Blog Post

Darlene Jones

Anthro Blog Post week 3 Homolgous/Analogous Traits

1a) The two species chosen to express the homologus trait are humans and the aye-aye’s. Homologous traits are those that are from a common ancestor but use the trait in different ways. Fingers were the homologous trait that was chosen to compare these two species. Aye Aye’s are a part of a group of primates known as prosimians. They are related to chimpanzees, apes, and humans. They live in the tropical rainforest of the Madagascar. Humans are primates, and are related to the same species. Unlike the Aye Aye’s only being native to one location, humans live in variety of terrains and landscapes.

1b) Aye aye’s use its long middle digit to tap on the bark of the trees and listens for the movements of the larvae of wood-boring insects and grubs. If it does detect any sound, it cracks into the wood, biting through the exterior layers of the bark, and then using the same long middle finger to ferret the insect larvae out. This extra long finger is also used to scoop out the flesh from coconuts as well as other fruits which augment the aye-aye’s diet of insects. More than commonly humans use their fingers to use tools; Aye-Aye’s use their fingers as tools. Aye-Aye uses their fingers to hold onto when climbing since they live in a habitat requiring them to dwell in such environments. Humans use their fingers in a plethora of uses such as, nurturing, touch, and caress within social interactions. As mentioned above, humans fingers are also used for manipulation of tools such as; eating utensils. Aye-Aye haven’t evolved into using tools, they use their hands/fingers as such.

 The structure is different of the hands in both species. Aye-Aye’s have one very long slender finger and used mostly as a tool. Humans fingers are usually proportioned to their hand and not slender.. Aye-Aye’s middle finger, which is what they use the most to pull their food out of holes, is extended past all the other digits significantly. Human’s fingers usually have the middle finger longer but not noticeably longer than the other phalanges.

1c) The Lemurs are known generally as the immediate ancestor of the Aye- aye. Homo sapiens immediate ancestor would be the homo Rudolfensis. Since Aye Aye’s ancestry is closely related to Lemur’s we know that Lemurs use a similar style with their fingers for eating and climbing as the Aye Aye’s do. We also know that human ancestors used their fingers in a similar way as we do today.

1d)

Aye Aye uses their hands for grapsing

Aye Aye uses their hands as tools, notice the opposable thumbs.

Humans displaying touch with hands

2a) Two species chosen to express an analogous trait shared is the Sugar Glider (Petaurus breviceps) and the Flying Squirrel (scientifically known as Pteromyini or Petauristini).
The Sugar Glider is a marsupial that lives in Australia over a greater range of latitudes than any other Australian marsupial. It lives in northern, eastern, and south-eastern Australia. They are nocturnal, meaning they sleep in their nests during the day and are active at night. When legs are stretched out, this parachute like membrane allows it to glide distances of 50–150 meters. This gliding is regulated by changing the curvature of the membrane or moving the legs and tail.
The Gliding Squirrel lives in North America. This unusual creature is a placental mammal glider that has a squirrel-like body with a long partially prehensile tail.  They are not nocturnal. The Flying Squirrel has a parachute-like membrane that stretches from wrist to ankle. The recorded distance is 90 meters. It has a fluffy tail that stabilizes in flight.

2b) Similarities in structures and functions of the flying Squirrel and the Sugar Glider’s analogous traits are mainly focused on the membranous tissue that exists between both their abdominal areas. This membrane is an expansion of loose skin between their fore and hind limbs which allows them to glide. The “gliders” are both covered with fur. They both use their gliders to go from tree to tree or limb to limb; to relocate locations. When legs are stretched out, this membrane allows these two simular creatures to open up this tissue to allow this ability to take place. This gliding is regulated by changing the curvature of the membrane or moving the legs and tail. They use this to escape predators as well. This unique characteristic is native to both species of mammals.

2c) The common ancestors of the Sugar Glider are Kangaroos, wombats, and opossum. They did not have this analogous trait. None of these ancestors had ‘gliders’ or expansion of tissue for them to use in this way. The common ancestors of the Flying squirrel are rodents called Sciuridae such as the prarie dogs, chipmunks, and ground/tree squrriels.

2d)

Flying Squirel

Flying Squirel

Sugar Glider

                  Sugar Glider