Homologous and Analogous Traits

Homologous Traits

The homologous trait I decided to research is the tail of the cheetah and the snow leopard. The cheetah, also known as Acinonyx jubatus, lives predominantly in eastern and southern Africa. Cheetahs are large, spotted, and slender cats that are known for their speed. They have small rounded heads with short ears, and distinctive black tear marks under their eyes. Snow leopards, otherwise known as Panthera uncia, are found in parts of Asia, and are very similar to cheetahs. Snow leopards are generally shorter than cheetahs and have their own distinctive spots. They have long thick fur, short fore limbs, and long hind limbs.

Cheetah tails are usually 60-80 centimeters long and are exceptionally muscular. They are used for balance and steering when running. The rudder-like tail allows cheetahs to make sharp turns at high speeds. Snow Leopards' tails are longer than a cheetah's (~80-100 cm) and make up most of their total body length. The tail is fatty and is covered with long thick fur. This comes in handy because snow leopards use their tails as scarves when sleeping. Similar to the cheetah, the snow leopard also uses their tails for balance when walking along rocky terrain. Generally, the tails' of the two cats' structure are very similar, with the most differences being muscles and fur. The major differences seen in the tails are attributed to the different environments and needs: cheetahs for running and snow leopards for warmth.

In addition to other species with a similar trait, the cheetah and snow leopard are both mammals, which suggests that the common ancestor for this case is a prehistoric mammal. Knowing that there are other mammals that have functioning tails like these two cats, suggests that the common ancestor also had a functioning tail.

Cheetah

Snow Leopard

Analogous Traits 

Two species that have the analogous webbed feet trait are the American green tree frog (Hyla cinerea) and the duck-billed platypus (Ornithorhynchus anatinus). Tree frogs are found in central and southeastern United States, and vary in shades of green often with white or cream spots on their backs. They prefer to live in areas that have many floating vegetation or cattails in marshy or lake areas. Platypuses are eastern Australian mammals that live on land and hunt underwater. They have thick, waterproof fur covering their streamlined bodies, not found on their webbed feet and bill.

Although these two species are very different from one another, both have skin flaps that connect toes together (webbing). The tree frog's forefeet have large toe pads with minimal webbing at the base of their toes, while their hind feet have extensive webbing. The webbing for tree (and other) frogs allows them to swim faster and leap higher. The minimal webbing on the forefeet is made up for with sticky pads, so that they can sit and hang on vegetation and trees. Platypuses have larger webbed front feet that also helps propel them when swimming. The difference in webbed front and hind feet between these two species is because frogs use their hind legs for swimming (front webbed feet would not be as useful) and the platypus mainly uses their front feet for swimming. When on land, webbing retracts as claws protrude. This is to make it easier for them to walk and dig burrows for living in.

I do not believe a common ancestor shared this trait. In my opinion, webbed feet came about through evolution in order to make swimming easier and more efficient for different environments. Many animals have this trait, but it is clear that there are minute differences between each animal possessing it.

Platypus

Tree Frog