Homologous & Analogous Traits

HOMOLOGOUS TRAIT

Homology is a reference to two things that have an equivalent role or some sort of relationship. Two species have related parts that may do the similar things but are not really the same. Homology is very important when it comes to comparative biology because it helps identify if any species have a common ancestor. Two examples of species that possess a homologous trait would be a human being and a Golden Retriever. These two species come from two very different environments in which they have adjusted to it accordingly. Humans are mammals with a diet being classified as omnivores because of both the meat and vegetable intake. However, according to recent studies, scientists have classified humans as being more carnivores than omnivores due to the meat intake yearly.  A Golden Retriever was officially recognized in 1925 by the American Kennel Club and it is a large-sized breed of dog bred. Their diet is basically under omnivore because they eat both meat and vegetables. Their environment of course is basically anywhere around the world except the oceans. Both of these two species have been classified as vertebrae.
 

 
 

There are quite a few examples as to how humans and dogs both carry a homologus trait and one of them would be the tailbone of a human and the tail of a dog (Golden Retriever). The tailbone of the human or the coccyx has become a vestigial structure, dogs have their tails intact. The coccyx serves as a sort of attachment to tendons, ligaments, and muscles. It also works as an insertion point to some of the muscles in relation to the pelvic floor. On the other hand the canine tail consists of about six to at least 23 mobile vertebrae. Muscles line the tail vertebrae by tendons. The usage of the tail is for a dog to communicate. That’s how they express if they are happy, full of aggression, stressed and many other emotions. It also serves as a balance when dogs are carrying out complicated tasks. We don’t have a visible tail like the dogs do but the structure of the coccyx and the bones supporting it are similar to the tailbones to the dogs.

 

 Protungulatum Donnae

Humans and dogs have shared a common ancestor over 100 million years ago. The ancestor they both share is speculated by researchers to be an insectivore. It was a small, adorable, long-tailed insect eater called Protungulatum Donnae. This was the one to begin the sprang of every “placental mammal.” This common ancestor through evidence showed that it may have lived in North America, but there are still possibilities that animal may have existed in other continents as well. Some of the characteristics are full-term live births, the Protungulatum was found with two horn uterus and a placenta in which the blood came in close contact the membranes that surrounded the fetus just like it is in humans or any other mammal.

ANALOGOUS TRAIT 

  
An analogous trait or structure is when two different species have similar traits but they are not related to each other. The species may live in similar environments and both fill in similar ecological roles. A great example of analogous trait possessors would be the Great White Shark and the Bottle-nose Dolphin. The Great White Shark is the largest predator fish in the world. They can be anywhere from fifteen to twenty feet and weigh about 5,000 lbs. They are found in cool, coastal waters throughout the world. Their bodies are slate-gray on the upper bodies in order to blend in with the rocky coastal sea floor, but because of their white bellies is how they got their name. The shark’s skeleton is composed of cartilage. Their diet is classified as carnivores. On the other hand Bottle-nose Dolphins are known as a very charismatic, intelligent and because of their curved mouths it makes them the friendliest smiling creatures. They are classified as mammals with a carnivorous diet. They are about ten to fourteen feet in size and weigh about 1,100 lbs. live about 50 years. Their skeleton is made up of bone unlike the sharks.  Usually are found in tropical oceans and other warms water around the world. Another unique difference between the two would be that dolphins go up the surface to breathe air while sharks use their gills to extract oxygen from the water.











 
Although both of these species are in similar in appearance such as their color, how their fins are placed, and body shape and behave similarity and even to their diets, sharks are fishes while dolphins are mammals as previously mentioned. The difference between the shark’s fin and dolphin’s fin is that the dolphin’s dorsal fin is curved backward toward the animal’s rear. It has an arc that is definite to its shape and has quite a sharp curved tip. A shark’s dorsal fin stands straight up and it is broad right at the animal’s back. The front edge of the fin is angled backward while the back edge is straight. These are some of the differences in their structure but their similarity is that they both have fins that help them navigate through the aquatic environments. The shaping of their fins were formed according to the feature environment they inhabited instead of inheriting it from a common ancestor. That is the shark uses his broad straight up fin to navigate in the depths of the cool, coastal waters. While the dolphin uses his curved backward fin in order to navigate in tropical, warm aquatic environments. 

The reason why the traits are relevant as analogous is because the dolphin derived from a common mammal ancestor while the shark derived from a common fish ancestor. Two different species that have similar qualities and behavior due to adjusting to the environment they were living in. it is said that Dolphins evolved from a land mammal that had even number of toes and also known as an artiodactyla. The great white shark evolved from Megalodon 50 feet long shark that also evolved from Cretolamna appendiculata which lived about 60 to 100 million years ago. This all happened due to convergent evolution is when two different species evolve functionally features known as “analogous structures.” Both these species have evolved analogous traits instead having it from a common ancestor. Their streamlines bodies, dorsal fins, flippers and pectoral fins are there for the same goal which is to swim quickly through the ocean and catch a prey to eat off of.