Homologus and Analogous Traits.

For your homologus traits provide the following information:

a.      Briefly describe the two different species that possess the homologus trait.

My comparison for homologous traits will be between a penguin and a seagull.

Penguins are flightless birds that live half of their lives in the ocean and half of their lives on land. Seagulls are airborne birds that live on land. Both animals lay eggs to reproduce and have beaks, wings, and feathers. The major difference is that penguins will spend months of each year swimming, while seagulls will be flying. Although seagulls are found near the ocean around the world, they must make their nests on land. Meanwhile, penguins will spend about half their lives at sea coming ashore only to mate and to molt.

b.     Describe the homologus trait of each species, focusing on the differences in structure and function of the trait. Why do these homologus traits exhibit differences between the two species? Make sure your explanation is clear and complete.

There are two homologous traits that both birds have but have evolved over time to adapt to their environment. First, both birds have feathers but a seagull’s feathers are much larger than a penguin’s feathers. A seagull’s feathers are essential for flight. Like the wings of an airplane, the feather is broader on one side and taper down to the other side providing lift for the seagull when it flies. On the other hand, penguins are flightless animals and their feathers are much smaller and closer together as their primary purpose is insulation from water and cold. A penguin also has so many more feathers than the average bird that it almost looks like they have fur.

Secondly, both birds have wings. A penguin’s wings have evolved into a flipper where the bones are much denser and closer together forming something more like a “paddle” to help propel the penguin through water. Their wings or “flippers” are too heavy to support flight. Alternately, the bone structure in a seagull’s wing is much more elongated and the bones are less dense as to not hinder flight.

  

c.      Who was (generally, not specifically) the common ancestor of these two species and how do you know that ancestor possessed this homologus trait?

Both penguins and pigeons descended from a species of bird long ago. They have the same traits in their body structures – wings and feathers and they also reproduce in the same way. Both birds evolved to adapt to their environment. A seagull lives on land and requires flight (wings and feathers) to find food and shelter while a penguin lives in the ocean and requires flippers and special feathers to insulate them for survival.

d.     Provide an image of each species in this comparison.

For your analogous traits provide the following information:

Briefly describe the two different species that possess the analogous trait.

Two species that have an analogous trait are penguins and sharks. They both have fins or fin-like structures.

Penguins are flightless birds that typically live in the southern hemisphere – usually around Antarctica. They spend half of their lives on land and half of their lives in the water.  They are very social animals and usually live in large colonies together.

Sharks are fish that live in every ocean on the planet. Most sharks live in salt water although there are a few breeds that can live in brackish water as well. They can be either very solitary animals or very social animals depending on the type of shark. Sharks also reproduce by laying “eggs” and in much smaller numbers than other species of fish.

a.      Describe the analogous trait of each species, focusing on the similarities in structure and function of the trait. Clearly explain why these analogous traits exhibit similarities between the two species.

The analogous trait I would like to focus on are fins (sharks) and flippers (penguins). Penguin’s flippers were adapted from wings to allow them to live and hunt in water. Their flippers are flat and broad with a tapered shape and are used primarily for propulsion through water.

Sharks have several types of fins that they use to propel them through the water and assist in direction. Two of the types of fins include pectoral fins and caudal fins. Pectoral fins are by the head and are used for direction and to help keep the sharks from sinking. The caudal fin is essentially just the tail of the shark and is used for propulsion. Both of these fins look similar to a penguin’s flipper. These fins are flat, broad and tapered in shape just as a penguin’s flippers are.

b.     All pairs of organisms share some common ancestor if you go back far enough in time. Could the common ancestor of these two species have possessed this analogous trait? How do we know these traits are analogous and not genetically related from common descent? (5 pts)

We know these traits are analogous because penguins are birds while sharks are fish and they could not have come from the same species. Both developed these traits to navigate their environment. Penguins evolved from their feathered air born friends so that they could survive part of their lives in the water. Sharks developed their different types of fins to better live in their environment efficiently.

c.      Provide an image of each species in this comparison.