Though a certain degree despite their current differences.

Though some species may appear to be related, if you take a deeper look you’ll be surprised at how different they really are.

Analogous structures can provide information about how natural selection leads to similar adaptations in the same environment.

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What are Analogous Structures?

Many species have similar traits because they are descendants of a single common ancestor. These species developed from a single source and are related to a certain degree despite their current differences. The traits they share are known as homologous structures. Homologous structures are similar in structure and function because they originated from the same ancestor long ago.Species may also have similar traits even though they are not related to each other. This usually results because the species live in similar environments and fill similar ecological roles.

The structures in this case are known as analogous structures.The process that brings these traits forward is called convergent evolution. Convergent evolution is natural selection that favors the same type of structure in different ancestors. The similarity between convergent evolution-affected species is called homoplasy, which literally means ‘from the same mold or form.

Examples of Analogous Structures

There are many examples of analogous structures available for us to examine in nature. We can observe various flying animals such as bats, birds, insects, and even fish. However, even though these wing structures serve the same function for these different animals, the bone structures, wing coverings (such as feathers, scales, hair, etc.

), shapes, and sizes are quite different.

analogous structure

Another example of an analogous trait is fins. Animals such as penguins and fish both have fin-like structures to help them navigate through their aquatic environments. However, because one is a bird and one is a fish, it is clear that the fin evolved in these very different species because it was the best functional feature for the environment they inhabit instead of from a common ancestor.While analogous traits may be most easily seen in animals, all organisms can exhibit convergent evolution. Many species of plants, fungi, bacteria, and even molecules can have analogous traits based on their environmental demands and not their ancestral lineage.

For example, sweet potatoes and potatoes have the same function of food storage. The difference is that sweet potatoes are an underground root and potatoes are an underground stem.Analogous traits are not limited to visual body structures; behavioral traits can also be analogous. Bird songs are quite varied, not just between different species but also between different flocks.

However, it has been found that some bird species that are quite unrelated can develop analogous song characteristics if held together in similar conditions for periods of time in a lab.

Identifying Analogous Structures

To examine how species are related, evolutionary biologists construct phylogenies, which are evolutionary histories of groups of species. Phylogenies are based on homologous structures and describe species that are derived from a common ancestor. Because analogous traits can be so similar, it may be difficult to distinguish them from homologies. Comparing the trait in several different ways (such as fossil evidence and molecular comparisons) can often lead to an answer. The more similarities that are found, the more likely the traits are derived from the same source.There is certainly more than meets the eye when examining analogous structures.

Simply looking at body structures does not provide enough information to determine whether species have developed features from a common ancestor or from a common environment. And while they may not be easily identifiable, analogous structures provide quite a bit of evidence for adaptations through natural selection.

Lesson Summary

Let’s review.

Many species have similar traits because they are descendants of a single common ancestor. These species developed from a single source and are related to a certain degree despite their current differences. The traits they share are known as homologous structures. Homologous structures are similar in structure and function because they originated from the same ancestor long ago.

Species may also have similar traits even though they are not related to each other. This usually results because the species live in similar environments and fill similar ecological roles. The structures in this case are known as analogous structures.Examples of analogous structures range from wings in flying animals like bats, birds, and insects, to fins in animals like penguins and fish.

Plants and other organisms can also demonstrate analogous structures, such as sweet potatoes and potatoes, which have the same function of food storage. And analogous structures can include behavioral traits, such as the songs of many different species of birds.Finally, it can be hard for evolutionary biologists to distinguish homologous from analogous structures. They use phylogenies to describe species that are derived from a common ancestor, but must use methods like fossil evidence and molecular comparisons to understand if a trait is actually an analogous structure.

Learning Outcomes

Watch this lesson, then use your accumulated knowledge to:

  • Compare homologous and analogous structures
  • List examples of analogous traits
  • Recognize the purpose of phylogenies
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