Lisa has taught at all levels from kindergarten to college and has a master's degree in human relations.
What Is Evolution?
Do you ever wonder what an animal's origins are? How did a giraffe develop such a long neck and tongue? Why do some birds fly while others cannot? These questions can be answered through an understanding of the theory of evolution. Evolution is the idea that the animals and plants that are alive today have developed from past organisms. Changes took place slowly over time until the development of the characteristics we see in plants and animals today. When learning about this process, you may have seen silly cartoons like this one:
While this depiction may not be completely accurate, it does give you the overall idea of what we are talking about when we are discussing evolution on a large scale, which is called macroevolution. We are going to look at two types of macroevolution in this lesson: divergent evolution and convergent evolution.
What Is Divergent Evolution?
Divergent evolution occurs when two different species share a common ancestor but have different characteristics from one another. This is probably the type of evolution that first comes to mind when the topic of evolution comes up. After all, evolutionary theory teaches us that every form of life on Earth today developed from the first living cells! Over time, the original cells took vastly different paths of development and ultimately created the diversity of life on Earth—from trees to humans. Each time one ancestral species diverges into multiple descendant species it is called speciation. Speciation is an important result of divergent evolution.
Of course, divergent evolution doesn't have to take place on such a grand scale. It can also be as simple as different populations of an organism that have adapted to different environments. Darwin's finches are a good example of this. Darwin's finches are a group of about 15 different species of finches that live on the Galapagos Islands. Each separate species of finch adapted to a different diet, causing variation in their beak shape and/or size. All of them evolved from one species of finch that was a common ancestor.
What Is Convergent Evolution?
Convergent evolution occurs when two different species do not share a common ancestor but have developed similar characteristics through adaption to similar environmental conditions. It is important to understand convergent evolution; otherwise, we might mistakenly assume a relationship between two animals that have similar features.
A hummingbird and the hummingbird moth are a good example of convergent evolution. They are the same size, eat the nectar of the same flowers, and have wings that work in a similar manner. They are so similar that people often mistake the moths for real hummingbirds. However, we know that one is an insect and the other is a bird. They did not evolve from a common ancestor. They each evolved from different ancestors in a similar environment and developed the same characteristics.
Can you think of more examples of divergent or convergent evolution? Remember, similar animals that have developed through the process of divergent evolution started with a common ancestor, and animals that have developed through the process of convergent evolution started with different ancestors adapting to a similar environment. Let's consider a few more examples:
- Apes and humans both evolved from a common primate ancestor. This is an example of divergent evolution.
- Flying squirrels and sugar gliders are very similar, yet different. They do not share a common ancestor. This is an example of convergent evolution.
- About six million years ago, the woolly mammoth family tree split off from an ancient ancestor of the elephant. The evolution of this ancient animal into two separate species is an example of divergent evolution.
- Dolphins are mammals. Like fish, dolphins had to evolve an efficient means for traveling through water. Because of this, dolphins and fish have some similar characteristics. This is an example of convergent evolution.
The idea that past organisms changed into the plants and animals that are alive today is known as evolution. Evolution on a large scale is called macroevolution. Two types of macroevolution are divergent evolution and convergent evolution. Divergent evolution occurs when two separate species evolve differently from a common ancestor. Speciation is a result of divergent evolution and occurs when one species diverges into multiple descendant species. Darwin's finches are an example of this. Convergent evolution occurs when species have different ancestral origins but have developed similar features. A good example of convergent evolution is the similarities between the hummingbird and the hummingbird moth.
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