The term speciation, which was first coined by biologist Orator F. Cook, refers to the process of evolution through which new species arise. In nature, there are four different means of speciation: allopatric, parapatric, sympatric and peripatric. Learn about the different types and discover speciation examples.
Examples of Speciation
It is very important to understand the types of natural speciation to understand how it occurs. Each type of speciation is an important part of the process of evolution within plant and animal kingdoms.
Allopatric speciation occurs when an animal population is forced to be split between two geographical areas as a result of a geographical change. There is some type of barrier keeping the groups apart. As a result, the groups remain isolated from each other and cannot interbreed.
Each group adapts to its specific habitat. As a result, mutations occur in the split populations which affect the ability of the two groups to reproduce if and when they are reintroduced. This type of speciation is also referred to as geographic speciation. Scientists have observed this in Solomon Island bird species.
Peripatric speciation is similar to allopatric speciation in that the different groups are separated from each other by a physical barrier. With this type of speciation, though, one of the groups that split from the original group is significantly smaller than the other. Due to the small size of this group, the unique traits that develop become more predominant in that group.
The differences in this group will become more pronounced in the offspring of subsequent generations, making them more and more distinct from the larger group. As in allopatric speciation, the new species is unable to reproduce with others in the original population. Researchers have observed this type of speciation with the Scrophularia lowei, a plant that developed in Macaronesia.
Parapatric speciation occurs when new species are dispersed across a large area. There isn't a barrier separating groups that inhabit different parts of the area from one another. They are only partially separated and therefore do sometimes make contact and could feasibly mate. However, due to distance, they tend to reproduce with other species members that occupy the same geographic region.
Environmental differences in the area, such as pollution or habitat destruction in certain parts, lead to unique characteristics. An example of this is when a species of grass becomes tolerant to heavy metals in the soil near a contamination source, such as a mine, even though such tolerance does not exist in other grass of the same species that is not in a contaminated area.
Sympatric speciation is differentiated from the other three because it occurs in one geographic location. It starts with a group of same-species animals sharing the same habitat, with some members evolving differently to the point where a new species (that cannot breed with the other) results. While this type of speciation may not be as common as the other types, it does occur, as evidenced by the sympatric speciation of cichlid fish in Africa and Nicaragua. The cause of sympatric speciation is not known but could be based on pollution or varied food sources or traits that spontaneously develop.
Some Examples of Speciation
Once you know what is speciation, it's easier to recognize different examples of speciation in nature. There are many interesting examples of speciation.
- Kaibab and Abert's squirrels - Separate squirrel species evolved after the Grand Canyon was formed, resulting in different squirrel species evolving on either side of the canyon.
- Hawthorn and apple maggot flies - Apple maggot flies originally only laid eggs on hawthorn apples, but now lay eggs on both hawthorn apples and other domestic applies in the United States. As a result, there are now hawthorn flies and apple flies that do not tend to interbreed.
- Tennessee cave salamanders - These unique salamanders that spend their lives in caves, mostly in the larval stage, are believed to have interbred with above-ground spring salamanders millions of years ago prior to undergoing speciation to their unique dark underground environment.
- Greenish Warbler birds - Species is evident in greenish warbler birds due to different song patterns that have developed among the male birds based on the ring patterns they travel within a geographic area; those in the same area with different song patterns behave as different species.
- Ensatina salamanders - It is believed that Ensatina salamanders started off in the cooler regions of northern California and Oregon, then moved south into warmer regions to which they had to significantly adapt to heat in order to survive, leading to the development of new subspecies, then entirely different species.
- Larus gulls - Herring gulls (Larus argentatus) and Lesser Black gulls (Larus fuscus) are a result of geographic speciation. They now live within the same habitat, but arrived at it through different routes, creating unique sub-species along the way.
- Petroica multicolor - Until 2015, Norfolk robins and Scarlet robins were believed to be in the same species (Petroica multicolor). However, they live in different regions, as a result of a small segment of the original population moving to the Norfolk islands and developing unique characteristics.
- Drosophila flies - There are many species of drosophila flies, which are believed to have adapted and undergone speciation through a process of natural selection.
- Galápago Finches - Different species of finches make their homes on the different islands in the Galápago archipelago. They are isolated from each other due to the ocean. Their beaks have adapted based on the food sources available on the island on which they reside.
- Faroe Island House mouse - Faroe House mice live on the various Faroe Islands, which are volcanic. Those on the most isolated of the islands have very little genetic diversity, while more variation exists among the populations residing on islands that are less isolated.
- Primula kewensis - A new species of primrose, Primula kewenesis is a cross between Primula verticillata and Primula florbunda, two other species of this common plant, making it a hybrid. It cannot breed with plants from either of its parent species but can reproduce by breeding with plants of its own kind.
- Croatian lizards - As an experiment, scientists introduced Italian wall lizards from one island off Croatia's coast (Pod Kopsite) to a neighboring island (Pod Mrcaru). The lizards quickly adapted to the harsh climate, developing bigger heads, a stronger bite and a totally different gut structure.
Speciation vs. Sub-Species
It is important to note that speciation occurs when there is a new species, not just a new sub-species. A new species is not able to reproduce with members of the original population.
- For example, when dogs are bred together to create a hybrid or new breed, the new breed is not considered a new species. The reason for this is that the new breed is still able to reproduce with the other breed.
- As another example, plants like Brussels sprouts, collards, kohlrabi, cabbage, and broccoli do not represent different species. They are different food plants that taste different when eaten, but they all belong to the Brassica oleracea species.
Natural and Artificial Speciation
Speciation can be natural and can occur as a normal part of the evolutionary process. Artificial speciation is also possible and can be created by laboratory experiments or through agriculture and animal husbandry. Fruit flies are a primary example of artificial speciation. Another well-known example is domestic sheep.