Difference Between Parallel and Convergent Evolution

Main Difference – Parallel vs Convergent Evolution

Groups of organisms or species undergo natural selection over time due to environmental pressure, giving rise to different patterns of evolution. Parallel evolution, divergent evolution, and convergent evolution are the three main patterns of evolution. Divergent evolution differs from the other two evolutionary patterns as it forms distinct species from a common ancestor species. However, the evolution of two parent species under the influence of similar environment is described in both parallel and convergent evolution. The main difference between parallel and convergent evolution is that parallel evolution describes the independent evolution of two species, maintaining a same level of similarity whereas convergent evolution describes the origination of analogous traits in distinct species.

Key Areas Covered

1. What is Parallel Evolution
– Definition, Facts, Examples
2. What is Convergent Evolution
– Definition, Facts, Examples
3. What are the Similarities Between Parallel and Convergent Evolution
– Outline of Common Features
4. What is the Difference Between Parallel and Convergent Evolution
– Comparison of Key Differences

Key Terms: Adaptation, Analogous Traits, Convergent Evolution, Divergent Evolution, Equivalent Habitat, Parallel Evolution, Species

What is Parallel Evolution

Parallel evolution refers to the independent evolution of similar traits in different but, equivalent habitats. It occurs in geographically separated but equivalent habitats. Parallel evolution gives morphological resemblance to two species. Both unrelated and distantly-related species may undergo parallel evolution in equivalent habitats as the environmental influence on the species is similar. Different evolutionary patterns are shown in figure 1.

Main Difference -Parallel vs Convergent Evolution

Figure 1: Evolutionary Patterns

The marsupial mammals of Australia, which are similar to placental mammals elsewhere, are an example of parallel evolution. Wolf, mole, mice, rat, etc. are examples of marsupial mammals. The evolution of old world monkeys and new world monkeys is another example of parallel evolution. Both old and new world monkeys shared a common ancestor a long time ago. Though they were split apart by the Atlantic Ocean, both old and new world monkeys evolve in a very similar manner.

What is Convergent Evolution

Convergent evolution refers to the independent evolution of analogous structures in unrelated species. It occurs when unrelated species live in the same habitat. Convergent evolution gives rise to analogous traits in unrelated species as an adaptation to the similar environmental pressure. Though the anatomical structure is different in analogous traits, they are functionally similar. As an example, though North American cactuses (family Cactaceae) and South African euphorbias (family Euphorbiaceae) belong to two different families, both types of plants have thick stems and are succulent as an adaptation to survive in desert regions. Family Cactaceae and family Euphorbiaceae are shown in figure 2.

Difference Between Parallel and Convergent Evolution

Figure 2: Family Cactaceae and family Euphorbiaceae

Another example of convergent evolution is the emergence of wings in birds, bats, and insects as an adaptation to fly. The body shape of dolphins and sharks is also evolved due to convergent evolution. Though dolphins and sharks are distantly related animals, their body shapes are adapted for fast swimming. Thus, the environment forces the phenotype of distantly related organisms to become analogous. The development of the eye of vertebrates, cephalopods, and cnidarian is another example of convergent evolution. The development of analogous structures is referred to as homoplasy.

Similarities Between Parallel and Convergent Evolution

Parallel and convergent evolution are two types of evolutionary patterns.
Both parallel and convergent evolution occur independently in distinct species.
Both parallel and convergent evolution occur under the influence of same environmental pressures.
Both parallel and convergent evolution do not lead to speciation.

Definition

Parallel Evolution: Parallel evolution refers to the independent evolution of similar traits in different but equivalent habitats.

Convergent Evolution: Convergent evolution refers to the independent evolution of analogous structures in unrelated species.

Type of Habitat

Parallel Evolution: Parallel evolution occurs in different but equivalent habitats.

Convergent Evolution: Convergent evolution occurs within a particular habitat.

Significance

Parallel Evolution: The two distinct species evolve independently, maintaining the same level of similarity in parallel evolution.

Convergent Evolution: The two distinct species evolve analogous traits in convergent evolution.

Types of Species

Parallel Evolution: Parallel evolution occurs in unrelated or distantly-related species.

Convergent Evolution: Convergent evolution occurs in unrelated species.

Examples

Parallel Evolution: The evolution of old world monkeys and new world monkeys is an example of parallel evolution.

Convergent Evolution: The development of the eye of vertebrates, cephalopods, and cnidarian is an example of convergent evolution.

Conclusion

Parallel and convergent evolution are two types of evolutionary patterns seen in distinct species. Parallel evolution gives rise to similar evolutionary patterns in distinct species whereas convergent evolution gives rise to analogous structures in distinct species. Both parallel and convergent evolution occur due to similar environmental influences. The main difference between parallel and convergent evolution is the mechanism of each type of evolutionary pattern.

Reference:

1. “Parallel evolution.” Encyclopædia Britannica, Encyclopædia Britannica, inc., 10 Mar. 2008, Available here.
2.Pianka, Eric R. “Convergent Evolution .” School of Biological Sciences , UT Austin. Available here.

Image Courtesy:

1. “Evolutionary trends” By Oleg Alexandrov – Own work, Public Domain) via Commons Wikimedia
2. “Mammillaria spinosissima by RO” By Rationalobserver – Own work (CC BY-SA 4.0) via Commons Wikimedia and “Euphorbia obesa obesa3 ies” By Frank Vincentz – Own work (CC BY-SA 3.0) via Commons Wikimedia [Merged]