The key difference between convergent and divergent evolution is that the distinct species that do not share a common ancestor show similar traits in convergent evolution while the species that share a common ancestor show different traits and separate into different forms in divergent evolution.
When considering living organisms, we can define evolution as the development of differentiated organisms from less differentiated pre-existing organisms over time. Moreover, there are many sources, which provide evidence to the theory of evolution. These include palaeontology, geographical distribution, classification, plant and animal breeding, comparative anatomy, adaptive radiation, comparative embryology, and comparative biochemistry.
CONTENTS
1. Overview and Key Difference
2. What is Convergent Evolution
3. What is Divergent Evolution
4. Similarities Between Convergent and Divergent Evolution
5. Side by Side Comparison – Convergent vs Divergent Evolution in Tabular Form
6. Summary
What is Convergent Evolution?
Convergent evolution is a type of evolution that explains how phylogenetically unrelated organisms show similar traits and physiological processes. Furthermore, they may show similar adaptations to perform the same function, which is referred to as analogous. Some examples for analogous structures are eyes of vertebrates and cephalopods, wings of insects and birds, jointed legs of vertebrates and insects, thorns on plants and spines on animals etc. However, similarities found in analogous structures are only superficial. For example, insect wings and wings of bats and birds are analogous structures. However, the veins composed of cuticle in insects support the wings of them while the bones support the wings of birds and bats.
Figure 01: Convergent Evolution
In addition, vertebrate eyes and cephalopod eyes are analogous structures. But, the embryological development of the two is different. Likewise, Cephalopods have an erect retina, and photoreceptors are facing the incoming light. In contrast, in vertebrates, the retina is inverted, and the photoreceptors are separated from the incoming light by the connecting neurons. Therefore, the vertebrates have a blind spot, and the cephalopods do not have a blind spot.
What is Divergent Evolution?
Divergent evolution is a type of evolution that explains the development of different traits among the closely related organisms and separate them into different forms. When a group of organisms has a homologous structure specialized to perform a variety of different functions, it shows a principle known as adaptive radiation. For example, all the insects share the same basic plan for the structure of the mouthparts. A labrum, a pair of mandibles, a hypopharynx, a pair of maxillae, and a labium collectively form the basic plan of the mouthparts structure. In certain insects, certain mouthparts are enlarged and modified, and others are reduced and lost. Due to this, they can utilize a maximum range of food material. It gives rise to a variety of feeding structures.
Figure 02: Divergent Evolution
Likewise, insects show a relatively high degree of adaptive radiation. It shows the adaptability of the basic features of the group. Also, this can be called as the evolutionary plasticity. Consequently, this has enabled them to occupy a wide range of ecological niches.
Moreover, when a structure present in an ancestral organism becomes greatly modified and specialized, it can be called a process of descent by modification. The significance of adaptive radiation is that it indicates the existence of divergent evolution, which is based on the modification of homologous structures over time.
What are the Similarities Between Convergent and Divergent Evolution?
- Convergent and divergent evolution are two types of evolution that are occurring over time.
- Both types describe how organisms changed with time and how new species developed.
- Furthermore, both show the way how organisms responded to natural selection.
What is the Difference Between Convergent and Divergent Evolution?
Convergent evolution describes how dissimilar organisms develop similar traits while divergent evolution describes how similar or related organisms develop different traits and separate into different forms. Thus, it is the key difference between convergent and divergent evolution. Also, another significant difference between convergent and divergent evolution is that the convergent evolution occurs among the groups of organisms that are not related to phylogenetically. But, divergent evolution occurs among the groups of organisms that are phylogenetically related.
Furthermore, analogous structures support the convergent evolution while the homologous structures support the divergent evolution. Therefore, we can consider this also as a difference between convergent and divergent evolution. Moreover, a further difference between convergent and divergent evolution is that the convergent evolution is a result of organisms living under similar environmental conditions while the divergent evolution is a result of organisms living in different environments and conditions.
Below infographic on the difference between convergent and divergent evolution explains these differences comparatively.
Summary – Convergent vs Divergent Evolution
Convergent and divergent evolution are two types of evolution. Convergent evolution occurs between unrelated species that do not share a common ancestor. On the other hand, divergent evolution occurs between related species that share a common ancestor. Moreover, convergent evolution is supported by the analogous structures while the homologous structures support the divergent evolution. Furthermore, convergent evolution occurs when unrelated species live and adapt to a similar environment and environmental conditions. Divergent evolution occurs when related species live in different environments and develop different traits. This summarizes the difference between convergent and divergent evolution.
Reference:
1. “Convergent Evolution.” Biology Reference. Available here
2. Editors. “Divergent Evolution – Definition and Examples.” Biology Dictionary, Biology Dictionary, 28 Apr. 2017. Available here
Image Courtesy:
1.”3790813865″ by Craig Pemberton (CC BY-SA 2.0) via Flickr
2.”Darwin’s finches”By John Gould (Public Domain) via Commons Wikimedia