Question

Give any two striking similarities in the structure of embryos of all vertebrates. What is the significance of such similarities in the concept of organic evolution?

Answer 1

Hint: Evolution leads to formation of new organisms or species. There are many theories of evolution. One of the types of evolution is organic evolution which relates that the genetic makeup of species in a population changes due to change in environmental conditions.

Complete Answer:
Vertebrates are the organisms that have a well-developed notochord or vertebral column at some point of their lives. Some of the similarities in the embryos of all vertebrates are:
1. Presence of ventral heart.
2. Aortic arches.
3. Gills and gill slits are present.
4. They also possess tail at some point of their developmental stage.

All these similarities show that all the vertebrates are similar in their origin and they are related to each other in some or the other parameters. This type of evolution is also known as organic evolution. In this type of evolution, the organisms originate at one point but follow different routes leading to different changes in their life. The basic embryonic structure in this evolution remains the same.

Additional information: Some of the characteristics possessed by vertebrates are:
- A vertebral column or notochord present in them.
- They usually have a notochord in the embryonic stage which develops into a vertebral column in the adult stage.
- There are many spinal nerves along with the alimentary canal present below it.
- In the end of the alimentary canal, there is an opening known as the anus or which can further extend to form a tail.
- The anterior portion is marked by the mouth.
- The vertebrates are further classified into- Class Mammalia, Class Aves, Class Reptilia, Class Amphibia, Class Osteichthyes, Class Chondrichthyes, and Class Agnatha.

Note: Vertebrates are the organisms which consist of vertebral columns. The embryonic stage of all vertebrates represents some similarities and thus show a link in their evolution. Evolution is the change in the features of organisms over several generations due to natural selection or mutation.