EVIDENCE OF EVOLUTION.




(Morphological, Anatomical Evidence)

Physical, Anatomical, Embryological, Paleontological, Taxonomical, Zoogeographical, Physiological, Biochemical, Cytological, and Genetic Evidences of Evolution

The only concrete evidence that evolution has occurred and that species are dynamic, ever-changing entities is seen in fossils. Sadly, the fossil record of practically all species is fragmentary, meaning that the data provided by fossils in evolutionary research cannot be fully trusted. Thus, when examining evolution, other evidence—albeit circumstantial—must be taken into account. Below are a few of these examples.

MORPHOLOGICAL AND ANATOMICAL EVIDENCES: 

By comparing the bodies of different animal groups, some intriguing facts surface that can be utilized to show that species have in fact undergone gradual change.

HOMOLOGOUS ORGANS:

Organs that are similar in origin and ancestry but have distinct functions are referred to as homologous organs. For instance, the limbs of all tetrapods share a basic structure with amphibians, but they have evolved to serve different purposes in different groups. For instance, the forelimb of humans, horses, frogs, bats, and birds, as well as the dolphin's flipper and the mole's fossorial leg, all share the same basic bone arrangement.

In the fore leg, they all have the humerus, radius, and ulna; in the hind leg, they have the femur, tibia, and fibula; and in the carpals, metacarpals, and phalanges. Only their size and shape have changed to accommodate the animal's unique needs. Another remarkable illustration of evolutionary modifications is the serial homology found in the limbs of various groups of arthropods from the basic crustacean plan.

 

ANALOGOUS ORGANS:

Organs that serve the same purpose but did not develop from the same ancestral form are considered analogous organs because they have separate origins. For instance, although the wings of birds, bats, and insects are all used for flight, their structures are distinct due to independent evolution. All of these wings are used for flight: bat wings are made of skin called patagonian, which is stretched between fingers, insect wings are made of chitinous venation and membrane, and bird wings are made of feathers. The patagium and feathers of a bird and a bat are not homologous, but their supporting bones are.

Adaptations: Over an extended period of time, there is a constant change in the environment and ecological conditions. The animals and plants are under pressure to adapt or perish as a result. As a result, we discover members of the same group of animals living in various environments and undergoing various morphological and behavioral changes. This could result in species evolving in a convergent, divergent, or parallel manner.

Convergent evolution: Despite having evolved into fish-like creatures due to their extended aquatic lives, whales and dolphins still possess traits unique to mammals, such as the ability to breathe air and nurse their young. Convergent evolution is the process by which unrelated organisms begin to resemble one another as a result of environmental influences. Due to convergence, the pectoral fins of fish and the forelimbs of dolphins, sea turtles, and penguins that resemble flippers show similarities.

Parallel evolution: Owing to comparable environmental circumstances, related animals can occasionally evolve side by side and resemble one another. An example of this is the ungulate family, which includes deer, antelopes, goats, sheep, cows, bison, and others. These animals all have similar adaptations for quick running and grazing. Every carnivore in the dog and cat families exhibits comparable evolution in adaptations that facilitate prey hunting. Because Australian marsupials and placentals share the same ecological niches, they have evolved in parallel.

Mimicry: Mimicry is the process wherein two distinct creatures imitate one another in order to shield themselves from potential predators. In Batesian mimicry, the mimic gains protection by sharing morphological similarities with the model, which protects the model. Because of their confusion, the predators release the imitation as well. For instance, the female Hypolimnas butterfly mimics the toxic Danaus butterfly, which the birds avoid.

In Mullerian mimicry, the two species share the harm caused to the population by the learning predators since the model and the mimic are both protected while both resembling one another. Wasps and distasteful moths bear resemblance to each other, as do certain tailed amphibians possessing venomous glands.

Vestigial Organs: Organs that were functional in the ancestors but have lost relevance as a result of changing conditions are known as vestigial organs. Organs begin to atrophy and finally become primitive when they become useless. A few examples of these organs found in humans are the vermiform appendix, ear muscles, plica semilunaris in the eye, a primitive form of the nictitating membrane, the coccyx, small canines, the third molar, and body hairs.

When prehistoric humans began to cook food and live in sheltered environments, these organs became less useful. At that time, prehistoric humans lived in caves and had a raw diet. Similar to this, the wings of ostriches and other flightless birds are useless since they stopped being useful when they had to rely only on their speed to avoid predators.