Describe the evidences of organic evolution

Evidences of organic Evolution

Evidence of organic evolution are scientific indications that in deed organic evolution took place that is they are statements that supports organic evolution. Major evidences of organic evolution include;
ii)Cell Biology
ii)Geographical distribution
iii)Comparative embryology
iv)Comparative Anatomy
v)Fossil records

Before we start explaining these evidences, it is important to clearly state that, originally, the organisms shared a common ancestry but due to some factors as we are going to explain, these organisms stated to evolve in different lines leading to present diversity in living organisms.
In each evidence of organic evolution, I have given definition, short description and an example.
Explanation of evidences of Organic Evolution

i) Cell biology
Cell biology is the study of structures and functions of cells of living organisms.
Study of cells shows that plants and animals share a common ancestry because
°Plant and animal cells share some cell organelles. For instance, both plant and animal cell have nucleus, plasma membrane, lysosomes, endoplasmic reticulum, mitochondria, etc.
°However, from a common ancestry, plants and animals started to evolve in different lines of development leading to the present day differences between their cells. For instance, Plant cells have cellulose cell wall, chloroplast and large central vacuole while animal cell lack these organelles,
Also, animal cells have centrioles while pant cells lack centrioles

°Study of cell of mammals also indicate that living organisms share some biological compounds, for example, Adenosine triphosphate (A.T.P), DNA (Deoxyribonucleic acid).
°Mammals share some blood pigments like haemoglobin which shows that they are from the same origin.

ii)Geographical Distribution
Originally there was one land mass with living organisms
Due to continental drift, the single land mass broke apart to give rise to present day continents
This lead to the isolation of organisms of the same ancestry
Organism of the same species evolved to give rise to variety of species in the separate regions. This was due to the need to adapt to the similar climatic conditions in the different regions.
Example. Emergence of (Monkey with different length of tails) different species of monkey in Africa forest and forest in South America.

iii)Comparative Embryology
Embryology is defined as the study of how embryo formed and its development.
Comparison of embryo of different animals reveals similar morphological features at some stages of their development. This close resemblance of embryo at early stages of development shows that the organisms share a common ancestry.
The closer the resemblance of the two or more embryos of different organisms, the closer the phylogeny relationship between the two organisms
For example, the embryo of both man and fish posses a tail at some stages of their development.

iv)Fossil records
Fossil are defined as the remains of ancestral forms which have been deposited in the sedimentary rocks.
Fossil are very good source of evidence of organic evolution because they show they act as direct evidence of organic evolution.
Fossil can be used to determine the time of existence of an organism through dating of the fossils.
Fossil of organisms which lived long time ago are deposited on the deeper strata of sedimentary rocks while fossils of organisms which lived recently are deposited on the upper part of the sedimentary rocks.
Therefore, the fossils vary in complexity depending on the time the organism existed. For early organisms, their fossils are less complex and for the recently lived organisms have very complex fossils.
Fossil can also show the phylogeny relationship of two or more organisms, depending on the closeness of resemblance of the fossils.
Use of fossils as an evidence of organic evolution is limited due to;
ii)Destruction by physical phenomenon like faulting and earthquakes
ii)Distortion
iii)Missing links due to total decomposition of the fossil by saprophytic

v)Comparative Anatomy
Anatomy is the study of structures of living organisms.
Comparison of structures of different organisms reveal a common ancestry of living organisms and their evolution. There are three types of structures that have been studied for evolution
a)Homologous structures.
These are structures of the same embryonic origin which have been modified to be used for different functions in different organisms.
For instance, pentadactyl limb and beaks of birds.
>The pentadactyl limb have a common basic structure but it have been modified to do different functions in different organisms as follows;
man for grasping,
zebra use it for running
bat use it for flying
>Beak of birds have a common basic structure but have been modified to perform different functions in birds making the birds to feed in different types of food as follows

Flesh eaters
Filter feeders
Grain eaters
This phenomenon where structure of a common embryonic origin is modified to perform different functions in different organisms is called Divergent of evolution.

ii)Analogous structures
These are structures from different embryonic origin that perform the same function in different organisms. Example include, wings of birds and wings of insects which are used for flight by the organisms. Wings of insects and wings of birds are structurally different but perform the same function.
The phenomenon where the structures of different embryonic origin are modified to perform similar function is called convergent evolution

iii) Vestigial structures
These are structures that have greatly decreased in size and have no function in an organism.
Example of vestigial structures
ii)Nictitating membrane in mammals
ii)Wings of Kiwi (flightless bird)
iii)Human appendix
iv)Human caecum
v)Vestigial tail in man

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Biokenya answered the question on April 30, 2018 at 08:40