Expression of variability, Biology

Assignment Help:

In the preceding section we emphasised the fact that cvolution or the continuous adaptations to the environment can take place only when pheiiotypes exhibit variability. In the absense of variability, the chances arc that existing living organisms would become extinct since with the change in the environment these organisms would die without leaving progeny. Fortunatcly in living systems mutations and recombinations generate the required variability. However, organisms often strive to arrive at populations which are more or less uniform. This is possible because selection process acts in such a way that a certain degree of uniformity of phenotype is imposed among individuals of n population. If an individual were to be vcry different in some way from thc rest of the population. he would be less well adapted to the environment as compared to other members of the population and therefore unable to compete successfully with them. However, in a continuously changing environment, a slight phenotypic variability should be maintained in a population. In a changing environment no phenotype remains optimally adapted for long. This is the precise reason why variability needs to be generated continuously in a population and used to develop adaptations in the way Darwin suggested. We shall look into the mechanisms that generate variability.


Related Discussions:- Expression of variability

Explain briefly about the nutrition, Explain briefly about the Nutrition? ...

Explain briefly about the Nutrition? This unit covers the scope of advanced nutrition. It begins with some definitions and basic concepts and briefly traces the history of nutr

What are angiosperms, What are angiosperms, the flowering plants? What is t...

What are angiosperms, the flowering plants? What is the major feature that distinguishes them from the gymnosperms? Flowering plants have flowers and seeds (phanerogamic plants

Define st elevation in avr, Q. Define ST Elevation in aVR? Lead aVR oft...

Q. Define ST Elevation in aVR? Lead aVR often develops ST elevation as a reciprocal of ST depression in lead V2 to V6 or leads 2 and 3. It may occasionally show ST elevation in

Explain bone resorption, An  osteoclast  is a type of bone cell that absorb...

An  osteoclast  is a type of bone cell that absorbs bone tissue by removing its mineralized matrix and breaking up the  organic bone. This process is known as bone resorption

Are environmental phenotypical changes, Are environmental phenotypical chan...

Are environmental phenotypical changes transmitted to the offspring? Changes caused on phenotypes by the environment are not transmitted to the offspring (unless their primary

Zone of polarizing activity (zpa), Zone of Polarizing Activity (ZPA) T...

Zone of Polarizing Activity (ZPA) The A-P axis is the 1 st axis to be fixed in the presumptive limb mesoderm at a very early stage. On the basis of results of a series of cur

Standard titration - estimation of vitamin c in chillies, Define Standard t...

Define Standard titration - estimation of vitamin c in Chillies? Pipette 5 ml of standard ascorbic acid solution into a 100 ml conical flask. Fill the burette with the dye solu

What are the substances transferred from the mother to fetus, What are the ...

What are the main substances transferred from the mother to the fetus through the placenta? And from the fetus to the mother? From the mother to the fetus the major transferre

Strawberry slain - common disorders of skin, Strawberry Slain: It  sig...

Strawberry Slain: It  signfies the dilatation  of deeper vessels  to form  cavernous spaces like those seen  in  the erectile tissue of the penis. The  lesion  is well-defined

What is phytates, Q. What is Phytates? Phytates are widely distributed...

Q. What is Phytates? Phytates are widely distributed in seeds of vegetables, fruits and grains. Unrefined cereals and millets are the richest sources of phytates. Refined or

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd