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 about atrial septal defect, Explain about Atrial Septal Defect (ASD...

Explain about Atrial Septal Defect (ASD) ? ASD occurs as an isolated anomaly in 5- 10 per cent of all CHDs. These communications occur in four sites i.e. in the central portion

Explain phylum ascomycetes, Phylum Ascomycetes 1) Sexual reproduction i...

Phylum Ascomycetes 1) Sexual reproduction is by conjugation and is followed by the formation of ascospores inside a sac called ascus. 2) The asci may be grouped together to

How many kcal of gross energy were formed, The question asks . . . 18 moles...

The question asks . . . 18 moles of moles of maltose are completely oxidized by the reactions of the final oxidative pathways (Embden-Myerhoff Pathway and Krebs Cycle). How many AT

Name the different systems of the body, The Different systems of the body a...

The Different systems of the body are: 1) Nervous System 2) Respiratory System 3) Cardiovascular System 4) Neurological and Sensory System 5) Gastrointestinal Syste

Describe tr murmur and vsd murmur in details- heart diease, Describe TR Mur...

Describe TR Murmur and VSD murmur in details? TR Murmur :   Characteristic: Holosystolic murmur, loudest at left lower-sternal border and becomes louder with inspiration (Carv

Endocrine glands - kidney, KIDNEY S - Origin . They develop from the ...

KIDNEY S - Origin . They develop from the mesoderm of the embryo. The kidneys secrete three hormones: renin, erythropoetin and calcitriol. (i) Renin . Whenever the rat

Polygonum type - monosporic embryo sacs, Polygonum Type - Monosporic Embryo...

Polygonum Type - Monosporic Embryo Sacs The embryo sac is formed from the chalazal megaspore in the tetrad and is eight-nucleate. The development of the embryo sac begins with

Define meal pattern and feeding considerations, Define Meal Pattern and Fee...

Define Meal Pattern and Feeding Considerations? The meal pattern and the feeding considerations include the following: - Meal timings play an important role in ensuring adeq

What will happen to resting membrane potential, What will happen to resting...

What will happen to resting membrane potential if potassium succinate were injected into the intracellular environment (cytoplasm) of a neuron?

Food and digestion, what is the pH inside the stomach?Why is there a need t...

what is the pH inside the stomach?Why is there a need to keep that pH level? How is it maintained?

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