Examples of natural selection, Biology

Assignment Help:

EXAMPLES OF NATURAL SELECTION -

1.       INDUSTRIAL MELANISM -

  • First studied by Fischer & Ford (1845) on pepperd moth (Biston betularia) of two types : grey moth (B. betularia betularia) and black moth (B. betularia carbonaria); the black moth population in Britain in (1845) was 1% which by 1895 came to 99%, it was thought that due to industrial pollution the grey moth changed into black. When coal run industries were replaced by electric / petroleum run industries the number of grey moths again increased (also correlated as reverse evolution) as pollution did not eliminate the gene of grey color.
  • As explained by Neo-Darwinians both populations (grey & black) existed together, the environment favoured the one and disfavoured the other at different times resulting into their changed frequency.
  • Bernard Kettlewell (1950) tested this by releasing equal numbers of grey and black moths in both polluted (Birmingham) and unpolluted (Dorset) areas. Later he captured 19% grey and 40% black moths from polluted areas and 12.5% grey and 6% black from unpolluted areas. This indicates the patterns of differential survival of the moths in respectively areas.

2.       SICKLE CELL ANAEMIA -

  • It is a genetic disorder caused by a single base substitution in a gene.
  • The mutated gene changes the normal haemoglobin (HbA) to defective haemoglobin (HbS) and also makes the red blood corpuscles sickle shaped.
  • The persons homozygous for the defective haemoglobin (HbS, HbS) die at an early age. In the heterozygous (HbA, HbS) the cell containing abnormal haemoglobin become sickle-shaped, and unable to bind oxygen efficiently.

3.       BIO-INDICATOR PLANTS & ANIMALS -

  • Plants which are specialized to grow under specific habitual conditions so that their presence in an area can indicate the same.
  • Prosopis eineraria. P. dilensis, Acacai glandulosa. -Underground water
  • Impatiens balsamina - Zinc (Zwar zinc mines, Udaipur)
  • Haplopappus and Astragulus species - Selenium tolerant plant from U.S.A.
  • Agrostis tenuis - On tailing of lead mines in wales, U.K. the variety from normal pasture couldn't survive on Pb-rich soil.
  • Tubifix (Animal) - Pollution in water.

Related Discussions:- Examples of natural selection

Illustrate in detail about the cell, Illustrate in detail about the Cell ...

Illustrate in detail about the Cell The present day study of cells combines many scientific disciplines, like biochemistry, biophysics, genetics, microscopy and physiology. A g

What is manifest squint, What is Manifest Squint (Heterotropia) Manifes...

What is Manifest Squint (Heterotropia) Manifest squint is a deviation of one eye from the normal position when the fusion reflex is present. The subcategories of manifest squin

Disability evaluations after injuries, Disability evaluations after injurie...

Disability evaluations after injuries: (a) Explain the following terms: "duration of disability" and "degree of disability". (b) Explain how degrees of disability after injur

Discuss the evolution of implants in dentistry, Q. Discuss the evolution of...

Q. Discuss the evolution of implants in dentistry? The first use of Implants dates back to 600 A.D. in the Mayan population where intraosseous implantation of animal teeth or t

Explain oral feeding, Oral Feeding This is the preferred and most palat...

Oral Feeding This is the preferred and most palatable method of feeding for meeting the increased nutritional demands of catabolism, it  should be  used as long as possible. If

What are the symptoms of mitral stenosis, Q. What are the Symptoms of Mitra...

Q. What are the Symptoms of Mitral stenosis? The cardinal symptom of mitral stenosis is dyspnoea on exertion. Typically it progresses over a period of years. As the severity in

The first carbon having 2 h atoms, Given a polymer backbone of H-C-C with t...

Given a polymer backbone of H-C-C with the first carbon having 2 H atoms attached and the 2nd carbon with 3 atoms attached, a bond with a water molecule attaches to the left H atom

Explain the numerical taxonomy, Explain the Numerical Taxonomy? Numeric...

Explain the Numerical Taxonomy? Numerical methods in taxonomy are not new. Simple statistical methods like standard deviations, t-tests and chi-squared have been used for sever

What is mucic acid test and its principle, What is Mucic Acid Test and its ...

What is Mucic Acid Test and its principle? This is a specific test for galactose and is given by galactose as well as lactose, which is made up of galactose and glucose. Pr

Express the term - aboral surface, In radially symmetric animals there is n...

In radially symmetric animals there is no posterior, or anterior, right sides to the animal. Rather we refer to two sides of the animal by referring to the location of the mouth. I

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