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

Is it possible x chromosome of women come from father, Is it possible that ...

Is it possible that an X chromosome of a woman can have come from her father? It isn't only possible that an X chromosome of a woman is from her father, it is certain. Each wom

Explain brachial or radial approach, Q. Explain Brachial or Radial Approach...

Q. Explain Brachial or Radial Approach ? This technique involves performing the coronary angiogram through the right brachial artery in the right ante-cubital fossa. Usually a

Homogeneity to the nucleic acid chains, Q. Do the phosphate and the pentose...

Q. Do the phosphate and the pentose groups give heterogeneity or homogeneity to the nucleic acid chains? What about the nitrogen- containing groups? Supported by that, which of tho

Explain the use of benzoates acid, Q. Explain the use of Benzoates acid? ...

Q. Explain the use of Benzoates acid? Benzoic acid, sodium benzoate and the parahydroxy esters (parabens) are used as preservatives. Benzoic acid and its sodium salt, sodium be

What is nucleotides, What is Nucleotides? Nucleotides are the basic b...

What is Nucleotides? Nucleotides are the basic building blocks of nucleic acids. Each nucleotide is composed of a nitrogen base, a 5-carbon sugar called a pentose, and an ass

Explain the types of photoelectric cells, Question 1. State the basic p...

Question 1. State the basic properties of light. Discuss the special features of ultra-microscopy and phase contrast microscopy 2. What are ultrasonic waves? Explain the dif

Why bacteria called extremophiles, Bacteria called extremophiles are able t...

Bacteria called extremophiles are able to grow in hot springs such as Old Faithful at Yellowstone National Park in Wyoming. Do you think that the DNA of extremophiles would have a

Prawn.., Ask question #Minimum 2o pages accepted#

Ask question #Minimum 2o pages accepted#

What is ground meristem in primary growing shoot, What is Ground Meristem i...

What is Ground Meristem in primary growing shoot? The ground meristem produces new cells which ultimately develop into parenchyma cells. The central portion of the primary shoo

Explain the cost utility analysis, Explain the Cost Utility Analysis? C...

Explain the Cost Utility Analysis? Cost utility analysis: Cost utility analysis provides for measurement of health outcomes for a given cost. The health outcomes are measured q

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