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

Embryology, what is the full name of Balfour in Balour''s law of cleavage?

what is the full name of Balfour in Balour''s law of cleavage?

Storage excretion, Storage Excretion Many insects exhibit a phenomenon...

Storage Excretion Many insects exhibit a phenomenon known as storage excretion. If excretory products are stored in the body instead of being eliminated, no water is expended

Protein synthesis, Protein Synthesis The central dogma of modern bioche...

Protein Synthesis The central dogma of modern biochemistry is totally based on the coded information holds within deoxyribonucleic acid (DNA). Double stranded DNA is converted

Viral diseases, How do measles and HIV virus affects the bodies organisms

How do measles and HIV virus affects the bodies organisms

What are the dietary principles, The dietary principles underlying the ente...

The dietary principles underlying the enteric diet  include: High calorie High protein High carbohydrate Moderate fat High  fluid Low fibre and soft diet

What is the menstrual cycle, What is the menstrual cycle? The menstrual...

What is the menstrual cycle? The menstrual cycle is the periodic succession of interactions among hormones and the organs of the female reproductive system that, after the star

Nutrition, mode of nutrition in follow animal lizard,bird,grasshopper,rat

mode of nutrition in follow animal lizard,bird,grasshopper,rat

Selective destruction - wildlife, Selective Destruction - Wildlife The...

Selective Destruction - Wildlife The selective destruction of one species of an existing fauna can produce equally unfortunate results. The perfect demonstration of unexpected

Explain the alterations occurring in meat and poultry, Alterations occurrin...

Alterations occurring in meat and poultry Meat, as you already know, is  rich in proteins and contains most of the essential amino acids.  It is also rich in minerals such as c

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