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

Patient care plan for hypertensives, Q. Patient care plan for hypertensives...

Q. Patient care plan for hypertensives? - Lifestyle changes: Avoiding smoking, use of tobacco, and excess alcohol intake Physical activity like walking, 4 times a week or 40 mi

Dormant vegetative structures, Dormant Vegetative Structures You have ...

Dormant Vegetative Structures You have learnt that light a period of chilling or application of gibberellin often breaks seed dormancy and stimulates seed germination. Vegetat

What property of the dna fragments permits this separation, DNA can be divi...

DNA can be divide into fragments using restriction enzymes.    (a) Outline the technique used to separate these fragments.    (b) What property of the DNA f

What is the use of vitamin a dry powder, Vitamin A dry powder Vitamin A...

Vitamin A dry powder Vitamin A dry powder is used in the (manufacture of dry mixtures) for which the oily ester concentrates are unsuitable or undesirable. Mainly, they are inc

Transport through plasma membrane, TRANSPOR T THROUGH P.M. P.M. regula...

TRANSPOR T THROUGH P.M. P.M. regulates transport of materials in and outside of cell P.M. is semi- permeable as it allows rapid passage to water molecules. P.M. is selectively

Serotonin - enhancement of memory, Q. Serotonin - Enhancement of memory? ...

Q. Serotonin - Enhancement of memory? Increased level of serotonin is implicated in the enhancement of memory. It plays a significant role in classical conditioning wherein sti

Techniques of counselling, Counseling is a process whereby a qualified pers...

Counseling is a process whereby a qualified person purposefully assists another person to handle his or her problems. Counselling is not just giving advice. It is dependent  on mut

Anabolism and catabolism, Anabolism and Catabolism Cellular metabolism...

Anabolism and Catabolism Cellular metabolism  has two aspects 1.      Anabolism  :  This aspect includes metabolic  process  by which  complex  cellular  compounds  are

Steroids, STEROIDS They are a group of tetracyclic lipid derivative...

STEROIDS They are a group of tetracyclic lipid derivatives which have a nucleus of cyclopentano-perhydrophenanthrene  with phenanthrene part made of 3 hexane rings whil

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