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

Rna secondary structure, Most  RNA  molecules  are  single-stranded  but  a...

Most  RNA  molecules  are  single-stranded  but  an  RNA  molecule  should  hold regions  that  can  form  complementary   base  pairing  where  the  RNA  strand loops  back  on  i

What is an etiological agent of disease, What is an etiological agent of di...

What is an etiological agent of disease? An etiological agent of disease is the agent that causes the disease. It might be a living being, substance or environmental fact.

What are the limits of pest control, How could knowledge of a pest organism...

How could knowledge of a pest organism's tolerance limits be used in pest control? Pesticides could be developed that make those limits narrower, environmental conditions could

Status of dehydration, The first step should be to determine the status of ...

The first step should be to determine the status of dehydration. We have already talked about the mild, inoderate and severe dehydration. In mild to moderate cases fluid, electroly

Test, which area of the basal nuclei is responsible for controlling appendi...

which area of the basal nuclei is responsible for controlling appendicular muscle tone?

Illustrate the tear flow direction of drainage, Illustrate the tear flow di...

Illustrate the tear flow direction of drainage. Tear Drainage: Tear are drained by the combined action of gravity, capillary action and lid movements (Lacrimal pump)

What do you mean by ganglia, Q. What are ganglia? Neural ganglia or Gan...

Q. What are ganglia? Neural ganglia or Ganglia (singular ganglion) are structures located outside the central nervous system (for instance, beside the spinal column or near vis

What do you know about tricuspid stenosis, Q. What do you know about Tricus...

Q. What do you know about Tricuspid stenosis? It is rare disease, with rheumatic etiology seen in 90 per cent of cases. In patients with rheumatic mitral stenosis only 3-5 per

Coordination and response, Name the two hormones produced by the pancreas a...

Name the two hormones produced by the pancreas ans say in what circumstances, in what way, they adjust the glucose concentration in the blood.

State the important role of microorganisms, State the important role of mic...

State the important role of microorganisms The important role of microorganisms was recognised as early as 1838, when J.B. Boussingeutt a French agricultural chemist observed t

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