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

Secondary egg envelopes, Secondary Egg Envelopes These are secreted b...

Secondary Egg Envelopes These are secreted by oviducts and other accessory parts of genital organs while the egg is passing through them from ovary to the exterior. a) In

What is the auditory tube and its function, Q. What is the auditory tube an...

Q. What is the auditory tube and its function? Auditory tube (Eustachian tube) connects each middle ear to the throat. This tube conducts air between tympanic cavity and outsid

Do bacteria cells have a nucleus, Q. Do bacteria cells have a nucleus? ...

Q. Do bacteria cells have a nucleus? In bacteria the genetic material is dispersed in the cytosol and there is no inner membrane that delimits a nucleus.

Polynephritis in cattle, Polynephritis in cattle Contagious bovine pol...

Polynephritis in cattle Contagious bovine polynephritis is a specific infection of urinary tract of cattle. The causative agent is Corynebacterium renale, a rod shaped gram-po

Describe about the term - neuropsychological assessment, Describe about the...

Describe about the term - Neuropsychological assessment Neuropsychological assessment has its roots in neurology, the branch of medicine that focuses on the nervous system and

What are coacervates, What are coacervates? Coarcervates are small stru...

What are coacervates? Coarcervates are small structures made of the aggregation of organic molecules under water solution. By electrical attraction the molecules join into bigg

How many grams of sodium dodecyl sulfate need, How many grams of sodium dod...

How many grams of sodium dodecyl sulfate (mw = 288.37) would you dissolve in 80mLs of water to make a 20% solution of SDS?

Explain the repair mechanisms of brain, Explain the repair mechanisms of br...

Explain the repair mechanisms of brain Scientists are just beginning to understand how these innate repair mechanisms might be harnessed to treat disease. On leading edge of th

Female reproductive system - ovaries, OVARIES - 2 in number (didelph...

OVARIES - 2 in number (didelphic). White / pinkish. Almond like. 3 cm long, 2 cm wide, 1 cm thick. Lie in the lower part of abdomen attached to dorsal wall by mesovarium.

Define the maxillary tuberosity, Maxillary Tuberosity Incision and refl...

Maxillary Tuberosity Incision and reflection of the mucosa overlying the areas of the maxillary tuberosity and hamular notch when taking impressions for maxillary subperiosteal

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