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

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 radiological anatomy, Q. Define Radiological anatomy? The border...

Q. Define Radiological anatomy? The borders of the mediastinum on the CXR are defined by the contrast produced by adjacent air filled lung. Postero-Anterior View It in

Are the alleles of a gene essentially originated, Are the alleles of a gene...

Are the alleles of a gene essentially originated one from the father and the other from the mother? Are there exceptions? It is natural so that alleles have come one from the m

Whta is the effect of processing on mineral content of foods, Effect of pro...

Effect of processing on mineral content of foods Minerals are comparatively stable under processing conditions such as heat, light, use of oxidizing agents and extremes in pH.

Explain the flow phase of stress response, Explain the Flow Phase of Stress...

Explain the Flow Phase of Stress Response? This is a neuro-endocrine response to physiological stress following the ebb phase. This phase is characterized by: Normal or

Describe how the various molecular mechanisms act, 1. Using specific exampl...

1. Using specific examples describe how variations in DNA sequence between individuals can lead to risk of disease. Describe how a range of techniques have been adapted to detect s

Explain requirements and recommended dietary intake, Explain Requirements a...

Explain Requirements and Recommended Dietary Intake? A very small daily intake of vitamin C (10-15 mg/day for an adult) is required to avoid deficiency and stave off scurvy. Ho

Explain significance of mitosis for embryonic development, Q. What is the s...

Q. What is the significance of mitosis for the embryonic development? Every embryo grows from a single cell that bears mitosis and generates other cells that also divide themse

Could this be accomplished by passive diffusion, In the human body, the pot...

In the human body, the potassium ion can pass easily through cell membranes, yet the potassium ion concentration is higher inside many cells than it is outside these cells. Could t

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.

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