Examples of natural selection, Biology

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.
Posted Date: 10/9/2012 1:20:11 AM | Location : United States







Related Discussions:- Examples of natural selection, Assignment Help, Ask Question on Examples of natural selection, Get Answer, Expert's Help, Examples of natural selection Discussions

Write discussion on Examples of natural selection
Your posts are moderated
Related Questions
HYPOTHALAMUS - Hypothalamus develops from the ectoderm of the embryo. Location and Structure. It lies below or inferior to the thalamus. The hypothalamus is connected to t

What organic molecules make up the cell membrane?

Explain Class Oligochaeta - Earthworms in details? This group of annelids includes the earthworms. Oligochaetes live in the soil or in fresh water habitats, and a few inhabit m

BRONCHUS - In thorax trachea is devided in to 2 bronchi that enter into lungs of its own side. Rings present in it. BRONCHIOLES - These are branches of bronchus.

Explain the Dietary Management in Trauma? Trauma As a result of metabolic responses to injury, there is an increase in the energy expenditure. Oxidation of body fat stores take

Pregnancy toxaemia in sheep (twin lamb disease, sleeping ewes disease, pregnancy ketosis). Pregnancy toxaemia is a multifactor disorder of energy metabolism affecting sheep du

What are colonies and societies? Colonies are functional integrated aggregates produced by individuals of the same species. Colonies are often confused with a one individual. E

By the technology development, the price of computer has become lower and lower. For this reason, a majority of family can afford this technology. A large amount of applications so

MECHANISM - 1 .      AURICULAR SYSTOLE - First of all from complete body impure blood comes in R.A. by superior and inferior vena cava or pre and post cavals. Pure blo

Q. How does synaptic transmission between neurons take place? The propagation of the action potential along the axon reaches the region immediately anterior to the presynaptic