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

Basal metabolism and energy expenditure at high altitude, Define Basal Meta...

Define Basal Metabolism and Energy Expenditure at High Altitude? The energy and nutrient requirements depend upon total energy expenditure and metabolic rate of the individual.

Pharmacological management, Once the decision to start drug treatment of hy...

Once the decision to start drug treatment of hypertension is made, the aim should be to provide 24 hour BP control, with agents that would encourage patient adherence. The patient

Explain the major classes of lipids, Explain the major classes of lipids ...

Explain the major classes of lipids The major classes of lipids are simple lipids (acylglycerols and waxes); Compound lipids (glycerophospholipids); Derived lipids (compounds t

Phylum protozoa, what is holozoic, holophytic, saprozoic nutrition

what is holozoic, holophytic, saprozoic nutrition

Illustrate the different types of drug receptor interactions, Problem 1: ...

Problem 1: Briefly describe the different types of parenteral routes of drug administration. Definition of parenteral routes of administration. Show different types of

Explain the health benefits of polyphenols, Explain the Health Benefits of ...

Explain the Health Benefits of Polyphenols ? Various health benefits have been attributed to polyphenols. These include: - anti-microbial - anti-viral - anti-oxidant - hy

Define titrimetric estimation of carbohydrates, Define Titrimetric Estimati...

Define Titrimetric Estimation of Carbohydrates? The Fehling's Soxhlet method is the commonly used method for titrimetric estimation of carbohydrates. In the following section y

Explain the intracellular perfusion fluid, At 1 AM, a healthy squid giant a...

At 1 AM, a healthy squid giant axon is placed in a bath of normal squid physiological extracellular saline and is internally perfused with normal squid intracellular saline.

Platelet, What happens if platelets aren''t present in blood?

What happens if platelets aren''t present in blood?

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