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

Clinical manifestations of chronic bronchitis, Clinical Manifestations ...

Clinical Manifestations Early Symptoms Symptoms are episodic in nature or continuous with very little response to bronchodialators. Productive cough especially on awake

Which is utilized by other reactions, The breakdown of ATP releases energy,...

The breakdown of ATP releases energy, which is utilized by other reactions that require energy. Identify other examples where inventions have utilized a similar principle, where en

What is bone modeling, Bone Modeling It is a surface-specific activity ...

Bone Modeling It is a surface-specific activity (apposition or resorption) that produces a net change in the size and/or shape of a bone after initial bone formation in the emb

Define the term - peroxisomes and glyoxisomes, Peroxisomes and Glyoxisomes ...

Peroxisomes and Glyoxisomes A number of metabolic reactions, such as, the oxidation of amino acids and lipids result in the production of hydrogen peroxide. As hydrogen peroxid

Structure into which follicle is transformed after ovulation, Q. What is th...

Q. What is the structure into which the follicle is transformed after ovulation? What is the importance of that structure in the menstrual cycle? The follicle that released the

Theileriosis, T h e i l e r io s i s It is also referred as t...

T h e i l e r io s i s It is also referred as tropical theileriosis and results in fever, enlargement of superficial lymphnodes, anaemia and jaundice. E tiolo

Explain the feeding 6-12 months infant, Explain the Feeding 6-12 Months Inf...

Explain the Feeding 6-12 Months Infant? As the infant grows older, mother's milk alone is not sufficient to meet his increasing needs. This could be seen in few infants between

Bacterial diseases-sheep and goats, Sheep and goats The disease is rea...

Sheep and goats The disease is readily transmissible to human being from goats, and is known as Malta fever, Mediterranean fever or undulant fever. The chief causal agent is B

Vesicular exanthema, Vesicular exanthema Vesicular exanthema of pigs close...

Vesicular exanthema Vesicular exanthema of pigs closely resembles foot-and-mouth disease in these animals. The virus causing the disease belongs to the genus Calicivirus in the fa

Mycoplasmosis-contagious caprine pleuropneumonia (ccpp), Contagious caprine...

Contagious caprine pleuropneumonia (CCPP) Mycoplasma mycoides subsp. capri (Mmc) is the main causative agent of caprine pleuropneumonia, a serious malady of goats in our countr

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