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

Zoonotic diseases-yellow fever, Yellow fever Yellow fever also known a...

Yellow fever Yellow fever also known as Black Vomit and American plaque is a viral disease primarily of monkeys and transmitted to man by female Aedes mosquitoes. It is caused

Role of private sector in health care - contracting, Role of Private Sector...

Role of Private Sector in Health Care - Contracting The government can transfer some of its work to the private sector by contracting. If the cost of resultant services (inclu

Define primary motor cortex corticospinal interneuron a, Define Primary mot...

Define Primary motor cortex corticospinal interneuron A Primary motor cortex (M1) corticospinal interneuron A that produces action potentials during movements of the big toe of

Determine the importance of calcium in soils, Determine the importance of C...

Determine the importance of Calcium in soils Calcium in soils is usually abundant except in acid soils, which occur in humid areas due to excessive leaching. Deficiency of calc

To study if bacteria grow better where it is warm or cold, To study if bact...

To study if bacteria grow better where it is warm or cold Again inoculate two sterile dishes. Label one 'warm'  and the other 'cold'. Place the 1st dish in a dark warm place an

Endosperm with micropylar and chalazal haustoria, Endosperm with Micropylar...

Endosperm with Micropylar and Chalazal Haustoria Some plants develop haustoria from both micropylar and chalazal ends of endosperm. In Nemophila aggressive haustoria arise fr

Explain puewabilitation programme in details, Explain puewabilitation progr...

Explain puewabilitation programme in details ? Education, counselling, and behavioural interventions are important elements of cardiac rehabilitation. In this guideline, "educ

Action of antibodies against virus and against bacteria, Q. How different a...

Q. How different are the actions of antibodies against virus and against bacteria? Why is the cellular immune response activated in case of chronic viral infection? The antibod

Obelia, whyis it considered to showintermideate grade oforganisation

whyis it considered to showintermideate grade oforganisation

How are the antibodies against the rh factor formed, How are the antibodies...

How are the antibodies against the Rh factor formed? The Anti-Rh antibodies are made by humoral immune response. When the Rh- individual makes contact with the Rh factor this i

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