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

Water cycle-hydrological cycle, Water Cycle (Hydrological Cycle) The mo...

Water Cycle (Hydrological Cycle) The movement of water on the earth is continuous and forms many complex inter-related loops (Figure shown below). Cycling of water involves atm

What are dendritic cells, Dendritic Cells a. Are the same as macrophages b....

Dendritic Cells a. Are the same as macrophages b. Bind and digest pathogen proteins c. Secrete immunoglobulin d. All of the above

Planning of nursing care - acute glomerulonephritis, Planning of Nursing Ca...

Planning of Nursing Care   Provide supportive and symptomatic treatment.  Provide bed rest.  Encourage diet restriction,  Implementation  of Nursing Care

202, sizes in some biological systems glucose

sizes in some biological systems glucose

Digestion in coakroach, Awhat is the function of malpigrium tubulessk quest...

Awhat is the function of malpigrium tubulessk question #Minimum 100 words accepted#

What is the leaf cuticle, What is the leaf cuticle? The leaf cuticle is...

What is the leaf cuticle? The leaf cuticle is a thin waxy layer made of cutin and waxes on the outer surface of the leaf epidermis. Its function is to control the cellular tran

Development of nutritional biochemistry, Development of Nutritional Biochem...

Development of Nutritional Biochemistry Nutrition,  in  general, and  particularly nutritional biochemistry, has  traveled a  long way since 1926, when nutrition was first reco

Caryopsis - development of fruit, Caryopsis - Development of Fruit In ...

Caryopsis - Development of Fruit In cereals each carpel has one ovule and therefore the mature fruit has, just one seed. During maturation, very little or no cell divisions ar

Describe the positive end expiratory pressure, Describe the Positive End Ex...

Describe the Positive End Expiratory Pressure (PEEP)? A positive pressure may be applied at the end of the expiratory phase during mechanical ventilation, instead of allowing t

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