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

Regeneration and its examples, R E GENER A TIO N - Natural ability...

R E GENER A TIO N - Natural ability of living being to replace worn out parts, to repair damaged parts, to regrow cost off organs & to reform entire body from a small piec

Lead, Le a d It is common cause of poisoning in cattle. Lead poisonin...

Le a d It is common cause of poisoning in cattle. Lead poisoning in other species is limited by reduced accessibility, more selective eating habits, or lower susceptibility.

Which of structures is the nuclear membrane composed, Q. which of structure...

Q. which of structures is the nuclear membrane composed? Eukaryotic cells have nucleus delimited with two juxtaposed membranes that continue with the membrane of the endoplasmi

Ecosystem diversity, Ecosystem diversity measures based on the species com...

Ecosystem diversity measures based on the species composition of flora, or fauna, or other ecosystem properties, are all equally justifiable: but measures based on different crite

Precursors for gluconeogenesis, Glycerol can act as a substrate for glucose...

Glycerol can act as a substrate for glucose synthesis by conversion to dihydroxyacetone phosphate and an intermediate in gluconeogenesis.  In  order  for citric  acid  cycle pyruva

What is the normal duration of the menstrual cycle, What is the normal dura...

What is the normal duration of the menstrual cycle? How does the calendar contraceptive method work? The normal duration of the menstrual cycle is 28 days but it can vary betwe

Explain tocopherols, Explain Tocopherols These are the most widely dist...

Explain Tocopherols These are the most widely distributed antioxidants in nature, and they constitute the principal antioxidants in vegetable oils.  A relatively high proportio

How b and t cells recognize antigen are true explain, Which of the followin...

Which of the following statements about how B and T cells recognize antigen are true? a. B cells only recognize antigen presented by class I or class II MHC molecules. b. Both cell

TAKHTAJANS classification, comparison between takhtajans and natural classi...

comparison between takhtajans and natural classification

Phylum protozoa, classification of organisms in phylum protozoa according t...

classification of organisms in phylum protozoa according to their class,order,family,genus,species.

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