Saturday, October 4, 2014

Variation within Species with Manmade Selection Pressures


  • How does manmade influences affect the species of cats, doges, mice, weasels, doves, hoopoe, craws, home sparrows and bats in urban areas in Cairo? (It probably has a lesser effects on birds, since they travel even more easily than the other animals. On the same token, trees must be affected the most, since they are immobile.)
  • Pigeons at Siwa and donkeys at Siwa appeared to be much healthier than those in Cairo. They live amongst nature, feed on a healthy natural diet and live in a healthy environment with no air pollution. (Siwa also is in the North West of Egypt, from wear most of the wind comes, and is located at the lowest place in Egypt, almost, which makes it insusceptible to winds blowing off industrial pollution from anywhere.)
  • It is good (for humans) to live away from the direction of wind that brings airborne industrial pollutants. Helwan is one such area where many suffer health issues due to high pollution caused by the presence of cement factories there.


  • Local specialization within species (natural selection in action) has sometimes been driven by manmade ecological forces, especially those of environmental pollution.
  • Dark (melanic) forms peppered moth (Biston betularia) increased in industrial polluted areas in the UK
  • Many populations of peppered moths in the UK were polymorphic: melanic and nonmelanic forms coexisted
  • Transient polymorphism:
    • The dark form of moth increase in the UK
    • The fall in the population of dark peppered moths after pollution was reduced is again a from of transient polymorphism
  • Industrial melanism:
    • Definition: Industrial melanims is the phenomenon in which black or blackish forms of species have come to dominate populations in industrial areas
    • In the dark individuals, a dominant gene is typically responsible for producing an excess of the black pigment melanin
  • Birds preying on peppered moth are those causing natural selection to work, they eat the typical (light colored) moths in industrial places while they prey on the dark ones in pollution free places
  • Sulfur dioxide destroyed most of the moss and lichen on tree trunks on which nonmelanic moths rest thus depriving them from their ability to camouflage
  • Transition from coal to oil and electricity in addition to legislation passed to impose smoke free zones and to reduce industrial emissions of sulfur dioxide in Western Europe and the US caused the frequency of melanic forms of peppered moth to falll back to near pre-industrial levels
Melanic and non-melanic peppered moth
Melanic and non-melanic peppered moth


  1. What manmade factors, other than pollution, can affect selection in species?
  2. How does breeding affect the balance of evolution?
  3. Can manmade interference in any way have a positive effect on populations and communities compared to leaving them without any manmade influence?