Selective pressure - Explain precisely how the interaction between variation and the environment leads to adaptation. Be sure to address both positive and negative selective pressure. Do not use an example; talk about individuals, populations, and species. Solution Natural selection has been a driving force for evolutionary development of all life-forms that exist today. The natural selection indicates and emphasizes that the present or the current life- form or say, species is relatively better and flexible in terms of its fitting and survival in the present environment scenerios. The very basis of this entire phenomenon are some random errors of genetics what we call \"variations\". These genetic variations and the prevalent environment stay mutually intricately related. For a better understanding of environment-variation play let us assume a grit-making mill. Grit is made from big rocks which are then hammered down to final acceptable particle sizes for construction purposes. Hammered rocks resemble a random, unsorted mixture of all particle sizes of rock. Then, this mixtute is passed through a mesh of a desired opening size. Only particles of right size are allowed to pass the mesh leaving rest on the mesh. The above example can directly be related to any species living in a locality under certain environment. The VARIATIONS are random which are campared with \"random grit particles before the mesh\" and the ENVIRONMENT acts like the \"mesh\" in the analogy given above. In the above analogy, the mesh acted as a screening device which allowed a proper and DESIRED type of particles out. The same happens with the variation-environment interaction wherein only adapted individuals passes to the next level in evolutionary development. In a nutshell, the frequencies of the variations with favorable characters would be enhanced in the population. Thus selected group of individuals make a new population with advance adaptations to thrive in the new environment. This is everlasting and steady phenomena..

1. Selective pressure - Explain precisely how the interaction between variation and the
environment leads to adaptation. Be sure to address both positive and negative selective pressure.
Do not use an example; talk about individuals, populations, and species.
Solution
Natural selection has been a driving force for evolutionary development of all life-forms that
exist today. The natural selection indicates and emphasizes that the present or the current life-
form or say, species is relatively better and flexible in terms of its fitting and survival in the
present environment scenerios. The very basis of this entire phenomenon are some random errors
of genetics what we call "variations". These genetic variations and the prevalent environment
stay mutually intricately related.
For a better understanding of environment-variation play let us assume a grit-making mill. Grit is
made from big rocks which are then hammered down to final acceptable particle sizes for
construction purposes.
Hammered rocks resemble a random, unsorted mixture of all particle sizes of rock. Then, this
mixtute is passed through a mesh of a desired opening size.
Only particles of right size are allowed to pass the mesh leaving rest on the mesh.
The above example can directly be related to any species living in a locality under certain
environment. The VARIATIONS are random which are campared with "random grit particles
before the mesh" and the ENVIRONMENT acts like the "mesh" in the analogy given above.
In the above analogy, the mesh acted as a screening device which allowed a proper and
DESIRED type of particles out. The same happens with the variation-environment interaction
wherein only adapted individuals passes to the next level in evolutionary development. In a
nutshell, the frequencies of the variations with favorable characters would be enhanced in the
population. Thus selected group of individuals make a new population with advance adaptations
to thrive in the new environment. This is everlasting and steady phenomena.