Evolution is the adaptability of species
through a period of time for surviving in changing environmental
conditions. Two problems with that definition of evolution we have
been using are:
- There are many different mechanisms which results in
evolution, for example natural selection, genetic drift and
mutation. Mutation changes the allelic frequency and
genetic drift occurs due to random fluctuations of any allele in a
gene pool and loss of any allele from a homogeneous gene pool is
called genetic drift whereas natural selection allows the best
fitted genotype to survive in changing environmental conditions and
eliminate the other gennotype which are not fit.
- Evolution follows sequential manner of somatic changes,
genetic changes and reproductive isolation and leads to formation
of new species from ancestral species, this in turn
increases the heterogenisity in the population