v populations may be evolved. v In addition to

v Macroevolution is the evolution of the organism in macro level. It will
lead to the development of new adaptive trait which
in turn leads to the formation of new group of organisms which results in the
formation of new

v Macroevolution operates at species level or
above the species level.

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v It will spilt the population into
groups and each of the groups will adapt themselves as a result of it new species will form. This kind of Evolution is known as Adaptive

v Speciation is the formation of the
new species. It is an important aspect of Macroevolution. The following are the
two major types of speciation. They are

Ø Allopatric Speciation

Ø Sympatric Speciation

v Allopatric speciation-When two related population occupy two different
geographical areas it is known as Allopatric Species. The evolution of allopatric
population into two separate species is known as Allopatric speciation.

v It is mainly due to

Ø Geographical Isolation-The isolation of two species due to Geographical Barriers
such as mountain, river, sea, etc.,

Ø Reproductive Isolation-The isolation of organisms due to Reproductive barriers. It

ü Extrinsic- external factors

ü Intrinsic factors-Mechanical , Ecological, Temporal, Behavioural, Gametic
Isolation, Hybrid inviability, etc.,

v Sympatric speciation-Related population remain side by side but it is isolated by
intrinsic mechanism not geographical isolation. They will evolve into two
different species.

v Among the members of the sympatric
population there will be a competition for food, space, etc.,

v In the competition one population may
themselves for survival. They may change their diet pattern, they may change
their habitat and they may migrate to other places.

v As a result, of these changes two
different populations may be evolved.

v In addition to these, other factors
like mutation,
Polyploidy and hybridization may
also contribute to speciation.

Thus macroevolution leads to the formation of new species.