According to the book Life by R. Lewis, B. Parker, D. Gaffin, M. Hoefnagels, he categorises these barriers into two main groups namely:
Prezygotic reproductive isolation and
Postzygotic reproductive isolation
Under Prezygotic reproductive isolation he talks about six factors that hinders reproduction in species resulting in speciation.
I. Mechanical isolation- this occurs where the mating organs do not fit.
II. Ecological (habitat) isolation- this comes as a result of the same specie living in different environments hence they cannot meet or mate.
III. Temporal isolation- this is a result of species being sexually active or fertile at different times hence no effective reproduction occurs.
IV. Behavioural isolation- these are the differences in the activities of the species that hinders them to mate.
V. Gametic isolation- in this he talks of the gametes that cannot combine even if the species would have mated hence resulting in speciation over …show more content…
It is checked, monitored and supervised after any environmental change. For example climatical changes or land elevations. This leads to the fight of struggle between the species and eventually becoming adapted to the new places. This changes their character states, needs and even diet which gives the organisms better chances to survive the struggle and change in the environment.
According to the researchers who studied the concept of speciation they all come into agreement that there are four types of speciation that can take place and these are as a result of different conditions as mentioned below in their definitions:
• Allopatric speciation: “this is the classic island speciation. Individuals of species migrate to an island and become isolated from their parent population; natural selection acts to modify the founder population”. This is according to Ernst Mayr.
• Peripatric speciation: this is almost the same with allopatric speciation the difference is that this type of isolation does not have to be necessarily on an island.
• Parapatric speciation: “should a new species come into contact with a new abiding area, natural selection will occur to favor adaptation as according to the new