1. In , a population isolated by a geographic barrier becomes a new species as it accumulates changes by natural selection or genetic drift.
2. In , a new species may arise as mating and gene flow are reduced between populations that share the same area.
3. Many plant species have formed by , in which accidents in cell division result in extra sets of chromosomes.
4. Both allopatric speciation and sympatric speciation depend on the establishment of , which prevent(s) gene flow between a new species and its parent species.
5. occur(s) when a species gives rise to many new species after colonizing a region with diverse habitats.

Answer and Explanation:

1. In , a population isolated by a geographic barrier becomes a new species as it accumulates changes by natural selection or genetic drift.

This signifies Allopatric speciation. Selective pressures in the  new  habitats, brings about  morphological, physiological and behavioural changes in the isolated species of organisms  of the new habitats, thus makes them to be different from organisms of the old habitats.thus a new species is formed.

2. A new species may arise as mating and gene flow are reduced between populations that share the same area.

This is sympatric speciation, new species of organisms are produced with no geographical isolation, but rather when the rate of reshuffle of genes is reduced. Polyploidy is one way through which this occurs.

3.. Many plant species have formed by , in which accidents in cell division result in extra sets of chromosomes.

This polyploid speciation.When an organism has more than one complete set of chromosomes in the cell, a result of anomalies in meiotic cell divisions, so that extra set of chromosomes is present in some  gametes cells.The condition is called Polyploid speciation. If two gametes with such polyploid state  mate, they formed a tetraploid which is a new species.

4.4. Both allopatric speciation and sympatric speciation depend on the establishment of , which prevent(s) gene flow between a new species and its parent species.

Reproductive barriers which prevented mating and  gene flow, and therefore developments of different, morphological, behavioural and physiological features, ensures the emergence of new species.

5. occur(s) when a species gives rise to many new species after colonizing a region with diverse habitats.

Adaptive radiation The diversification of organism to new forms,as a results, of exposure to new  environments, with new resources, and new challenges to survive> Thus in order to survive the new challenges bring about phenotypic changes in the  organism, which results in developments of new morphological and physiology  features,and therefore emergence of new species.

Explanation:

population. population is the number of people or animals in a particular place. an example of population is over eight million people living in new york city.

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