2. What kind of speciation do we normally associate with members of a population that become ecologically, genetically or behaviorally distinct within that population such that they become reproductively isolated? 3. Explain which force of evolution is seen here by a hybrid bird landing on an island that is not its home and breeding with the indigenous population.
4. Explain which force of evolution randomly chooses an individual from a larger gene pool to form a new, smaller population with less genetic variety.

estuaries are the partially enclosed coastal bodies of brackish water formed at the mouth of sea where river meets an ocean. it is a transition zone between river and sea water so estuaries are influenced to both marine environment such as tides, waves and to riverine such as flow of fresh water and sediments. the mixing of sea and fresh water provide high level of nutrients, making estuaries a high product habitats.

many estuaries suffers degradation from a variety of human activities like erosion from deforestation, overgrazing, overfishing, drainage and eutrophication.

so from the above statement answers will be

1. false as estuaries are formed due to both brackish and freshwater.

2.true, due to high productivity estuaries are breeding ground for many marine species.

3. direct and indirect activities of man that contribute to pollution and deposition of sediments.

1. is geographic distribution

2 is increasing complexity

3 is transitional forms