Correct Answer - Option 1 : 1, 2 and 3
An ecological niche is the role and position a species has in its environment; how it meets its needs for food and shelter, how it survives, and how it reproduces. A species' niche includes all of its interactions with the biotic and abiotic factors of its environment.
Climax ecosystem is an ecological community in which populations of plants or animals remain stable and exist in balance with each other and their environment. A climax community is the final stage of succession, remaining relatively unchanged until destroyed by an event such as fire or human interference.
In the ecotone (a zone of transition between two or more diverse ecological communities) , a mixture of species are found belonging to both ecosystem and often some additional species is found. Often both the number of species and the population density of some of the species are greater in ecotone than in community flagging it. This phenomenon is called edge effect.
Examples:
Edge effect can be seen in coastal zones.
Mangroves vegetation is best example of edge effect. It has rich biological diversity and provide habitat for organisms that can survive in water and on land.
An estuary. Here, there is a constant exchange of fresh and sea water and biodiversity is very high.