a)Ecological succession is the change in the structure of a biological community over a period of time. This time can vary from years to decades. There are two types of ecological succession:
1.Primary Succession: It occurs in areas which are basically lifeless such as bare rocks, glaciers and lava etc.
2.Secondary Succession: It occurs in area which already had an established ecosystem such as forest etc. which are destroyed by natural calamities like fire, hurricane and is changed to an ecology having lesser number of species.
b) Xerach Succession: This succession takes place in dry regions; phytoplanktons are replaced by free floating angiosperms which further invade grasses and trees.
Hydrach Succession: This succession takes place in wet areas, Lichens are the pioneer species, which are then invaded by bryophytes.
In both the successions a stable community is formed.
1. Orchid Ophrys uses sexual deceit to attract the female bees.
2. In such case one of the petals of the flower resembles the female bee in size, color and markings.
3.The male bee gets attracted to it, as it resembles the female bee.
4. After which it pseudocoputes with the flower in turn of which the male bee dusts pollen on the flower.
5. When the male bee sits on another flower, to pseudocopulate , the male bee dusts the flower with pollen and pollinates it.
a) Loss of biodiversity affects :
1. Overexploitation of resources such as land, water, mineral etc leads to their unavailability for humans in the future. For example shrimp farming in Ecuador, Thailand and India is causing wetland destruction.
2. Habitat destruction takes place which is due to increased urbanization, industrialization, deforestation and fire etc.
b) Two causes of biodiversity loss are:
1. Overexploitation for commercialization:
The overexploitation of resources has led to extensive use of land, water and other such resources. Which are decreasing these resources to such an extent that we are constantly losing the habitat For example: shrimp farming in India is decreasing it’s habitat.
2. Pollution: Day by day increase in the air, water, land pollution is leading to various harmful effects, not only to the mankind but also to other life forms on the planet for example: use of fertilizers and pesticides are harming the life forms and the soil as these pesticides goes deep into the soil.
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