Fungi? Question is a bit vague.
Answer:
The answer could be snakes or hawks but snakes is your best bet.
Explanation:
Rabbits eat the grass(the producer) making them the first consumer but the hawks and the snakes can both eat the rabbits making then secondary consumers.
Answer:
Geographical isolation
Explanation:
The formation of new species by a small number of fruit flies colonized each new island. This mechanism is called geographical speciation or allopatric speciation.
The geographical speciation takes place when some members (biological populations) of the same species become isolated due to geographical changes such as mountain building or migration. Due to isolation, the organisms prevents two or more groups from mating with each other on regular basis. The gene flow between them is greatly reduced which eventually causing that formation of new species.
Spell this in english maybe i can help :)