In which of the following groups of organisms is the sympatric speciation most likely to occur?
1. amphibians
2. arthropods
3. plants
4. birds

Jurassic period of the Mesozoic era is characterized by  

In sympatric speciation, reproductive isolation:
1. develops without a geographic barrier
2. develops due to a geographic barrier
3. is due to a change in chromosome number
4. does not lead to development of a barrier to mating

Evolution of life shows that life forms had a trend of moving from:

1. land to water

2. dryland to wet land

3. fresh water to sea water

4. water to land

Viviparity is considered to be more evolved because: