Integrated Principles of Zoology Study Set 3
Quiz 37 :
The reasons why a species may be absent from a region or habitat to which it should adapt well are: • Extinction of the species in that region through hunting or other reasons • The species is prevented from colonizing by other species • There may be barriers to the spread or dispersal of the species • Change in the previous habitat
Vicariance is the separation of a group of organisms by a geographic barrier, resulting in differentiation of the original group into new varieties or species. The geological events which produce such barriers are volcano, earthquakes etc. Dispersal is the movement or expansion of a species into a new area from their places of origin. Animals move into favorable habitats that are geographically adjacent to their places of origin. Dispersal occurs without the interference of nature while Vicariance occurs with the interference of nature. In dispersal, the species migrate or move into better or favorable habitats on their own while in Vicariance the species are separated by force and may or may not be moved to a favorable location.
Alfred Wegener first proposed the theory of continental drift in 1912. The three sources of evidence which convinced geologists that the theory was correct are: • Theory of plate tectonics which supported the hypothesis of drifting continents • The presence of marsupials only in and • The fact that temporary land bridges could serve as pathways for the dispersal of animals to other parts of the world