AboutWalter Hintz Expertise Science teacher for over 50 years. MSc. in biology. I can answer questions in general biology, zoology, botany, anatomy and physiology and biochemistry.
Experience I have a MSc in biology and have been a science teacher for over 50 years. At present I am a faculty member at a college and a science consultant at seven catholic schools.
Publications The Ohio journal of Science
Momentum-The Journal of the Catholic Education Association
Question Why do you suppose there are so many endemic species on islands? Why have the overwhelming majority of recent extinctions occurred on islands?
Answer Hi Kim:
Isolation is a common factor in speciation since there is little interplay in the gene pool. The Galapagos Islands are a good example. Almost all animals there are found only there. Consider the iguanas for example. They descended from the Green Iguanas that were rafted from Central America. Environmental factors on the islands led to the evovling of two separate species: the land iguana that eats cactus and the marine iguana that feeds on water plants.
I am unaware of recent extinctions on islands but even the slightest change of the environment on an island can cause death because the conditions under which the animals exist are limited and there is no input of new DNA due to the isolation Again returning to the Galapagos. An El Nino in the late 1980s caused a slight rise in the water temperature that killed the plants upon which the marine iguanas feed. Since the biodiversity of water plants is low they eat nothing else so there was a mass starvation. If the temperature had not changed they would have become extinct. The huge Galapagos tortoise is probably going to become extinct basically because their eggs are destroyed by rodents.
