Island Biogeography in Hawaii

This is a topic that one could talk about for days and days, so I'll try to bring a really short overview of interesting facts about island biogeography in another set of islands, the Hawaiian islands. This may be the first of several posts as it is interesting to compare island biogeography in different contexts.

1. A comparison in distance. Tasmania is about 160 miles from Australia, a continent of 7 million square miles. Polynesia is over 16 million square miles of unforgiving ocean, and land is just a tiny fraction of that square mileage. The closest land of any type is a tiny 1 sq mi (!!!) island called Johnson Atoll. The nearest land of considerable size, island or non-island, is actually not the Pacific Ocean - it is California, as 2,500 miles. What does extreme isolation do to an island group?

2. 89% of native Hawaiian plants are endemic (found nowhere else).
http://wildlifeofhawaii.com/flowers/category/native-status/native-plants/

3. Hawaii is really, really young. Oahu is only 3-4 million years old. The largest island, Hawaii Island, is only 400,000 years old! Remember, we were talking about when the continents split apart 200,000,000 years ago? Well, the Hawaiian islands only appeared in the last 1/100 of that time frame. In other words, 1/100 of that time frame for other species to get there.
http://www.soest.hawaii.edu/Library/Garcia1.pdf

4. There are some genera (plural of genus) with only one species- monotypic genera. Some of the species in those genera are the rarest plants in the world. One famous example is Kanaloa Kahoolawensis, which was unknown to humanity, only discovered in 1992. Only two individuals were ever discovered in the wild. Think about it - only two of these plants that are not only the only ones of their species on earth, but also the only types of their entire genus on earth. They have no living relatives, anywhere. Now, about 13 individuals of this plant exist, although most only live while grafted onto other plants (the scientists aren't able to get the tree to survive when it is planted directly into the ground). This kind of thing happens because Hawaii is tiny and extremely isolated, so species don't have a lot of space to diversity. If they do, there is no land nearby where relatives can also diversify.
http://en.wikipedia.org/wiki/Kanaloa_kahoolawensis



-Zheng