We will now look at the other side of that general tree, which is all of the species found in the Indo-Pacific tropics from the coast of Africa over to Hawaii.
We start by looking at sister species, look at the sister species of those two and so on down the tree, what do we find about their color patterns? Well, this is one of those two sister species. This is one that's only found in the outer atolls of the Hawaiian Islands, places like Midway, Laysan, and a few isolated atolls. Its sister species is only found on the high volcanic islands of the Hawaiian Island and you can see that it has a very similar color pattern. Both of them have same sort of general body color. Both of them have opaque white lines and bright purplish blue bands and red bands on the sensory structures in the front and on the gill.
The sister species to these two also has some of these attributes. It has some purple marking but that band is not continuous.
 It has purple gills and purple spots on the sensory organs as opposed to red ones. So, there are some similarities in terms of this. In terms of the distribution of this species, this is a species that's also found only in the Hawaiian Islands. This is the sister species to those three. It is very wide in its distribution. It's not found in the Hawaiian Islands but it's found basically from the coast of Africa to about the Marshall Islands in the central Pacific. So it again, shows some vicariance separation geographically from its sister group which is restricted to the Hawaiian Islands, three different species that are endemic to different portions of the Hawaiian Islands.
So, going back to the examples that Joel was talking about in terms of Australia and separation of different units within that phylogenetic tree, these nudibranchs show some of those same patterns but on a much broader geographic scale. You can see again that there are opaque white lines and that there are other similarities in the color pattern but we're getting farther and farther removed from the condition found in those two sister species that were the highest up in that branching diagram.
|
Narrative Index
BioForum Index
